Re: Irritator and Spinosaurids

[Dinogeorge@aol.com]

In a message dated 96-01-29 23:48:08 EST, zooamy@zoo.latrobe.edu.au (Adam
Yates) writes:

>I'd like to fly an highly speculative kite for the troops to take shots at.
>I've just got hold of the description of Irritator and a few points 
>strikeme as very interesting. The authors note that there is a similarity 
>between the teeth of Irritator and those of Spinosaurids. I was also 
>struck by the similarity of Irritator to Baryonyx in gross skull shape, 
>mostly the long low shape, the placement of the nostrils far back from 
>the snout tip and the strong postero-lateral inclination of the ramus of 
>the lacrimal that forms the preorbital bar. Perhaps Irritator is indeed a 
>spinosaurid and spinosaurids are infact coelurosaurs (bullatosaurs even?) 
>rather than megalosauroids

You betcha, Red Riding Hood. I've already installed family Irritatoridae as
the fourth family of Theropod suborder Spinosauria for exactly the reasons
you cite.

Bullatosauria would be more remote, however. The key character is the
inflated parasphenoid capsule, and that's not available in the specimen as
far as I can tell. The other troodontid apomorphies seem weak to me.