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Re: Young Allosaur feathers?
T. Michael Keesey <firstname.lastname@example.org> wrote:
1) Feathery integument first evolved in some tetanuran ancestor of the
aforementioned unnamed clade.
2) Feathery integument evolved even earlier, and _Carnotaurus_ is
I think (1) is more likely to be correct - though I'd be quite happy to be
proved wrong (feathered eoraptors, for example). However the presence or
absence of a feathery integument in a given taxon may also depend on other,
non-phylogenetic factors. After all, _Sinosauropteryx_ has a feathery
integument; but its kissing cousin _Compsognathus_ does not. In
_Compsognathus_, the absence of feathers (especially in a specimen preserved
in the same depositional environment as _Archaeopteryx_) is likely due to
Geographical, seasonal, ontogenetic and size-related factors almost
certainly impacted upon whether a theropod exhibited the feathery body
covering of its ancestors. For example, baby tyrannosaurs may have been
clothed in down; but they shed their coats by the time they reached
maturity. Ditto for allosaurs. Phylogenetic bracketing has its limitatons.
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