When Did Theropods Become Feathered?--Evidence for Pre-Archaeopteryx Feathery Appendages

[Nick Gardner <pyroraptor86@yahoo.com>]

MARTIN KUNDRA ´ T (2004). When Did Theropods Become
Feathered?--Evidence for Pre-Archaeopteryx Feathery
Appendages.  Journal of Experimental Zoology (Mol Dev
Evol) 302B: 1-10.

ABSTRACT Filamentous impressions associated with
locomotive theropod tracks in the Lower Jurassic
Turners Falls Formation of western Massachusetts,
U.S.A. represent the oldest evidence of feathered
dinosaurs. Feather impressions are preserved with
sitting traces which bear integumentary structures
along the outlines of the pre-pubic and ischiadic
impressions. Extant palaeognathous down feathers
provide a valuable comparative model for these
filamentous integumental structures and for similar
structures described in Chinese theropods from younger
deposits. The described morphologies are congruent
with Stage II of Prum (?99) and support that
plumulaceous morphologies evolved before the origin of
the rhachis and the planar vane. Appearance of
feathery appendages in theropods may be linked to
evolution of higher metabolic rates, improved
locomotory abilities, and/or distinct behavior(s) and
visual communication. Development of feathery
integument might have also played a crucial role in
the competitiveness and successful radiation of
maniraptoriform theropods and their actively flying
descendants in the Jurassic.


                
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