Dear Constant Readers,
I really avoid re-hashing news articles as much as possible; but occasionally something comes along that I feel strongly prompted to write about. After seeing a recent online article in National Geographic and the Science article it was based on, I knew I had to comment on the subject. The subject in question are freshwater "Megafishes": 20 unrelated species over 2 meters in length and/or 100 kilograms in weight. The Nat. Geo. article colorfully refers to them as the "real-life Loch Ness monsters and Bigfoots of the aquatic world", which isn't too much of a hyperbole. Not being charismatic megafauna like pandas; many of these species are poorly known and could possibly be nearing extinction. For those that didn't click the link, it focuses on the 3-year multi-continental research project by Zeb Hogan which hopes to address this dire situation. I laud the articles and the research bringing attention to and trying to remedy this mess.
I do have a gripe with these articles (preliminary though they are) and it is that even they fall prey to the traditional "big fish" exaggerations. No matter how big or interesting a species is, there are always poorly supported and widely reproduced claims of far larger sizes. Though I am probably just a stickler for this sort of thing; I think factual accuracy is of vital importance in order for this to be taken quite seriously. If something as basic as size is wrong, then what do we know about Megafishes?
I was originally planning to do a review of some of the more interesting species of Megafishes, but it was beginning to get rather cluttered. So, I will split the Megafishes up into installments. I will not be able to cover all of them, but I hope to get the most interesting a vital information put up. Who knows, perhaps in the Honkin' Big Animals grand finale you'll see them all together...
What do we know about Chinese Paddlefish?
Psephurus gladius
Chinese Paddlefish
Chinese Swordfish
Elephant fish
Psephurus is a large fish placed in the order Acipenseriformes along with a related American species of paddlefish and 21 species of sturgeon. Although they have cartilaginous skeletons, as you can see from this cladogram they are actually fairly basal "bony fishes". Palaeos.com's entry on this group gives a great deal of information on their strange anatomy and evolutionary development. But perhaps the most important thing to know about this group is that most members are threatened and this has been called an "endangered order" (Artyukhin, 2006).
Information on this species appears to be mostly found in China, making research rather difficult. A paper (more like a note) by Chenchan & Zeng provides a decent amount of information. Unlike the planktivorous American paddlefish, Psephurus is a strong-swimming predator of small to medium size fish as well as shrimp and crabs. This fish is commonly said to be known from the Yangtze river and tributaries, but is also known from the unconnected Qiantang and Yangjian rivers. It apparently has been known to live in the Yellow river as well (Fan, 2006). Despite being called a freshwater fish (e.g. by Science), this species was apparently capable of living in the East China and Yellow seas. I can't help but wonder if the American paddlefish is also capable of being anadromous, as sturgeons are as well.
A controversial matter is exactly how big this fish can get. There have been no length/weight before Chenchan & Zeng in 1988. They measured 46 yearlings (12 - 46 cm) from '74 to '75 and strongly correlated them with larger individuals (1 - 1.54 m). I'll be using their measurement of a 1 m fish weighting 3.3 kg as a benchmark for future estimations. To test this: a recent powerpoint gives a figure of a 3.3 m/117 kg specimen, which I predict will weigh (3.3/1)^3 x 3.3 kg = 118.6 kg, a very close approximation. Why do this? Well, Nat. Geo./Science state the maximum size is 7 m and 500 kg, whereas I predict ~1.1 tonnes. Hmm. Chenchan & Zeng mention a size of over 7 m in papers from the 30's and 40's. Curious. Fishbase reveals that these measurements came from different sources and one "Paxton" (none other than Charles Paxton?) regards these sizes as dubious. However, their measurement of 3 m and 300 kg is considerably heavier than predicted (~90 kg) and thus suspect. The powerpoint by Qiwei Wei unambiguously demonstrates that the fish can reach over 3.5 meters and presumably 140+ kg (they estimated 220 kg). So while not strictly a freshwater fish and maybe not a 7-meter leviathan, this is still a very big and interesting species. But also in a lot of trouble.
Chenchan & Zeng note that specimens over 100 kg were quite rare in the 70's, making the Yibin specimen rather impressive. A 1995 conference found the situation grim for Acipenseriformes in Eurasia, noting that now only a few adult paddlefish were seen annually. So how could it go from 25 tonnes caught a year to just a few individuals seen? Despite it being listed as a protected animal since 1989, the creation of hydroelectric dams has cut off access to spawning grounds and the species has thus lost many valuable resources (Fan, 2006). Even effects such as cooler water in deep places negatively affects spawning and individual growth (Fan again). This is not to mention poaching (this species carries caviar), boat traffic, and pollution and their negative effects. What makes the aforementioned Yibin specimen all the more remarkable is that as of 2003, it has been the last captured paddlefish (Fan, 2006 & Science). While Science speculates that there probably are other specimens swimming around, the species could very well be beyond saving. There was a recent report of a captured paddlefish, but it was in fact a sturgeon, see here for info (and rare pictures).
I hope that Zeb Hogan and affiliated researchers turn up some sort of pocket population, but it looks like we'll have to say goodbye to old Psephurus. And what a shame that is, before we could ever really learn anything about this fish. Hopefully this could be an example of what to avoid in the future with other Megafish.
-Cameron
References:
Artyukhin, Evgenii. 2006. Morphological Phylogeny of the Order Acipenseriformes. Journal of Applied Ichthyology. 22 (Suppl. 1) 66-69. Available: Here
Chenchan, Liu & Yongjun, Zeng. 1988. Notes on the Chinese Paddlefish, Psephurus gladius (Martens). Copeia. Volume 1988, 482-484. Available: Here
Fan, Xiang-guo. 2006. A review of the concervation issues in the upper Yangtze River - a last big challenge: Can Chinese paddlefish, Dabry's sturgeon, and other fish be saved? Journal of Applied Ichthyology. 22 (Suppl. 1) 32-39.
Stone, Richard. 2007. The Last of the Leviathans. Science. 316, 1684-1688. Available: Here
Tuesday, July 31, 2007
Wednesday, July 25, 2007
Corked Fangs: Giant Hypercarnivores or Big Omnivores?
Dear Constant Readers,
I've been entertaining the idea of some sort of trivia point system (to be awarded upon meeting in person) for this blog. Maybe I'll appoint someone to an arbitrary position of sorts somewhere along the line. If somebody is able to identify this reference and the non-mammalian amniote rendered a warning via being "corked", those will be some big points. If a screenshot is provided, that is a near-guarantee of becoming an Internet hero.
On an actual topic: after the last post I've realized that trying to do a somewhat comprehensive overview can become rather difficult when the group is seldom written upon. I like to put up information that is fairly uncommon, but also controversial and ergo with enough information to write upon. This particular post will focus on so-called giant mammalian predators and if they are actually just big omnivores.
And no, this will not count as my conclusion to the "Honkin' Big Animals" trilogy (last seen here and here).
The biggest extant land-based mammalian hypercarnivore (a near-exclusive vertebrate predator) is the Siberian tiger Panthera tigris altaica which averages 250-260 kg/551-573 lbs (Wood, 1982) for males (all these sizes are presumably the larger males). The largest cited size is 320 kg/700 lbs (Sorkin 2005, Christiansen & Harris 2005---fig. 5) and reports of larger sizes are probably due to abnormally fat individuals and/or exaggeration (Wood, 1982). The Pleistocene saber-toothed cat Smilodon populator ranged from around 240 to 360 kg (~500 to 800 lbs) and perhaps over 400 kg (~900 lbs +) for "record" specimens (Christiansen & Harris 2005). I should note that the same source states that the American lion Panthera atrox / Panthera leo atrox was a rival for the largest feline, although an earlier paper (Christiansen 1999) gives the weight as 500 kg (1100 lbs). This is even bigger than unnatural ligers and really big claims around that size (see "Nook") are probably of overweight cats. The cat-like ecomorph is of course undoubtedly hypercarnivorous with more than 70% vertebrate prey (Van Valkenburgh, 2007) and, though extreme, I haven't seen any major revisions to the sizes proposed. So those are two giant hypercarnivores definitely not in danger of being reclassified as omnivores. Judging by proportionate changes in energy expended in capturing prey to energy intake, Carbone et al 2007 estimate the largest carnivorous mammals could get up to 1.1 tonnes (2400 lbs). So are there predators that exceed these super-felines? Can they reach the hypothetical size?
To answer the first question, yes, there are extant near-exclusive faunivores that are alive today. Polar bears are some really big animals. Despite their hypercarnivorous diet, the dentition of the bears differs little from their omnivorous relatives (Van Valkenburgh, 2007), but their poorly developed carnassials (for shearing) are explained because of their blubber eating habits (Sorkin, 2006). Polar bears are larger than other bear species and have been weighed at 654 kg (1440 lbs) and estimated up to 800 kg (1760 lbs) for individuals too large to be weighed (Schliebe et al 2006). There have been claims of gargantuan individuals up to a metric tonne (2210 pounds) and standing 11'1"/3.39 m tall (Wood, 1982) (non-obese?) which of course is seen as needing verification (Christiansen 1999). Mentioned by Bjvrn Kurtin were the remains of (Ursus maritimus tyrannus), a sub-species of polar bear "greatly exceeding" the living polar bear in size. A post (in German - poorly translated here) by Markus Bühler has a size comparison of a huge bear 6' (1.82 m) at the shoulder and presumably in the area of a ton (900 kg) or more. This sub-species seems incredibly obscure (not mentioned in any recent .pdf) and I can't help but wonder if somebody downsized it and I didn't notice (unlikely) or if it hadn't adapted towards being a complete faunivore (possible). There is of course the possibility that this was the species that straddled the 1.1 tonne limit hypothesized by Carbone et al and was presumably the largest hypercarnivorous mammal ever. This is all speculation of course until better remains and/or a study is released.
Enter: Arctodus
According to good ol' Wikipedia and other popular sources "The Giant Short Faced Bear was arguably in its heyday the largest true terrestrial mammalian predator on Earth" and estimates a size of 900 kg/1 ton and a height of 5.5 feet/1.67 m at the shoulder. Note: the statement of "true terrestrial" which appears to exclude the polar bear in a weaselly sort of way. But still, a predator that sized that lived as recently as 11,000 years ago and presumably interacted with humans is most remarkable indeed! The 900 kg figure is high, according to Christiansen 1999, previous studies pegged it at 470-766 kilograms (1000-1700 lbs), the smaller values being based on body size and the larger figures based on limb bone dimensions. The theory for the bones is that since of course they support the mass of the animal, their dimensions can provide a clue as to how much it weighed. The estimates ranged in the 6-800 kg range (1300-1750 lbs) although it was hypothesized that outsized individuals could weight a tonne (2204 lbs)! As for the anatomy of the animal, Christiansen said that Arctodus had a short and broad cat-like skull, well-developed carnassials, long limbs with a possible "more digitigrade" stance, and presumably a fast running speed. Van Valkenburgh notes that the dentition is not distinguishable from omnivorous bears (like the polar bear), which contradicts the "well-developed carnassials" assertion. The Carbone et al 2007 paper that hypothesized a 1.1 tonne carnivore cited Christiansen's study, but gave a figure of 800 kg - 1000 kg as the size for Arctodus! The abstract also states that Arctodus reached about twice the mass of a polar bear!! A paper discussing controversies as to whether Arctodus was carnivorous or not was dismissed by stating that "ancient bears had morphological similarities to the carnivorous polar bear"!!! I have a dangerous lack of credentials, but these very, um, interesting, statements certainly do need looking in to.
Enter: Agriotherium
Sorkin's controversial 2006 paper on Arctodus and Agriotherium certainly does have a lot of interesting things to say, and it is such a shame the popular press didn't cover it. What is astounding is that Agriotherium is a convergence upon the Arctodus bauplan (e.g. short skull, long limbs, very large size, cranial and dental features); this particular species seems hardly mentioned in the "largest hypercarnivore" discussions for unclear reasons. Also worthy of note are the alternate theories that the short-faced bears were largely herbivorous or carnivores that scavenged; these theories seem to be ignored in popular media in light of the more exciting "1 ton superpredator" theory. Sorkin re-interprets the size of the bears at 540 kg/1200 lbs for Agriotherium and 570 kg/1250 lbs for Arctodus, a full 40% lower than Christiansen's maximum estimate. But is this plausible? If a polar bear 6' at the shoulder theoretically weighs about a ton, then I suppose it would be reasonable for a short-faced bear 5'6" at the shoulder with long legs to weigh about 3/5 of that. They certainly didn't use my reasoning. Criticisms of Christiansen's method revolve around using a width/length ratio for limb bones of an animal with disproportionately long limbs. While the limbs were longer, the authors reasoned that they were proportionately slimmer than that of a brown bear and probably actually weighed the same in proportion. This assumption of isometry was used to estimate weight using the skull length of other species vs. weight. I will admit their reasoning is confusing to me (more lightly muscled limbs yet wider humerus and femur proportionately?) and I generally find estimations based on the whole body (e.g. models) to be the most convincing. But I still think their estimate is more realistic and not totally unprecedented.
Aside from sheer size, the paper focused a great deal on the, well, ecology and morphology. The relative grinding area (RGA) was calculated by the differing proportion of the molar used for slicing rather than for grinding. Their value is more suggestive of a more carnivorous animal, except that the value is similar to the herbivorous spectacled bear (Tremarctos). Sectorial carnassials and the position of the mandibular condyle were also interpreted as being from a carnivorous animal, but these features are also shared with the spectacled bear. Prominent buccal cusps are shared with the largely herbivorous Kodiak bear (U. a. middendorfi). The most prominent arguments for carnivory are molecular are large amounts of the isotope 15N. However, the amount of this isotope in the animal's bone collagen overlaps with omnivorous brown bears (the 13C did as well) making it apparent that the tests are inadequate to distinguish diets. These findings are fairly neutral, but there are features suggesting it wasn't a predator. The upper canines are proportionately short, the eyes were small and more laterally placed (than felines), limbs were ill-suited to subduing prey, they were unable to accelerate from a crouching position, they had a spine more suggestive of a slower animal, plantigrade feet were present (contra: Christiansen), and other reasons. This is an interesting and I think, fairly convincing, pile of evidence against a giant feline-like bear. I should note that Arctodus lived alongside the giant felines previously mentioned. So what were Arctodus and Agriotherium? The authors criticize the notion that they subsided completely on carrion, but suggested that they also grazed on coarse foliage. As to modern analogies, they suggest instead of a being feline-like, it was hyena like. They specifically linked it to the striped (Hyena) and brown (Parahyena) hyenas which in addition to small prey and carrion often eat large amounts of fruit.
And if you think Sorkin is a habitual fang-corker, a paper he put out later in 2006 written on much the same format proposed that Amphicyon and Ischyrocyon were 550 and 410kg predatory bear-dogs that were the biggest predators in the North American Miocene. Since it is written in much the same format and arrives at opposite conclusions, I think that supports the validity of the short-faced bear paper.
The points raised by the short-faced bear paper are a fascinating new take on this traditional "superpredator", and as far as I can tell the arguments are convincing. Given how people often become attached to the "godzillafication" of animals, I'm sure somebody is going to respond to this. Hopefully there will be some discussions on this, and not strange dismissals. If they are 1 ton superbears, good, if they're not, just as good. The idea of a short-faced bear ecomorph as its own entity is a fascinating concept that I wish I knew more about.
Oh yes, Agriotherium lived in Africa (Arctodus in North America) and Markus Bühler appears to be the first to (half-seriously) connect it to the Nandi Bear. Points for apparently being first to do this (before me anyways).
Exit: Arctodus and Agriotherium
Enter: Andrewsarchus, Megistotherium, and Sarkastodon
Don't worry, the amount of technical literature on these genera are very limited. I'll put them in order from best known to most enigmatic.
Aside from the short-faced bear, the non-carnivoran ungulate (mesonychid) Andrewsarchus is often given the title of "largest terrestrial carnivorous mammal known to have ever existed" such as by Wiki P's. You'll see a number of phenomenal claims on that article suggesting it averaged at 1.5 tonnes and got up to 2, preyed on giant brontotheres and ate their "already dead" carcasses, and had the strongest jaws in a land mammal. Yowza. This is of course rampant Internet speculation masquerading as some sort of authority (I, for one, don't hide who I am). The very first article written about it speculates on an omnivorous diet and estimates a body size of 3.82 m/12'6.5" long and a shoulder height of 1.89 m/6'2"...but alas no body weight estimation. The picture of the skull juxtaposed to that of a brown bear is quite stupendous by the way. Following a hot lead on a website supposedly aimed at children (specifically an ambiguous statement by...dun dun duuuun...Darren Naish) I found a paper on maximal body size for free (here). Animal body size is a fascinating subject in general, and hopefully a big name like Jared Diamond will be enough to convince you to read it. Anyways, it gives a weight of 6-900 kg (1300-2000 lbs) from a personal communication and mentions the ambiguous diet. The skull appears to be the only remain known, so much about this animal is just speculation.
Megistotherium is not a carnivoran either, but a related group known as creodonts. It is another candidate of the "world's largest terrestrial predator", and apparently weighs 880 kg/~2000 lbs (Rasmussen 1989). Wiki estimates "at least" 900 kg of course and predatory behavior, although it mentions the possibility of scavenging. This paper provides further anatomical details. The Rasmussen article says it is indeed conventionally regarded as a big predator, but could very well be an omnivore as well. Naish noted that reconstruction was based on an outdated reconstruction, so there definitely is a need to re-examine it. I should mention an awesome drawing of it here.
Sarkastodon is another creodont (an oxyaenid) which Wik's of course portrays it as a 1 ton predator. Where does that information come from? I've never read that in popular literature; it is conventionally portrayed as an omnivore. The only technical article I could find is from the 30's and only discusses skull anatomy. It is short-faced, but reconstructions show otherwise (basically portraying it as a long-tailed bear). Nothing about the size or presumed diet is discussed, so clearly I'm missing something. But even so, I doubt it would have been very recent or comprehensive. So other than this being a rather big creodont, nothing can really be said.
As you can see, all three of these beasties were fairly poorly known. Were they actually hypercarnivores, or just big omnivores? In the current state of knowledge it can't be known with any degree of certainty. I (or better yet, somebody else) could make an educated guess, but that's all it would be, a guess. Popular media gives the impression that scientists have a definite grasp on everything, but that isn't the case. There is confusion, arguments, and it definitely is a growing process. The more I learn, the more I see how big the gaps in knowledge really are. And knowing that there I things I can never truly learn or even hear about is frustrating in a way. But hey, it's a start.
It certainly doesn't matter how large an animal is; but size attracts attention which means there is likely to be more information. I think that, if presented well, there really is no boring group of animals.
Come up next week, Honkin' Big Animals!
I'm not quite certain if that's a joke or not.
-Cameron
P.S. Here is an illustration of Andrewsarchus and Sarkastodon; the latter is looking extremely creepy in the background I might add.
References:
Same deal.
Burness, Gary P. & Diamond, Jared & Flannery, Timothy. 2001. Dinosaurs, dragons, and dwarfs: The evolution of maximal body size. PNAS, 98: 14518-14523. Available for free here.
Carbone, Chris et al. 2007. The costs of carnivory. PLos Biology. Published for free online: Here
Christiansen, Per. 1999. What size were Arctodus simus and Ursus splenaeus (Carnivora: Ursidae)?. Ann. Zoo. Fennici 36: 93-102. Available for free here.
Christiansen, Per & Harris, John M. 2005. Body size of Smilodon. Journal of Morphology: 266, 369-384. Available: Here
Granger, Walter. 1938. A giant oxyaenid from the upper Eocene of Mongolia. American Museum Novitates. Available for free here
Kurtin, Bjvrn. On Evolution and Fossil Mammals. Pages 185-186. Available (partially) for free: Here
Osborn, Henry Fairfield. 1924. Andrewsarchus, giant mesonychid from Mongolia. American Museum Novitates. 146. Available for free here.
Rasmussen, D. et al. 1989. New Specimens of the Giant Creodont Megistotherium (Hyaenodontidae) from Moghara, Egypt. Journal of Mammalology. Vol 70, 442-447. Available: Here
Schliebe, Scott et al. 2006. Range-wide status review of the polar bear (Ursus maritimus). Available for free here
Sorkin, B. 2006. Ecomorphology of the giant short-faced bears Agriotherium and Arctodus. Historical Biology: 18, 1-20. Available: Here
Sorkin, B. 2006a. Ecomorphology of the giant bear-dogs Amphicyon and Ischyrocyon. Historical Biology: 18, 375-388. Available: Here
Van Valkenburgh, Blaire. 2007. Déjà vu the evolution of feeding morphologies in the Carnivora. Integr. Comp. Biol.: 47, 147-163. Available: Here
Wood, Gerald. Guinness book of Animal Facts and Feats. Guinness Superlatives, Middlesex, 1982.
I've been entertaining the idea of some sort of trivia point system (to be awarded upon meeting in person) for this blog. Maybe I'll appoint someone to an arbitrary position of sorts somewhere along the line. If somebody is able to identify this reference and the non-mammalian amniote rendered a warning via being "corked", those will be some big points. If a screenshot is provided, that is a near-guarantee of becoming an Internet hero.
On an actual topic: after the last post I've realized that trying to do a somewhat comprehensive overview can become rather difficult when the group is seldom written upon. I like to put up information that is fairly uncommon, but also controversial and ergo with enough information to write upon. This particular post will focus on so-called giant mammalian predators and if they are actually just big omnivores.
And no, this will not count as my conclusion to the "Honkin' Big Animals" trilogy (last seen here and here).
The biggest extant land-based mammalian hypercarnivore (a near-exclusive vertebrate predator) is the Siberian tiger Panthera tigris altaica which averages 250-260 kg/551-573 lbs (Wood, 1982) for males (all these sizes are presumably the larger males). The largest cited size is 320 kg/700 lbs (Sorkin 2005, Christiansen & Harris 2005---fig. 5) and reports of larger sizes are probably due to abnormally fat individuals and/or exaggeration (Wood, 1982). The Pleistocene saber-toothed cat Smilodon populator ranged from around 240 to 360 kg (~500 to 800 lbs) and perhaps over 400 kg (~900 lbs +) for "record" specimens (Christiansen & Harris 2005). I should note that the same source states that the American lion Panthera atrox / Panthera leo atrox was a rival for the largest feline, although an earlier paper (Christiansen 1999) gives the weight as 500 kg (1100 lbs). This is even bigger than unnatural ligers and really big claims around that size (see "Nook") are probably of overweight cats. The cat-like ecomorph is of course undoubtedly hypercarnivorous with more than 70% vertebrate prey (Van Valkenburgh, 2007) and, though extreme, I haven't seen any major revisions to the sizes proposed. So those are two giant hypercarnivores definitely not in danger of being reclassified as omnivores. Judging by proportionate changes in energy expended in capturing prey to energy intake, Carbone et al 2007 estimate the largest carnivorous mammals could get up to 1.1 tonnes (2400 lbs). So are there predators that exceed these super-felines? Can they reach the hypothetical size?
To answer the first question, yes, there are extant near-exclusive faunivores that are alive today. Polar bears are some really big animals. Despite their hypercarnivorous diet, the dentition of the bears differs little from their omnivorous relatives (Van Valkenburgh, 2007), but their poorly developed carnassials (for shearing) are explained because of their blubber eating habits (Sorkin, 2006). Polar bears are larger than other bear species and have been weighed at 654 kg (1440 lbs) and estimated up to 800 kg (1760 lbs) for individuals too large to be weighed (Schliebe et al 2006). There have been claims of gargantuan individuals up to a metric tonne (2210 pounds) and standing 11'1"/3.39 m tall (Wood, 1982) (non-obese?) which of course is seen as needing verification (Christiansen 1999). Mentioned by Bjvrn Kurtin were the remains of (Ursus maritimus tyrannus), a sub-species of polar bear "greatly exceeding" the living polar bear in size. A post (in German - poorly translated here) by Markus Bühler has a size comparison of a huge bear 6' (1.82 m) at the shoulder and presumably in the area of a ton (900 kg) or more. This sub-species seems incredibly obscure (not mentioned in any recent .pdf) and I can't help but wonder if somebody downsized it and I didn't notice (unlikely) or if it hadn't adapted towards being a complete faunivore (possible). There is of course the possibility that this was the species that straddled the 1.1 tonne limit hypothesized by Carbone et al and was presumably the largest hypercarnivorous mammal ever. This is all speculation of course until better remains and/or a study is released.
Enter: Arctodus
According to good ol' Wikipedia and other popular sources "The Giant Short Faced Bear was arguably in its heyday the largest true terrestrial mammalian predator on Earth" and estimates a size of 900 kg/1 ton and a height of 5.5 feet/1.67 m at the shoulder. Note: the statement of "true terrestrial" which appears to exclude the polar bear in a weaselly sort of way. But still, a predator that sized that lived as recently as 11,000 years ago and presumably interacted with humans is most remarkable indeed! The 900 kg figure is high, according to Christiansen 1999, previous studies pegged it at 470-766 kilograms (1000-1700 lbs), the smaller values being based on body size and the larger figures based on limb bone dimensions. The theory for the bones is that since of course they support the mass of the animal, their dimensions can provide a clue as to how much it weighed. The estimates ranged in the 6-800 kg range (1300-1750 lbs) although it was hypothesized that outsized individuals could weight a tonne (2204 lbs)! As for the anatomy of the animal, Christiansen said that Arctodus had a short and broad cat-like skull, well-developed carnassials, long limbs with a possible "more digitigrade" stance, and presumably a fast running speed. Van Valkenburgh notes that the dentition is not distinguishable from omnivorous bears (like the polar bear), which contradicts the "well-developed carnassials" assertion. The Carbone et al 2007 paper that hypothesized a 1.1 tonne carnivore cited Christiansen's study, but gave a figure of 800 kg - 1000 kg as the size for Arctodus! The abstract also states that Arctodus reached about twice the mass of a polar bear!! A paper discussing controversies as to whether Arctodus was carnivorous or not was dismissed by stating that "ancient bears had morphological similarities to the carnivorous polar bear"!!! I have a dangerous lack of credentials, but these very, um, interesting, statements certainly do need looking in to.
Enter: Agriotherium
Sorkin's controversial 2006 paper on Arctodus and Agriotherium certainly does have a lot of interesting things to say, and it is such a shame the popular press didn't cover it. What is astounding is that Agriotherium is a convergence upon the Arctodus bauplan (e.g. short skull, long limbs, very large size, cranial and dental features); this particular species seems hardly mentioned in the "largest hypercarnivore" discussions for unclear reasons. Also worthy of note are the alternate theories that the short-faced bears were largely herbivorous or carnivores that scavenged; these theories seem to be ignored in popular media in light of the more exciting "1 ton superpredator" theory. Sorkin re-interprets the size of the bears at 540 kg/1200 lbs for Agriotherium and 570 kg/1250 lbs for Arctodus, a full 40% lower than Christiansen's maximum estimate. But is this plausible? If a polar bear 6' at the shoulder theoretically weighs about a ton, then I suppose it would be reasonable for a short-faced bear 5'6" at the shoulder with long legs to weigh about 3/5 of that. They certainly didn't use my reasoning. Criticisms of Christiansen's method revolve around using a width/length ratio for limb bones of an animal with disproportionately long limbs. While the limbs were longer, the authors reasoned that they were proportionately slimmer than that of a brown bear and probably actually weighed the same in proportion. This assumption of isometry was used to estimate weight using the skull length of other species vs. weight. I will admit their reasoning is confusing to me (more lightly muscled limbs yet wider humerus and femur proportionately?) and I generally find estimations based on the whole body (e.g. models) to be the most convincing. But I still think their estimate is more realistic and not totally unprecedented.
Aside from sheer size, the paper focused a great deal on the, well, ecology and morphology. The relative grinding area (RGA) was calculated by the differing proportion of the molar used for slicing rather than for grinding. Their value is more suggestive of a more carnivorous animal, except that the value is similar to the herbivorous spectacled bear (Tremarctos). Sectorial carnassials and the position of the mandibular condyle were also interpreted as being from a carnivorous animal, but these features are also shared with the spectacled bear. Prominent buccal cusps are shared with the largely herbivorous Kodiak bear (U. a. middendorfi). The most prominent arguments for carnivory are molecular are large amounts of the isotope 15N. However, the amount of this isotope in the animal's bone collagen overlaps with omnivorous brown bears (the 13C did as well) making it apparent that the tests are inadequate to distinguish diets. These findings are fairly neutral, but there are features suggesting it wasn't a predator. The upper canines are proportionately short, the eyes were small and more laterally placed (than felines), limbs were ill-suited to subduing prey, they were unable to accelerate from a crouching position, they had a spine more suggestive of a slower animal, plantigrade feet were present (contra: Christiansen), and other reasons. This is an interesting and I think, fairly convincing, pile of evidence against a giant feline-like bear. I should note that Arctodus lived alongside the giant felines previously mentioned. So what were Arctodus and Agriotherium? The authors criticize the notion that they subsided completely on carrion, but suggested that they also grazed on coarse foliage. As to modern analogies, they suggest instead of a being feline-like, it was hyena like. They specifically linked it to the striped (Hyena) and brown (Parahyena) hyenas which in addition to small prey and carrion often eat large amounts of fruit.
And if you think Sorkin is a habitual fang-corker, a paper he put out later in 2006 written on much the same format proposed that Amphicyon and Ischyrocyon were 550 and 410kg predatory bear-dogs that were the biggest predators in the North American Miocene. Since it is written in much the same format and arrives at opposite conclusions, I think that supports the validity of the short-faced bear paper.
The points raised by the short-faced bear paper are a fascinating new take on this traditional "superpredator", and as far as I can tell the arguments are convincing. Given how people often become attached to the "godzillafication" of animals, I'm sure somebody is going to respond to this. Hopefully there will be some discussions on this, and not strange dismissals. If they are 1 ton superbears, good, if they're not, just as good. The idea of a short-faced bear ecomorph as its own entity is a fascinating concept that I wish I knew more about.
Oh yes, Agriotherium lived in Africa (Arctodus in North America) and Markus Bühler appears to be the first to (half-seriously) connect it to the Nandi Bear. Points for apparently being first to do this (before me anyways).
Exit: Arctodus and Agriotherium
Enter: Andrewsarchus, Megistotherium, and Sarkastodon
Don't worry, the amount of technical literature on these genera are very limited. I'll put them in order from best known to most enigmatic.
Aside from the short-faced bear, the non-carnivoran ungulate (mesonychid) Andrewsarchus is often given the title of "largest terrestrial carnivorous mammal known to have ever existed" such as by Wiki P's. You'll see a number of phenomenal claims on that article suggesting it averaged at 1.5 tonnes and got up to 2, preyed on giant brontotheres and ate their "already dead" carcasses, and had the strongest jaws in a land mammal. Yowza. This is of course rampant Internet speculation masquerading as some sort of authority (I, for one, don't hide who I am). The very first article written about it speculates on an omnivorous diet and estimates a body size of 3.82 m/12'6.5" long and a shoulder height of 1.89 m/6'2"...but alas no body weight estimation. The picture of the skull juxtaposed to that of a brown bear is quite stupendous by the way. Following a hot lead on a website supposedly aimed at children (specifically an ambiguous statement by...dun dun duuuun...Darren Naish) I found a paper on maximal body size for free (here). Animal body size is a fascinating subject in general, and hopefully a big name like Jared Diamond will be enough to convince you to read it. Anyways, it gives a weight of 6-900 kg (1300-2000 lbs) from a personal communication and mentions the ambiguous diet. The skull appears to be the only remain known, so much about this animal is just speculation.
Megistotherium is not a carnivoran either, but a related group known as creodonts. It is another candidate of the "world's largest terrestrial predator", and apparently weighs 880 kg/~2000 lbs (Rasmussen 1989). Wiki estimates "at least" 900 kg of course and predatory behavior, although it mentions the possibility of scavenging. This paper provides further anatomical details. The Rasmussen article says it is indeed conventionally regarded as a big predator, but could very well be an omnivore as well. Naish noted that reconstruction was based on an outdated reconstruction, so there definitely is a need to re-examine it. I should mention an awesome drawing of it here.
Sarkastodon is another creodont (an oxyaenid) which Wik's of course portrays it as a 1 ton predator. Where does that information come from? I've never read that in popular literature; it is conventionally portrayed as an omnivore. The only technical article I could find is from the 30's and only discusses skull anatomy. It is short-faced, but reconstructions show otherwise (basically portraying it as a long-tailed bear). Nothing about the size or presumed diet is discussed, so clearly I'm missing something. But even so, I doubt it would have been very recent or comprehensive. So other than this being a rather big creodont, nothing can really be said.
As you can see, all three of these beasties were fairly poorly known. Were they actually hypercarnivores, or just big omnivores? In the current state of knowledge it can't be known with any degree of certainty. I (or better yet, somebody else) could make an educated guess, but that's all it would be, a guess. Popular media gives the impression that scientists have a definite grasp on everything, but that isn't the case. There is confusion, arguments, and it definitely is a growing process. The more I learn, the more I see how big the gaps in knowledge really are. And knowing that there I things I can never truly learn or even hear about is frustrating in a way. But hey, it's a start.
It certainly doesn't matter how large an animal is; but size attracts attention which means there is likely to be more information. I think that, if presented well, there really is no boring group of animals.
Come up next week, Honkin' Big Animals!
I'm not quite certain if that's a joke or not.
-Cameron
P.S. Here is an illustration of Andrewsarchus and Sarkastodon; the latter is looking extremely creepy in the background I might add.
References:
Same deal.
Burness, Gary P. & Diamond, Jared & Flannery, Timothy. 2001. Dinosaurs, dragons, and dwarfs: The evolution of maximal body size. PNAS, 98: 14518-14523. Available for free here.
Carbone, Chris et al. 2007. The costs of carnivory. PLos Biology. Published for free online: Here
Christiansen, Per. 1999. What size were Arctodus simus and Ursus splenaeus (Carnivora: Ursidae)?. Ann. Zoo. Fennici 36: 93-102. Available for free here.
Christiansen, Per & Harris, John M. 2005. Body size of Smilodon. Journal of Morphology: 266, 369-384. Available: Here
Granger, Walter. 1938. A giant oxyaenid from the upper Eocene of Mongolia. American Museum Novitates. Available for free here
Kurtin, Bjvrn. On Evolution and Fossil Mammals. Pages 185-186. Available (partially) for free: Here
Osborn, Henry Fairfield. 1924. Andrewsarchus, giant mesonychid from Mongolia. American Museum Novitates. 146. Available for free here.
Rasmussen, D. et al. 1989. New Specimens of the Giant Creodont Megistotherium (Hyaenodontidae) from Moghara, Egypt. Journal of Mammalology. Vol 70, 442-447. Available: Here
Schliebe, Scott et al. 2006. Range-wide status review of the polar bear (Ursus maritimus). Available for free here
Sorkin, B. 2006. Ecomorphology of the giant short-faced bears Agriotherium and Arctodus. Historical Biology: 18, 1-20. Available: Here
Sorkin, B. 2006a. Ecomorphology of the giant bear-dogs Amphicyon and Ischyrocyon. Historical Biology: 18, 375-388. Available: Here
Van Valkenburgh, Blaire. 2007. Déjà vu the evolution of feeding morphologies in the Carnivora. Integr. Comp. Biol.: 47, 147-163. Available: Here
Wood, Gerald. Guinness book of Animal Facts and Feats. Guinness Superlatives, Middlesex, 1982.
Sunday, July 22, 2007
The Yellow-Headed Vultures
Dear Constant Readers,
This is not actually new, but an expanded last half of the previous post. It was just getting too cumbersome or "epic" and I think the tone of this is different enough to warrant splitting. I finally did get a good source on these species too, so they won't be as spotty. As always, don't hesitate to correct me on anything.
Contrary to just about everything written about birds, they do not have a rudimentary/absent sense of smell (Beason 2003). Uniquely among aegypiines, cathartids, and probably just about every other avian, members of the genus Cathartes detect the chemical ethanethiol which is produced by rotting corpses. Even fairly close relations such as the black and king vulture conspicuously lack this ability. Additionally, Cathartes cathartids are all large, dark birds with two-toned wings and brightly colored heads.
Cathartes melambrotus
Greater Yellow-Headed Vulture
Forest Vulture
Interestingly, this was by far the last known extant cathartid to be named, all the way back in 1964. The animals themselves were assumed to be a race of C. burrovianus; but differences in size, head color, range and habitat were enough to convincingly make this a distinct species (Amadon, 1977). The IUCN Redlist states that this species inhabits subtropical rain forest and is of least concern despite a downwards population trend. Their range is 6.7 million square kilometers (~2.5 million square miles), which is the smallest of any non-condor cathartid. The population is estimated at 100,000 to 1,000,000 animals, roughly the same as most non-condors excluding turkey vultures. Unfortunately there do not appear to be many recent publications on this species, so I'm going to have to rely on some more popular material.
The book "Raptors of the World" gives this range, about 3-4 million square kilometers/1.1 to 1.5 million square kilometers. Confusingly the IUCN cites this book as a reference, so it is possible new data subsequently came out to support a larger range. The whole of South America is, by the way, about 6.8 million square miles/17.8 million square kilometers. Given that it is common over its range and nearly replaces turkey vultures, Ferguson-Lees and Christie feel the 6-figure estimate is justified. Presumably it is on the lower side of that broad estimate. They also feel that it is potentially threatened with deforestation. The name (which unfortunately hasn't caught on) indicates that this bird is specialized to living in tropical to near-temperate primary forest in lowlands but also some adjacent grasslands. They range vertically from sea level to 1000 meters/3200 feet (normally over 700m) but can be found as high as 2000 meters/6500 feet.
Despite the name, as you can see from this illustration, the heads of these birds are not exclusively yellow, but have a blue crown and blue spot in front of the eyes. The overall coloration of the head varies into yellow-orange with the crown varying into gray and pink. Irises on this species are red. The plumage is black with a variable greenish to purplish tinge. The two-toned underwings of this genus are the least pronounced in this species. This species is similarly sized to the turkey vulture but has wider wings which are held flat or in a slight dihedral and the rocking behavior while soaring is not exhibited. These birds are solitary or travel in pairs, but have been known to roost which turkey vultures, whom they dominate at kills. There is little information known about food and breeding.
I have noticed that some recent movies (Big Fish, Sideways deleted scene) have used this species in lieu of the turkey vulture. Apparently there is some sort of protective law for the native turkey vulture against using it, but not for this species. It was definitely odd to see such an obscure species in major films.
Additionally, this page has some videos, this one has photographs and discusses differences with the lesser yellow-headed vulture.
Cathartes burrovianus
Lesser Yellow-Headed Vulture
Savannah Vulture
According to the IUCN this species is also of "least concern" and occupies a territory of 7.8 million square kilometers (~3 million square miles) of grasslands, wetlands, and degraded former forest. The territory occupied is still much less than most non-condor cathartids. "Raptors" cites a figure of 12 million square kilometers, but estimates that 2/3rds of that is unsuitable and the rest is patchily distributed. Marsh, coastal swamps, mangroves, grasslands, open woodlands, rice fields and urban areas are inhabited, but not forest. It also engages in nomadic wanderings and migrations. Despite all these difficulties in measuring population, the authors still feel it is probably in the 6-figures somewhere. The map included is of course a vast simplification of the distribution:
As one can see from this illustration, "yellow-headed" is a bit of a misnomer for this species. The head ranges from yellow to orange and the neck and crown are sometimes red. The crown and neck can also vary to blue-gray, blue-green, or violet. The wings are two-toned, but the tips are noticeably lighter colored for a member of the genus. Feathers are blackish with a green tinge but wear away into a brown color. An additional field characteristic is that while on land, the wings are held in a way that makes them appear much longer than other Cathartes. Unlike the forest vulture and like the turkey vulture, this species flies with a dihedral and characteristic "rocking". It apparently does not soar as high as the turkey vulture though.
These birds are also solitary, in pairs, or rarely in groups. There was at least one report of hundreds flying in a possible seasonal migration however. As far as food, they tend to avoid large carcasses and go for smaller mammals, reptiles, and amphibians. Given that it often lives in wetlands, dead fish are commonly eaten. Invertebrates, their larvae, and frogs may be eaten alive.
Unlike the forest vulture, this species is believed to have some geographical variation. Individuals increase in size eastwards and southwards and tend to have straw colored primaries. Some authorities treat them as Cathartes burrovianus urubitinga. They have also been seen in more northwestern portions, but this may be due to seasonal migration.
As you can see from this information, there really are a number of uncertainties about these two species. Other cathartids are better known, but this demonstrates how for every common species there seem to be a few neglected ones. This isn't the last we'll hear about cathartids, but who knows what things I'll move on to next...
-Cameron
References:
Some free, some not.
Beason, Robert C. 2003. Through a Bird's Eye - Exploring Avian Sensory Perception. Bird Strike Committee Proceedings. Published online (for free) Here
BirdLife International 2004. Cathartes burrovianus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 18 July 2007.
BirdLife International 2004. Cathartes melambrotus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 18 July 2007.
Ferguson-Lees, James and Christie, David A. Raptors of the World. Houghton Mifflin, New York, 2001.
This is not actually new, but an expanded last half of the previous post. It was just getting too cumbersome or "epic" and I think the tone of this is different enough to warrant splitting. I finally did get a good source on these species too, so they won't be as spotty. As always, don't hesitate to correct me on anything.
Contrary to just about everything written about birds, they do not have a rudimentary/absent sense of smell (Beason 2003). Uniquely among aegypiines, cathartids, and probably just about every other avian, members of the genus Cathartes detect the chemical ethanethiol which is produced by rotting corpses. Even fairly close relations such as the black and king vulture conspicuously lack this ability. Additionally, Cathartes cathartids are all large, dark birds with two-toned wings and brightly colored heads.
Cathartes melambrotus
Greater Yellow-Headed Vulture
Forest Vulture
Interestingly, this was by far the last known extant cathartid to be named, all the way back in 1964. The animals themselves were assumed to be a race of C. burrovianus; but differences in size, head color, range and habitat were enough to convincingly make this a distinct species (Amadon, 1977). The IUCN Redlist states that this species inhabits subtropical rain forest and is of least concern despite a downwards population trend. Their range is 6.7 million square kilometers (~2.5 million square miles), which is the smallest of any non-condor cathartid. The population is estimated at 100,000 to 1,000,000 animals, roughly the same as most non-condors excluding turkey vultures. Unfortunately there do not appear to be many recent publications on this species, so I'm going to have to rely on some more popular material.
The book "Raptors of the World" gives this range, about 3-4 million square kilometers/1.1 to 1.5 million square kilometers. Confusingly the IUCN cites this book as a reference, so it is possible new data subsequently came out to support a larger range. The whole of South America is, by the way, about 6.8 million square miles/17.8 million square kilometers. Given that it is common over its range and nearly replaces turkey vultures, Ferguson-Lees and Christie feel the 6-figure estimate is justified. Presumably it is on the lower side of that broad estimate. They also feel that it is potentially threatened with deforestation. The name (which unfortunately hasn't caught on) indicates that this bird is specialized to living in tropical to near-temperate primary forest in lowlands but also some adjacent grasslands. They range vertically from sea level to 1000 meters/3200 feet (normally over 700m) but can be found as high as 2000 meters/6500 feet.Despite the name, as you can see from this illustration, the heads of these birds are not exclusively yellow, but have a blue crown and blue spot in front of the eyes. The overall coloration of the head varies into yellow-orange with the crown varying into gray and pink. Irises on this species are red. The plumage is black with a variable greenish to purplish tinge. The two-toned underwings of this genus are the least pronounced in this species. This species is similarly sized to the turkey vulture but has wider wings which are held flat or in a slight dihedral and the rocking behavior while soaring is not exhibited. These birds are solitary or travel in pairs, but have been known to roost which turkey vultures, whom they dominate at kills. There is little information known about food and breeding.
I have noticed that some recent movies (Big Fish, Sideways deleted scene) have used this species in lieu of the turkey vulture. Apparently there is some sort of protective law for the native turkey vulture against using it, but not for this species. It was definitely odd to see such an obscure species in major films.
Additionally, this page has some videos, this one has photographs and discusses differences with the lesser yellow-headed vulture.
Cathartes burrovianus
Lesser Yellow-Headed Vulture
Savannah Vulture
According to the IUCN this species is also of "least concern" and occupies a territory of 7.8 million square kilometers (~3 million square miles) of grasslands, wetlands, and degraded former forest. The territory occupied is still much less than most non-condor cathartids. "Raptors" cites a figure of 12 million square kilometers, but estimates that 2/3rds of that is unsuitable and the rest is patchily distributed. Marsh, coastal swamps, mangroves, grasslands, open woodlands, rice fields and urban areas are inhabited, but not forest. It also engages in nomadic wanderings and migrations. Despite all these difficulties in measuring population, the authors still feel it is probably in the 6-figures somewhere. The map included is of course a vast simplification of the distribution:
As one can see from this illustration, "yellow-headed" is a bit of a misnomer for this species. The head ranges from yellow to orange and the neck and crown are sometimes red. The crown and neck can also vary to blue-gray, blue-green, or violet. The wings are two-toned, but the tips are noticeably lighter colored for a member of the genus. Feathers are blackish with a green tinge but wear away into a brown color. An additional field characteristic is that while on land, the wings are held in a way that makes them appear much longer than other Cathartes. Unlike the forest vulture and like the turkey vulture, this species flies with a dihedral and characteristic "rocking". It apparently does not soar as high as the turkey vulture though.
These birds are also solitary, in pairs, or rarely in groups. There was at least one report of hundreds flying in a possible seasonal migration however. As far as food, they tend to avoid large carcasses and go for smaller mammals, reptiles, and amphibians. Given that it often lives in wetlands, dead fish are commonly eaten. Invertebrates, their larvae, and frogs may be eaten alive.
Unlike the forest vulture, this species is believed to have some geographical variation. Individuals increase in size eastwards and southwards and tend to have straw colored primaries. Some authorities treat them as Cathartes burrovianus urubitinga. They have also been seen in more northwestern portions, but this may be due to seasonal migration.
As you can see from this information, there really are a number of uncertainties about these two species. Other cathartids are better known, but this demonstrates how for every common species there seem to be a few neglected ones. This isn't the last we'll hear about cathartids, but who knows what things I'll move on to next...
-Cameron
References:
Some free, some not.
Beason, Robert C. 2003. Through a Bird's Eye - Exploring Avian Sensory Perception. Bird Strike Committee Proceedings. Published online (for free) Here
BirdLife International 2004. Cathartes burrovianus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 18 July 2007.
BirdLife International 2004. Cathartes melambrotus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 18 July 2007.
Ferguson-Lees, James and Christie, David A. Raptors of the World. Houghton Mifflin, New York, 2001.
Wednesday, July 18, 2007
Vulture Mimics: An Introduction to Cathartids
I'll level with you, cathartids actually aren't vulture mimics, vulture originators would technically be more appropriate. Technicalities such as earlier fossil/implied genetic age aside, the "Old World" vultures were known to the West much earlier (obviously) and still remain the by far the most popular conception of what a "vulture" is*. Why is this important do you ask? For instance, ostrich-mimics (ornithomimosaurids) are older than ostriches, but unfortunately they were discovered later and are less familiar. There is even a non-dinosaurian ostrich-mimic-mimic (Effigia) that is even older and less familiar still. While cathartids are often called "New World" vultures, as we'll see that is a very poor name indeed. I won't call them vulture mimics either, that was just a scam to initiate discussion, I'll call them cathartids**. But as we'll see...
*Actually the genus Gyps (Griffin vultures) seems to be the long-necked "vulture" archetype. Ever notice how in cartoons taking place in the American West the vultures are all Griffins? Vultures most certainly are not limited to deserts either, by the way. Aegypiine vultures have some interesting forms and classification controversies, they might get discussed later.
**According to Amadon 1977, at least one authority called the whole group "condors".
Some sources such as Mikko's phylogeny put cathartidae and vulturidae as synonyms. Curiously I've noticed that papers on condors (e.g. Vultur) classify them as vulturids but just about everything else calls them cathartids (e.g. Cathartes aura, the turkey vulture).I suspect vulturidae may be a functional sub-family in most classifications, but I have yet to find a source specifically stating this [Edit: "Vulturid" is a synonym with priority nonetheless. However, it likely that it was named with "old world" vultures in mind. See comments]. The big-picture classification of cathartids is more confusing still. Traditionally they were classified as falconiformes along with the familiar birds of prey. Their overall appearance is similar, although cathartids have odd features such as weak feet and perforate nostrils. The oft-cited Sibley-Ahlquist taxonomy upheaval placed them in the order ciconiiformes along with storks and relatives. To cite something, why not the Turkey Vulture Society page, yep, turkey vultures are more popular than what I'd previously thought. A stork/vulture association isn't as nonsensical as it seems; the shockingly hideous marabou stork is a bald-headed (occasional) scavenger with the same self-urination (the white stuff in bird poop isn't poop) habit of keeping cool. Interestingly, the stork/vulture connection has been suspected as early as 1967 (Fedduccia, 1974). However, it most certainly is yet another vulture-mimic of sorts.
But here's the problem: cathartids aren't ciconiiformes either. Popular literature is often outdated and/or a simplification of controversial issues. As a layman, the world of bird phylogeny seems ludicrously confusing and unsettled. A 2006 paper by Ericson et al places them closer to falconiformes (and near-passerines, apparently) than ciconiiformes, although their split apparently took place slightly before the K/T event. Slack et al in a 2007 paper places them in a super-group called the Cracrafti/Conglomerati, although they are positioned in an unstable area in between the falcon/buzzard, gull/oystercatcher, and albatross/loon/stork/penguin lineages. Another paper by Gibb et al in 2007 again with more species included it the synonymous "water-carnivore" super-group and interestingly placed cathartids closer to the seabirds/shorebirds than anything. However, they are still clearly quite isolated. The phylogenetic trees also demonstrates a surprising distance between falcons and buzzards making falconiformes apparently paraphyletic; and demonstrated storks and pelicans grouping rather than with herons, making the traditional ciconiiformes polyphyletic. With more species getting studied, it seems like birds phylogeny is going to need a radical overhaul. Cathartids are now apparently an incertae sedis, although I have seen a proposal for the creation of the order cathartiformes. I've seen this used in a recent Spanish-language publication (here), although widespread acceptance is lacking.
Despite taxonomic upheavals galore the extinct family teratornithidae is still attached to cathartids in recent publications (e.g. Chatterjee 2007). Mikko's phylogeny page places both groups in an encompassing group called vulturides. Usage of that group appears exceedingly rare in publications and I am not certain if it could be synonymous with cathartiformes or not. Despite traditionally being portrayed as super-condors (such as here) tetatorns are now believed to be predatory and distinctive. Given their size (bigger than even super-marabous) they might just be present in the final post of some trilogy.
Let us now discuss cathartids proper, the extinct ones. The reason I don't call cathartids "New World vultures" is that they were certainly present in the Eocene-Oligocene of Europe. To make matters worse, aegypiine vultures are known from both Old and New Worlds from the lower Miocene to Pleistocene, obscuring their "world" of origin (Fedduccia 1974). That's a tale for another day though. Cracraft & Rich in their 1972 paper discuss how for years possible remains of Old World cathartids were discounted or ignored due to their problematic nature (the vice versa was true as well interestingly). Despite their outwards similarity to aegypiines, cathartids are very distinctive from a skeletal standpoint, particularly the shape of the tarsometatarsus and to a lesser degree the tibiotarsus. They named four genera, one of which (Amphiserpentarius) was apparently re-classified as a secretary bird, but according to Mikko's the rest still stand up. [[Edit: Peer editing has revealed to me that the alleged smallest crow-sized cathartid, Plesiocathartes, is a leptosomid. The paper is unfortunately unavailable to me, but see comments]]. The authors raise the remarkable possibility that cathartids in fact originated in Europe in between the late Cretaceous and Eocene and branched out to the New World in the Early Eocene. This was presented as an alternate hypothesis and not a replacement. I haven't seen much more discussion on this, but it should be noted that they used the non-cathartid Neocathartes in their theory. This was alleged to be a "walking turkey vulture" of sorts, but turned out not to be. Sorry for not being able to find the actual paper for that one.
I hope that this was an adequate prelude to the cathartids. There are still some fossil forms that I'll probably cover some time in the future, but I'd like to talk more about extant species. Perhaps I can do a cathartid-of-the-random-time-interval sort of feature. Or maybe not, I like to focus on obscurity...
Oh, I'm not done just yet.
-Cameron
References:
Some free, some not.
Amadon, Dean. 1977. Note on the Taxonomy of Vultures. The Condor. 79: 413-416. Available: Here
Chatterjee, Sankar & Templin, R. Jack & Campbell, Kenneth E. 2007. The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina. Proceedings of the National Academy of Sciences. Published online (for free) Here
Cracraft, Joel & Rich, Pat Vickers. 1972. The Systematics and Evolution of the Cathartidae in the Old World Tertiary. The Condor. 74: 272-283. Available: Here
Ericson, G.P. et al. 2006. Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters. 2: 543-547. Available: Here
Fedduccia, A. 1974. Another Old World vulture from the New World. Wilson Bull. 86: 251-255. Available online Here (for free)
Gibb, Gillian C. et al. 2007. Mitochondrial Genomes and Avian Phylogeny: Complex Characters and Resolvability without Explosive Radiations. Mol Biol Evol. 24: 269-280. Available: Here
Slack, Kerryn E. et al. 2007. Resolving the root of the avian mitogenomic tree by breaking up long branches. Molecular Phylogenetics and Evolution. 42: 1-14. Available: Here
*Actually the genus Gyps (Griffin vultures) seems to be the long-necked "vulture" archetype. Ever notice how in cartoons taking place in the American West the vultures are all Griffins? Vultures most certainly are not limited to deserts either, by the way. Aegypiine vultures have some interesting forms and classification controversies, they might get discussed later.
**According to Amadon 1977, at least one authority called the whole group "condors".
Some sources such as Mikko's phylogeny put cathartidae and vulturidae as synonyms. Curiously I've noticed that papers on condors (e.g. Vultur) classify them as vulturids but just about everything else calls them cathartids (e.g. Cathartes aura, the turkey vulture).
But here's the problem: cathartids aren't ciconiiformes either. Popular literature is often outdated and/or a simplification of controversial issues. As a layman, the world of bird phylogeny seems ludicrously confusing and unsettled. A 2006 paper by Ericson et al places them closer to falconiformes (and near-passerines, apparently) than ciconiiformes, although their split apparently took place slightly before the K/T event. Slack et al in a 2007 paper places them in a super-group called the Cracrafti/Conglomerati, although they are positioned in an unstable area in between the falcon/buzzard, gull/oystercatcher, and albatross/loon/stork/penguin lineages. Another paper by Gibb et al in 2007 again with more species included it the synonymous "water-carnivore" super-group and interestingly placed cathartids closer to the seabirds/shorebirds than anything. However, they are still clearly quite isolated. The phylogenetic trees also demonstrates a surprising distance between falcons and buzzards making falconiformes apparently paraphyletic; and demonstrated storks and pelicans grouping rather than with herons, making the traditional ciconiiformes polyphyletic. With more species getting studied, it seems like birds phylogeny is going to need a radical overhaul. Cathartids are now apparently an incertae sedis, although I have seen a proposal for the creation of the order cathartiformes. I've seen this used in a recent Spanish-language publication (here), although widespread acceptance is lacking.
Despite taxonomic upheavals galore the extinct family teratornithidae is still attached to cathartids in recent publications (e.g. Chatterjee 2007). Mikko's phylogeny page places both groups in an encompassing group called vulturides. Usage of that group appears exceedingly rare in publications and I am not certain if it could be synonymous with cathartiformes or not. Despite traditionally being portrayed as super-condors (such as here) tetatorns are now believed to be predatory and distinctive. Given their size (bigger than even super-marabous) they might just be present in the final post of some trilogy.
Let us now discuss cathartids proper, the extinct ones. The reason I don't call cathartids "New World vultures" is that they were certainly present in the Eocene-Oligocene of Europe. To make matters worse, aegypiine vultures are known from both Old and New Worlds from the lower Miocene to Pleistocene, obscuring their "world" of origin (Fedduccia 1974). That's a tale for another day though. Cracraft & Rich in their 1972 paper discuss how for years possible remains of Old World cathartids were discounted or ignored due to their problematic nature (the vice versa was true as well interestingly). Despite their outwards similarity to aegypiines, cathartids are very distinctive from a skeletal standpoint, particularly the shape of the tarsometatarsus and to a lesser degree the tibiotarsus. They named four genera, one of which (Amphiserpentarius) was apparently re-classified as a secretary bird, but according to Mikko's the rest still stand up. [[Edit: Peer editing has revealed to me that the alleged smallest crow-sized cathartid, Plesiocathartes, is a leptosomid. The paper is unfortunately unavailable to me, but see comments]]. The authors raise the remarkable possibility that cathartids in fact originated in Europe in between the late Cretaceous and Eocene and branched out to the New World in the Early Eocene. This was presented as an alternate hypothesis and not a replacement. I haven't seen much more discussion on this, but it should be noted that they used the non-cathartid Neocathartes in their theory. This was alleged to be a "walking turkey vulture" of sorts, but turned out not to be. Sorry for not being able to find the actual paper for that one.
I hope that this was an adequate prelude to the cathartids. There are still some fossil forms that I'll probably cover some time in the future, but I'd like to talk more about extant species. Perhaps I can do a cathartid-of-the-random-time-interval sort of feature. Or maybe not, I like to focus on obscurity...
Oh, I'm not done just yet.
-Cameron
References:
Some free, some not.
Amadon, Dean. 1977. Note on the Taxonomy of Vultures. The Condor. 79: 413-416. Available: Here
Chatterjee, Sankar & Templin, R. Jack & Campbell, Kenneth E. 2007. The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina. Proceedings of the National Academy of Sciences. Published online (for free) Here
Cracraft, Joel & Rich, Pat Vickers. 1972. The Systematics and Evolution of the Cathartidae in the Old World Tertiary. The Condor. 74: 272-283. Available: Here
Ericson, G.P. et al. 2006. Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters. 2: 543-547. Available: Here
Fedduccia, A. 1974. Another Old World vulture from the New World. Wilson Bull. 86: 251-255. Available online Here (for free)
Gibb, Gillian C. et al. 2007. Mitochondrial Genomes and Avian Phylogeny: Complex Characters and Resolvability without Explosive Radiations. Mol Biol Evol. 24: 269-280. Available: Here
Slack, Kerryn E. et al. 2007. Resolving the root of the avian mitogenomic tree by breaking up long branches. Molecular Phylogenetics and Evolution. 42: 1-14. Available: Here
Sunday, July 15, 2007
Horrendously Antiquated Illustrations
Dear Constant Readers,
I've always had a fondness for those archaic illustrations done by individuals who speculated on poorly known, extinct, or outright fictional beasties. Having nothing to compare them to and often having less than reliable sources, they imagined them as bizarre monstrosities with inconceivable features. Perhaps one of the most famous was Dürer's Rhinoceros, which is iconic enough to get its own fairly detailed Wikipedia article. Even though it was replaced as the stereotypical image for a rhinoceros in Europe, its likeness was still replicated into modern times. It's a good meme in other words. For those Lord Geekington trivia buffs out there, the Dürer's Horn is my favorite fictional anatomical feature. Re-railing here, these depictions are now often rather silly in an endearing sort of way. Early Science or proto-science was rather preliminary and simple, and we clearly have come a long way. Looking back, I can't help but wonder if some of our reconstructions and beliefs will be looked upon as being rather silly themselves in the future. I could get into posterity but I'll spare you, for now.
I have covered at least one illustration in this vein before: the surreal Cetacean Centipede of Rondelet. You can read the full blog here. This appears to be a chimera of sorts combining a perciform fish, shark, whale, polychaete worm and perhaps lobster. This is almost certainly an obscure mythological animal, although there have been vague and sporadic reports of "sea-serpents" with a plethora of appendages. It is quite possible, but unproven, that the less vague reports were inspired by memories of this image or even hoaxes based upon it. This also reminds me that surrealism-like images from the Medieval/Renaissance periods may get written upon soon enough.
Aquatic animals always seem prone to really odd depictions. This here is an imaginative illustration from Harper's Weekly in 1868. The encircling gill slits, giant mouth and size make it probable this was a basking shark. But, umm, what on earth is up with those mammalian legs that make it look ready to pounce? Did the illustrator imagine this fish bounding majestically along the sea floor? The Stronsay "beast" of six decades earlier was perhaps another instance of fins (and claspers?) getting confused for limbs on a basking shark. The vertebrae size was smaller than (but otherwise identical to) that of an above average 25 foot (7.6 m) basking shark despite the reported length of 55 feet (16.8 m). Thank you Guinness Book of Animal Facts and Feats. This was probably just exaggeration, but there is the remote possibility of some freak basking shark that doubled its vertebral count that somehow lived to maturity.
Mentioned in this not-too-recent post is the Carta Marina of Olaus Magnus. As far as weird and mythological aquatic creatures go, this is their holy grail. You'd better click on this and pray you don't have dialup:
You can spend a lot of time picking out crazy stuff in this map. Judging by the names the "Balena" and "Orcha" are supposed to be extant cetaceans, but you can't really tell by the weird collars, tube-like nostrils, piggish faces, and other really strange features. The "Ziphius" sounds like it could be a beaked whale, but the eagle head doesn't seem quite right. Also of note are people camping out on a big "island fish", what appears to be a devil/pan sweeping a stable, a monster with three eyes on its body, a feathery dragon, and lots of other strange things. Like Dürer's Rhinoceros, this is another one of those really iconic images/memes that symbolizes the time period. I for one miss maps that alert us to potential terrors waiting for us in exotic, far away lands. Also take note trivia buffs: the man's face in the clouds blowing wind is another one of my favorite images.
While Magnus worked in the 15th and 16th centuries, fantastic illustrations continued into the 19th century, my favorite era (for this). I recently came across an amazing flickr album (which prompted this post) on a book called Sea and Land from 1889. Not only are the illustrations fantastic and iconic but they're all in the public domain, making this all the sweeter for me. Due to many of these illustrations being fairly common in the Cryptozoology domain, plus me uncontrollably discussing the subject, I suppose the label is justified. Here are some favorites from this volume:
Crab lifting a goat, hmm. Robber crabs/Coconut crabs are pretty big for crustaceans and utterly colossal for a land arthropod (~9 lbs, ~3 foot span max) but lifting a goat? The appearance does seem accurate, but I'll assume this was based on somebody's crazy story/myth.
As usual, marine creatures, in this case reptiles, are depicted rather oddly. The long-tailed fellow with a puppy-dog expression is a plesiosaur with the head placed on the wrong end. Despite the traditional swan-neck pose which is common even today, plesiosaurs and elasmosaurs could not (and probably had no reason to) assume that position. The ichthyosaurs were also portrayed as being rather crocodile-like as opposed to fish like. An actual marine crocodile does seem fairly reasonable, undoubtedly due to living relatives. The small beaked swimmer in the bottom left-hand corner is something is a mystery to me, perhaps a rhynchosaur erroneously depicted as swimming?
[Correction thanks to Matt Celeskey: The "plesiosaur" is actually a mosasaur, and the beaked creature is actually the turtle Osteopygis. See "comments" for more.]
My favorite depiction of the "Kraken" sinking a ship. This is a wonderfully dark and moody piece, or wait no, dark and disturbing, muhaha. I remember as a much younger Crypto-enthusiast I was tantalized by what appear to be two small fins low on the mantle on this cephalopod. Y'see, there was this theory that the St. Augustine monster was in fact a cirrate octopus. Here is a depiction of "Otoctopus giganteus" from Michael Raynal's Institut Virtuel de Cryptozoologie.
An image supposedly representing the St. Augustine carcass. Both the description and drawing in the Pennsylvania Grit were horrendously naive, more like something out of the middle ages than 1896. It actually is a pretty cool monster design though, I'll have to steal it. The carcass wasn't a cephalopod/fish hybrid or a giant octopus, but in fact a sperm whale. I'll discuss globsters some other day.
I've always had a fondness for those archaic illustrations done by individuals who speculated on poorly known, extinct, or outright fictional beasties. Having nothing to compare them to and often having less than reliable sources, they imagined them as bizarre monstrosities with inconceivable features. Perhaps one of the most famous was Dürer's Rhinoceros, which is iconic enough to get its own fairly detailed Wikipedia article. Even though it was replaced as the stereotypical image for a rhinoceros in Europe, its likeness was still replicated into modern times. It's a good meme in other words. For those Lord Geekington trivia buffs out there, the Dürer's Horn is my favorite fictional anatomical feature. Re-railing here, these depictions are now often rather silly in an endearing sort of way. Early Science or proto-science was rather preliminary and simple, and we clearly have come a long way. Looking back, I can't help but wonder if some of our reconstructions and beliefs will be looked upon as being rather silly themselves in the future. I could get into posterity but I'll spare you, for now.
I have covered at least one illustration in this vein before: the surreal Cetacean Centipede of Rondelet. You can read the full blog here. This appears to be a chimera of sorts combining a perciform fish, shark, whale, polychaete worm and perhaps lobster. This is almost certainly an obscure mythological animal, although there have been vague and sporadic reports of "sea-serpents" with a plethora of appendages. It is quite possible, but unproven, that the less vague reports were inspired by memories of this image or even hoaxes based upon it. This also reminds me that surrealism-like images from the Medieval/Renaissance periods may get written upon soon enough.
Aquatic animals always seem prone to really odd depictions. This here is an imaginative illustration from Harper's Weekly in 1868. The encircling gill slits, giant mouth and size make it probable this was a basking shark. But, umm, what on earth is up with those mammalian legs that make it look ready to pounce? Did the illustrator imagine this fish bounding majestically along the sea floor? The Stronsay "beast" of six decades earlier was perhaps another instance of fins (and claspers?) getting confused for limbs on a basking shark. The vertebrae size was smaller than (but otherwise identical to) that of an above average 25 foot (7.6 m) basking shark despite the reported length of 55 feet (16.8 m). Thank you Guinness Book of Animal Facts and Feats. This was probably just exaggeration, but there is the remote possibility of some freak basking shark that doubled its vertebral count that somehow lived to maturity.
Mentioned in this not-too-recent post is the Carta Marina of Olaus Magnus. As far as weird and mythological aquatic creatures go, this is their holy grail. You'd better click on this and pray you don't have dialup:
You can spend a lot of time picking out crazy stuff in this map. Judging by the names the "Balena" and "Orcha" are supposed to be extant cetaceans, but you can't really tell by the weird collars, tube-like nostrils, piggish faces, and other really strange features. The "Ziphius" sounds like it could be a beaked whale, but the eagle head doesn't seem quite right. Also of note are people camping out on a big "island fish", what appears to be a devil/pan sweeping a stable, a monster with three eyes on its body, a feathery dragon, and lots of other strange things. Like Dürer's Rhinoceros, this is another one of those really iconic images/memes that symbolizes the time period. I for one miss maps that alert us to potential terrors waiting for us in exotic, far away lands. Also take note trivia buffs: the man's face in the clouds blowing wind is another one of my favorite images.
While Magnus worked in the 15th and 16th centuries, fantastic illustrations continued into the 19th century, my favorite era (for this). I recently came across an amazing flickr album (which prompted this post) on a book called Sea and Land from 1889. Not only are the illustrations fantastic and iconic but they're all in the public domain, making this all the sweeter for me. Due to many of these illustrations being fairly common in the Cryptozoology domain, plus me uncontrollably discussing the subject, I suppose the label is justified. Here are some favorites from this volume:
Crab lifting a goat, hmm. Robber crabs/Coconut crabs are pretty big for crustaceans and utterly colossal for a land arthropod (~9 lbs, ~3 foot span max) but lifting a goat? The appearance does seem accurate, but I'll assume this was based on somebody's crazy story/myth.
As usual, marine creatures, in this case reptiles, are depicted rather oddly. The long-tailed fellow with a puppy-dog expression is a plesiosaur with the head placed on the wrong end. Despite the traditional swan-neck pose which is common even today, plesiosaurs and elasmosaurs could not (and probably had no reason to) assume that position. The ichthyosaurs were also portrayed as being rather crocodile-like as opposed to fish like. An actual marine crocodile does seem fairly reasonable, undoubtedly due to living relatives. The small beaked swimmer in the bottom left-hand corner is something is a mystery to me, perhaps a rhynchosaur erroneously depicted as swimming?[Correction thanks to Matt Celeskey: The "plesiosaur" is actually a mosasaur, and the beaked creature is actually the turtle Osteopygis. See "comments" for more.]
My favorite depiction of the "Kraken" sinking a ship. This is a wonderfully dark and moody piece, or wait no, dark and disturbing, muhaha. I remember as a much younger Crypto-enthusiast I was tantalized by what appear to be two small fins low on the mantle on this cephalopod. Y'see, there was this theory that the St. Augustine monster was in fact a cirrate octopus. Here is a depiction of "Otoctopus giganteus" from Michael Raynal's Institut Virtuel de Cryptozoologie.
An image supposedly representing the St. Augustine carcass. Both the description and drawing in the Pennsylvania Grit were horrendously naive, more like something out of the middle ages than 1896. It actually is a pretty cool monster design though, I'll have to steal it. The carcass wasn't a cephalopod/fish hybrid or a giant octopus, but in fact a sperm whale. I'll discuss globsters some other day.The best source on the Internet for strange science is, well, Strange Science. Their website has the cream of the crop of all this weird stuff, as well as biographies and an excellent primer on evolution. I'd love to post everything, but, I can't. Here are some of my favorites:
Very very strange things were thought about the appearance of a mammoth. It was assumed to be a burrower and was compared to an ox for size and, well, there you have it.
Very strangely, Japetus Steenstrup realized that two reported instances of a "sea monk" bore a remarkable resemblance to a recently captured squid. If this is in fact the case, it demonstrates that people had some horrendously overactive imaginations in that time period. This is why anecdotal evidence, even (or especially) today can never be used as proof of anything. The squid might be the Octopoteuthid Taningia danae.
I am really lost for an explanation on this one.
Very very strange things were thought about the appearance of a mammoth. It was assumed to be a burrower and was compared to an ox for size and, well, there you have it.
Very strangely, Japetus Steenstrup realized that two reported instances of a "sea monk" bore a remarkable resemblance to a recently captured squid. If this is in fact the case, it demonstrates that people had some horrendously overactive imaginations in that time period. This is why anecdotal evidence, even (or especially) today can never be used as proof of anything. The squid might be the Octopoteuthid Taningia danae.
I am really lost for an explanation on this one.So there you have it, a sampling of some of the strangest drawings I've ever seen. Some of these, such as the marine reptiles, were taken seriously; but I wonder about some of the others. Regardless, for some people a bestiary-like mindset lives on in their personal take on cryptozoology. They still think that there are fantastic monsters lurking in the mysterious and not-so-mysterious reaches of the globe. As a kid, I myself depicted bestiary scenes of aquatic cryptids I read about. Consequently, Darren Naish at about the same age made a far-superior depiction...sigh. Older now, I learned that value of critical thinking and realized that upon closer inspection, many of these beasts are most certainly figments of the imagination, modern day mythological creatures. What truly astounds me is that actual discoveries are often more strange than fiction. Take the cnidarian worm (!) Buddenbrockia for example. Coming up with your own world and your own fiction is difficult considering how fantastic our world already is.
I've got a lot of options for posting now, hopefully I'll squeeze something out soon here.
-Cameron
[Addendum 7/15/07: As per suggestion of Kevin Z, I'll talk about the Anthropomorpha of Linneus here. This excellent website was used as a source.
Carolus Linnaeus (born Carl von Linné) as you all known, is the great father of taxonomy. Sure his system is rather antiquated right now thanks to cladistics, but it was definitely a step in the right direction. In another interesting move, Linnaeus chose to classify humans among the animals. Despite being a creationist (like everybody back then) he recognized the obvious similarity between primates and man. His classifications (quite confusingly) changed with publications, and in one scheme he broke the genus Homo into two sub-genera: Homo diurnus and Homo nocturnus. H. diurnus included our species which was (unfortunately) divided into four races. Feral humans were considered a separate species (H. ferus) and a wastebin taxa of various monsters was called H. monstrosus. This included mythical Patagonian giants, Alpine dwarfs, and very real (but not one-testicled) "Hottentots".
Left to Right: "Trogloodyte", "Lucifer", "Satyr", "Pygmee"
The poorly named Homo nocturnus (aka troglodytes) made up the other half of the Anthropomorpha. Linnaeus was far from rigorous in some instances, and despite trying to "de-mythologize" some creatures, ended up making a mess. The above depicted apes were not created with specimens, but with heresy and second-hand accounts of a medieval bestiary quality. For instance, the first one is evidently supposed to be an orangutan! Probably because of him, depictions of apes were very, well, strange for a while and also still have rather peculiar scientific names (Pan troglodytes, Pongo pygmaeus). Eventually this convoluted mess got (mostly) ironed out into neat little families, sub-families and tribes today. Let this be a lesson to cryptozoologists who want to describe and classify with secondhand knowledge!
Even though he did not classify them as Homo monstrosus or even talk about them, that category reminded me of some of my favorite humanoid bestiary monsters.
The giant cyclopes probably* originated from elephants skulls perhaps mixed with observations of the actual disease cyclopia. I find images of that very disturbing, I warn you in advance of googling that. The cynocephali (dog-headed fellow) is evidently based on baboons and perhaps soon-to-be-extinct giant lemurs. The foot-parasol fellow is baffling, perhaps based on elephantiasis? The Strong Mad-esque Anthropophagi is unexplainable, for me at least. The book Curious Creatures in Zoology by John Ashton is online here for more bestiary fun.
*As in probably not. Darren Naish will some day explain this...
Phew, and I'm spent]
I've got a lot of options for posting now, hopefully I'll squeeze something out soon here.
-Cameron
[Addendum 7/15/07: As per suggestion of Kevin Z, I'll talk about the Anthropomorpha of Linneus here. This excellent website was used as a source.
Carolus Linnaeus (born Carl von Linné) as you all known, is the great father of taxonomy. Sure his system is rather antiquated right now thanks to cladistics, but it was definitely a step in the right direction. In another interesting move, Linnaeus chose to classify humans among the animals. Despite being a creationist (like everybody back then) he recognized the obvious similarity between primates and man. His classifications (quite confusingly) changed with publications, and in one scheme he broke the genus Homo into two sub-genera: Homo diurnus and Homo nocturnus. H. diurnus included our species which was (unfortunately) divided into four races. Feral humans were considered a separate species (H. ferus) and a wastebin taxa of various monsters was called H. monstrosus. This included mythical Patagonian giants, Alpine dwarfs, and very real (but not one-testicled) "Hottentots".
Left to Right: "Trogloodyte", "Lucifer", "Satyr", "Pygmee"The poorly named Homo nocturnus (aka troglodytes) made up the other half of the Anthropomorpha. Linnaeus was far from rigorous in some instances, and despite trying to "de-mythologize" some creatures, ended up making a mess. The above depicted apes were not created with specimens, but with heresy and second-hand accounts of a medieval bestiary quality. For instance, the first one is evidently supposed to be an orangutan! Probably because of him, depictions of apes were very, well, strange for a while and also still have rather peculiar scientific names (Pan troglodytes, Pongo pygmaeus). Eventually this convoluted mess got (mostly) ironed out into neat little families, sub-families and tribes today. Let this be a lesson to cryptozoologists who want to describe and classify with secondhand knowledge!
Even though he did not classify them as Homo monstrosus or even talk about them, that category reminded me of some of my favorite humanoid bestiary monsters.
The giant cyclopes probably* originated from elephants skulls perhaps mixed with observations of the actual disease cyclopia. I find images of that very disturbing, I warn you in advance of googling that. The cynocephali (dog-headed fellow) is evidently based on baboons and perhaps soon-to-be-extinct giant lemurs. The foot-parasol fellow is baffling, perhaps based on elephantiasis? The Strong Mad-esque Anthropophagi is unexplainable, for me at least. The book Curious Creatures in Zoology by John Ashton is online here for more bestiary fun.
*As in probably not. Darren Naish will some day explain this...
Phew, and I'm spent]
Wednesday, July 4, 2007
Those Super-Cryptic Choristoderes
Dear Constant Readers,
The last time I talked about choristoderes was way back here, and a cursory glance revealed that I have a lot of updating to do. And now with newfound access to scientific journals (like a kid in a candy store) I finally have the materials I need to create a post on these enigmatic reptiles.
If the name "choristodera" hasn't been heard in your household, I won't hold it against you. They were first described by Cope (of the Bone Wars fame) in 1884* and for 100 years they were portrayed as moderately sized (2-2.5 meters) gavial-like reptiles that arose in the late Cretaceous and went extinct in the Eocene, apparently little affected by the massive K/T extinction event (Evens & Klembara 2005). Gao et al (2000) do an excellent job of summarizing the recent work done on this group. In the last 20 years, 9 new genera (only 2 known previously) were described from Western North America, and Eurasia from England to Japan ranging from the sub-tropics to the Arctic. They state that the choristoderes "are beginning to emerge from the shadows as a group of unexpected phylogenetic and ecological diversity"; and given my tendency to focus on emerging fields (see here and here) I could hardly resist.
One noticeable change is the temporal range choristoderes now occupy. Cteniogenys described in the late 80's pushed the choristoderans back to the latter half of the Jurassic and re-analysis of Pachystropheus (discovered in 1935) in the early 90's potentially pushed them 45 million years farther into the late Triassic. If choristoderes are considered basal Archosauromorphs** judging by cladistics this would mean their lineage could be another 50 million years older and originate in the late Permian (Storrs & Gower 1993). This would imply that choristoderes (or their direct ancestors) survived an even bigger extinction event earlier in the past only to go extinct later on. The range of choristoderes in the other direction is the story I'll focus on here.
* Date given by Evens & Klembara 2005. Other (older) sources (Storrs & Gower 1993, Gao & Fox 1998) confusingly give the date as 1876.
**DeBraga & Rieppel (1997) classify choristoderes as a sister group to the Archosauromorpha. Palaeos.com places them there as well, but don't exclude the possibility that they're closer to basal diapsids. Recent papers seem to avoid classification, perhaps for good reason.
Lazarussuchus
So when did choristoderes finally go extinct? In 1992 Lazarussuchus inexpectatus was described by Hecht (paper unavailable, dang) from France from the late Oligocene i.e. several millions of years later than the presumed Eocene extinction. But there's a problem Gao & Fox (1998) do not consider Lazarussuchus to be choristoderan! The authors define Choristodera as the last common ancestor of Cteniogenys and Champsosaurus and suggest that if Lazarussuchus is a sister group, another more inclusive name is needed for the new group. The authors also do not believe that choristoderes belong in the Archosauromorpha or Lepidosauromorpha and are possibly even outside of the Neodiapsida. I should mention that DeBraga and Rieppel's 1997 paper on reptile phylogeny is used frequently in these papers for clade definitions, but you can consult Palaeos.com for easier access and cheekier commentary. Back on subject, a position all the way out there would imply that Lazarussuchus belonged to a lineage that presumably evolved sometime in the Permian and didn't fossilize until over 200 million years later. Considering that freshwater animals should have a very good fossil record, this is a problem. It could be possible that they went through a marine phase, and it should be noted that gaps of lesser magnitude in freshwater animals are known (Storrs & Gower 1993). I haven't heard about any other ghost lineage of that magnitude, but of course I haven't read everything yet.
Before I write my own edition of Animal Facts and Feats, I should mention that the story of course does not end there. Susan E. Evans and Jozef Klembara described a new species of Lazarussuchus (L. dvoraki) from the early Miocene of the Czech republic in 2005. Differences between the taxa were slight, but if more of the skull and post-cranial skeleton is recovered, L. dvoraki may need to be reclassified (different genus?). These remains still complimented the previous species and helped resolve ambiguous damaged areas. Unlike Gao* and Fox the authors state that "the Merkur reptile is clearly a choristodere" although outside the Neochoristodera (including the more familiar Champsosaurs). Lazarussuchus shows a mixture of primitive and derived traits, and cladistic analysis in most cases puts it at the base of Choristodera. However, the authors also mention the possibility that since Lazarussuchus is so small (skull length 43-45 mm) it could have had a number of size-related character reversals. There is a lot of missing data from other basal choristoderes, so it looks like we'll have to wait to see what Lazarussuchus truly was.
* A later paper (2007) by Gao et al puts them as being choristoderan again. Evans was part of that "et al" interestingly enough.
Evans and Klembara finish up their paper by demonstrating that cooling and drying in the Eocene and Oligocene wiped out the large (neo-) choristoderes, leaving only this small branch. The next period of cooling occurred in the late Pliocene, so it is quite possible they survived until a couple million years ago. There are apparently other locations similar to Merkur and choristoderes in North America at this time have yet to be mentioned, so a lot about the final hour of this group can be untangled and learned from. If the final death of these extinction-busting super-stragglers was so close to the present, I suppose that can say a lot about where our planet is careening off to.
Since Evans' original paper covering the skeleton isn't available to me, I unfortunately can't try and make an illustration that wouldn't be horrendously speculative. Well, I could, but it wouldn't be much of a service to anyone. This little reptile probably looked like a moderately-sized aquatic lizard, nothing too exciting.
Strange Asian Choristoderes
While Lazarussuchus was conceptually interesting and conservative, Chinese fossils revealed that choristoderes could be surprisingly diverse. Champosaur-like Simoedosaurids (unpublished), bizarre Hyphalosaurids (keep reading), and another group all occupied the same area (Gao et al 2007b). It appears that all three were contemporary and occupied radically different niches.
The other group mentioned are the Monjurosuchids, which were surprisingly known since 1940. They were oddly classified as Rhynchocephalians in the family Sphenodontidae until 1995 without a firm basis (Gao et al 2007a). In other words, they were considered relatives of the tuatara. The original specimen was apparently lost in the Second World War, but Gao et al in 2000 described spectacular new specimens. They showed all of the diagnostic traits of choristoderes, but were clearly outside the familiar neochoristoderans. They were only about 30 cm (1 foot) in length with a tapering tail and webbed feet. The appearance was described as being surprisingly similar to Shinisaurus crocodilurus, the Chinese crocodile lizard which it probably resembled in niche as well. One spectacularly preserved specimen had a double row of ovoid keels which appear to resemble those on Shinisaurus. There was no discussion on what this curiously converged trait accomplished. Unlike the apparent scaly skin of the modern Shinisaurus, the choristodere had small scales (larger dorsally) and appeared to have fairly soft skin. The description of another genus (Phylidosaurus) in Gao et al 2007b illustrates this interesting pattern. There seems to be a trend of increasing number of life illustrations in these papers, which is a relief from the typical picture of a jumble of bones. Well, then again I'm not a worker on this and I'm more of the visual type.
When Philydrosaurus was described by (who else) Gao et al in 2005, there was a discussion of cladistics and the Monjurosuchids formed a tenuous clade with the enigmatic Hyphalosaurids (group defined for that analysis). Even if they aren't actually closely related, this group certainly is worth discussing. Two papers on the respective Chinese and Japanese genera are unavailable to me, so I'll have to make do. This group radically departs from the aquatic lizard, crocodile, and gavial-like bauplans then known from choristoderes; it has a long neck and superficially resembles a nothosaur (Gao et al 2000). I think that they resemble Plachypleurosaurs such as Keichousaurus even more strongly in size and shape despite one being marine and the other being freshwater. These choristoderes appear to have been fully aquatic and occurred in deeper-water environments (Gao et al 2007b). In the papers it isn't certain if choristoderes were aquatic or semi-aquatic, but the structure of this bizarre family probably would hinder them significantly on land. However, Hyphalosaurus was known to lay eggs (Gao et all 2007b). Hyphalosaurus recently made the news after a two headed juvenile was discovered, the oldest known case of polycephaly. This is an example of another article I'd like to read but again can't access.
I of course can't pretend that this is anywhere near a complete treatment of the choristoderes; there are of course 3 other families and some controversies (e.g. Pachystropheus) that I just barely touched upon. There's always the chance of there being another post, especially if more papers and discoveries are published. I think for now this illustrates the great potential for this poorly known group. Their ability to occupy surprisingly different niches is certainly something to look into, and doubtless more oddballs will show up. It would also be interesting to see if the ghost lineages can cut shorter, or if there are genuine limitations to the fossil record. Are there marine groups? Their potential super-late survival is of course most interesting to me. How does such an adaptive and resilient group go extinct? Unfortunately, I haven't heard even the slightest indication of strange little crocodilian/lizard-like still swimming about. Dang.
References:
These are unfortunately not freebies but only available to those of you fortunate enough with access. I'd like to thank Brown University for indirectly supplying me with this newfound ability. I am not certain how to cite the Chinese family name of one frequent author (Gao) which varies from paper to paper, so I'm tenuously putting it last i.e. the one being alphabetized. According to the vast knowledge of my father, Brits apparently do the whole thing in reverse. Just FYI.
DeBraga, Michael & Rieppel, Oliver. 1997. Reptile phylogeny and the interrelationships of turtles. Zoological Journal of the Linnean Society 120: 281-354. Available: Here
Evans, Susan E. & Klembara, Jozef. 2005. A choristoderan reptile (Reptilia: Diapsida) from the lower Miocene of Northwest Bohemia. Journal of Vertebrate Paleontology 25: 171-184. Available: Here
Gao, Keqin & Fox, Richard C. 1998. New choristoderes (Reptilia: Diapsida) from the Upper Cretaceous and Palaeocene, Alberta and Saskatchewan, Canada, and phylogenetic relationships of Choristodera. Zoological Journal of the Linnean Society 124: 303-354. Available: Here
Gao, Kequin & Evans, Susan &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Ji, Qiang & Norell, Mark & Ji, Shu'an. 2000. Exceptional fossil material of a semi-aquatic reptile from China: The resolution of an enigma. Journal of Vertebrate Paleontology 20: 417-421. Available: Here
Gao, Ke-Qin & Fox, Richard C. A new choristodere (Reptilia: Diapsida) from the Cretaceous of western Liaoning Province, China, phylogenetic relationships of Monjurosuchidae. Zoological Journal of the Linnean Society145: 427-444. Available: Here
Gao, Ke-Qin & Li, Quanguo. 2007a. Osteology of Monjurosuchus splendens (Diapsida: Choristodera) based on a new specimen from the Lower Cretaceous of western Liaoning, China. Cretaceous Research 28: 261-271. Available: Here
Gao, Keqin & Ksepka, Danial & Lianhai, Hou & Dongyu, Hu. 2007b. Cranial morphology of an Early Cretaceous Monjurosuchid (Reptilia: Diapsida) from Liaoning Province of China and evolution of the choristoderan palate. Historical Biology 19: 215-224. Available: Here
Smith, J.B. & Harris, J.D. 2001. A taxonomic problem concerning two diapsid genera from the Lower Yixian Formation of Liaoning Province, China. Journal of Vertebrate Paleontology 21 (2): 389-391. Available: Here
Storrs, G.W. & Gower D. J. 1993. The earliest possible choristodere (Diapsida) and gaps in the fossil record of semi-aquatic reptiles. Journal of the Geological Society, London 150: 1103-1107. Available: Here
Here's a little drawing of a fairly generalized Monjurosuchid (top) and Hyphalosaurid (bottom), approximately to scale. I could only find dorsal views of the fossils, so their lateral nature is speculative. The Monjurosuchid is based off of an illustration of Philydrosaurus with the proportions of Monjurosuchus from fossils. The Hyphalosaurid was imagined as being unarmored and flippered, and the lateral head view is an imagined adult form of this. For a sense of scale, it measures about 2 feet long. I think if you click on it, it should be around life sized...that was not intentional.
The last time I talked about choristoderes was way back here, and a cursory glance revealed that I have a lot of updating to do. And now with newfound access to scientific journals (like a kid in a candy store) I finally have the materials I need to create a post on these enigmatic reptiles.
If the name "choristodera" hasn't been heard in your household, I won't hold it against you. They were first described by Cope (of the Bone Wars fame) in 1884* and for 100 years they were portrayed as moderately sized (2-2.5 meters) gavial-like reptiles that arose in the late Cretaceous and went extinct in the Eocene, apparently little affected by the massive K/T extinction event (Evens & Klembara 2005). Gao et al (2000) do an excellent job of summarizing the recent work done on this group. In the last 20 years, 9 new genera (only 2 known previously) were described from Western North America, and Eurasia from England to Japan ranging from the sub-tropics to the Arctic. They state that the choristoderes "are beginning to emerge from the shadows as a group of unexpected phylogenetic and ecological diversity"; and given my tendency to focus on emerging fields (see here and here) I could hardly resist.
One noticeable change is the temporal range choristoderes now occupy. Cteniogenys described in the late 80's pushed the choristoderans back to the latter half of the Jurassic and re-analysis of Pachystropheus (discovered in 1935) in the early 90's potentially pushed them 45 million years farther into the late Triassic. If choristoderes are considered basal Archosauromorphs** judging by cladistics this would mean their lineage could be another 50 million years older and originate in the late Permian (Storrs & Gower 1993). This would imply that choristoderes (or their direct ancestors) survived an even bigger extinction event earlier in the past only to go extinct later on. The range of choristoderes in the other direction is the story I'll focus on here.
* Date given by Evens & Klembara 2005. Other (older) sources (Storrs & Gower 1993, Gao & Fox 1998) confusingly give the date as 1876.
**DeBraga & Rieppel (1997) classify choristoderes as a sister group to the Archosauromorpha. Palaeos.com places them there as well, but don't exclude the possibility that they're closer to basal diapsids. Recent papers seem to avoid classification, perhaps for good reason.
Lazarussuchus
So when did choristoderes finally go extinct? In 1992 Lazarussuchus inexpectatus was described by Hecht (paper unavailable, dang) from France from the late Oligocene i.e. several millions of years later than the presumed Eocene extinction. But there's a problem Gao & Fox (1998) do not consider Lazarussuchus to be choristoderan! The authors define Choristodera as the last common ancestor of Cteniogenys and Champsosaurus and suggest that if Lazarussuchus is a sister group, another more inclusive name is needed for the new group. The authors also do not believe that choristoderes belong in the Archosauromorpha or Lepidosauromorpha and are possibly even outside of the Neodiapsida. I should mention that DeBraga and Rieppel's 1997 paper on reptile phylogeny is used frequently in these papers for clade definitions, but you can consult Palaeos.com for easier access and cheekier commentary. Back on subject, a position all the way out there would imply that Lazarussuchus belonged to a lineage that presumably evolved sometime in the Permian and didn't fossilize until over 200 million years later. Considering that freshwater animals should have a very good fossil record, this is a problem. It could be possible that they went through a marine phase, and it should be noted that gaps of lesser magnitude in freshwater animals are known (Storrs & Gower 1993). I haven't heard about any other ghost lineage of that magnitude, but of course I haven't read everything yet.
Before I write my own edition of Animal Facts and Feats, I should mention that the story of course does not end there. Susan E. Evans and Jozef Klembara described a new species of Lazarussuchus (L. dvoraki) from the early Miocene of the Czech republic in 2005. Differences between the taxa were slight, but if more of the skull and post-cranial skeleton is recovered, L. dvoraki may need to be reclassified (different genus?). These remains still complimented the previous species and helped resolve ambiguous damaged areas. Unlike Gao* and Fox the authors state that "the Merkur reptile is clearly a choristodere" although outside the Neochoristodera (including the more familiar Champsosaurs). Lazarussuchus shows a mixture of primitive and derived traits, and cladistic analysis in most cases puts it at the base of Choristodera. However, the authors also mention the possibility that since Lazarussuchus is so small (skull length 43-45 mm) it could have had a number of size-related character reversals. There is a lot of missing data from other basal choristoderes, so it looks like we'll have to wait to see what Lazarussuchus truly was.
* A later paper (2007) by Gao et al puts them as being choristoderan again. Evans was part of that "et al" interestingly enough.
Evans and Klembara finish up their paper by demonstrating that cooling and drying in the Eocene and Oligocene wiped out the large (neo-) choristoderes, leaving only this small branch. The next period of cooling occurred in the late Pliocene, so it is quite possible they survived until a couple million years ago. There are apparently other locations similar to Merkur and choristoderes in North America at this time have yet to be mentioned, so a lot about the final hour of this group can be untangled and learned from. If the final death of these extinction-busting super-stragglers was so close to the present, I suppose that can say a lot about where our planet is careening off to.
Since Evans' original paper covering the skeleton isn't available to me, I unfortunately can't try and make an illustration that wouldn't be horrendously speculative. Well, I could, but it wouldn't be much of a service to anyone. This little reptile probably looked like a moderately-sized aquatic lizard, nothing too exciting.
Strange Asian Choristoderes
While Lazarussuchus was conceptually interesting and conservative, Chinese fossils revealed that choristoderes could be surprisingly diverse. Champosaur-like Simoedosaurids (unpublished), bizarre Hyphalosaurids (keep reading), and another group all occupied the same area (Gao et al 2007b). It appears that all three were contemporary and occupied radically different niches.
The other group mentioned are the Monjurosuchids, which were surprisingly known since 1940. They were oddly classified as Rhynchocephalians in the family Sphenodontidae until 1995 without a firm basis (Gao et al 2007a). In other words, they were considered relatives of the tuatara. The original specimen was apparently lost in the Second World War, but Gao et al in 2000 described spectacular new specimens. They showed all of the diagnostic traits of choristoderes, but were clearly outside the familiar neochoristoderans. They were only about 30 cm (1 foot) in length with a tapering tail and webbed feet. The appearance was described as being surprisingly similar to Shinisaurus crocodilurus, the Chinese crocodile lizard which it probably resembled in niche as well. One spectacularly preserved specimen had a double row of ovoid keels which appear to resemble those on Shinisaurus. There was no discussion on what this curiously converged trait accomplished. Unlike the apparent scaly skin of the modern Shinisaurus, the choristodere had small scales (larger dorsally) and appeared to have fairly soft skin. The description of another genus (Phylidosaurus) in Gao et al 2007b illustrates this interesting pattern. There seems to be a trend of increasing number of life illustrations in these papers, which is a relief from the typical picture of a jumble of bones. Well, then again I'm not a worker on this and I'm more of the visual type.
When Philydrosaurus was described by (who else) Gao et al in 2005, there was a discussion of cladistics and the Monjurosuchids formed a tenuous clade with the enigmatic Hyphalosaurids (group defined for that analysis). Even if they aren't actually closely related, this group certainly is worth discussing. Two papers on the respective Chinese and Japanese genera are unavailable to me, so I'll have to make do. This group radically departs from the aquatic lizard, crocodile, and gavial-like bauplans then known from choristoderes; it has a long neck and superficially resembles a nothosaur (Gao et al 2000). I think that they resemble Plachypleurosaurs such as Keichousaurus even more strongly in size and shape despite one being marine and the other being freshwater. These choristoderes appear to have been fully aquatic and occurred in deeper-water environments (Gao et al 2007b). In the papers it isn't certain if choristoderes were aquatic or semi-aquatic, but the structure of this bizarre family probably would hinder them significantly on land. However, Hyphalosaurus was known to lay eggs (Gao et all 2007b). Hyphalosaurus recently made the news after a two headed juvenile was discovered, the oldest known case of polycephaly. This is an example of another article I'd like to read but again can't access.
I of course can't pretend that this is anywhere near a complete treatment of the choristoderes; there are of course 3 other families and some controversies (e.g. Pachystropheus) that I just barely touched upon. There's always the chance of there being another post, especially if more papers and discoveries are published. I think for now this illustrates the great potential for this poorly known group. Their ability to occupy surprisingly different niches is certainly something to look into, and doubtless more oddballs will show up. It would also be interesting to see if the ghost lineages can cut shorter, or if there are genuine limitations to the fossil record. Are there marine groups? Their potential super-late survival is of course most interesting to me. How does such an adaptive and resilient group go extinct? Unfortunately, I haven't heard even the slightest indication of strange little crocodilian/lizard-like still swimming about. Dang.
References:
These are unfortunately not freebies but only available to those of you fortunate enough with access. I'd like to thank Brown University for indirectly supplying me with this newfound ability. I am not certain how to cite the Chinese family name of one frequent author (Gao) which varies from paper to paper, so I'm tenuously putting it last i.e. the one being alphabetized. According to the vast knowledge of my father, Brits apparently do the whole thing in reverse. Just FYI.
DeBraga, Michael & Rieppel, Oliver. 1997. Reptile phylogeny and the interrelationships of turtles. Zoological Journal of the Linnean Society 120: 281-354. Available: Here
Evans, Susan E. & Klembara, Jozef. 2005. A choristoderan reptile (Reptilia: Diapsida) from the lower Miocene of Northwest Bohemia. Journal of Vertebrate Paleontology 25: 171-184. Available: Here
Gao, Keqin & Fox, Richard C. 1998. New choristoderes (Reptilia: Diapsida) from the Upper Cretaceous and Palaeocene, Alberta and Saskatchewan, Canada, and phylogenetic relationships of Choristodera. Zoological Journal of the Linnean Society 124: 303-354. Available: Here
Gao, Kequin & Evans, Susan &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Ji, Qiang & Norell, Mark & Ji, Shu'an. 2000. Exceptional fossil material of a semi-aquatic reptile from China: The resolution of an enigma. Journal of Vertebrate Paleontology 20: 417-421. Available: Here
Gao, Ke-Qin & Fox, Richard C. A new choristodere (Reptilia: Diapsida) from the Cretaceous of western Liaoning Province, China, phylogenetic relationships of Monjurosuchidae. Zoological Journal of the Linnean Society145: 427-444. Available: Here
Gao, Ke-Qin & Li, Quanguo. 2007a. Osteology of Monjurosuchus splendens (Diapsida: Choristodera) based on a new specimen from the Lower Cretaceous of western Liaoning, China. Cretaceous Research 28: 261-271. Available: Here
Gao, Keqin & Ksepka, Danial & Lianhai, Hou & Dongyu, Hu. 2007b. Cranial morphology of an Early Cretaceous Monjurosuchid (Reptilia: Diapsida) from Liaoning Province of China and evolution of the choristoderan palate. Historical Biology 19: 215-224. Available: Here
Smith, J.B. & Harris, J.D. 2001. A taxonomic problem concerning two diapsid genera from the Lower Yixian Formation of Liaoning Province, China. Journal of Vertebrate Paleontology 21 (2): 389-391. Available: Here
Storrs, G.W. & Gower D. J. 1993. The earliest possible choristodere (Diapsida) and gaps in the fossil record of semi-aquatic reptiles. Journal of the Geological Society, London 150: 1103-1107. Available: Here
Addendum: Later the same day
Here's a little drawing of a fairly generalized Monjurosuchid (top) and Hyphalosaurid (bottom), approximately to scale. I could only find dorsal views of the fossils, so their lateral nature is speculative. The Monjurosuchid is based off of an illustration of Philydrosaurus with the proportions of Monjurosuchus from fossils. The Hyphalosaurid was imagined as being unarmored and flippered, and the lateral head view is an imagined adult form of this. For a sense of scale, it measures about 2 feet long. I think if you click on it, it should be around life sized...that was not intentional.
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