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Re: *Unquillosaurus* questions



Nicholas Gardner wrote-

> What is the type species of *Unquillosaurus*?  The specimen numbers?  The
> affinities? The reference for it?  Photos of the material?

Unquillosaurus Powell 1979
U. ceibalii Powell 1979
Campanian, Late Cretaceous
Los Blanquitos Formation, Argentina
Holotype- (PVL 3670-11) pubis (451 mm)

As for what it is, it's hard to say from just a pubis.  There is no
obturator foramen, so it's either an allosaurid/carcharodontosaurid (with
Neovenator being intermediate, perhaps we should sink Carchaodontosauridae
into Allosauridae, as Holtz does) or coelurosaur.  In 1997, Ford suggested
on the DML that Unquillosaurus was similar to Unenlagia, which has gone so
far as to prompt discussion of synonymy.  I just want to make it clear now-
Unquillosaurus is not synonymous with Unenlagia.  First, I should note the
pubis was described incorrectly, the medial side being lateral and vice
versa.  Jaime also independently deduced this.  The supposed "lateral crest"
is really the pubic apron, the "lateral" facets on the pubic boot are really
for the pubic symphysis.  Compared to Unenlagia- the pubis is more propubic;
the ischial peduncle is longer; there was an obturator notch; the shaft is
anteroposteriorly thicker distally; the pubic boot projects slightly
anteriorly; there is a proximomedial sulcus; the ilial peduncle is less
transversly expanded; the pelvic canal is narrower; the proximal shaft
expands laterally; the distal end is expanded transversely, not compressed;
there is a gap in the symphysis proximal to the pubic boot.  Also keep in
mind Unquillosaurus is from the Los Blanquitos Formation, while Unenlagia is
from the Rio Neuquen Formation.  The obturator notch makes it less derived
than most coelurosaurs (Coelurus and SMNK 2349 PAL being exceptions).
Though the anteriorly reduced pubic boot has been cited as evidence for a
paravian affinity, several more basal theropods exhibit this too-
Monolophosaurus, Gasosaurus, Yangchuanosaurus, Sinraptor, Marshosaurus,
compsognathids, Sinosauropteryx, Coelurus, etc..  The symphyseal gap is
known in Acrocanthosaurus, Allosaurus, SMNK 2349 PAL, Coelurus and
Velociraptor, but is absent in most maniraptoriformes, tyrannosaurids and
Sinraptor.  I think Unquillosaurus resembles Acrocanthosaurus most in
anterior view, and Coelurus in lateral view.  So it's probably a carnosaur
or basal coelurosaur.  I hear there is undescribed material which may
elucidate its relationships......
The original description can be read on Polyglot-
http://blackwidow.informatics.sunysb.edu/anatsci/files/Powell_79.doc

Mickey Mortimer