Re: Ankylosauria and Scelidosaurus

[Tim Williams <twilliams_alpha@hotmail.com>]

Jay <sappororaptor@yahoo.com> wrote:

> Another possibility would be Ankylosauria be *restricted to Nodosauridae + 
> Ankylosaurid*.

One potential downside to the above definition is that we might have a 
situation in which there are traditional ankylosaurs that fall outside the 
clade bounded by _Nodosaurus_ and _Ankylosaurus_.  For example, if future 
analyses uphold the validity of Polacanthidae, then polacanthids would not 
be ankylosaurs under the "Nodosauridae+Ankylosauridae" definition.

> In this case, it doesn't really matter if Nodosauridae turn out to be 
> paraphletic to Ankylosauridae or
> not.

Given that Nodosauridae (stem-based) is defined by Sereno to include 
_Nodosaurus_ and _Panoplosaurus_ but not _Ankylosaurus_, a paraphyletic 
Nodosauridae would probably be invalid.

> Bottomline: Wheather Scelidosaurus becomes is closer to Ankylosauria or 
> outside Eurypoda isn't
> going to change the clade names, which seem pretty stable in my opinion 
> (the definitions of).

Agreed.

Cheers

Tim