HYPSILOPHODONTIDS: MONO-, POLY- OR PARAPHYLETIC

[darren.naish@port.ac.uk]

Delayed response to Rutger Jansma's and Pete's comments 
on validity of Hypsilophodontidae. Rutger wrote...
 
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2)  Naish & Martill thought that the Hypsies and their 
relatives do not really constitute a single family, instead, 
they thought it was more paraphyletic, with some genera 
more closely related to Lesothosaurus, while others more 
closely to the iguanodontids. Is this correct?
----------------------

Naish & Martill write that 'yandusaurs and agilisaurs appear 
archaic compared to _Hypsilophodon_ and some of them 
may not even be ornithopods' (p. 66). As Pete will tell you 
this isn't exactly right but that text was clearly not the place 
to discuss views on _'Y'. multidens_ et al. Also, the Naish & 
Martill statement does not apply to all things that have been 
allocated to _Agilisaurus_ and _Yandusaurus_, but to 'some 
of them'. 

Naish & Martill do not state that 'some genera are more 
closely related to _Lesothosaurus_'; our implication (though 
you'd need psychic powers to know this) is that some of the 
taxa involved may be non-ornithopodan cerapodans. 

Pete wrote...

> Mmmm kind of.  Although it seems to be the word on the street that 
> Hypsilophodontidae is paraphyletic, the only thing that has produced that 
> result that is even close to published is Rod Scheetz'  phD thesis on 
> Orodromeus.  

The full results are unpublished but note that there is an 
abstract out there..

Scheetz, R. D. 1998. Phylogeny of basal ornithopod 
dinosaurs and the dissolution of the Hypsilophodontidae. 
_Journal of Vertebrate Paleontology_ 18 (supp. 3), 75A.

Somewhere out there also is a Norman and Barrett MS with 
comments on these taxa. I have spoken about it with Paul 
but am not sure on its current status. Note that there is quite 
a bit of stuff on these taxa in the DML archives and assorted 
cladograms have been offered by Mickey M, Pete and 
others.

-- 
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045