[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: New Feathered Dinosaur



 
     Bat wing membranes are mostly uninsulated, but then again, the low blood supply probably reduces the cooling effect due to this. But are there *any* small, uninsulated, terrestrial endotherms (other than naked mole rats, which are tropical fossorial anyway, and probably live in a relatively constant temperature environment :) ) ? I think it is likely that all small ornithodirans were insulated, considering that they are unlikely to have been ectotherms.
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.