RE: Ceratops analyzed in the Sampson et al. (2010) matrix

[Tim Williams <tijawi@yahoo.com>]

On Thu, 23/9/10, Michael Mortimer <mickey_mortimer111@msn.com> wrote:


> Well, it found Torosaurus and Triceratops (and Nedoceratops) to be 
> sister taxa.  They were entered as separate OTUs, so their distinction 
> was assumed by the authors.  But being sister taxa in the cladogram is 
> just as congruent with the hypothesis they're synonymous.  


What's the bootstrap support?  Unless it's high, then you effectively have a 
polytomy.


> At worst,
> this could make Utahceratops a junior synonym of Ceratops.


Never gonna happen.


> As for Eoceratops, Longrich notes the long brow horns and hooked 
> squamosal distinguish it from Chasmosaurus, but he doesn't say anything 
> about comparison to Agujaceratops or other long-horned ceratopsines.
> Just because a specimen is juvenile is not a reason to ignore it as a 
> holotype.


Given the poor track record of ceratopsians that have immature specimens as 
theirholotypes (_Brachyceratops_, _Monoclonius_), then I think we have strong 
grounds to regard _Eoceratops_ as a nomen dubium.


Just to be clear... I'm not arguing that ALL genera based on juvenile/immature 
specimens should be dismissed as nomina dubia.  Otherwise _Apatosaurus_ would 
be sunk in favor of _Brontosaurus_.  Hmmm... now there's an idea.   ;-)



Cheers

Tim