Re: really big question

[Dino Guy Ralph <ralph.miller@alumni.usc.edu>]

"Jaime A. Headden" <qilongia@yahoo.com> wrote:
>  The holotype specimen of *Scansoriopteryx* shows a tail with tubercular,
> roughly rhomboid scales on a patch of the tail, preserved as impressions,
> leading some (including myself) to hypothesize that the tail lacked
> feathery integument at least on one portion (like scaly-tailed squirrels)
> or all of it (like in muroid rodents).

Thank you for pointing that out, Jaime.  I quote the text (Czerkas & 
Chongxi, 2002):
"In addition to the feathery integument, there is also a small patch of 
non-imbricating tubercles that looks like scaly skin.  It is located near 
the 19th caudal vertebra offset away the tail and extending for a distance 
of one cm.  The scales near the tail are clearly displaced from the natural 
orientation to the body, and its association with the tail, though possible, 
is not conclusively demonstrated.  In fact, the identification of the 
tubercles should be regarded as only being a tentative possibility.  This is 
because unless they are from the feet and lower legs, where these scales are 
from is uncertain, and as there is abundance of feathery structures 
preserved from the skull to along the tail it appears that the entire animal 
was covered much like a bird."

Elsewhere in the text, the authors state:
"Wispy, "hair-like" impressions can be seen around select parts of the body, 
including the back of the skull, pelvis, base of tail, trunk region, and 
significantly, emanating from the lateral edge of the ulna and manus where 
these impressions are more elongate.  Under microscopic inspection it can be 
seen that the hair-like impressions are composed of V-shaped patterns in 
which filaments branch from the base (FIGURES 16, 18, 19).  The filaments 
reporesent individual barbs.  Barbules branching from the barbs are not 
discernible.  But the minute size, morphology and pattern of distribution 
are consistent with representing down-like feathers, or perhaps even more 
specifically, natal-down.  This identification is also consistent with the 
interpretation of this particular specimen as being a juvenile or even a 
hatchling.  Sporadically associated among the V-shaped patterns are round 
impressions that appear to represent insertion points of follicles where the 
feathers are attached to the skin."

See also Tracy Ford's article in _Prehistoric Times_, #65, April/May 2004, 
entitled "How to Draw Dinosaurs: What is a feather? (Part 3, conclusion) 
Theropod Feathers."

The point of the foregoing is to make it quite clear that although this 
theropod apparently had a small patch of tubercular scales somewhere on the 
tail or feet, most of its body was covered with feathers (though perhaps not 
pannaceous feathers).  This is quite clear from the photographs and 
illustrations.

> In addition, "Dave" sports
> scutellate scales on the pes, similar to those few non-dinosaurian,
> non-pterosaurian reptiles recovered from the Yixian.

It isn't surprising that a bird-like theropod should have tubercles on the 
underside of one of its toes (Qiang et al., 2001, Figure 4b) -- let's just 
make it clear that almost every other aspect of this specimen of juvenile 
_Sinornithosaurus_ indicates that it was very fluffy and feathery!

What I meant to say was that the only good evidence for theropod dinosaurs 
completely covered in tubercular scales -- and lacking any evidence of 
feathers -- comes from a specimen of _Carnotaurus_ and a specimen of 
_Allosaurus_ (the latter unpublished).  These are not coelurosaurs, however, 
and a good variety of coelurosaurs from Liaoning and Mongolia show clear 
evidence of preserved feathers.  Thus far there is no evidence for a 
coelurosaur completely devoid of feathers (_Pelicanimimus_' gula 
notwithstanding).

--------
"Dino Guy" Ralph W. Miller III
Docent at the California Academy of Sciences
proud member of the Society of Vertebrate Paleontology