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

Re: Therizinosauroids (was Re: Giant Birds)



I wrote-

>In my latest analysis, therizinosaurs are actually closer to ovi's than
Caudipteryx is, but my work is far from complete.

Nick wrote-

>Yeah, from what little I've seen, I would say this is unlikely.  Loss of
maxillary and dentary teeth and the form of the mandible are among the
features that I would see as uniting oviraptorosaurs and _Caudipteryx_ to
the exclusion of the Therizinosauroidea.

True, but (this is based on an analysis in progress and does not reflect my
actual views) oviraptorosaurs and therizinosauroids do share a few
characters to the exclusion of Caudipteryx.  These include loss of
premaxillary teeth, presence of pleurocoels in posterior dorsal vertebrae*,
distal caudals not elongate and a radius over 90% of metatarsal length**.

Besides loss of maxillary and dentary teeth, Caudipteryx and oviraptorids
also share a pneumatic lacrimal, subequal parietal and frontal lengths and
two long caudal dentary processes.  Thanks for your input, If you know of
other synapomorphies, I'd be happy to add them to my database.

* Xu et al. (1999) code Beipiaosaurus as having dorsal pleurocoels, and the
only preserved dorsals are four posterior ones.  Currie (pers. comm. 1999)
stated that Caudipteryx has anterior dorsal pleurocoels, yet lacks posterior
ones.  Barsbold et al. (1990) state that oviraptorids have pleurocoels on
all dorsal vertebrae, as does Microvenator (Makovicky and Sues 1998).
** Present in Oviraptor and Beipiaosaurus (the lower arm is incomplete but
indicates that the metatarsus is shorter).  Ingenia would seem to have
shorter arms (radius 77% of mt), but this may be a reversal (As could
Caudipteryxs' condition. Anyone have data for Conchoraptor, Rinchenia, etc.
limb proportions?).

Mickey Mortimer