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Re: Phytodinosauria status



In a message dated 6/18/01 2:06:50 AM EST, Adam.Yates@bristol.ac.uk writes:

<< Just a word about the pendant fourth trochanter in Massospondylus. George 
has used it as a possible synapomorphy between the Ornithischia and 
Massospondylidae but it is only present in one individual of Massospondylus! 
There are dozens of other femora all of which have the typical non-pendant 
shape. No other members of the Massospondylidae have one either (I include 
Lufengosaurus, Yunnanosaurus, Jinshanosaurus and probably Coloradisaurus - 
there is an undescribed postcranial skeleton of this guy). I think that the 
one specimen that does have it is a pathologic individual (a bony lump 
growing on the ventral corner of  the 4th trochanter perhaps where the 
caudofemoralis had been torn off at some point in its life).  >>

I got the impression that Cooper had more than this, but unfortunately my 
copy of his big paper is buried and I can't check it. If this is true, then 
certainly that pendant massospondylid fourth trochanter is pathological and 
taxonomically useless. But I think he may have used this character when he 
set up Ornithischiformes. It has been years since I've looked at this stuff.

On another track, I think Massospondylidae right now includes only 
Massospondylus. Lufengosaurus and Coloradisaurus are good plateosaurids, not 
massospondylids; and Yunnanosaurus and Jingshanosaurus are good 
yunnanosaurids. So if they didn't have pendant 4th trochanters, it's not 
particularly relevant. I wouldn't consider ornithischians and plateosaurids 
or yunnanosaurids particularly closely related.