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Re: Serendipaceratops confirmed as Australian Early Cretaceous ceratopsian.

Yikes!  I've never seen such a heroic effort in support of reinstating
the validity of a species.  _Serendipaceratops arthurcclarkei_ is
known only from an isolated left ulna; but statistical analysis finds
that its proportions are unique.  So it's a valid taxon....

I have two reservations about this approach.  Firstly, it sets the bar
incredibly high for ascertaining whether or not any isolated element
justifies being diagnosed to the genus or species level.  Maybe this
is a good thing... but I'm not certain *every* isolated bone or tooth
deserves to be put through the same rigorous analysis as the
_Serendipaceratops_ ulna.

Secondly, the morphometric diagnosis provided for _Serendipaceratops_
(in Appendix) is so stringent that I wonder if *any* other ulna could
be referred to this taxon, including an ulna from the same species
(even the right ulna from the same individual, in the unlikely event
that it is ever discovered).  If an ulna is slightly different in its
proportions to the holotype (either due to natural variation or to
taphonomic distortion) it would fall outside the strict criteria set
forth in the formal diagnosis, e.g., proximodistal length/mediolateral
width ratio = 10.31.  There's no wiggle-room.  What if an ulna is
found that is an almost identical to the holotype, but the l/w ratio
is out by just a bit?

This study by Rich et al. also provides a brief re-description of
_Notoceratops bonarelli_ (based on the available figures, the original
specimen being lost).  They find support for _Notoceratops_ being a
ceratopsian, consistent with Tapia (1919) and Huene (1929), but contra
most later studies, such as (most recently) Coria & Cambiaso (2007).
But no mention of whether or not _Notoceratops_ is a valid genus.



On Sat, Apr 26, 2014 at 1:19 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> From: Ben Creisler
> bcreisler@gmail.com
> A new new online paper:
> Thomas H. Rich, Benjamin P. Kear, Robert Sinclair, Brenda Chinnery,
> Kenneth Carpenter, Mary L. McHugh & Patricia Vickers-Rich (2014)
> Serendipaceratops arthurcclarkei Rich & Vickers-Rich, 2003 is an
> Australian Early Cretaceous ceratopsian.
> Alcheringa (advance online publication)
> DOI:10.1080/03115518.2014.894809
> http://www.tandfonline.com/doi/full/10.1080/03115518.2014.894809#.U1p2_PldXeI
> Serendipaceratops arthurcclarkei is one of Australia’s most enigmatic
> dinosaur taxa. Based on a single ulna recovered from Early Cretaceous
> high-latitude deposits in southeastern Australia, the fossil was
> originally classified as a neoceratopsian, but subsequently reassigned
> to Genasauria indet. because of comparisons with atypical
> thyreophorans. However, a morphometric and structural re-examination
> of the holotype indicates that it is proportionally distinguishable
> among dinosaurians and, indeed, manifests decisive statistical
> compatibility with ceratopsians. Statistical assessment similarly
> yields a synapomorphy that places the taxon robustly within
> Ceratopsia. Most certainly, identification of a unique differential
> character state combination renders S. arthurcclarkei as valid. Its
> affinity with ceratopsians concurs with proliferating records of other
> Laurasian dinosaur lineages from the Southern Hemisphere, and may
> reflect ancient Pangaean dispersals into or out of Gondwana.