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Re: Re: DML Omnipedia stuff



>In a message dated 96-02-16 10:57:37 EST, Thomas_R_HOLTZ@umail.umd.edu (th81)
>writes:
>
>>Ornithodira is a node within Ornithosuchia joining Dinosauria, Pterosauria,
>>and Lagosuchus.  The current phylogeny for this group seems to be:
>> (Pterosauria + Schlermochlus ) + (Lagerpeton + ((Lagosuchus + Marasuchus) +
>>(Pseudolagosuchus + Dinosauria).
>
>_Megalancosaurus_ is clearly an ornithodiran, with cervical vertebrae that
>differ wildly from the dorsals and a skull that looks rather
>pterosaurian--the only skull available for Megalancosauridae. Also in
>Megalancosauridae: _Drepanosaurus_, _Dolabrosaurus_, and (provisionally)
>_Spinosuchus_. Bunch of derived _arboreal_ archosaurs.

Also the East Coast "deep-tailed swimmer".

Megalancosaurus is NOT clearly ornithodiran, or someone other than George
would accept it as such.  For that matter, it is not unambiguously an
archosaur.

It is such a highly transformed critter that indeed be an ornithodiran (and
certainly agrees with Dinogeorge's conception of arboreal ornithodirans).
On the other hand, the similiarities of its skull and neck may be convergent
with ornithodirans, as some other megalancosaurid/dolabrosaurids seem to
lack these derived features.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084