Re: Tyrannosaurus "Scavenger vs. Predator" debate (joke)

["Michael Mortimer" <mickey_mortimer111@msn.com>]

Tim Williams wrote-

> While on the subject of tyrannosaurs, but turning to phylogeny... its my 
> impression that there is a basal plexus of tyrannosaurids, comprising 
> _Iliosuchus_, _Stokesosaurus_, _Aviatyrannis_ and _Eotyrannus_.  These 
> critters make up a paraphyletic assemblage outside of the clade that 
> includes the 'big'ns' (_Tyrannosaurus_, _Albertosaurus_, &c).  However, 
> _Siamotyrannus_ is not a tyrannosaurid (or tyrannosauroid or 
> tyrannosaurian), but some form of carnosaur.  And the jury is still out for 
> _Itemirus_, which has been linked to both the dromaeosaurids and 
> tyrannosaurids in the past.  How correct is this assessment, based on 
> current evidence?

Don't forget Dryptosaurus, and quite possibly "Chilantaisaurus" maortuensis 
and Bagaraatan.  Figuring out how the basal taxa are related is difficult 
given their often incomparable remains, and the lack of positive association 
for Stokesosaurus.  Dryptosaurus and Eotyrannus both have high DSDI's, but 
juvenile Tarbosaurus (Shanshanosaurus) does too.  Adult tyrannosaurids 
don't.  Eotyrannus and "Chilantaisaurus" maortuensis both have fused 
interdental plates, as does the premaxilla referred to Stokesosaurus.  But 
the latter has teeth with a primitive cross section, unlike other Morrison 
teeth and those referred to Aviatyrannis.  Tyrannosaurids, Dryptosaurus and 
Bagaraatan have unfused plates.  Remember, though tyrannosaurids are 
completely known, we can only compare a few parts for the other taxa-

premaxilla- Eotyrannus, Stokesosaurus?
premaxillary teeth- Aviatyrannis?, Eotyrannus, Stokesosaurus?
maxilla- "Chilantaisaurus", Dryptosaurus (fragment), Eotyrannus
nasal- "Chilantaisaurus" (fragment), Eotyrannus
braincase- "Chilantaisaurus", Itemirus, Stokesosaurus?
dentary- Bagaraatan, Dryptosaurus, Eotyrannus
cervicals- "Chilantaisaurus", Eotyrannus
caudals- Bagaraatan, "Chilantaisaurus", Dryptosaurus
humerus- Dryptosaurus, Eotyrannus
manual phalanges- Dryptosaurus, Eotyrannus
ilium- Aviatyrannis, Bagaraatan, Iliosuchus, Stokesosaurus
pubis- Bagaraatan, Dryptosaurus
ischium- Aviatyrannis?, Bagaraatan, Dryptosaurus
femur- Bagaraatan, Dryptosaurus
tibia- Bagaraatan, Dryptosaurus
fibula- Bagaraatan, Dryptosaurus
metatarsus- Dryptosaurus?, Eotyrannus

In my analysis, Stokesosaurus and Bagaraatan are always tyrannosauroids, as 
is "Chilantaisaurus" maortuensis usually.  Dryptosaurus is often a 
carnosaur, and Eotyrannus is sometimes a more derived coelurosaur.  Itemirus 
is always a troodontid oddly.  I haven't coded Iliosuchus or Aviatyrannis.

Mickey Mortimer

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