Re: ornithosuchids

["David Marjanovic" <david.marjanovic@gmx.at>]

>      The definition of Crurotarsi (the only one I know of) which I am
going
> by *does* definitely depend on Ornithosuchus.  Sereno 1991 (p. 27) gives
the
> following definition of Crurotarsi:  "Crurotarsi includes Parasuchia,
> Ornithosuchidae, _Prestosuchus_, Suchia, and all descendants of their
common
> ancestor."
>     Therefore, if Ornithosuchidae is closer to birds than it is to crocs,
> then Crurotarsi (as defined by Sereno himself) is either paraphyletic or
> polyphyletic (and must be abandoned under a strictly phylogenetic
> taxonomy)---unless there is another definition that I don't know about, or
> there are plans to change the definition.

Nope, then it is just a junior synonym to (crown-group) Archosauria (and a
misnomer). I repeat "and all descendants of their common ancestor" (and add
"and that ancestor itself") -- it is unavoidably holophyletic, as all
phylogenetic definitions without the still very unusual qualifying clauses.
I'm BTW not sure that Sereno has named and first defined Crurotarsi.

>      There are still plenty of workers out there who believe
Ornithosuchids
> are closer to birds than to crocs,

???
I must have missed something... could you tell us one such worker?

> who do not take Sereno's topology for granted,

Why "Sereno's"? Lots of other people have published on this... this isn't
like Sereno's results that Alvarezsauridae and Ornithomimosauria are sister
groups, that tyrannosaurs are closer to birds (forming Tyrannoraptora) than
(to) IIRC ornithomimosaurs, and that *Euhelopus* is very close to
titanosaurs (forming Somphospondyli) while the rest of the "traditional"
Euhelopodidae is at the base of Sauropoda. (The latter is based on pneumatic
features that also occur in *Sauroposeidon*, so according to its JVP
description Somphospondyli is pretty useless.)