[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Rahonavis....Both!

>-----Original Message-----
>From: Thomas R. Holtz, Jr. <th81@umail.umd.edu>
>To: larryf@capital.net <larryf@capital.net>
>Cc: dinosaur@usc.edu <dinosaur@usc.edu>
>Date: Wednesday, February 24, 1999 1:38 PM
>Subject: Re: Rahonavis....Both!

>>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
>>>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,
>>elongated bony stiffening rods).  Just because a theropod group is more
>>advanced than Archie doesn't mean it is closer to modern birds than
>>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

By more "advanced" (I know..a vague term), I meant more like modern Avian
forms. Greg Paul, (in PDW pg 197), does say this..."Another odd and
surprising thing is that the Dromaeosaurs seem to be more advanced and
birdlike than Archaeopteryx." ...and goes on to mention the following
characters: more birdlike quadratojugal bone in the cheek, more hip
vertebrae, very short nonoverlapping neck ribs, shorter trunks, aux hooked
process on side of rib cage (uncinate?), more bird-like femoral heads and
hip sockets.
I`m not sure what Rahonavis has. I see very little written about it on the
net. I seem to remember it having those bony struts in the tail...(think I
saw it on TV). Anyway, I was just wondering if it wasn`t considered closer
to Dromaeosaur albertensis (lets say), than it is to the Archie group. And
that pedal claw, is that considered a synapomorphy with the Dromaeosaur
condition, or did it evolve separately?