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BEAKS etc IN THEROPODS



On dinosaur beaks, Mike Lovejoy asked..

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IIRC, in your Eotyrannus paper, Tyrannosauroidea is in 
Maniraptoriformes. Does this mean you feel T-rex had a 
beak? ( Not trying to be funny; this is a serious question.)
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Tim already pretty much answered this, but same answer: 
Maniraptoriformes is a more inclusive group than 
Maniraptora, so if all maniraptorans are beaked, that doesn't 
mean that all maniraptoriforms are. I don't think 
tyrannosauroids were beaked, nor non-maniraptoriform 
theropods like abelisauroids or allosauroids. Among non-
maniraptoran maniraptoriforms we know of course that 
ornithomimosaurs were beaked.

It's well known that keratinized ridges, bosses, horns and 
hornlets are thought to have decorated the skulls of 
theropods (and other dinosaurs). A rugose surface texture 
and low ridge of bumpy bone in _Eotyrannus_ and other 
tyrannosauroids (though strangely not in _T. rex_ specimen 
FMNH PR2081) suggests the presence of a mid-line 
keratinous covering or series of bumps or hornlets. Since 
Carr has shown that this is the case even in the smallest 
tyrannosaurids (and by inference that tyrannosaurids had 
bumpy keratinized nasals at all ontogenetic stages [FMNH 
PR2081 notwithstanding]), was nasal bumpiness NOT a 
secondary sexual characteristic?

We're having some second thoughts about 'keratinization' of 
the nasals in _Eotyrannus_ however, simply because some 
of the nasal foramina are both extremely large (see Text-
Fig. 9.32 in Naish et al. 2001) and open into what appears to 
be a pneumatic recess within the body of the nasal unit. 
Clearly _Eotyrannus_ actually had a huge inflatable nasal 
sac like a hooded seal. That was a joke. I would say wait for 
the paper but, the way things are going, I will probably 
never get it written.

-- 
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045