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Furculae (was Re: _Liaoningornis_)



At 12:32 PM 2/24/97 -0500, Pellucidar (Mitch Lamm) wrote:

>Pardon me if this has been asked before, but are furculae known in any
>non-Maniraptoran theropods?  Also, how would one view the furcula of
>Archaeopterx--as a derived character of the Maniraptora or an ancestral
>character of Aves?
>Thanks for the help.

Furculae are present in allosaurids and tyrannosaurids (and possibly
ornithomimosaurs and troodontids) outside of Maniraptora proper (and in some
dromaeosaurids, oviraptorosaurs, and birds within Maniraptora).

The possession of a furcula is an ancestral characters for Maniraptora, an
ancestral character for Maniraptora and Coelurosauria, and at present a
derived character for Avetheropoda.  However, without knowing the clavicle's
status in non-avetheropod tetanurines (Torvosaurus, Spinosauridae, etc.), it
is impossible to say where within Tetanurae this feature evolved.

A primitive, non-fused clavicle is known to be present in ceratosaurs and in
more distantly related dinosaurs.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661

"To trace that life in its manifold changes through past ages to the present
is a ... difficult task, but one from which modern science does not shrink.
In this wide field, every earnest effort will meet with some degree of
success; every year will add new and important facts; and every generation
will bring to light some law, in accordance with which ancient life has been
changed into life as we see it around us to-day."
        --O.C. Marsh, Vice Presidential Address, AAAS, August 30, 1877