Comment on Tylosaurus pembinensis by DrScottHartman
Hey Scott, this is great truly amazing. But wondering if you agree with my theory hypothesis...do you think that some of the later developed Mosasaurs did lack the tail fluke; do you think they're could've been two types of Mosasaurs swimmers or no?
I suspect all derived mosasaurs had some form of tail fluke (they all have tails that kink down to support them), but there was probably a range of how well developed it was in different clades.
I guess so, but then how would you explain the early Mosasaur, Dallasaurus and Cretaceous relatives Mosasaurus and Tylosaurus with at least one imprint or two from what I found lacking a fluke?
It will be hard to find the image, but I can try to find it again.
It will be hard to find the image, but I can try to find it again.
Dallasaurus is waaaay primitive - it's like one or two steps past marine iguanas in terms of aquatic adaptations, and isn't a good model for the more derived forms. Most importantly, it doesn't have the kink down in the tail that the derived forms do.
There is no imprint of Tylosaurus or Mosasaurus lacking a fluke, and frankly it would be pretty shocking if they didn't.
There is no imprint of Tylosaurus or Mosasaurus lacking a fluke, and frankly it would be pretty shocking if they didn't.
Yes I know, but I wouldn't include Dallasaurus if it wasn't a good reason. And actually from the images I found there are...I took the time to look at imprints of several Mosasaur skeletons in museums or so and three of them lacked any form of a tail fluke. Further information that I found is that when the fossils are usually are encased around glass or are one the ground those are the real ones. This is how I know these ones are real enough to support some evidence.
Here are the pictures I've come to inspect with a couple of new ones, with some of the contours at least there seems to be no sign of a fluke and the fossils are practically 100% genuine. I would even more good evidence, but I can't find the picture I saw before so I'm sorry for that, but this is all I can provide. So take a look a tell what you think about it...
2.bp.blogspot.com/_ZHv_I4h7INY…
2.bp.blogspot.com/-VaNr0UxjGJ8…
www.hgms.org/client_youth/Pale…
2.bp.blogspot.com/-ekdoa6V0jGw…
www.kansastravel.org/11naturer…
oceansofkansas.com/Lindgren/s-…
Here are the pictures I've come to inspect with a couple of new ones, with some of the contours at least there seems to be no sign of a fluke and the fossils are practically 100% genuine. I would even more good evidence, but I can't find the picture I saw before so I'm sorry for that, but this is all I can provide. So take a look a tell what you think about it...
2.bp.blogspot.com/_ZHv_I4h7INY…
2.bp.blogspot.com/-VaNr0UxjGJ8…
www.hgms.org/client_youth/Pale…
2.bp.blogspot.com/-ekdoa6V0jGw…
www.kansastravel.org/11naturer…
oceansofkansas.com/Lindgren/s-…
Those images don't have tail skin impressions at all! You can't look at a fossil that doesn't have the right skin impressions and then say "see, no fluke!". The only advanced mosasaurs with skin impressions on the tail show a fluke, and in every single other group of marine reptiles, including metriorhynchid crocodiles, when there is a king in the tail like in advanved mosasaurs AND there are skin impressions they always, always have a tail fluke. So it's a fallacy called "special pleading" to try and say there wasn't a fluke in a mosasaur with the same tail anatomy without very clear evidence.
Well I say this because I examined them; and it's not some cheap play calling to be even bias about. Plus have seen any other Mosasaur skin impressions other than in Prognathodon and Platecarpus (which I may add aren't even classified in the same families as Mosasaurus and Tylosaurus)?
The problem with Science and paleontology today is still the same thing went on since those crybabies Edward Drinker Cope and Othneil Marsh were still on with the Bone Wars; that being accusation, we all still go through this one swirl of acceptance that when one thing is changed and seen how it is everything must follow the same trend and personally I don't believe that. It's like with all the theropods (namely Coelurosaurs) we found only ten or six that have feathers and now we label all of them to have them, but in the case that the super predator ones didn't have any like T-rex; yes maybe the medium sized ones like Yutyrannus and Nanuqsaurus had down and fur, but it was only for warmth for the climates they lived under; Tyrannosaurus on the other hand at least as an adult may of never had feathers or Utahraptor and Gallimimus look like plump turkeys on Thanksgiving (though I still show respect for the conception; thank you, Dr. Grant). I know skin imprints from Mosasaurs are a rare thing, but from all the Mosasaurus and Tylosaurus fossils that have been found for centuries; have Paleontologists at least found one piece of evidence showing Mosasaurians and Tylosaurians to have a tail fluke (at least other than Plotosaurus of course)?
All going to show if they didn't have no then they'd still be good swimmers and be able to progress and the most ferocious sea creatures of their oceans up to date. The Plesiosaurs are the best example of evolution divergence among their species, some of them had really long-necks, some had short-necks and the others (the Pliosaurs) had fitted they're lives to eating other meats and have bigger heads and bodies than their cervically elongated cousins and even the Ichthyosaurs have some divergences in their families as well, with some having dorsal fins while others didn't and most eating fish while others went for other creatures like Cymbospondylus. If they lack bilobed tail; these Mosasaur familes could've used a similar method of swimming like crocodilians do; I mean prefeerentially Mosasaurs had their tails down like a crocodilians so in other cases they could've used that method of swimming like they're cousins today use. Yes you may note indeed that Metriorhynchids did have kinks in their tails to help them swim more efficiently within open-ocean currents, but then the crocodilian, Teleosaurus was an open-sea predator as well and it really didn't need a fluke or kink bend to support itself within the waters; this also going for modern crocodilians like the Salt-water Crocodile that usually swims long distances in the water, even the Mosasaurs' living relative the Komodo Dragon swims across long distances to get to other islands on the shores of Komodo and they use their powerful tails to swim across and rarely use their own limbs.
I don't mean tamper with you're further analysis on the assessments given, but you also have to prepare for the impact if somebody like were to come along with their idea, I mean it's like not like I'm wrong and neither are you, but there is the thought that maybe Mosasaurs came into two separate groups when it came to swimming methods; I mean what as the suggested the estimated number of dinosaur species is over 1000 and yet we still discovery new ones every year and what Mosasaurs made up at least 60% that roamed the earth and yet there are still new species discovered and that one could've had a flukeless and still be fully developed like the Cretaceous mosasaurs. So just like the other sea creatures Mosasaurs had different types ...like ones with kneeled scales!? www.wired.com/wp-content/uploa…
In other words it's best to take other speculations as well get and increase you're no how; this way to further analyze the situation; other wise it make you unaware of what to expect in the least.
oceansofkansas.com/Mosasaurs/v…
The problem with Science and paleontology today is still the same thing went on since those crybabies Edward Drinker Cope and Othneil Marsh were still on with the Bone Wars; that being accusation, we all still go through this one swirl of acceptance that when one thing is changed and seen how it is everything must follow the same trend and personally I don't believe that. It's like with all the theropods (namely Coelurosaurs) we found only ten or six that have feathers and now we label all of them to have them, but in the case that the super predator ones didn't have any like T-rex; yes maybe the medium sized ones like Yutyrannus and Nanuqsaurus had down and fur, but it was only for warmth for the climates they lived under; Tyrannosaurus on the other hand at least as an adult may of never had feathers or Utahraptor and Gallimimus look like plump turkeys on Thanksgiving (though I still show respect for the conception; thank you, Dr. Grant). I know skin imprints from Mosasaurs are a rare thing, but from all the Mosasaurus and Tylosaurus fossils that have been found for centuries; have Paleontologists at least found one piece of evidence showing Mosasaurians and Tylosaurians to have a tail fluke (at least other than Plotosaurus of course)?
All going to show if they didn't have no then they'd still be good swimmers and be able to progress and the most ferocious sea creatures of their oceans up to date. The Plesiosaurs are the best example of evolution divergence among their species, some of them had really long-necks, some had short-necks and the others (the Pliosaurs) had fitted they're lives to eating other meats and have bigger heads and bodies than their cervically elongated cousins and even the Ichthyosaurs have some divergences in their families as well, with some having dorsal fins while others didn't and most eating fish while others went for other creatures like Cymbospondylus. If they lack bilobed tail; these Mosasaur familes could've used a similar method of swimming like crocodilians do; I mean prefeerentially Mosasaurs had their tails down like a crocodilians so in other cases they could've used that method of swimming like they're cousins today use. Yes you may note indeed that Metriorhynchids did have kinks in their tails to help them swim more efficiently within open-ocean currents, but then the crocodilian, Teleosaurus was an open-sea predator as well and it really didn't need a fluke or kink bend to support itself within the waters; this also going for modern crocodilians like the Salt-water Crocodile that usually swims long distances in the water, even the Mosasaurs' living relative the Komodo Dragon swims across long distances to get to other islands on the shores of Komodo and they use their powerful tails to swim across and rarely use their own limbs.
I don't mean tamper with you're further analysis on the assessments given, but you also have to prepare for the impact if somebody like were to come along with their idea, I mean it's like not like I'm wrong and neither are you, but there is the thought that maybe Mosasaurs came into two separate groups when it came to swimming methods; I mean what as the suggested the estimated number of dinosaur species is over 1000 and yet we still discovery new ones every year and what Mosasaurs made up at least 60% that roamed the earth and yet there are still new species discovered and that one could've had a flukeless and still be fully developed like the Cretaceous mosasaurs. So just like the other sea creatures Mosasaurs had different types ...like ones with kneeled scales!? www.wired.com/wp-content/uploa…
In other words it's best to take other speculations as well get and increase you're no how; this way to further analyze the situation; other wise it make you unaware of what to expect in the least.
oceansofkansas.com/Mosasaurs/v…
OK, first of all, you asked for my take so I gave it to you. You can believe they flew and had neon feathers if you want, I was just trying to share with you the state of science. Second, what do you mean by "you examined them"? Have you seen them in person? Have you published your data? Science isn't about who has ideas or who has ego, it's about what the data shows, and just hopping on the internet and making statements doesn't make it data. If you have photos or some other data that isn't published that you'd like to share that's great, otherwise what am I supposed to comment on?
Third, and this is really pretty cut and dried, but Prognathodon is in the Mosasaurinae with Mosasaurus, and Platecarpus is in the Russellosaurina with Tylosaurus, so both are found in subfamilies with known fluke impressions. There's only two accepted mosasaur families, and both are represented. Getting basic facts like this wrong doesn't lend much credence to claiming that others are biased against you.
Fourth, this is nothing like the Bone Wars. Cope and Marsh hated each other and would sometimes take a stance simply to disagree with the other. I don't even work on squamates,and I certainly don't care which side is right, but the actual, published scientific literature is clear: mosasaurs from both families have been found with tail fluke soft-tissue evidence, and outside of Dallasaurus (which is really primitive) all known mosasaurs share the characteristic downturn in the tail that is associated with tail flukes in every other known marine vertebrate that has them. This isn't accusation, it's just the data. Now is it possible that there is some explanation for the downturn AND the preserved tail flukes in both the Mosasaurinae and the Russellosaurina? Sure, but without any shred of evidence to explain why that's just special pleading. "Special pleading" isn't an accusation either, it's just the term for when someone is trying to invoke a non-parsimonious explanation without offering substantiating evidence.
Fifth, and speaking of special pleading - Until we find a single coelurosaur without some sort of fuzz or feathers, then it's special pleading to try and claim that any lacked them. Of course it's possible that say T. rex lacked them (and my presentation at SVP might have even hinted at why), but without evidence saying "they might have" is special pleading, period. Also, why Utahraptor and Gallimimus? Neither is anywhere near big enough to qualify for wanting to lose insulation for thermophysiological reasons, so it would seem like the only reason to bring them up is simple emotional attachment (who cares if it looks silly - it either was or wasn't, how it would look to us isn't a form of evidence).
You do bring up some interesting analogies with other marine reptiles. You are 100% right that plesiosaurs are a great example of a huge amount of phenotypic divergence, but remember that plesiosaurs had almost 140 million years to evolve those divurgent forms, while mosasaurs only had 26 million years. None of them could be that crazy different from one another, because there wasn't enough time for it to evolve. You are also right that ichthyosaurs show a divergence of taxa with very weak tail flukes to those with tuna-like heterocercal tail flukes. But the primitive forms are all very early on in the Triassic or earliest Jurassic, and soon they were all replaced by advanced forms with well-developed tail flukes. This is more or less what we see with mosasaurs, where the primitive Dallasaurus doesn't have a tail fluke (or a downturn in the tail) and more advanced forms have the downturn (like advanced ichthyosaurs) and almost certainly had tail flukes. You are also right that mosasaurs _could_ have been like Teleosaurus, or extant salt water crocs, or like komodo dragons. But we know for a fact that they _weren't_ like those animals, because their vertebral anatomy (not to mention their limb anatomy!) is completely different. Maybe we will find more mosasaurs that won't have this anatomy - it would seem like we should eventually find primitive forms close to Dallasaurus that either lack tail flukes or have weakly formed ones. But Mosasaurus and Tylosaurus are not those animals - we have their tails, and they clearly have tail-fluke morphology in them.
I don't quite understand your last couple of links. We expect mosasaurs to have lizard-like scales, after all, they are lizards! So why would a keeled scale be surprising? Also, why did you link to that mount at Oceans of Kansas? That image doesn't show anything that would help you. In fact you can clearly see in it both the kink in the tail where it is broken to try and straighten it out, as well as the displaced chevrons where the curve should occur. Here, I'll point it out: drive.google.com/file/d/0Bxtac…
That specimen without a doubt has a downturn in the tail, it's just mounted completely wrong, and it's so obvious that you can see it in a low resolution image on the internet without even having to go there in person, though of course seeing it in person and writing it up for submission would be necessary before it became scientific data.
Third, and this is really pretty cut and dried, but Prognathodon is in the Mosasaurinae with Mosasaurus, and Platecarpus is in the Russellosaurina with Tylosaurus, so both are found in subfamilies with known fluke impressions. There's only two accepted mosasaur families, and both are represented. Getting basic facts like this wrong doesn't lend much credence to claiming that others are biased against you.
Fourth, this is nothing like the Bone Wars. Cope and Marsh hated each other and would sometimes take a stance simply to disagree with the other. I don't even work on squamates,and I certainly don't care which side is right, but the actual, published scientific literature is clear: mosasaurs from both families have been found with tail fluke soft-tissue evidence, and outside of Dallasaurus (which is really primitive) all known mosasaurs share the characteristic downturn in the tail that is associated with tail flukes in every other known marine vertebrate that has them. This isn't accusation, it's just the data. Now is it possible that there is some explanation for the downturn AND the preserved tail flukes in both the Mosasaurinae and the Russellosaurina? Sure, but without any shred of evidence to explain why that's just special pleading. "Special pleading" isn't an accusation either, it's just the term for when someone is trying to invoke a non-parsimonious explanation without offering substantiating evidence.
Fifth, and speaking of special pleading - Until we find a single coelurosaur without some sort of fuzz or feathers, then it's special pleading to try and claim that any lacked them. Of course it's possible that say T. rex lacked them (and my presentation at SVP might have even hinted at why), but without evidence saying "they might have" is special pleading, period. Also, why Utahraptor and Gallimimus? Neither is anywhere near big enough to qualify for wanting to lose insulation for thermophysiological reasons, so it would seem like the only reason to bring them up is simple emotional attachment (who cares if it looks silly - it either was or wasn't, how it would look to us isn't a form of evidence).
You do bring up some interesting analogies with other marine reptiles. You are 100% right that plesiosaurs are a great example of a huge amount of phenotypic divergence, but remember that plesiosaurs had almost 140 million years to evolve those divurgent forms, while mosasaurs only had 26 million years. None of them could be that crazy different from one another, because there wasn't enough time for it to evolve. You are also right that ichthyosaurs show a divergence of taxa with very weak tail flukes to those with tuna-like heterocercal tail flukes. But the primitive forms are all very early on in the Triassic or earliest Jurassic, and soon they were all replaced by advanced forms with well-developed tail flukes. This is more or less what we see with mosasaurs, where the primitive Dallasaurus doesn't have a tail fluke (or a downturn in the tail) and more advanced forms have the downturn (like advanced ichthyosaurs) and almost certainly had tail flukes. You are also right that mosasaurs _could_ have been like Teleosaurus, or extant salt water crocs, or like komodo dragons. But we know for a fact that they _weren't_ like those animals, because their vertebral anatomy (not to mention their limb anatomy!) is completely different. Maybe we will find more mosasaurs that won't have this anatomy - it would seem like we should eventually find primitive forms close to Dallasaurus that either lack tail flukes or have weakly formed ones. But Mosasaurus and Tylosaurus are not those animals - we have their tails, and they clearly have tail-fluke morphology in them.
I don't quite understand your last couple of links. We expect mosasaurs to have lizard-like scales, after all, they are lizards! So why would a keeled scale be surprising? Also, why did you link to that mount at Oceans of Kansas? That image doesn't show anything that would help you. In fact you can clearly see in it both the kink in the tail where it is broken to try and straighten it out, as well as the displaced chevrons where the curve should occur. Here, I'll point it out: drive.google.com/file/d/0Bxtac…
That specimen without a doubt has a downturn in the tail, it's just mounted completely wrong, and it's so obvious that you can see it in a low resolution image on the internet without even having to go there in person, though of course seeing it in person and writing it up for submission would be necessary before it became scientific data.
View all replies