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Re: Perching, climbing, roosting was Re: 11th specimen of Archaeopteryx



Anthony Docimo <keenir@hotmail.com> wrote:

>  Really?  What part of a goat is adapted for gripping branches?

It's not "adapted for gripping branches".  It's adapted for climbing
challenging substrates, specifically rocks and narrow ledges.  There's
a reason why we say "as nimble as a goat".


>> Mammals aren't reptiles. Never have been.
>
>  as long as the word exists, people will use it.  best you get used to it. 
>  (and I know you know what I meant by "reptiles" in the first
> place)


Nup, I'm not getting used to it.  I've nothing against the word
"reptile" - turtles, lizards, snakes, tuataras and crocodiles are all
reptiles.  But the amniote line that lead to mammals split off from
the line that led to reptiles, and the mammal ancestor was never a
reptile itself.  The ancestors of mammals never had scaly skin - they
had glandular skin, like us humans.  I'm not being pedantic here in
the cause of "phylogenetic correctness".  But the claim that mammals
evolved from reptiles is incorrect, and needs to be jettisoned - along
with the term "mammal-like reptile".


>  So in other words, "no theropod could ever be in a tree.  ever.  full stop."


I never said that.  Obviously many birds live in trees, and birds are
theropods.  I'm also inclined to the view that some small basal
paravians also occasionally ventured into trees - like _Microraptor_,
_Epidendrosaurus_ and _Jeholornis_.  But their respective osteologies
tell me that they didn't spend too much time in trees, and were not
adapted for perching or roosting.  All these forms would have been
extremely inept at climbing branches, or clambering through
tree-crowns.  That doesn't mean they didn't do it.  But if they did
engage in these behaviors routinely AND arboreality was an integral
part of their ecologies, we would expect to see adaptations to suit.
We don't.  All we see are some changes to the extremities that *might*
indicate some rudimentary climbing (scansorial) capability.
Alternative scenarios might explain these changes at least equally as
well.


>  heck, I'm sure the mammals (Mammalia) have overcome constraints of their own 
> - constraints that surely separate them from their
> ancestral clades.


Mammals overcame these constraints by evolving new adaptations.  These
adaptations are usually clearly evident in their skeletons.


> and when adaptations are suggested, you dismiss them.


Nope, I don't.  I'm open to the idea that small basal paravians could
(and did) climb.  Like I've said, there were changes going on in the
extremities (especially in the pes), and these changes *might* be
associated with scansoriality.  (Then again, they may not be.)  But
these changes were just tinkering at the edges - there were no major
skeletal adaptations to an arboreal lifestyle.





Cheers

Tim