[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Piatnitzkysaurus and the perpetual taxonomic tempest

        On examination of the pelvis figured by Bonaparte in
Science (205, 1377-1379), which was listed in _The Dinosauria_ as
the reference for Piatnitzkysaurus, I am now officially thinking
about giving up on this taxon until I can get some good quality
pictures.  Basically, the figured bones have two possibilities,
plus the idiot option:
        Possibility one:  P. floresi is Tetanurae incerta sedis,
with a small pubic boot, a lobulate obdurator [can never spell
that right] process, and an open pubic obdurator notch.  The
figure does not convince me that the pubic nothc is open, as
there is much material distal to the notch which appears to be
the remains of a pubic apron.  The obdurator process is
illustrated as being part of the ischial apron, which would give
this taxon a very ceratosaur-like pelvis.  The slight ischial
boot seems to support this hypothesis.
        Possibility two:  P. floresi is Ceratosauria incerta
sedis, with a convergent ischial boot, a neoceratosaur-like pubic
boot, broad pubic apron (which is not restored, but, as I
mentioned above, appears plausible, closed pubic obdurator notch,
and an ischial apron like the one restored by Bonaparte.  In this
scenario, the "obdurator process" is really part of the ischial
apron, in which case it has a prominant notch at the distal end
of the margin of the apron and the ischium, which is a *very
solid ceratosaur synapomorphy*.
        Possibility three:  It has a mixed bag of primitive and
homoplasic characters of the pelvis which can only be resolved by
a detailed analysis of a complete specimen (which, rather
dissapointingly, was not figured [yes, I know we don't really
have a *complete* specimen.  :) ].
        As for Pitnitzkysaurus being frequently referred to the
Carnosauria, recall that, at the time it was found, there were
only two options.

ON another note, according to Walker's paper defining
Eustreptospondylus (Philosophical Transactions of the Royal
Society, B, 248, 55-134), Eustrep.  does *not* have the pointy
"lacrymal" horns which Greg Paul illustrates it with.

And finally (can you tell I've been to the library?), all who are
interested in taxonomy should check out T.R. Holtz's new article,
the ref. for which was recently supplied.  It redefines
Maniraptora into an extremely useful taxon, and hints at a
monophyletic "Mongolisauria" (Oviraptoridae+Therizinosauridae,
in a diagram partially from Sues' work on Elimsaurs, I