Re: Dilophosaurus and Syntarsus

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

On Fri, 23 Jun 2000, Rob Gay wrote:

> It also states that Dilophosaurus, Syntarsus et al. 
> are part of Ceratosauria, along with Ceratosaurus. It seems to me, from what 
> I've been able to get from the section, that there are not a whole lot of 
> similarities between Ceratosaurus and the rest of the group, beyond the fact 
> the it has horns, and some of the other "Ceratosaurs". Just wondering if 
> these animals were still grouped together, or has cladistics tackled this 

Cladistic studies have so far upheld the group, which contains two
divisions: Coelophysoidea and Neoceratosauria. _Ceratosaurus_ certainly
shares features with other Neoceratosauria (such as Abelisauria), such as
6 or 7 fused sacral vertebrae and tall, robust skull. I've heard that the
link between Coelophysoidea and Neoceratosauria might be weaker,
though; possibly based on primitive characters. I've seen the following
scheme, but am not sure if it has been published:

--+--Coelophysoidea
  `--+--Neoceratosauria
     `--Tetanurae

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