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Pterosaur eggs and ankles



Pterosaur eggs and ankles.

In light of recent comments on the pterosaur egg from the Yixian Formation of 
China, described a few weeks back by Wang and Zhou in Nature (2004, vol 429, p. 
621) perhaps it is worth pointing out that, so far as I am aware, with the 
single 
exception of David Peters, this fossil is universally accepted to be a 
pterosaur 
embryo in an egg. Admittedly, this is rather obvious from the preservation of 
the 
embryo in an egg-like structure, but there are other lines of evidence, not 
least 
the unique arrangement of the skeleton in this pterosaur, with the fore limbs 
folded up around the body on either side,a position that is typical of pre-
hatchling individuals in oviparous amniotes. There is much, much more to come 
in 
the pterosaur egg story, some of it will confirm what we already know (and 
how!) 
and some of it will no doubt become public at the SVP meeting later this year. 
I'll keep y'all posted. 

Alex Kellner kindly sent me a PDF of his pterosaur ankle paper, which I have 
now 
finished reading. I broadly agree with all his main points and am aware of 
further material from one of the basal-most pterosaur clades that supports his 
contention that the pterosaur ankle joint he describes for Anhanguera and 
Tapejera is universal for pterosaurs. It will be very interesting to see how 
the 
several ankle joint characters discussed by Kellner affect out understanding of 
pterosaur relationships to other diapsids - cladistic analyses are underway 
(literally as I write) and preliminary results tend to support the 'pterosaurs 
are ornithodirans' hypothesis. I prefer to keep an open mind on this issue, but 
would accept that the data that has come out recently does seem to be drifting 
things toward the Ornithodira. 

Toodle pip. 

Dave