Re: The position of tyrannosaurs (was Re: Armour Symposium Recollections)

["T. Mike Keesey" <tmk@dinosauricon.com>]

On Mon, 14 May 2001 Dinogeorge@aol.com wrote:

> In a message dated 5/14/01 4:56:53 PM EST, tmk@dinosauricon.com writes:
>
> << Actually, _Ornithodira_ would include _Prolacertiformes_ -- not to mention
>  _Pseudosuchia_! >>
>
> Although Dave has it going all the way to the root node of Prolacertiformes,
> he also shows the root node as an unresolved polychotomy, so that, e.g.,
> Protorosaurus, Prolacerta, drepanosaurids, and so forth could be
> non-ornithodiran prolacertiforms.

Here's the phylogeny on Peters' site, compiled from the text and the
diagrams, going by the text if they disagree (HP Peters, correct me if
anything's misrepresented):

Archosauromorpha
|--Rhynchosauria
`--+--Prolacertiformes
   |  |--Protorosaurus
   |  |--Prolacerta
   |  |--Boreopricea
   |  |--Jesairosaurus
   |  `--Tapinoplatia
   |     |--Macrocnemus
   |     `--Characiopoda
   |        |--Langobardisaurus (or in Tanystropheidae? I can't tell)
   |        |--Tanystropheidae
   |        |  |--Tanystropheus
   |        |  `--Tanytrachelos
   |        `--Fenestrasauria
   |           |--Cosesaurus
   |           |--Longisquama
   |           `--+--Sharovipteryx
   |              `--Pterosauria
   `--Archosauriformes
      |--Proterosuchidae
      `--+--Erythrosuchidae
         `--+--Proterochampsidae
            `--Archosauria (actually should be below)
               |--Euparkeria
               `--+--Parasuchia
                  `--(this is where Archosauria should be)
                     |--Suchia
                     `--+--Ornithosuchidae
                        `--+--Scleromochlus
                           `--+--Lagosuchus
                              `--Dinosauria
(The archosauriform part of this is somewhat outdated, but it will do for
this discussion.)

So if we use the definition of _Ornithodira_ as Clade(_Pterosauria_ +
_Dinosauria_), *everything* in the above cladogram, except for
_Rhynchosauria_, is included in _Ornithodira_! Hence my recommendation of
a restrictive clause, effectively invalidating _Ornithodira_ if pterosaurs
are not archosaurs.

(Incidentally, apparently he no longer considers _Megalancosauridae_ [or
is _Drepanosauridae_ the correct name?] to be prolacertiforms.)

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