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Natural Science Forum / Biology / Paleontology / March 2005Could sea dinosaurs have lived during ancient times?
I vaguely recall some documentary where it was suggested Megalodon might have survived until the beginning of mankind's seafaring. How can we be sure some large sea-dwelling dinosaurs did not survive much longer than expected and might account for some of the old sea monster stories? > I vaguely recall some documentary where it was suggested Megalodon > might have survived until the beginning of mankind's seafaring. How can > we be sure some large sea-dwelling dinosaurs did not survive much > longer than expected and might account for some of the old sea monster > stories? We can't. Of course we don't know of any large sea-dwelling dinosaurs, living or extinct. The largest I know of are plotopterids, a bit less than 2 meters long, or albatrosses, with 3-meter wingspans. Were you perhaps thinking of plesiosaurs or mosasaurs? Not dinosaurs. At any rate, this assumption isn't very parsimonious, since it's easy for a dugong to turn into a mermaid. Have you ever seen an actual dugong? >> I vaguely recall some documentary where it was suggested Megalodon >> might have survived until the beginning of mankind's seafaring. How can [quoted text clipped - 8 lines] > rate, this assumption isn't very parsimonious, since it's easy for a > dugong to turn into a mermaid. Have you ever seen an actual dugong? Hey, those sailors were at sea for a _long_ time. --RC We only recently learned of the colossal squid... imagine ancient seafarers encountering that! > We only recently learned of the colossal squid... imagine ancient > seafarers encountering that! They called it something else. Krakan. I hope my spelling was right. Such as Basilosaurus,Mosasaurus,Liopleurodon,etc. How do we know they didn't live much longer than previosuly thought? Picture one of these creatures attacking an ancient seagoing vessel! How would they describe it? In the 'Odyssey" Scylla and Charybdis is described. Picture for example, an area where say some plesiosaurs frequented. Wouldn't you describe a plesiosaur as having a long neck and mouthful of teeth? > Such as Basilosaurus,Mosasaurus,Liopleurodon,etc. How do we know they > didn't live much longer than previosuly thought? Picture one of these > creatures attacking an ancient seagoing vessel! How would they describe > it? Basilosaurus was a whale, not a dinosaur. Mosasaurus was a lizard, not a dinosaur. Liopleurodon was a plesiosaur, a group with no close living relatives, and definitely not a dinosaur. > In the 'Odyssey" Scylla and Charybdis is described. Picture for > example, an area where say some plesiosaurs frequented. Wouldn't you > describe a plesiosaur as having a long neck and mouthful of teeth? Yes. And would you also claim that one-eyed giants once lived in Sicily? I guess part of the problem is separating the myth from reality.I have heard some accounts that the Cyclops might simply have been a group of large people with respect to the time in a world where people generally travel much or get much exposure. I should have rephrased the question as "prehistoric,large aquatic life" > > In the 'Odyssey" Scylla and Charybdis is described. Picture for > > example, an area where say some plesiosaurs frequented. Wouldn't you > > describe a plesiosaur as having a long neck and mouthful of teeth? Alternatively, if I was bitten by a large moray eel protruding from its cave while diving in the ancient Mediterranean I might conclude that I was attacked by a creature with a long neck and a mouthful of teeth. Cheers Brian >Such as Basilosaurus,Mosasaurus,Liopleurodon,etc. How do we know they >didn't live much longer than previosuly thought? Picture one of these [quoted text clipped - 4 lines] >example, an area where say some plesiosaurs frequented. Wouldn't you >describe a plesiosaur as having a long neck and mouthful of teeth? The basic problem is that we have no fossils of these creatures from later than the Cretaceous, so the size of any surviving populations would have to have remained small over the last 65 million years. But small populations don't survive over millions of years -- they either expand into larger populations or they go extinct. The idea that a small population of ancient sea creatures might have persisted over 65 million years from the time of the dinosaurs until the time of the ancient Greeks (and only then conveniently going extinct) is not impossible in any strict sense, but statistically it is so implausible that it might as well be.  SignatureJohn Brock jbrock@panix.com "John Brock" <jbrock@panix.com> kirjoitti viestissä:cvldsd$10l$1@reader2.panix.com... > The basic problem is that we have no fossils of these creatures > from later than the Cretaceous, so the size of any surviving [quoted text clipped - 6 lines] > conveniently going extinct) is not impossible in any strict sense, > but statistically it is so implausible that it might as well be. A counterexample: latimeria chalumnae http://www.austmus.gov.au/fishes/fishfacts/fish/coela.htm Quote: "The Coelacanth specimen caught in 1938 is still considered to be the zoological find of the century. This 'living fossil' comes from a lineage of fishes that was thought to have been extinct since the time of the dinosaurs." "Coelacanths are known from the fossil record dating back over 360 million years, with a peak in abundance about 240 million years ago. Before 1938 they were believed to have become extinct approximately 80 million years ago, when they disappeared from the fossil record." H Tavaila > http://www.austmus.gov.au/fishes/fishfacts/fish/coela.htm > [quoted text clipped - 10 lines] > > H Tavaila Yes, but look at the habits and habitat of the creature - the coelacanth is a sedentary benthic fish that spends its entire life cycle restricted to a handful of deep rocky slopes without ever coming near the surface. Large marine reptiles certainly would not be able to maintain this lifestyle without a) starving - especially an apex predator like a pliosaur or mosasaur which would have to prowl through a large area of ocean or b) drowning. In other words, the coelacanth's lifestyle gives it an excuse for remaining hidden for all these years - I don't sea large predatory air-breathing reptiles using the same strategy. I'd wager that legends of giant serpentine creatures are based on sightings of this critter rather than some late-surviving mosasaur or plesiosaur... http://www.amonline.net.au/fishes/fishfacts/fish/rglesne.htm Cheers Brian > I'd wager that legends of giant serpentine creatures are based on > sightings of this critter rather than some late-surviving mosasaur or [quoted text clipped - 4 lines] > Cheers > Brian The following images gives a better idea as to how freaking huge this "serpent" gets... http://www.thejump.net/id/oarfish.htm http://www.saranair.com/article.php?sid=8002&mode=nested&order=0&thold=0 Cheers Brian >> http://www.austmus.gov.au/fishes/fishfacts/fish/coela.htm >> [quoted text clipped - 33 lines] > Cheers > Brian In general I agree with you but a couple of fairly decent sized toothed whales are only known from one or two bodies that happened to be found washed up on the beach. A few known kinds live over ocean deeps and aren't found anywhere else. At least one carcus of what is believed to have been a huge octipus washed up in Florida back around the turn of the century. Nothing else has shown up that seems to relate to it. The way they preserved the tissue sample prevents genetic studies. What I'm saying is I agree it isn't very likely but something might still turn up. In another twenty years I'd say virtually impossible for a large unknown animal to show up. As yet nobody has caught a live adult gaint squid or so I've heard and those things seem to be fairly common in some locations. >In general I agree with you but a couple of fairly decent sized toothed >whales are only known from one or two bodies that happened to be found [quoted text clipped - 3 lines] >Nothing else has shown up that seems to relate to it. The way they preserved >the tissue sample prevents genetic studies. Some people think that the Florida "octopus", and other "globsters", were badly decomposed whales - see <URL:http://www.cephbase.utmb.edu/ref db/pdf/7662.pdf> SignatureStewart Robert Hinsley >>In general I agree with you but a couple of fairly decent sized toothed >>whales are only known from one or two bodies that happened to be found [quoted text clipped - 9 lines] > were badly decomposed whales - see <URL:http://www.cephbase.utmb.edu/ref > db/pdf/7662.pdf> About the Florida sample. To repeat they have a tissue sample that negates that idea. The best match is octipus though certainly an unkown kind. I saw a photo. There is no bleeping way that was a whale. The arms were stumps but it wasn't that far gone. Anybody that thinks this was a whale is ignoring the evidence. > In general I agree with you but a couple of fairly decent sized toothed > whales are only known from one or two bodies that happened to be found > washed up on the beach. A few known kinds live over ocean deeps and aren't > found anywhere else. Yeah - I'm assuming you mean beaked whales (Ziphiidae). But in general, aside from the fact that we know little of their life history, beaked whales as a group are not that mysterious - many researchers see and film them, many bones and carcasses are present in museums, until the 1970s the Soviets and Norwegians ate them (the Japanese still do I think from small-scale harpoon fisheries). In other words, beaked whales as a GROUP are common and well established, but some SPECIES of beaked whale are very rare, poorly understood and still being discovered (Mesoplodon peruvianus was described as recently as 1991) - and their existence is based on physical evidence (skeletons & carcasses preserved in museums and universities). > What I'm saying is I agree it isn't very likely but something might still > turn up. In another twenty years I'd say virtually impossible for a large > unknown animal to show up. As yet nobody has caught a live adult gaint squid > or so I've heard and those things seem to be fairly common in some > locations. Well - New Zealand fishermen fishing for Hoki quite regularly catch live giant squid in their nets but they die soon after being brought to the surface. Juvenile giant squid have been kept in aquaria for about 4 weeks by Dr Steve O'Shea. Hmm...with regards to the original Seeker question of the post (giant Mesozoic marine reptiles surviving into the Quaternary) - I'm sure that there are many unknown animals out there in the ocean - some of them really big, ancient and unexpected (megamouth and giant Riftia tubeworms came as complete surprises). However, I seriously doubt that there are any more MARINE TETRAPOD GROUPS waiting to be found - there may be plenty of undescribed families of sharks, cephalopods, jellyfish or whatever but no mosasaurs, plesiosaurs or archaeocete whales. When you breathe air, have a carcass that floats, plus a nice bony skeleton to leave behind, you cannot hide from non-cryptozoological researchers for long... Note that new large marine tetrapod SPECIES are still being discovered (usually whales) - but they always fit into established modern groups. For example there are at least 2 undescribed rorqual whales out there, misidentified as Minke and Bryde's. Cheers Brian >"John Brock" <jbrock@panix.com> kirjoitti >viestissä:cvldsd$10l$1@reader2.panix.com... >> The basic problem is that we have no fossils of these creatures >> from later than the Cretaceous, so the size of any surviving [quoted text clipped - 6 lines] >> conveniently going extinct) is not impossible in any strict sense, >> but statistically it is so implausible that it might as well be. >A counterexample: latimeria chalumnae > [quoted text clipped - 10 lines] >they were believed to have become extinct approximately 80 million years >ago, when they disappeared from the fossil record." I was wondering if anyone would mention the Coelacanth. It's not a good counterexample though. As mentioned in your link, two widely separated populations have been discovered, which suggests that there are probably other populations as well. In fact this link: http://www.saiab.ru.ac.za/educoel4.htm mentions several additional populations. The individual populations aren't that small either (est. 300 - 700+ for Grand Comoro, which is not large, but hardly tiny). In addition, the Coelacanth isn't exceptionally big physically, and modern populations live in an environment which doesn't favor fossilization, so it's not that surprising there is a gap in the fossil record. For all we know the Coelacanth might have been even more common and more widely distributed in the fairly recent past than it is today, and its population may well have had many ups and downs over the 80 million years since it last appeared in the fossil record. This is very different from the sort of situation we're talking about, where a tiny population of large, air breathing, Loch Ness type sea monsters persists over millions of years in a single location, never colonizing other, easily accessible, habitats, and, despite their low numbers, never going extinct. Small populations of large animals are very vulnerable, and statistically this sort of thing just isn't going to happen. Another interesting "counterexample" to my thesis -- although still not good -- is the Monotremes. With only three living species, humans may have been fortunate enough to have caught the the very tail end of the era of egg laying mammals, which have probably been steadily declining throughout the Cenozioc. The Tuatara, last of its Order, is another example of this. I wonder how many interesting animals we just missed seeing (aside from those we wiped out ourselves). For example, I wonder when the last Multituberculate died? It could have been long after they disappeared from the fossil record. SignatureJohn Brock jbrock@panix.com >>"John Brock" <jbrock@panix.com> kirjoitti >>viestissä:cvldsd$10l$1@reader2.panix.com... [quoted text clipped - 61 lines] > died? It could have been long after they disappeared from the > fossil record. That reminds me of this: Thulborn, T., and S. Turner. 2003. The last dicynodont: An Australian Cretaceous relict. Proc. R. Soc. Lond. B 270:985-993. OK, it's not recent, but it is a pretty big gap in the fossil record. Just pretend we're living in the Cretaceous and have just discovered Australia (or that region of Gondwana). And dicynodonts aren't that small. >> Another interesting "counterexample" to my thesis -- although still >> not good -- is the Monotremes. With only three living species, [quoted text clipped - 6 lines] >> died? It could have been long after they disappeared from the >> fossil record. >That reminds me of this: > [quoted text clipped - 4 lines] >Just pretend we're living in the Cretaceous and have just discovered >Australia (or that region of Gondwana). And dicynodonts aren't that small. Hmmm..., Australia does seem to be the place to go for relicts, doesn't it? You know, it's a pity that there wasn't some Australia or India sized continent somewhere that was *really* separate from everything else for, say, the last 400 million years or so. Think what an interesting place *that* might be! SignatureJohn Brock jbrock@panix.com > Such as Basilosaurus,Mosasaurus,Liopleurodon,etc. How do we know they > didn't live much longer than previosuly thought? Picture one of these [quoted text clipped - 4 lines] > example, an area where say some plesiosaurs frequented. Wouldn't you > describe a plesiosaur as having a long neck and mouthful of teeth? The long necked one had small heads and most likely ate fairly small food. A Mosasaurus looks much like some of the primitive whales. >>Such as Basilosaurus,Mosasaurus,Liopleurodon,etc. How do we know they >>didn't live much longer than previosuly thought? Picture one of these [quoted text clipped - 7 lines] > The long necked one had small heads and most likely ate fairly small food. A > Mosasaurus looks much like some of the primitive whales. Doesn't one of them (I forget whether it's Scylla or Charibdis) have 12 heads? Shouldn't we then be looking for fossil plesiosaurs with 12 heads? Or is it just the details you *like* that must be based on facts? No need to be nasty! What i was suggesting as pure speculation is possibility of nesting ground of multiple creatures matching that description of long necks and heads full of teeth. We always hear theories that ancient accounts are pure exaggeration or myth but no one ever seems to look at it from the opposite point of view.. ancient seafarers describing experiences in the best way they knew how.. > No need to be nasty! What i was suggesting as pure speculation is > possibility of nesting ground of multiple creatures matching that [quoted text clipped - 4 lines] > view.. ancient seafarers describing experiences in the best way they > knew how.. It's always possible that some of the fantastic tales have a little bit of truth in them. And I suppose speculation is harmless. But I just want you to notice that you are picking those aspects of the tales that you want to in order to fit your speculation and ignoring those aspects that don't fit. That's not a good way to work. If you accept Scylla and Charibdis as real monsters, why not Pegasus, or the gorgons, or hydras, or people with faces in the middles of their chests, etc.? What's most likely? I think it's most likely that there were no plesiosaurs (or whatever) surviving in the last several thousand years, and that the stories of the Odyssey had sources in imagination or had less fantastic kernels of inspiration. The recently discovered sea animals like coelacanths and giant squid have one simple feature in common: they inhabit deep waters and rarely venture very near the surface. No air-breathers need apply, whether or not they breed in caves. >> No need to be nasty! What i was suggesting as pure speculation is >> possibility of nesting ground of multiple creatures matching that [quoted text clipped - 20 lines] > inhabit deep waters and rarely venture very near the surface. No > air-breathers need apply, whether or not they breed in caves. Large squid have been known to come to the surface. A few people on small boats and life rafts have been attacked. They have the scars to prove it. The suckers on some of the squid are lined with spins or spikes that could convince people that they had been bitten. It would certainly feel like it and the sucker marks would look more or less like it. People on large modern ships would of course be more or less oblivous of these animals even if they were traveling at high speed through school of them. During WW II people on life rafts did have a few close encounters with these creatures. I'm not sure what the squid thought but the humans didn't enjoy it. >>>No need to be nasty! What i was suggesting as pure speculation is >>>possibility of nesting ground of multiple creatures matching that [quoted text clipped - 22 lines] > > Large squid have been known to come to the surface. That's why I said "rarely". [snip] >>>Such as Basilosaurus,Mosasaurus,Liopleurodon,etc. How do we know they >>>didn't live much longer than previosuly thought? Picture one of these [quoted text clipped - 10 lines] > heads? Shouldn't we then be looking for fossil plesiosaurs with 12 heads? > Or is it just the details you *like* that must be based on facts? With me everything not considered fiction or speculation has to be based on facts. You might go back and try and sort out what I was responding to from what I said. >>>>Such as Basilosaurus,Mosasaurus,Liopleurodon,etc. How do we know they >>>>didn't live much longer than previosuly thought? Picture one of these [quoted text clipped - 15 lines] > facts. You might go back and try and sort out what I was responding to from > what I said. Sorry, I was actually responding to "seeker". You just got in the crossfire. > I vaguely recall some documentary where it was suggested Megalodon > might have survived until the beginning of mankind's seafaring. How can > we be sure some large sea-dwelling dinosaurs did not survive much > longer than expected and might account for some of the old sea monster > stories? Well, compared to some other sharks, Megalodon isn't really that ancient (oldest Carcharocles - Eocene, oldest C.megalodon - Miocene) - so if megalodon HAD co-habited the planet with early humans, it would be no more wondrous than say mastodons or giant ground-sloths co-habiting the the planet with early humans. Given the number of teeth a shark sheds in its lifetime, if meg had survived beyond the Pliocene, then it has no excuses for not leaving a fossil record. As John pointed out, there were no large sea-dwelling dinosaurs - well I suppose Hesperornis WAS a bloody big bird, not to mention Anthropornis... Cheers Brian >I vaguely recall some documentary where it was suggested Megalodon >might have survived until the beginning of mankind's seafaring. How can >we be sure some large sea-dwelling dinosaurs did not survive much >longer than expected and might account for some of the old sea monster >stories? I think that you are really asking about large marine reptiles, not specifically about dinosaurs. Some good sized marine reptiles did survive -- crocodiles and turtles. As for the others. There were three kinds. Fishlike icthyosaurs seem to have died out well before the demise of the dinosaurs. My impression is that nobdy has any idea why. Long necked plesiosaurs seem to have been doing poorly and may already have been extinct at the end of the Cretaceous when the dinosaurs died out. But the lizard-like mososaurs were doing just fine until the extinction at the end of the Cretaceous where they simply vanish. It's not entirely impossible that some population of one of these groups might have survived. A few fish thought to have died out many millions of years ago have turned up alive and biting -- the Goblin shark -- Scapanoprhynchus and the ceolocanths are best known examples. But it's not really all that likely as reptiles, unlike fish, need to come to the surface regularly in order to refresh their air supply. Makes it harder to hide. These critters -- especially plesiosaurs -- are regualrly invoked to account for various lake monsters. Personally, I'm really skeptical. I live near a lake (Lake Champlain) that is purportedly inhabited by one of them and I have just a bit of trouble with the thesis. For one thing, you can see maybe half the lake surface from Main Street in Burlington, Vermont. Surely, a lot of people would notice a good sized reptile sunbathing out there. There have been large numbers of boats plying the lake for 200 years. In the Summer, there are four ferries crossing the lake just as fast as they can and many hundreds of pleasure craft cruising the lake. And in the Winter, the entire lake often freezes over. You could presumably walk from New York to Vermont although I don't think that the Coast Guard encourages that As for Megalodon, it was apparently never all that common. Some unmineralized teeth that might be pretty recent have been reported. Might still be around. But probably not. And look at the Coelocanth, thought to be extinct until its 20th century re-discovery But what if some of these creatures were amphibious to some degree,such as turtles? Could plesiosaurs have perhaps used caves and cavernous areas (above or below water) to produce offspring? Like turtles coming ashore and laying eggs on the beach? > But what if some of these creatures were amphibious to some degree,such > as turtles? Could plesiosaurs have perhaps used caves and cavernous > areas (above or below water) to produce offspring? Like turtles coming > ashore and laying eggs on the beach? You seem to constantly troll for support of strange or unlikely scenarios. Is there a reason why you do this? Z Not trying to troll.. i remember seeing a discovery channel show in which some of the scientists speculated that Megalodon might have survived up to the times of ancient seafarers. > But what if some of these creatures were amphibious to some degree,such > as turtles? Could plesiosaurs have perhaps used caves and cavernous > areas (above or below water) to produce offspring? Like turtles coming > ashore and laying eggs on the beach? Try this: Cheng et al. 2004. Triassic marine reptiles gave birth to live young. Letters to Nature. Nature 432: 383-386. (18.XI.2004). Probably plesiosaurs were also viviparious. Cheers, Dawid. |
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