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Re: questions about the Odontochelys study
>> seeing an aquatic pleurodire run much faster than a tortoise,
> Tortoises are outright graviportal... they have adaptations for
> energy-efficient walking that make running difficult or impossible.
All right, but it was just an example that turtles with a heavy
cuirass are relatively fast, and that I doubt that turtles with less
completely covering shells, as the snapping, can really be faster.
Just to say I do not know exactly to what is decreased coverage of the
bony shell in turtles related.
> What does that mean? Storing? (That's a guess. It looks like an Arabic
> import into Spanish that hasn't spread any further.)
Well, my origins became revealed by lack of adequate knowledge of
English. And yes, it means storing, and is an Arabic loan word.
>> As far as I know, many salamanders are bottom-dwellers in rivers and
>> are not pachyostotic, and I do not think all of them are lungless...
> While having lungs and not being pachyostotic, they are still
> osteosclerotic: the bones look unspectacular from the outside, but on the
> inside, there is almost no or no spongiosa and almost no or no marrow
> cavity, it's all just massive cortex. This has the same effect as
> pachyostosis, only less extremely so. It is often found in amphibious
Not opposing to that, but considering that limb bones in salamanders,
except perhaps the cryptobranchids, seem to be small and thin in
urodeles, and in relatively thin bones the marrow cavity tends to
collapse, can not we explain the lack of marrow cavity alternatively
because of relatively small size? In any case, it would be useful to
see if terrestrial salamanders with similarly developed limbs (I
should expect them generally to have relatively longer and larger
bones) present marrow cavities.
If the limbs are relatively small in aquatic salamanders generally,
when compared to terrestrial ones, is not the weight increase too
small to be considered an advantage to be selected?