Re: Tyrant Notes

[Stanley Friesen <sarima@ix.netcom.com>]

At 12:02 PM 4/5/98 PDT, DE SOSA wrote:
>       I've been looking at various cladograms available on the web 
>(Mike Keesey's and Stan Friesen's, mostly) and they both seem to 
>say that all Lancian tyrannosaurs of North America should be 
>included in Tyrannosaurus.  This includes Nanotyrannus lancensis 
>and Dinotyrannus megagracilis.  Also, they say Maleevosaurus 
>novojilovi should be in included in T. bataar or T. efremovi 
>(what's the diff between these two, anyway?).

This is a matter of considerable ongoing debate.

It is perhaps better to say that my cladogram *excludes* _Nanotyrannus_ and
_Dinotyrannus_ per se.  My *current* opinion about those is represented by
my generic level synonymies and my classification.

[Also, my cladogram is hideously out of date - I have not updated for a
very long time - the classification is more frequently updated].

The fact is, I have vacillated back and forth on the position of
_Nanotyrannus_.  However, I have been fairly consistent in keeping
_Tarbosaurus_ in _Tyrannosaurus_ - though I could be convinced otherwise by
a new adult _Tarbosaurus_ skull.

>        Are they simply growth stages, or can they be put in 
>subgenuses of Tyrannosaurus?

Well, *if* _Nanotyrannus_ and _Dinotyrannus_ are junior synonyms of
_Tyrannosaurus_, then they are growth phases.   That is the center of the
debate: are they adults or juveniles?

> I read somewheres that the Nanotyrannus skull was from an adult. 

Bakker has so claimed.

Others have cited reasons to believe the contrary.

Who is right?  I do not know.

>       I'm probably sounding like an idiot right now, but sorry, I 
>don't have access to much more than Science,

Not really.  The status of the later tyrannosaurids is quite confusing.

--------------
May the peace of God be with you.         sarima@ix.netcom.com
                                          sfriesen@netlock.com