[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Removing segnosaurs from Theropoda



In a message dated 95-08-29 20:50:22 EDT, head@lust.isem.smu.edu (Jason Head)
writes:

>        Yes, and if  crocodylian mandibles were found in Triassic deposits,
>they'd be called phytosaurs.  The downturned Maxillae are very similar, but
>the story is just not that simple.

Right. But it does help my case.

> Until we learn more about segnosaurs, a generally accepted answer will have
to wait >(esp. the relationships between segnosaurs and therizinosaurs:  I am
not convinced by 
>Russell's descriptions and analyses).

When you get right down to it, Russell's _Alxasaurus_ is the genus that
places _Therizinosaurus_ into Segnosauria, because it has both a tetradactyl
pes like that of  _Segnosaurus_ and a tridacyl manus with large claws like
that of _Therizinosaurus_. There is a tetradactyl pes that Perle referred to
_Therizinosaurus_ provisionally, but we didn't really know he was right until
_Alxasaurus_ was described.

>As for "Thecodontians", you don't have to be a cladist (and/or strictly
adhere to >monophyletic groupings), to recognize that "thecodont" has NEVER
described an >actual group of related taxa.  It was a garbage can ( a la
megalosaur), for poorly 
>understood archosaurs, and has since been abandoned.

Except by me, an old stick-in-the-mud.

G.O.