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

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.


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