Re: New Theropods

[Dinogeorge@aol.com]

In a message dated 96-05-24 11:23:43 EDT, Stang1996@aol.com writes:

>Also, I must now admit publicly that I believe Segnosaurs (I will
>not say the Th word) are probably bullatosaurs because of their
>theropod like braincases and nerve anatomy that I doubt would result
>from parallelism.  They are damned strange bullatosaurs, but
>bullatosaurs nonetheless.  

So--all of their numerous prosauropod characters would be parallelisms
instead? Why should a few features of braincase anatomy outweigh
pedal, pelvic, dental, and mandibular anatomy? All bullatosaurs had
narrow, arctometatarsalian feet, so in segnosaur feet we would have a
reversal of the pinched metatarsal III, reversal of retroverted digit
I and realignment of metatarsal I with II-IV, re-expansion and
rearticulation of the proximal end of metatarsal I with the tarsus,
great narrowing of the pedal unguals, and broadening and relative
shortening of the essentially cursorial bullatosaur/arctometatarsalian
foot into the graviportal segnosaur foot. All these features occurred
in the relatively small, lightweight _Alxasaurus_, not just the more
highly derived later segnosaurs, so it is difficult to account for
them as adaptations to a graviportal lifestyle. It is far more likely
that these features are relicts of sauropodomorph ancestry that
allowed segnosaurs to become graviportal.