tag:blogger.com,1999:blog-6903316070344664352.post5069031516829826616..comments2024-03-21T07:21:10.901-04:00Comments on The Lord Geekington: Swimming OpossumsCameron McCormickhttp://www.blogger.com/profile/08521083680718243221noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-6903316070344664352.post-69625692889119949182008-08-03T19:56:00.000-04:002008-08-03T19:56:00.000-04:00Prehensile hands & semi-semi-aquaticism can go...Prehensile hands & semi-semi-aquaticism can go together: we've written a few papers on vertically wading-floating-hanging Mio-Pliocene hominoid apes in densely vegetated swamp forests, please google "aquarboreal".Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6903316070344664352.post-81998900750579609262007-11-19T13:01:00.000-05:002007-11-19T13:01:00.000-05:00Further note: I saw "Pole to Pole" on the Planet E...Further note: I saw "Pole to Pole" on the Planet Earth documentary today and it did show a giraffe walking across a flooded area. Curiously, it mentioned that impala can "barely swim", suggesting (to me) that an even longer neck and more spindly legs in the giraffe would render it nearly incapable of swimming.Cameron McCormickhttps://www.blogger.com/profile/08521083680718243221noreply@blogger.comtag:blogger.com,1999:blog-6903316070344664352.post-62613804605002509532007-11-11T00:25:00.000-05:002007-11-11T00:25:00.000-05:00admittedly they're not truly "aquatic"Exactly. Tho...<I>admittedly they're not truly "aquatic"</I><BR/><BR/>Exactly. Those are all either semi-aquatic animals like the opossum or terrestrial like humans. What I was going for is that fully aquatic mammals (cetaceans, sirenians) and near-fully aquatic ones (pinnipeds) lack prehensile limbs, having traded them in for flippers. How efficient could a swimmer be if it still had prehensile limbs? Granted sea otters have prehensile hands and can even give birth in the ocean, but they're still not adapted (capable of speeds in the 5-6 knot area). So perhaps a marine marsupial could have been possible had it been rather limited (and some strange selective pressure taking place).<BR/><BR/><BR/><I>It's more likely that the successful mammal and bird clades that made it to the water first were simply more mandibular oriented than anything else.Same applies to the mesozoic and paleozoic aquatic reptiles and birds.This seems to be the most parsimonious explaination at the moment.</I><BR/><BR/>But if you are going to be a marine tetrapod capable of swimming the open ocean, you're probably going to need your forelimbs for stability - or in the case of sea snakes, no limbs at all. I really do not think it would be possible to be an open ocean animal with prehensile limbs, everything so far seems to be mandibular based. I did give prehensile limbed animals too little credit, but I don't think anything "beyond" the adaptation of a sea otter would be possible without losing the prehensile limbs. Cephalopods have prehensile limbs, but their morphology is so radically different I hardly think they could be compared.<BR/><BR/><BR/><I>As for apes being bad swimmers, well, what is present today are highly specialized members which are mere shadow of a once far more diverse clade.It's somewhat akin to saying apes can't thrive in temperate zones because none are present today.Yet pliocene remains of Dryopithicus are known from quite seasonal european deposits that indicate cold winters.</I><BR/><BR/>But if the diversity of apes (including gibbons and siamangs) is incompetent at swimming, wouldn't that hint at it being an ancestral characteristic and/or morphological issue? There could have been a specialized ape that took more to water than normal, but that's just speculative.Cameron McCormickhttps://www.blogger.com/profile/08521083680718243221noreply@blogger.comtag:blogger.com,1999:blog-6903316070344664352.post-78296883107707855912007-11-10T19:52:00.000-05:002007-11-10T19:52:00.000-05:00"Good point about the hands, I wonder how far an a..."Good point about the hands, I wonder how far an aquatic creature can adapt and still have prehensile hands? Probably not very. I don't recall any of the aquatic ape theorists mentioning that...or the fact that apes are incompetent swimmers at best."<BR/><BR/>Proboscis monkeys?Otter shrews?<BR/>Desmans?Otters?Humans?"Thalassocnus"? etc.etc.<BR/><BR/>admittedly they're not truly "aquatic" but certainly in the case of the sea sloths, there's no evidence they were losing the ability to grasp kelp strands with their manus throughout their evolutionary history IIRC.<BR/><BR/>It's more likely that the successful mammal and bird clades that made it to the water first were simply more mandibular oriented than anything else.Same applies to the mesozoic and paleozoic aquatic reptiles and birds.This seems to be the most parsimonious explaination at the moment.<BR/><BR/>As for apes being bad swimmers, well, what is present today are highly specialized members which are mere shadow of a once far more diverse clade.It's somewhat akin to saying apes can't thrive in temperate zones because none are present today.Yet pliocene remains of Dryopithicus are known from quite seasonal european deposits that indicate cold winters.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6903316070344664352.post-37128456891221296612007-11-08T16:09:00.000-05:002007-11-08T16:09:00.000-05:00Giraffes have never been observed swimming, they h...Giraffes have never been observed swimming, they have been observed sinking though. <BR/><BR/>They have also been found on island surrounded by 14 ft deep water, but they could have easily walked across it. <BR/><BR/>I demand a blog to settle this once and for all. A few giraffes and a very deep pool would also be useful.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6903316070344664352.post-30003592374139651362007-11-08T12:22:00.000-05:002007-11-08T12:22:00.000-05:00Well, my sister is fairly certain of it at least. ...Well, my sister is fairly certain of it at least. It's an age-old argument. I've seen some videos of giraffes crossing rivers, but it never got deep enough that they had to start swimming. The Guinness Book of Animal facts and feats claims that:<BR/><BR/>"Because of its extraordinarily anatomical shape the giraffe is one of the very few mammals that cannot swim - even in an emergency! Deep rivers are an impassable barrier to them, and they will avoid large expanses of water like the plague. On 26 September 1960 a giraffe escaped from its crate shortly after it panicked and fell into the water from a jetty. According to one eye-witness report the terrified animal sank like a stone without making any attempt to swim"<BR/><BR/><BR/>That's the only evidence backing that notion up, and maybe panicking had something to do with it. Surely if camels can swim giraffes could at least thrash around a little...<BR/><BR/>Good point about the hands, I wonder how far an aquatic creature can adapt and still have prehensile hands? Probably not very. I don't recall any of the aquatic ape theorists mentioning that...or the fact that apes are incompetent swimmers at best.Cameron McCormickhttps://www.blogger.com/profile/08521083680718243221noreply@blogger.comtag:blogger.com,1999:blog-6903316070344664352.post-55484165552209631422007-11-08T09:41:00.000-05:002007-11-08T09:41:00.000-05:00Are you sure that giraffes can't swim? This is one...Are you sure that giraffes can't swim? This is one of those oft-mentioned factoids, but I'd like to know if it's true. It's also said in the books that camels can't swim, but I can state with absolute certainty that this is incorrect. Some people say that white rhinos can't swim - I have a hard time accepting this, but I've never seen it tested :)<BR/><BR/>Regarding the Ecuadorian 'mystery mammal', an examination by Didier Sanchez showed that it was a taxiderm hoax, and you're almost certainly right that it's a modified yapok.<BR/><BR/>Incidentally, marsupials may owe their paucity of amphibious/aquatic species to the fact that their babies tend to need prehensile hands at birth. This constraint may prevent them from evolving webbed digits and flippers. The pouch is less of a problem, as of course lots of marsupial clades have lost it.Darren Naishhttps://www.blogger.com/profile/00324870234525004643noreply@blogger.comtag:blogger.com,1999:blog-6903316070344664352.post-88244103831795323292007-11-07T19:46:00.000-05:002007-11-07T19:46:00.000-05:00The sewers of nyc should really upgrade to those w...The sewers of nyc should really upgrade to those water opossums, they're so much cuter! I mean, come on, they have spots. <BR/><BR/>Thank you for owning up to the fact that giraffes cannot swim. In fact, I think that it is worthy of it's very own blog, where you can tell the world why this is physically impossible.Anonymousnoreply@blogger.com