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Re: carcharodontine furculae



Ekaterina Amalitzkaya wrote-

> Has a furcula ever been found in Acrocanthosaurus or the
carcharodontosaurs.
> If yes I was wondering if it would have any bearing on laying to rest the
> hypothesis of Coria
> about the car.d.saur- abelisaur connection. Which is the most inclusive
> clade for which the presence of the furcula is now a synapomorphy? Thanks
in
> advance for the enlightenment.

Yes, a carcharodontosaurid furcula has been found.  My info on the specimen
is:

undescribed Carcharodontosaurid (Alcober, Sereno, Larsson, Martinez and
Varricchio 1998)
Santonian-Campanian, LC
Rio Colorado Formation, Argentina
material- partial skeleton including quadrate, vertebrae including axis,
gastralia, furcula, ilium, pubis and
astragalus
description- large canal near the base of the quadrate suggest and avian
course for the pneumonic
siphonium, camellate pneumaticity in postcranium, axis extremely pneumatic,
pneumatic cavities present in
centra, neural arches, furcula and ilium, gastralia fused at midline,
furcula present, large pubic foot,
ascending process of astragalus taller than other allosauroids and closer to
coelurosaurs
comments- This is the first occurance of the pneumonic siphonium in
non-avian theropods.
reference- Alcober, Sereno, Larsson, Martinez and Varricchio, 1998. A Late
Cretaceous
carcharodontosaurid (Theropoda: Allosauroidea) from Argentina. JVP 18(3) 23A

Ignoring Longisquama, which most paleontologists do not see as particularily
close to dinosaurs, the most basal theropod with a furcula is Syntarsus
kayentakatae, as described in:

Tykoski, R.S.  1998.  The osteology of Syntarsus kayentakatae and its
implications for ceratosaurid phylogeny.  Unpublished Masters
Thesis,University of Texas at Austin, 217 pp.

Therefore, the most inclusive clade with furculae would be the Eutheropoda,
which may equal Theropoda depending on the position of Eoraptor and
herrerasaurids.  The furcula has been lost in several lineages though,
including Carnotaurus, Segisaurus, Pelecanimimus (and probably other
ornithomimosaurs), Sinosauropteryx and Sinornithoides.

Mickey Mortimer