was: Sericipterus - now: anurogathids

[David Peters <davidpeters@att.net>]

Anurognathid jugals don't have large ascending processes. Some have none. And 
the lacrimal is wirelike, as in Dimorphodon, only thinner. That makes it 
difficult, but not impossible to find. The lacrimal is topped by an expanded 
head with a little foramen. That's what you look for. 

If one agrees that the old antorbital fenestra is now the new orbit (as in 
Bennett, 2007 and Andres, Clark and Xu 2010), then you won't find another 
process rising to separate the "naris" from the "aof," which gives rise to the 
new hypothesis of confluence. Bennett invented a maxillary ascending process to 
avoid this problem. Andres, Clark and Xu did not. 

Follow this model and you'll have another problem. Your jugal now has teeth (or 
as Bennett illustrated it, the maxilla peeks out for about an eigth of the 
tooth row, the rest is covered by jugal). No other pterosaurs are like this. 
Bennett rechristened the ascending process of the maxilla a jugal/naris, 
completely avoiding the lacrimal question and perhaps not realizing that the 
naris articulates with the ascending process of the maxilla, not that of the 
jugal. Bennett's model also does completely away with the postorbital 
ascendingprocess of the jugal. He just stretches  and stretches the jugal until 
it reaches the quardrate. The postorbital connects to the jugal like I've never 
seen before. 

So much invention. So much imagination. So little homology.

So, you won't be able to find outgroups that have the orbit crossing into the 
anterior half of the skull, much less occupying it. Former air-heads, for all 
their lightweight construction anurognathid skulls would now be fluid-filled 
(vitreous and aqueous humors) with those giant eyeballs. Minor point, granted. 
The major point is that the big "sclerotic ring" in Bennett's interpretation 
has tiny teeth. Yes, it is a maxilla, complete with convex ventral rim. Those 
divisions are tooth roots. Sceral rings NEVER crush edge on, as Bennett 
envisions. You'll always seem them fall apart like a house of cards, often 
preserving the entire ring like a circle.

Point is: You can't just reconstruct one anurognathid skull and call it a day. 
Try two. Then all of them and their purported outgroups. Line them up in a 
matrix or any sort of a chart and see if there are any bogies in the bunch. If 
you find yourself inventing bone shapes and articulations without homologies, 
take a step back and call a friend. 

David Peters
St. Louis


On Mar 19, 2010, at 2:02 PM, villesink@gmail.com wrote:

> Well Andres et al. make pretty convincing case for anurognathid NAOF. I must 
> say I was very skeptical when I first read about this from the Sericipterus 
> paper but after hours and hours of looking trough the papers and all the 
> available material I could find, I must say I have to agree with the 
> conclusions made by Andres et al. 
> 
> Ofcourse this whole thing is very reliant on the accuracy of the 
> interpertation of skull elements by Bennett. 
> 
> My first thought was that the anterior body of the maxilla was reduced to a 
> stub and the ascending bar identified by Bennett as jugal/nasal bar was 
> actually the fully fledged ascending process of maxilla, but then there 
> should be a jugal/Lachrymal bar anterior to the orbit yet no Anurognathid 
> specimen shows such a thing so there goes my idea out the window. 
> 
> Ville Sinkkonen