Re: Rahonavis....Both!

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 10:52 AM 2/24/99 -0500, Larry Febo wrote:

>Well, yeah, but...I`ve been hearing lately (sorry no specific refs) that
>Dromaeosaurs seem in many ways MORE advanced that Archeopteryx, and for that
>matter,...so is Rahonavis.

Wish you could provide the refs to back this up.  Now there are one or two
features that are more like advanced birds in dromaeosaurids than in
_Archaeopteryx_ (full opisthopuby, for one), but most of the weight of the
data puts Archie closer to modern birds.  In fact, under Greg Paul's
hypothesis in PDW, neither Archie nor dromaeosaurids were closer to later
birds than the other one: his hypothesis was (Archie + dromaeosaurids) +
(various maniraptorans in series + later birds).

In a different way, dromaeosaurids are a LOT more advanced than
_Archaeopteryx_, but in dromaeosaurid ways, not bird ways (for example, the
elongated bony stiffening rods).  Just because a theropod group is more
advanced than Archie doesn't mean it is closer to modern birds than Archie:
it just means it has a lot of its own specializations.  Tyrannosaurids are
arguable more advanced anatomically than _Archaeopteryx_, but I wouldn't
claim that they are closer to modern birds than Archie was.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661