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feathers and furculae
Title: feathers and furculae
fibrous integumentary structures on many of the Liaoning forms: to
clarify, from my knowledge (from working 30ft from him most of the
day for 5 years), Kevin Padian does not call the structures
protofeathers, at least not 100% certainly protofeathers. He
calls them fibrous integumentary structures. He likely would
agree that they fit many researchers' mental image of what a
protofeather would look like, but that is a more subjective matter of
character coding that involves the assumption that the fibrous
structures are the ancestral transformational homologs of the derived
state, feathers. Currently this is not testable but it could be
a reasonable assumption. Many more studies are underway
by multiple groups of researchers.
Another clarification, Segisaurus has a clavicle but
it has not been more completely prepared to reveal that it is a
furcula. It could be one, but the work has not yet been
done. Until such work is done I would avoid coding it as either
having unfused clavicles or a furcula; "?" best represents
our understanding of this small theropod's pectoral structures.
It is also not clear whether the single known specimen was mature or
not; if the clavicles were unfused it could be an ontogenetic
artifact but at present we don't know.
John R. Hutchinson
Department of Integrative
Phone: (510) 643-2109
3060 Valley Life Sciences Bldg.
Fax: (510) 642-1822
University of California
Berkeley, CA 94720-3140