Re: DinosaurAH!torium

["Jerry D. Harris" <jdharris@dixie.edu>]

Hey Nick et al. -

> >     As Cliff noted, it's s'posed to be _Megapnosaurus_, the dreaded
> > (although rather comedic) rename of "Syntarsus" (stupid beetles).
>
> Ah.  _M. (?) kayentakatae_, I take it?

    Well, depends on what you believe.  _M. kayentakatae_ sensu stricto is 
from the Kayenta Formation. _Megapnosaurus_ ("_Syntarsus_") sp. has been 
reported based on a couple of pelves from the underlying Moenave Formation, 
in which the tracks at Johnson Farm are found (Lucas, S. G. & Heckert, A. B. 
2001. Theropod dinosaurs and the Early Jurassic age of the Moenave 
Formation, Arizona-Utah, USA. Neues Jahrbuch für Geologie und Paläontologie 
Monatshefte, 2001: 435-448.)  So if you want to believe that _M. 
kayentakatae_ ranges stratigraphically downward, then there's no evidence 
against that at present (nor for it, for that matter).  Personally, I see no 
reason to assume that there's only one theropod of this size in either the 
Kayenta or Moenave, just as there isn't just one in the underlying Chinle 
Group (e.g., _Coelophysis_ and _Eucoelophysis_).  For that matter, I see no 
particular reason to assume that the trackmaker for the _Eubrontes_ tracks 
at Johnson Farm was _Dilophosaurus_ (also from the Kayenta Fm.), although 
it's certainly the best-known sizeable theropod from both the physiographic 
area and the generalized time period, and thus makes a good visual.  But 
since there are also sizeable theropods in the Chinle (_Gojirasaurus_), it's 
just as likely with current evidence that _Gojirasaurus_ ranged upward as it 
is that _Dilophosaurus_ ranged downward.  Of course, it's also possible that 
theropods of the Moenave were indigenous to that formation and match species 
from neither the Kayenta or the Chinle...  Cliff simply chose (and he isn't 
the first, or the last!) to use _Dilophosaurus_ and _M. kayentakatae_ as 
models to reconstruct the Johnson Farm trackmakers, again simply because 
they're the best-known theropods in the stratigraphic and geographic 
vicinity.  Whether or not those are the actual trackmakers is a whole 
'nother ball of wax!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jdharris@dixie.edu
and     dinogami@hotmail.com
http://www.sas.upenn.edu/~jdharris

"The subject which I have chosed for the customary
Address this year lays no claim to authoritativeness; it is
not a wide synthesis of the state of knowledge reached
in any particular field; nor does it pretend to any
particular intrinsic importance." -- Sir Gavin de Beer,
opening sentence of his 1947 Presidential Address to
the Linnean Society of London