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Re: Last Dinosaur of 2011



Happy new Gregorian year, everyone. I celebrate the occasion by rescuing from truncation:

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