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> I'm also confused about the
> Bullatosauria, Spinosauridae & Irritator mess.
Makes two of us. In their original description of _Irritator_, Kellner and
friends shoehorned _Irritator_ into the Bullatosauria (Troodontidae and
Ornithomimosauria), but this assignment (by the authors' own
admission) was precarious.
Other authors (informally I believe - I haven't seen anything published) think
_Irritator_ may be more comfortable in the Spinosauria. The conical
teeth and long snout with the nares moved far back from the tip are
characters reminiscent of _Spinosaurus_ and _Baryonyx_. Postcranial
elements would help to place _Irritator_, but if wishes were horses ...
< Where does Archaeornithoides fit;
The specimen is tiny (<30mm) and probably from a juvenile (even a
neonate or embryo). _Archaeornithoides_ was regarded by Elzanowski and
Wellnhofer (1992) as an avian-relative; more specifically, a link between birds
and spinosaurids. The authors also allied _Archaeornithoides_ closely with
a critter named _Lisboasaurus_. However, _Lisboasaurus_ was then regarded as
a mini-maniraptoran, but has since been re-interpreted as a
crocodilian! In general, subsequent authors have tended not to take
E and W's ideas on theropod phylogeny on board.
Considering the presumed ontogenetic stage of the _Archaeornithoides_ specimen,
jaw material may be of negligible phylogenetic value. (Is it true that the
was originally regarded as a coming from an embryo tarbosaur?)