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Re: Sinosauropteryx tail colors

Kris Kripchak <saurierlagen1978@gmail.com> wrote:

> Tim, so how do you interpret Juravenator?  If memory serves, patches
> of fossilized Juravenator skin (from the tail base and hind
> leg) shows primarily scales... but I think I remember reading
> something about how there may be  traces of simple, filamentous feathers
> present as well.

If the _Juravenator_ specimen preserves feathers (even filamentous ones, or 
'protofeathers'), then it is not mentioned by Gohlich and Chiappe (2006).  This 
study states that feathers were not preserved.  The tail does preserve fibers, 
but these are interpreted as either hypaxial musculature or subcutaneous 
collagen bundles.

> I also think that Xu considered it most likely
> that Juravenator and other feathered dinosaurs simply possessed
> more extensive scales on their bodies than modern birds.

I agree - and there is no reason why feathers (and their precursors) should 
have replaced scales.  This is mentioned in the description of _Dilong_, where 
Xu et al. (2004) state:

      "Large, derived tyrannosauroids were reported to have scaled skin
       (28), but the presence of two kinds of body covering is not 
       unexpected. However, current understanding of the integumentary
       morphology in non-avian theropods is hindered by poor information
       on distribution. Given the diverse morphologies of integumentary
       structures in living birds, it is possible that non-avian 
       theropods had different integumentary morphologies on different
       regions of the body, and derived, large tyrannosauroids might bear 
       both scale-like and filamentous integumental appendages. 
       Alternatively, the lack of filamentous integumentary structures in
       derived tyrannosauroids is correlated with the large size, a 
       physiological strategy also adopted by some mammals such as 
       elephants, which lose most of their body hairs as they mature
       (29). This therefore supports the hypothesis that the original
       function of protofeathers is correlated with thermoregulation

5 years later, I think this still holds true.  Feathers could theoretically 
co-exist with scales over much of the body.  However, a certain 'critical mass' 
of feathers over most of the body (especially the trunk) would be needed in 
order for them to serve effectively in insulation.