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Re: Archaeopteryx or Velociraptor



 (I'm back...)...

Thomas R. Holtz, Jr. wrote:
>Archaeopteryx is exceedingly primitive, and the common ancestor of
>dromaeosaurids and birds probably looked like something very similar
>to Archaeopteryx.

   As such, early bird ancestors and related groups probably still retained
the theropod socketed teeth, tail, and hand claws.  In other words, they
were flying theropods.  It seems highly probable that many of these
flying theropods flew to isolated islands and reverted to the predatory
bipedal predator niche that their theropod features allowed, becoming
flightless, but still retaining some of the flight adaptations.
   With the primary locomotion means being flight in this ancestral group,
the need for tail based Caudi-femoralis running muscles would have been
reduced, possibly resulting in the rear facing pubic bones (for balance)
and thinner, stiffer tails.
   Since not all flying theropod groups would have adapted the same weight
reducing changes in the same sequence, there may be many theropod groups
such as the velociraptors or ostrich mimics that do not look similar to each
other but evolved from flying theropod dinosaurs.
   If modern birds had not given up their teeth and hand claws during their
evolution, the predominant predator might still be very theropod-like.

Mark Shelly