On , Michael OSullivan<Michael.OSullivan@port.ac.uk> wrote: > I'm still incredibly skeptical about the validity of Spinops as a > distinct taxon from Centrosaurus. How so? We have solid autapomorphies (as outlined in the paper), we have two specimens from the same site with the same morphology (showing that the autapomorphies aren't just an individual fluke), and we have good growth series for Centrosaurus (and Styracosaurus) for comparison. None of the growth series show anything Spinops-like at all at any stage (or even a trend in that direction), so I think we can be confident it's not just a very old or very young C. apertus. Or are you referring to the issue of whether it should be in a separate genus? As outlined in the paper and associated supplemental information (and as I think Jaime was saying), Spinops could just as easily be closer to Styracosaurus or C. apertus (the best resolution was achieved when C. brinkmani was removed from the analysis - obviously, not the best solution!). Shoehorning Spinops into Centrosaurus makes a hypothesis of phylogeny that just isn't well-supported, and hence the new genus. I suppose one could put the whole mess (C. apertus, C. brinkmani, S. albertensis. S. sternbergorum) into Centrosaurus, but then this too is yet another phylogenetic hypothesis that gets exploded again in the next round of analysis by the next set of authors! Jaime - in your email I saw the sentence "These analyses are based on weak me," - I suspect a few words are missing there. Did you mean to say "weak characters"? I didn't want to put words in your mouth before addressing your reply! Andy