Protoavis (was Re: solnhofen)

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

Rob Gay wrote:


> Indeed, most of _Protoavis_ seems to be made up of several animals.

I don't believe there has been a definitive publication which directly 
addresses (a) that _Protoavis_ is certainly a chimera or (b) if so, the 
identity of the specimens that make up the chimera.  Rob, if you know of 
such a paper, let me know!  :-)  If it's not published... well, you know...

> The skull is part of a megalancosaurid,

Silvio Renesto found uncanny similarities between the skull and neck of 
_Megalancosaurus_ and the skull and neck of _Protoavis_.  He could find no 
obvious siimilarities between the two in the rest of the skeleton.  Hence, 
Renesto speculated that the skull and neck of _Protoavis_ *may* belong to a 
drepanosaurid (=megalancosaurid).

Incidentally, John Ruben has been keen to link _Megalancosaurus_ to the 
origin of birds.  It has a superficially bird-like skull (= triangular in 
profile; apparently that qualifies as "bird-like"), elongate scapula, and 
certain postcranial features which suggest that _Megalancosaurus_ might have 
been a gliding animal (all challenged by Renesto, who restores 
_Megalancosaurus_ as a tree-climbing, non-gliding chameleon-like animal).  
Drepanosaurids are basal archosauromorphs, and as such are no more relevant 
to the origin of birds than (for example) _Tanystropheus_.


> the hindlimbs are non-avian theropod,
> the "hand" is some archosaur with a crocodile-normal ankle, and wait for 
> the paper on the pectoral girdle. However, it is generally >accepeted (from 
> what I know), that the verts are something new (and >are what I refer to as 
> _Protoavis_).

Again, you appear to have some inside information.


> However, due to the chimerical nature of the rest of the specimen, this is 
> usualy looked over.
> Other note on early birds...apparently there are bird tracks in the L. 
> Jurassic Kayenta Formation...


L. = Lower.  These might be nonavian theropod tracks.  Unless the 
bird/theropod dropped dead on the spot after making the tracks, and was 
preserved along with them, then it may be very difficult to draw the line 
between bird and bird-like theropod solely (no pun intended) on the basis of 
footprints.

Thanks for a very interesting post!


Tim

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

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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