In a message dated 7/16/00 9:54:18 AM EST, sarima@friesen.net writes:
<< But even if so, the ancestors of sauropods must have been very *similar*
to
prosauropods, in order to get from a _Herrerasaurus_-like condition to the
sauropod condition. That is why I said "prosauropod-ish", not
"prosauropod". >>
It more likely went from sauropod-ish to prosauropod-ish to herrerasaur-ish
and, separately, to ornithischian-ish. Early sauropods retain all five
functioning pedal digits, whereas in prosauropods the fifth digit is reduced,
vestigial, or lost (only a splint metatarsal V remains). It is extremely
unlikely that sauropods re-evolved a complete fifth pedal digit from the
prosauropod or herrerasaur condition. The primitive dinosaur state is five
functional pedal digits, from which the dinosaurs with reduced to missing
pedal digits V must be descended.