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Re: really big question



"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