feathers and furculae

["John R. Hutchinson" <jrhutch@socrates.berkeley.edu>]

Title: feathers and furculae

Hi all,

        On the 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.

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John R. Hutchinson
Department of Integrative Biology                Phone:  (510) 643-2109
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