Re: new Struthionid?

[Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com>]

>The holotype will be a fragment of eggshell, and no body fossils are
>referred. What is difficult for me, while their grounding is solid in
>distinguishing this species from others on the basis of eggshell thickness,
>pore density, and pore diameter, is why they chose to discard precedent in
>naming the taxon as a body fossil and a species of _Struthio_ rather than 
name
>ootaxa and apply the ootaxa to the species. This is, of course, rather
>excessive, but serves the point of referring a fossil egg to a body taxon 
that
>you cannot now demonstrate relevant without finding an adult in proximity 
or in
>fact whether you can determinately indicate the likelihood of bone to egg
>adherence. Not so here. The eggshell occurs in the Upper Laetoli beds 
below the
>Tuff 3, and eggshell determined to belong to *Struthio camelus* occurs above
>that, but also intermingles in part of Tuff 3 with the new taxon. This allows
>them to show sympatric struthionids occured. An hypothesis I would suggest
>would be that environmental factors can lead to eggshell variation in a 
single
>species without altering skeletal anatomy, a response to different humidity,
>laying conditions, or the health of the layer (i.e., the one who lays the 
egg,
>not the stratigraphic level), and this would lead to questioning fossil
>association of eggshell to body fossils without clear associative evidence
>("Big Momma" associative evidence, for example).

Unfortunately naming new struthionids from eggshells is not unusual. Just 
taking cases from Africa I can think of at least nine:

Psammornis rothschildi Andrews 1910
Psammornis lybicus Moltoni 1928 (= Struthio camelus)
Diamantornis corbetti Pickford, Senut & Dauphin 1995
Diamantornis laini Pickford, Senut & Dauphin 1995
Struthio daberasensis Pickford, Senut & Dauphin 1995
Diamantornis wardi Pickford & Dauphin 1993
Diamantornis spaggiarii Senut, Dauphin & Pickford 1998
Struthio karingarabensis Senut, Dauphin & Pickford 1998
Struthio oshanai Sauer 1966

Did they compare their eggshells with all these? Most *might* show up at 
Laetoli based on biogeography and stratigraphy. There are also a couple of 
ostriches described from body fossils that should be considered before 
erecting more late neogene ostriches from Africa:

Struthio coppensi Mourer-Chauviré et al. 1996
Struthio oldawayi Lowe 1933

Additionally there exists remains of a large Pliocene/Early Pleistocene 
ostrich from North Africa that have never been properly described.

Tommy Tyrberg