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Post by creature386 on May 31, 2019 2:50:58 GMT 5
Good points, but you missed(understandably, as it was not an obvious one) the context of me bringing up the endothermy here. It is the main detail setting apart dinosaurs and non-avian reptiles. And it makes a huge differentiating effect, in some non-taxonomic aspects greater than any genetical difference between reptiles and amphibians. It is the single factor that allowed dinosaurs to thrive on the land for 60 million years in most spectacular and diverse fashion ; to grow from hummingbird to giant sauropods, to survive on Antarctica( the Emperor Penguin) and traverse the planet from pole to pole(the Arctic tern) each year, etc etc. Reptiles and amphibians otoh, ultimately are limited to relatively similar niches and ranges(with comparatively great advantage to reptiles, of course, but that's why I used the word relative). well reptiles share much more in comman with amphibans they are equally related to amphibans as they are with mammals which is not very close but still closer than to fish but still pretty distant Mammals and reptiles can reproduce independently of water, amphibians can't. Again, that's no controversial topic and can be solved by looking at a cladogram. |
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rock
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Post by rock on May 31, 2019 5:26:17 GMT 5
^Equally? How do you know that? because reptiles came from amphibians and later evovled into mammals so this would make them equally as close |
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Post by dinosauria101 on May 31, 2019 5:30:10 GMT 5
^Equally? How do you know that? because reptiles came from amphibians and later evovled into mammals so this would make them equally as close Umm....okay? |
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Post by creature386 on May 31, 2019 15:03:45 GMT 5
^Equally? How do you know that? because reptiles came from amphibians and later evovled into mammals so this would make them equally as close Evolution is a tree, not a ladder. Modern mammals did almost certainly not evolve from modern reptiles, they merely share a common ancestor who looked a bit more like a reptile than a mammal. |
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Post by dinosauria101 on May 31, 2019 15:05:08 GMT 5
because reptiles came from amphibians and later evovled into mammals so this would make them equally as close Evolution is a tree, not a ladder. Modern mammals did almost certainly not evolve from modern reptiles, they merely share a common ancestor who looked a bit more like a reptile than a mammal. Thanks for clarifying. I was also unable to really see any such link |
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rock
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Post by rock on May 31, 2019 15:10:23 GMT 5
Evolution is a tree, not a ladder. Modern mammals did almost certainly not evolve from modern reptiles, they merely share a common ancestor who looked a bit more like a reptile than a mammal. Thanks for clarifying. I was also unable to really see any such link  |
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Post by dinosauria101 on May 31, 2019 15:13:07 GMT 5
Thanks for clarifying. I was also unable to really see any such link I just meant the 'ladder' aspect was the link I could not see. |
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rock
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Post by rock on May 31, 2019 15:19:46 GMT 5
I just meant the 'ladder' aspect was the link I could not see. ok |
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Post by theropod on May 31, 2019 17:43:27 GMT 5
Sam1: Endothermy is not limited to dinosaurs. As Creature already mentioned, the common ancestors of crocodilians may well have been endothermic, making it a synapomorphy of at least the crown group of archosauria (which a huge array of extinct reptile groups were part of besides just dinosaurs). Pterosaurs were undoubtedly endothermic, which lends support to that idea.
Mosasaurs, ichthyosaurs and sauropterygians are huge extinct groups of endothermic reptiles.
Endothermy is quite commonplace. That it’s not found in extant reptiles, except for birds (which are of course the majority of extant reptiles if we’re being scientific about it) is more of a coincidence of most of these taxa going extinct at the end of the Cretaceous.
That being said the whole binary of "warm-blooded"/"cold-blooded" is overly simplistic anyway. Modern biodiversity is a very limited sample in this regard, with the stem lines in between major radiations missing, and even there, upon a closer look, you can see variations on that scheme, such as homeothermy in leatherback turtles, increased aerobic potential in varanids etc.
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Post by theropod on May 31, 2019 17:47:11 GMT 5
Thanks for clarifying. I was also unable to really see any such link Note that that tree is not very accurate any more. Current consensus suggests that turtles are diapsids that merely secondarily lost their temporal fenestrae. |
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