Re: Titanoceratops, giant ceratopsian from New Mexico

[Denver Fowler <df9465@yahoo.co.uk>]

It's astonishing how many of "Titanoceratops"'s characters are known to vary 
(strongly) ontogenetically; I see no reason to split off the OMNH Pentaceratops 
into a new genus and species: it is entirely consistent with being a mature 
Pentaceratops. Should we be splitting up all the ceratopsid growth series into 
different taxa? They certainly have different morphologies, but then that's 
because animals change as they grow.

I am coming ever closer to the view that we're going to see a schism in 
dinosaur 
science; at least in ceratopsid workers, with one side splitting all 
ontogenetic 
and stratigraphic morphs into different taxa, and the other studying 
ontogenetic 
shifts through time. Taxa are testable hypotheses using ontogenetic and 
stratigraphic data. if you are just using morphology, then it's a judgement 
call, and not much different from the way taxonomy was conducted 100 years ago.

I can't see it is possible to continue with one side trying to convince the 
other: look at Longrich's discussion of Triceratops-Torosaurus. I hesitate to 
call Triceratops-Torosaurus a complex problem (I think it actually simplifies 
things), but Longrich goes into such little detail it feels very dismissive. 
Saying that there are no intermediates is absurd: we see nothing but 
intermediates with the squamosals and other parts of the skull. Why don't we 
find some parietals with tiny fenestrae (ie. intermediates)? because that's not 
how the fenestrae form, and if you read the papers and look at specimens, 
you'll 
see it. New specimens are revealing more data on this; but be patient, we 
collected so many new Triceratops (with the essential strat data) it takes time 
to prep them all. It is much more parsimonious if Torosaurus is Triceratops: so 
many of the weird biogeographic and stratigraphic trends that we see fall into 
place.

To be fair this paper was submitted before Scannella presented at SVP, and 
other 
talks at SVP (including mine) show some of the conclusions here to be invalid. 
Triceratopsins in the Campani
e my full critique of this paper for elsewhere.

D.

 ----------------------------------
Denver Fowler
df9465@yahoo.co.uk
http://www.denverfowler.com
-----------------------------------



----- Original Message ----
From: Tim Williams <tijawi@gmail.com>
To: dinosaur@usc.edu
Sent: Thu, 30 December, 2010 4:09:52
Subject: Re: Titanoceratops, giant ceratopsian from New Mexico

> In case this new advance publication paper has not been mentioned yet:
>
> Nicholas R. Longrich (2010) Titanoceratops ouranous, a giant horned dinosaur 
>from the
> Late Campanian of New Mexico. Cretaceous Research (advance online publication)
> doi:10.1016/j.cretres.2010.12.007


There seems to be a discrepancy in the spelling of the species name
between the title of the paper (ouranous) and the body of the paper
(ouranos), with the former having an extra (and unnecessary) 'u'.
Something to correct before final publication.  BTW, the inspiration
for the species name is Ouranos, the father of the Titans in Greek
mythology.  This is the same dude that gives his name to the planet
Uranus.  Apparently, the etymology is not the same as that of
_Ouranosaurus_, which comes from the Tuareg name for monitor lizard
('ourane'), and is cognate with 'varanus'.


Anyway, back to _Titanoceratops_ (cool name, IMHO).  Aside from
erecting a new genus for an erstwhile _Pentaceratops_ specimen, the
paper puts forward a few more taxonomic changes vis-a-vis
_Triceratops_.  The referral of _Torosaurus_ to _Triceratops_ is
explicitly rejected; a separate diagnosis is provided for each, and
the "absence of intermediate forms argues that the two are not part of
an ontogenetic series."   On the other hand, _Nedoceratops_
(=_Diceratops_) and _Ojoceratops_ are referred to _Triceratops_ as
junior synonyms.  For the latter: "the broad, squared-off end of the
squamosal, putatively a diagnostic feature of â_Ojoceratops_â is
approached by at least one specimen of _Triceratops_ (_Triceratops
âserratusâ_, AMNH 970)."  So I guess _Ojoceratops_ is the problem.
more so t
an _T. serratus_, which I assume is safe inside
_Triceratops_.  The status of another new genus, _Tatankaceratops_, is
given as "problematic".  It "preserves a bizarre mixture of characters
seen in juvenile and adult _Triceratops_", so the specimen is either
an aberrant _Triceratops_ that stopped growing before reaching full
size, or a dwarf triceratopsin species.  I wouldn't be surprised if
more taxonomic convulsions are in stall for the Triceratopsini.



Cheers

Tim