RE: Major new paper on dromaeosaurids, with other significant maniraptoran info

[Tim Williams <twilliams_alpha@hotmail.com>]

Thomas R. Holtz, Jr. wrote:

> Senter, P., Barsold R., B.B. Britt & D.A. Burnham. 2004. Systematics and
> evolution of Dromaeosauridae (Dinosauria, Theropoda). Bulletin of the Gunma
> Museum of Natural History 8: 1-20.

Where do the therizinosaurs end up?

> The authors regard Incivisosaurus a junior synonym of Protarchaeopteryx, 
> but
> different at the species level from P. robusta.

Something that springs to mind...  (I don't expect this idea to be taken too 
seriously, it's just meant as food for thought.)  Perhaps 
_Protarchaeopteryx_-_Incisivosaurus_ was an arboreal herbivore?  The 
distinctive dentiton of _Incisivosaurus_ appears specialized for eating 
plants, as argued by Xu et al. (2002).  Hopson (in the Ostrom symposium 
volume) notes that _Protarchaeopteryx_ has hindlimb proportions consistent 
with arboreality (although the pes is too poorly preserved to determine if 
it was designed for perching).

> Troodontids come out as bullatosaurian arctometatarsalians.  Whoa, now
> that's something I haven't seen for years...

If troodontids are put back in the Bullatosauria, and outside of the 
Maniraptora, then the propubic pelvis of troodontids represents a retention 
of the primitive condition, and not a secondary reversal (which is required 
if troodontid is a maniraptoran).  Oviraptorosaurs, therizinosaurs, 
dromaeosaurs and birds all have an opisthopubic pelvis.  It's been said that 
the retroversion of the pubis is a trait associated with herbivory, to 
accomodate a more capacious gut needed to process nutrient-poor plant matter 
(also seen in Ornithischia).

The irony is that within the clade Maniraptora (which means "raptorial 
hands"), only the dromaeosaurids appear to have used their hands to catch 
prey.  Basal oviraptorosaurs and therizinosaurs were probably herbivorous, 
and I doubt that microraptorians and basal birds used their wings to catch 
prey for fear of damaging the wing feathers.  I like the idea of large 
dromaeosaurids using the 'predatory stroke' to capture large prey; but I'm 
not sold on the idea that the same mechanism was used by other 
maniraptorans.



Tim

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