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Re: DinosaurAH!torium

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

"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