Dromies, birds - and Protoavis question

["Tim Williams" <twilliams_alpha@hotmail.com>]

> How can time not count? You can't be older than your ancestors? People say 
> that birds descended from dromeosaurs...but there are 0 dromeosaurs known 
> from before the late Jurassic! Time is very important.

Just a clarification.  I don't think anyone is saying that birds evolved 
directly FROM dromaeosaurids, any more than anthropologists claim that 
humans evolved from chimpanzees.  Birds and dromaeosaurids share a close 
common ancestor.  Much of the debate centers on just how close the 
Dromaeosauridae and Aves (or Avialae) are in theropod phylogeny.  Do 
dromaeosaurids and troodontids comprise a monophyletic sister taxon 
(Deinonychosauria) to the Aves?  Is _Rahonavis_ positioned between 
dromaeosaurids and Aves, or is it more derived than _Archaeopteryx_?  That 
sort of thing.

As for pre-Late Jurassic dromaeosaurids.  This was discussed fairly 
recently, and there are indeed a lot of dromaeosaurid-like teeth from 
pre-Tithonian strata.  I think these need to be attached to skeletal 
elements to be more certain of their affinities.  To me, the _Ozraptor_ 
tibia (Middle Jurassic, Australia) looks somewhat dromaeosaurid, and 
_Nuthetes_ (Middle Jurassic, England) is about to be re-described as a 
dromie (thanks for the info Darren):
(http://www.cmnh.org/fun/dinosaur-archive/1999Dec/msg00056.html).

There's also scrappy limb material from the Morrizon (including 
_Palaeopteryx_), which could be either avian or dromie.

The subject of _Protoavis_ has come up.  I've just been reading some of John 
Ostrom's comments on this critter.  Ouch!  He doesn't hold back.  Anyway, 
has there been any published illustrations of the *original* _Protoavis_ 
material.  In other words, are there pictures ANYWHERE of what the bones 
looked like when they came out of the ground, rather than just Chatterjee's 
interpretations of what they are.


Tim

------------------------------------------------------------

Dr Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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