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Re: Titanoceratops, giant ceratopsian from New Mexico

I figured I should jump into the fray too. . .

On 12/30/2010 04:19 AM, Denver Fowler wrote:
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


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.

No - but it also depends on agreement that we're looking at growth series. There's no question with taxa like Centrosaurus, Styracosaurus, Pachyrhinosaurus, etc., where you have bonebeds. The great majority of ceratopsid workers accept that various skulls called Monoclonius are juveniles of this or that centrosaurine. I think the only major sticking point right now is in Torosaurus/Triceratops. I would agree that this is a testable hypothesis, simply due to the large sample size (especially for the Triceratops morph).

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.

If it's truly going to be such a schism, then I suspect neither "side" is doing science! The greatest danger is the practice that "When the only tool you have is a hammer, every problem is a nail." This plays both in the direction of assuming all morphological differences are taxonomically significant, as well as assuming all morphological differences are ontogenetic in nature (to oversimplify grossly). I'm not saying that the happy middle is correct (a fallacy in its own right), but I would urge caution in veering too far in either direction for every taxonomic problem. That said, the recent work on Triceratops has been providing some fantastic data to address these questions.

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.

I agree that too little detail is provided; however, I'm sure the editor wouldn't have wanted a huge digression on the topic in the middle of the manuscript!

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.

Diceratops/Diceratus/Nedoceratops does have tiny fenestrae.

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.

Like. :-)

I would also note that I strongly disapprove of the introduction of "Triceratopsini". We have enough clade names cluttering up the literature already.

Look for much more on this part of the tree in the next few weeks.