The Giant Turtle Therizinosaurus

Therizinosaurus, you look... unwell. Reconstruction by K. K. Fierova, from Maleyev (1954).

I am quite fond of old, weird reconstructions, and the initial classification of Therizinosaurus cheloniformis as a "turtle-like reptile"¹ resulted in the magnificent specimen above. So how could the veritable Jabberwocky we're all familiar with be misinterpreted to such a colossal degree?

¹ This odd phrasing is mirrored in the scientific name ("saurus" = lizard, "cheloniformis" = turtle-like). Malayev (1954) linked Therizinosaurus with members of Protostegidae and thus (probably) didn't intend to suggest another clade of reptiles which converged on turtles. Bizarrely, Rozhdestvensky (1974) claimed Malayev/Maleev classified Therizinosaurus as a "turtle-like pangolin"! Rozhdestvensky (1977) does not reiterate that statement, and further notes that another worker (Sukhanov) classified Therizinosaurus as a turtle; I unfortunately cannot find that source ("The subclass Testudinata" in Osnovy Paleontologii).

Therizinosaurus in its non-turtle form. From Wikipedia Commons.

Malayev (1954) described Therizinosaurus from scrappy remains: a metacarpal fragment, 3 manual unguals, and rib fragments (Zanno 2010). One of the ribs was an estimated 1.5 meters long when complete and was used to calculate a maximum body width of 3.25 meters (10'8") and body length of 4.5 m (14'9") (Malayev 1954); this is of course quite a bit larger than even the largest known Stupendemys geographicus. The rib was noted to lack costal elements, which is curious since turtle skeletons generally look like this:

 

Common Snapping Turtle (Chelydra serpentina) skeleton. Note the plastron is missing. From Wikipedia Commons.

Surprisingly, this is not necessarily a critical flaw, as (all?) turtles have distinct ribs during development before the carapace is fully formed (Wyneken 2001, fig. 90; Sánchez-Villagra 2009, figs. 3, 4). Malayev (1954) did not mention this nor the obvious possibility of a multi-ton hatchling. Instead, the "form of the ribs" was compared to Archelon and Protostega:

Archelon skeleton. From Wikipedia Commons.

The similarity is very general and Malayev (1954) does not list any specific shared characteristics. Due to the lack of costal elements, Malayev (1954) speculated that Therizinosaurus was in a distinct clade and in life had "barely developed or almost completely absent bony armor". It is incredibly strange that the Leatherback Seaturtle (Dermochelys coriacea) was not mentioned, as it entirely lacks costal elements and instead has thousands of dermal ossicles (Cebra-Thomas et al. 2005). The skeleton (sans ossicles) looks like an attempt by turtles to become "normal" tetrapods again.. until you notice the pectoral girdle within the ribcage:

From Wikipedia Commons

The rib material used to describe Therizinosaurus cheloniformis is apparently not from a therizinosaur at all, but a sauropodomorph (Zanno 2010 citing Rozhdestvensky 1970). Isn't it a major problem that the holotype is a chimera? Whatever the case, Therizinosaurus cheloniformis has been re-described a few more times and other rib material has been referred to the species (Zanno 2010). However, all of the diagnostic traits (and most of the material) are from the forelimbs (Zanno 2010).

From Wikipedia Commons.

Malayev (1954) interpreted the metacarpal and phalanges to be "powerful swimming organs" and suggested the huge claws were used for "cutting aquatic vegetation or for another functions, constrained by movement and acquiring food". The longest phalanyx was 60-65 cm long, not including the keratin covering (Malayev 1954), which suggests that the claws were ridiculously huge in life, even for a turtle-like reptile with a 4.5 meter body. I have observed turtles using their claws to climb and tear apart food (maybe what Malayev had in mind...), but clearly claws this disproportionate were doing something special. Something like this:

I like to think that Therizinosaurus, despite not being turtle-shaped anymore, waved its giant claws seductively in the faces of prospective mates.

References:

Cebra-Thomas, J., Tan, F., Sistla, S., Estes, E., Bender, G., Kim, C., Riccio, P., and Gilbert S. F. (2005). How the Turtle Forms its Shell: A Paracrine Hypothesis of Carapace Formation. Journal of Experimental Zoology 304B, 558-569. Available.

Maleyev, E. A. (1954). A new turtle-like reptile from Mongolia. Priroda 3, 106-108. Available.

Rozhdestvensky, A. K. (1977). The study of Dinosaurs in Asia. Journal of the Palaeontological Society of India 20, 102-119. Available.

Rozhdestvensky, A. K. (1974). History of the dinosaur fauna of Asia and other continents and questions concerning paleogeography. Transactions of the Joint Soviet–Mongolia Paleontological Expedition 1, 107–131. Available.

Rozhdestvensky, A. K. (1970). On the gigantic claws of mysterious Mesozoic reptiles. Palaeontological Journal 1, 131-141.

Sánchez-Villagra, M. R., Müller, H., Sheil, C. A., Scheyer, T. M., Nagashima, H., and Kuratani, S. (2009).  Skeletal Development in the Chinese Soft-Shelled Turtle Pelodiscus sinensis (Testudines: Trionychidae). Journal of Morphology 270, 1381-1399. Available.

Wyneken, J. (2001). The Anatomy of Sea Turtles. U.S. Dept Commerce NOAA Tech Mem NMFS SEFSC-470. Available.

Zanno, L. E. (2010). A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology 8(4), 503-543. Draft Available.

A Giant Snapper At Last!

A common cliché in fringe anecdotes is that when eyewitnesses see something beyond belief, the camera has the lens cap on/no film/failed to work/been misplaced. Logically this should be taken as a strike against veracity... but I began to wonder otherwise when it happened to me. 

Of course, I've documented a big snapping turtle before, but my subsequent failures were astounding. I saw the turtles on multiple occasions this year (alluded to here), sometimes up close (touching, in fact) and once in triplicate. On all of these occasions I didn't bring my camera because I was commuting via bike, or the turtles fled before I could get their photographs. After a couple dozen failures, I gave up. Impulsively I decided on 8 November 2011 to take a trip searching for any reptiles or amphibians still active in the abnormally warm weather (about 70° F, 21° C) and saw this (plus a frog):

Blobturtle! I saw the turtle fairly clearly, but evidently my camera didn't. Rather than leave and be disappointed for a few months and then fail to see the turtles ever again, I realized I had no other option but to go in after it. Not only was the water very cold (it had snowed earlier in the year), it was murky and muddy and possibly had other snapping turtles I couldn't see. Gradually and with little subtlety, I made my way over to the turtle which had of course noticed me, but did not attempt to escape.

Remembering previous encounters and advice on pick-pocketing from Fagin, I approached the turtle from the rear, knowing it would eventually rotate around to defend itself. I also kept in mind how to fight the Cyberdemon from Doom - it's not just the shooting, it's the circle-strafing. With the cold water being slightly less of a hindrance for me, I managed to avoid something getting amputated. 

Getting closer, I confirmed my suspicions that, yes, this turtle is really really big.

The closest thing I could get to a measurement.

Eventually the turtle kicked up large amounts of silt and released gas (from... somewhere) and became impossible to see. I "ran" off, knowing that my luck in succeeding with this ill-conceived shenanigan was running out.

I know I'm never going to get an accurate length or weight measurement from this turtle... not without one or both of us getting hurt. Even if this specimen was a record (and there's no guarantee), it would not be worth risking the life of an old reptile to revise the SCLmax of 49.4 cm for Chelydra serpentina. From now on I'm leaving these turtles alone, my curiosity is satiated, and bothering them further will have no benefits. I'll have to live with the wonder that despite inhabiting a polluted body of water and having human hunt them and compete for their resources, things like this still exist.

A Baby Cadborosaur No More. Part 6b: Reptilian Reproduction

Here's that quote again, from LeBlond and Bousfield (1995), page 82:

The thinness and elongation of the body, the poikilothermy (or cold-bloodedness) which it seems to imply, and the great difference in size between the young and the adult are strong points in favour of a reptilian nature. 

The previous article argued that a "cold-blooded" 'Cadborosaurus' is actually strongly at odds with known 'reptilian' physiology; similarly, the birth of extremely small live young would in fact be highly unusual for a marine reptile.

Backing up, this is the evidence LeBlond and Bousfield (1995) present for comparatively tiny precocial young (page 80):

A very small individual, probably a baby, was caught (by W. Hagelund) and another one, perhaps, was seen at the shore (by P. Harsh); both in relatively warm water. If these very small individuals are correctly associated with the larger ones, their size and where they were found might provide more clues about Caddy's nature.

Woodley et al. (2011) is of course all about why the Hagelund specimen should not be used as evidence, but makes no mention of the Harsh case. Is this... a major flaw in our paper? Absolutely not. The Harsh sightings are vague to the degree that they can be graciously described as unanalyzable. Phyllis Harsh reportedly found a "baby dinosaur" 2 feet (0.61 meters) long on a beach (which was ultimately returned to the water) and (!) a "small dinosaur skeleton" beneath a Bald Eagle nest, both on Johns Island. The sheer lack of detail is remarkable† and the description "dinosaur" can refer to just about anything‡. I find it interesting that LeBlond and Bousfield drew conclusions from this valueless anecdote, despite apparently having some reservations about it.

† For comparison, Hagelund's account had 24 traits, of which only a few were worthless. 
‡ Dinosauria proper has a diverse assortment of body plans, many other creatures are often incorrectly labeled as dinosaurs (ichthyosaurs, plesiosaurs, mosasaurs, Dimetrodon...), and some extant animals (snapping turtles, alligator gars, bichirs, sturgeon...) are often compared to "dinosaurs". 


LeBlond and Bousfield (1995) hypothesized that 'Cadborosaurus' "probably" gives live birth, reasoning that it doesn't have suitable limb morphology for digging nests and inhabits areas which are too cold for incubating eggs. Strangely, they also speculate that it has some reproductive tie to land, although whether it is to lay eggs or give live birth they don't specify. It is worth mentioning that there are only two reports of 'Cadborosaurus' on land and they are very very weird; in 1936 the Stephenson family reported a "90 foot-long, three-foot-thick animal wriggling over the reef into a lagoon" which was "yellow and bluish in colour" and in 1991 Terry Osland reported something "bigger than a killer whale" which was "hard to describe" and yet described as having the "smooth skin of a dogfish" which was of a "grey, silvery color" and had "no hair", a "tail rounded like a lizard tail" with "like little feet on the back of the tail" [sic] and no long neck.


There is another major problem in connecting the Hagelund specimen to 'Cadborosaurus', aside from the utter lack of resemblance - marine reptiles give birth to proportionally large young.

Determining exactly how large the Hagelund specimen is compared to a 'Cadborosaurus' is challenging due to the latter probably not being a valid concept. LeBlond and Bousfield claim a size range of 5-15 meters (which is not supported by the actual sightings), so let's go with a nice round 10 meters. This makes the 40 cm long Hagelund specimen only 4% of the adult length and somewhere in the neighborhood of 5 orders of magnitude less massive, say, around 0.0064%.

Out of the five or so extant clades of marine reptiles†, only the "true" sea snakes (Hydrophiini) give live birth; however as this is by far the most speciose marine clade with ~60 representatives (Sanders et al. 2010) it could be argued that most extant marine reptiles are live-bearers. Anyways, sea snakes tend to have small clutches and large offspring; averaging data from 10 species in Lemen and Voris (1981) gives a mean reproductive effort per embryo of 6.8 (stdev = 2.5, min = 2.1, max = 10.9), reproductive effort being what percentage of the mother's mass the embryo is. While relative lengths were not recorded, assuming similar proportions, this could 'translate' into newborns averaging 41% of the maternal length (min = 27%, max = 48%). It's amazing that more than one of these can fit into the parent snake. The reproductive effort per clutch averaged 32 across the sampled species (stdev = 5, min = 23.6, max = 38.9) and appeared to be fairly stable compared to embryo size.

† The others being seaturtles (Chelonioidea), the marine iguana (Amblyrhynchus cristatus), sea kraits (Laticauda spp.), and saltwater crocodiles (Crocodylus porosus)... the lattermost makes me wonder if other reptiles deserve this status, certainly the softshell turtle Trionyx should be considered. As for how sea snakes, sea kraits, and other elapids are related (Wikipedia's article is highly untrustworthy), Catalogue of Organisms has an excellent summary.


Live birth appears to have been very common in extinct marine reptiles, although as can be imagined, data on this subject is quite scarce. It was recently confirmed that plesiosaurs gave live birth, with Polycotylus latippinis estimated to have a fetus 35% of the maternal length at full term (O'Keefe and Chiappe 2011). The mosasauroid Carsosaurus marchesetti was discovered with four embryos which (according to Figure 2) were around 30 cm long relative to a 2 meter adult (Caldwell and Lee 2001), making the young around 15% of the maternal length. Caldwell and Lee (2001) were uncertain how close to term the embryos were as they were placed posteriorly in the mother, but showed some signs of displacement. Then there is the famous fossil of the ichthyosaur Stenopterygius quadriscissus showing a juvenile half-emerged from its mother, which seems to be around a quarter of the parental length.


Thus, LeBlond and Bousfield's argument that tiny precocial young indicate a 'reptilian' identity is completely at odds with live birth in marine reptiles. There was a discussion of this in Woodley et al. (2011) but it was eventually deemed tangential as the Hagelund specimen was already reclassified and the dead horse was already beaten into a liquid.



References:

Caldwell, M. W., and Lee, M. S. Y. (2001). Live birth in Cretaceous marine lizards (mosasauroids). Proc. R. Soc. Lond. B. 268, 2397-2401. Available.

LeBlond, P. H. & Bousfield, E. L. (1995). Cadborosaurus, Survivor from the Deep. Victoria, British Columbia: Horsdal & Schubart.

Lemen, C. A. and Voris, H. K. A. (1981) Comparison of Reproductive Strategies among Marine Snakes. Animal Ecology 50, 89-101. Available.

O’Keefe, F. R. & Chiappe, L.M. (2011). Viviparity and K-selected life history in a Mesozoic marine reptile. Science 333, 870-873. DOI: 10.1126/science.1205689

Sanders, K. L., Mumpuni, Lee, M. S. Y. (2010). Uncoupling ecological innovation and speciation in sea snakes (Elapidae, Hydrophiinae, Hydrophiini). Journal of Evolutionary Biology 23(12) DOI: 10.1111/j.1420-9101.2010.02131.x

Woodley, M. A., Naish, D. & McCormick, C. A. (2011). A Baby Sea-Serpent No More: Reinterpreting Hagelund's Juvenile "Cadborosaur" Report. Journal of Scientific Exploration 25(3), 495-512.



Previous entries:

A Baby Cadborosaur No More. Part 1: Introduction

A Baby Cadborosaur No More. Part 2a: Hagelund's Account

A Baby Cadborosaur No More. Part 2b: Hagelund's Account - annotated

A Baby Cadborosaur No More. Part 3: Dealing With Traits

A Baby Cadborosaur No More. Part 4: What is 'Cadborosaurus'?
A Baby Cadborosaur No More. Part 5: Hagelund's Specimen And The Cadborosaurus
A Baby Cadborosaur No More. Part 6a: Cold Water on the 'Reptilian Hypothesis'

Tet Zoo Coverage: 
A baby sea-serpent no more: reinterpreting Hagelund’s juvenile Cadborosaurus

A Baby Cadborosaur No More. Part 6a: Cold Water on the 'Reptilian Hypothesis'

LeBlond and Bousfield (1995) made remarkable conclusions about the affinities of 'Cadborosaurus' (page 82):

The thinness and elongation of the body, the poikilothermy (or cold-bloodedness) which it seems to imply, and the great difference in size between the young and the adult are strong points in favour of a reptilian nature. 

I will cover why the second half of the sentence is incredibly wrong in a following post. This was originally going to be a footnote, but quickly got out of hand.

The authors hypothesized that since 'Cadborosaurus' is "long and narrow in shape" it has too much surface area to maintain a high body temperature and is thus an ectotherm†. I do not find this reasoning convincing. The slimmest cetacean is the Northern Right Whale Dolphin (Lissodelphis borealis) which has a fineness ratio (maximum length/maximum thickness) of up to 10.9 (Fish 1993 - citing Leatherwood and Walker 1979) and yet it occurs in the north Pacific up to the Aleutians (Baird and Stacey 1990). Leopard seals are also quite slender and occur in Antarctica. Both of these ectotherms are compared to snakes by some observers (L. borealis is sometimes even called the "snake porpoise") despite being elongated and not truly anguilliform, which makes me wonder how literally the "snake-like" description of 'Cadborosaurus' should be taken. LeBlond and Bousfield based their image of 'Cadborosaurus' on the ultra-svelte (fineness ratio of over 30) Naden Harbour carcass, which is probably the spinal column (and attached bits) from a known species.

† LeBlond and Bousfield actually state 'poikilothermic', but this is not the correct usage; 'ectothermic' refers to relying primarily on the environment for body temperature and 'poikilothermic' refers to the ability to withstand a wide range of body temperatures. The authors also erroneously used 'homeothermic' for 'endothermic'; 'endothermic' refers to relying primarily on internal sources for body temperature and 'homeothermic' refers to organisms which keep a stable body temperature, either internally or through the environment.

LeBlond and Bousfield claim that 'Cadborosaurus' normally inhabits 5-12 °C waters with inferred ventures into colder waters (from the Naden Harbour carcass being ingested by a Sperm Whale) and to warmer waters for reproduction... more on that later. Remarkably, there is an elongated marine reptile which can tolerate these temperatures. The Pelagic Sea Snake Pelamis platura barely straggles into California due to the 18 °C isotherm, but can tolerate 16-18 °C (stops eating), 7-8.5 °C (stops swimming), 6-6.5 °C (falls into torpor), and even exposure to temperatures of 5 °C for an hour (Graham et al. 1971). Graham et al. (1971) telling describe this snake as "weak swimming", which makes me wonder, isn't an ectothermic 'Cadborosaurus' with a "very high swimming speed" contradictory?

Pelamis platura, apparently the most cold-tolerant marine reptile which isn't a turtle. From Wikipedia Commons.

The Leatherback Seaturtle (Dermochelys coriacea) is presently viewed as an uncommon seasonal resident of British Columbia (McAlpine et al. 2004) and is suggested to be occupying marginal habitat as far north as Alaska (Hodge and Wing 2000). Leatherbacks are physiologically remarkable, as they are capable of diving into waters as cold as 0.4 °C (James et al. 2006) and retain heat through a thick layer of blubber (unique among reptiles) along with their large size (Wallace and Jones 2008, Davenport et al. 2009). Leatherbacks are not the only turtles known from high latitudes; Green Seaturtles (Chelonia mydas) have been reported from British Columbia (McAlpine et al. 2004) and Alaska, and there are records of Loggerhead (Caretta caretta) and Olive Ridley Seaturtles (Lepidochelys olivacea) in Alaska as well (Hodge and Wing 2000). Hodge and Wing (2000) suggest that the non-Leatherbacks in Alaska are straying out of their tolerable range, although McAlpine et al. (2007) warn that interest in Canadian seaturtles is recent and that their status off British Columbia needs assessment.

Dermochelys coriacea from Wikipedia Commons.

Since the only British Columbian marine reptiles are about as un-'Cadborosaurus'-like as is possible, I think that speaks volumes about the probability of the 'ectothermic' hypothesis.


Previous entries:

A Baby Cadborosaur No More. Part 1: Introduction

A Baby Cadborosaur No More. Part 2a: Hagelund's Account

A Baby Cadborosaur No More. Part 2b: Hagelund's Account - annotated

A Baby Cadborosaur No More. Part 3: Dealing With Traits

A Baby Cadborosaur No More. Part 4: What is 'Cadborosaurus'?
A Baby Cadborosaur No More. Part 5: Hagelund's Specimen And The Cadborosaurus


Tet Zoo Coverage: 
A baby sea-serpent no more: reinterpreting Hagelund’s juvenile Cadborosaurus


References: 

Baird, R. W. and Stacey, P. J. (1990). Status of the Northern Right Whale Dolphin (Lissodelphis borealis), in Canada. The Canadian Field-Naturalist 105, 243-250. Available.

Davenport, J., Fraher, J., Fitzgerald, E., McLaughlin, P., Doyle, T., Harman, L., and Cuffe, T. (2009). Fat head: an analysis of head and neck insulation in the leatherback turtle (Dermochelys coriacea). J Exp Biol 212, 2753-2759. doi: 10.1242/​jeb.026500.

Fish, F. E. (1993). Influence of Hydrodynamic Design and Propulsive Mode on Mammalian Swimming Energetics. Australian Journal of Zoology 42, 79-101. Available.

Graham, J. B., Rubinoff, I., and Hecht, M. K. (1971). Temperature Physiology of the Sea Snake Pelamis platurus: An Index of Its Colonization Potential in the Atlantic Ocean. PNAS 68(6), 1360-1363. Available.

Hodge, R. P., and B. L. Wing. (2000). Occurrences of marine turtles in Alaska waters 1960-1998. Herpetological Review 31,: 148-151. Available.

James, M. C., Davenport, J., and Hays, G. C. (2006). Expanded thermal niche for a diving vertebrate: A leatherback turtle diving into near-freezing water. Journal of Experimental Marine Biology and Ecology 335, 221–226. Available.

LeBlond, P. H. & Bousfield, E. L. (1995). Cadborosaurus, Survivor from the Deep. Victoria, British Columbia: Horsdal & Schubart.

McAlpine, D. F., James, M. C., Lien, J., Orchard, S. A. Status and Conservation of Marine Turtles in Canadian Waters. Herpetological Conservation 2, 85–112. Available.

McAlpine, D. F., Orchard, S. A., Sendall, K. A., and Palm, R. (2004). Status of marine turtles in British Columbia waters: a reassessment. Canadian Field-Naturalist 118(1), 72-76. Available.

Wallace, B. P., and Jones, T. J. (2008). What makes marine turtles go: A review of metabolic rates and their consequences. Journal of Experimental Marine Biology and Ecology 356, 8–24. Available.

Woodley, M. A., Naish, D. & McCormick, C. A. (2011). A Baby Sea-Serpent No More: Reinterpreting Hagelund's Juvenile "Cadborosaur" Report. Journal of Scientific Exploration 25(3), 495-512.


Secondary Reference:

Leatherwood, S., and Walker, W. A. (1979). The northern right whale dolphin Lissodelphis borealis Pede in the eastern North Pacific. In: Behavior of Marine Animal volume 3 (Eds H. E. Winn and
B. L. Olla.) pp. 85-141. (Plenum Press: New York.)