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On Mon, 5 Feb 1996 Dinogeorge@aol.com wrote:

> Conical teeth with unserrated carinae and elliptical to circular
> cross-section occur in _Spinosaurus_, _Siamosaurus_, _Baryonyx_, _Irritator_,
> and _Archaeornithoides_. 

> Elongate rostrum with
> narial openings placed caudally from the tip occurs in _Baryonyx_ and
> _Irritator_, material unavailable for _Spinosaurus_ and (I think)
> _Archaeornithoides_. 

Of course, both of these characters may well be directly related to 
piscivory.  They are also found in many pterosaurs.

I don't know if I would advise making sweeping statements about theropod 
phylogeny based on tooth characters.

> Sagittal cranial crest occurs in _Irritator_ and
> _Baryonyx_, material unavailable for _Spinosaurus_ and _Archaeornithoides_.

Troodontids have fairly descent sagittal crests, too.

> Considering the incredible scarcity of material for any of these taxa, this
> character suite isn't too bad. What's Martill talking about? I wouldn't place
> any of these genera together in the same family (there are four families here
> plus Spinosauria _incertae sedis_), of course, but they could well have
> shared a common ancestry somewhere in the Late Jurassic Coeluria.

If they are related at all, they are, IMHO, most likely related to 
troodonts, based on similarities between that family and _Irritator_ and 
_Archaeornithoides_.  Just like everyone else, I am eagerly awaiting any 
concrete info. on Russell's _Spinosaurus_ material.

Nick Pharris
Pacific Lutheran University
Tacoma, WA 98447

"If you can't convince them, confuse them." -- Harry S. Truman