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estemmenosuchids (was Re: PT: your opinion please)

> > I just received the latest issue of  Prehistoric Times magazine
> > (issue No. 23), and have two questions based on sculptures
> > unveiled in this issue:
> > 
> > 1) the Estemmosuchus on the first page has much longer
> > horizontal skull protrusions than I've ever seen illustrated,
> > which means that they are incredibly long.  If you have the issue,
> > please comment on the accuracy of this; if not, exactly how
> > outrageous were those things anyway?

> I'm looking at an illustration of Estemmenosuchus by John Sibbick in
> "Dinosaurs, A Global View". He shows two variations, and one of them
> does have very long horizontal skull potrusions. The other doesn't.
> Maybe these are sexual or age differences? By the way, "A Global View"
> is a great book for its illustrations of non-dinosaurs. I highly
> recommend it.

I have not seen the PT sculpture in fact, so I should perhaps better 
shut my mouth, but I cannot resist replying to a question about 
that marvellous beasts called estemmenosuchids.

There are more or less fifteen estemmenosuchid skulls found in the 
Ocher formation, ranging from 35cm to 65cm skull length. These skulls 
show a very great variation in overall appearance and shape and 
position of the bony protuberances. However in internal stucture the 
skulls are more similar. Postcrania also show some variation in 
robustness and dimensions.
Two very different estemmenosuchid skulls are 
illustrated in Chudinov's 1960 paper in Geological Magazine; the 
smaller skull shows indeed very large horizontal bone protrusions, 
and apparently served as model for one of the estemmenosuchids of 
John Sibbick's illustration (the one in frontal view, who is right 
looking you in the eyes from the illustration). It is possible that 
the large variation in skull morphology not just reflects ontogenetic 
stages or different sexes; at least one other genus, Molybdopygus, is 
erected on the cranial remains.
Also worth mentioning is that Tom Kemp in 'Mammal-like reptiles and 
the origin of mammals' suggests that the bony protrusions of the 
estemmenosuchid skulls might be covered by horns in life, thus 
further adding to the length...

By the way, nobody knows what estemmenosuchids really were: in most 
textbooks and publications they are considered as (whether primitive 
or derived) dinocephalians, but Ivachnenko says they are 
eotheriodonts, as those other 'horny' therapsids: the burnetiids...

Pieter Depuydt

'unimaginatively and quickly glancing at some articles'