Re: Mesozoic snow?

[Tim Williams <twilliams_alpha@hotmail.com>]

Amtoine Grant wrote:

> What feathered reptiles were these? Are you referring to Longisquama? 
> AFAIK, there are supposed feather impressions were a dilophosaur sat, 
> although some[maybe most] people claim that these are drag marks.

You're absolutely right.  The 'feather' imprints appear in reality to be 
drag marks in very thick and very slick mud.

> The earliest undisputedly feathered dinosaur is Archaeopteryx, if I recall 
> correctly, from the Late Jurassic.

Yep - with the emphasis on 'undisputed'.  We have direct proof of feathers 
in _Archaeopteryx_, but not for any other pre-Cretaceous theropod (or 
anything else, for that matter).  Phylogenetic bracketing would suggest that 
all coelurosaurs either have feathers, or are descended from taxa that did.  
Theropods like _Ornitholestes_ and _Gasosaurus_ fall into this category, 
although their feathers (if present) would have have been of the downy, 
non-pennaceous variety ('dino-fuzz').  After all, if tyrannosauorids did, 
why not these guys?  Of course, theropods might have been primitively fuzzy, 
so _Coelophysis_ and _Zupaysaurus_ might have been fuzzy too.  But these 
taxa currently fall outside the bracket for this character.

> The larger branches that could get get by by virtue of their size's 
> heat-retainment would not have needed to.

Downy body covering might have been advantageous to the young'ns, no matter 
how big the grown-ups got.

Cheers

Tim