AFAIK it is an adaptation that bat wings (unlike
AFAIK all mammalian gliding membranes) are uninsulated -- they are well
vascularized for cooling. After all, bats don't have air sacs.
I don't know
of any small, uninsulated, terrestrial endotherms.
About other things in this thread --
I don't think that pterosaurs and theropods are
particularly close. I wanted to write that feathers (protofeathers,
dinofuzz...) may be common to all ornithodirans. See http://www.dinosauria.com/jdp/archie/scutes.htm.
(Cites 3 postings to this list from 1995.) I should have compared pterosaur fur
rather to *Sinosauropteryx* protofeathers (but even these are branched) than to
the new one's.
Pterosaurs as prolacertiforms? The evidence is
accumulating, but is it more parsimonious than a single origin of the air sac
system?
From what I know (not much...) all terrestrial
crocs can be viewed as no more "warm-blooded" than monitor lizards. The
pan-Laurasian Palaeogene *Pristichampsus rollinatii* was apparently an ambusher,
capable of tremendous acceleration (and, at high speeds, bipedality), but not
long-distance running.
But I _am_
interested in the "little hairs" on the underside of alligator
throats...
AFAIK only one crocodylomorph, *Gracilisuchus
stipanicicorum* (the basalmost one AFAIK), is thought to have been bipedal
(others say semibipedal). I don't know anything about hallopodids, except that
they are from the Morrison formation, Marsh classified them with coelurosaurs,
and they are now regarded as the last sphenosuchians or
suchlike.
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