Thursday, December 30, 2010

A Taxonomic Shot at the Buzzer: Titanoceratops ouranos

There is more than one way to erect a new dinosaur taxa. One way, the way the public is more familiar with, is to simply find the fossil bones, determine that they are unique enough to warrant a new taxa, and name it in a descriptive paper. But often, an analysis of fossils already in a collection will lead a researcher to the conclusion that they warrant being renamed as a new species.

This is the case with the newest - presumably last - member of the ceratopsian class of 2010, Titanoceratops ouranos. In a paper published this week in Cretaceous Research, Nick Longrich of Yale proposes that an exceptionally large Pentaceratops specimen at the Sam Noble Oklahoma Museum of Natural History is unique enough to warrant its own genus.

Sam Noble Pentaceratops
The Sam Noble specimen. Photo by okiebadger, via flickr.

Though this ceratopsian giant was discovered in the early forties, it wasn't until 1995 that it was released from the rock matrix containing it. It's such an exceptional specimen that its skull made the Guinness Book of World records as the largest possessed by a land vertebrate, measuring about ten feet tall when stood nose to frill. Longrich's cladistic analysis concludes that it doesn't match well with other Pentaceratops specimens, instead looking more like the skulls of that most popular tribe of ceratopsians, the triceratopsins. Longrich's paper suggests that the triceratopsins were the sole tribe of truly giant horned dinosaurs, and that they originated in the southern part of the North American continent, several million years earlier than previously thought.

Ceratopsian research is particularly vigorous right now, and it's going to be a while before all of the twigs and branches of this part of the dinosaur family tree are figured out. Since we can't observe these creatures living in the wild, we can't be totally sure which features denote species and which denote variations within those species. In this paper, Longrich provides his version of the triceratopsin tribe and does not factor in Horner and Scannella's paper lumping Torosaurus into Triceratops. So, though Titanoceratops is a very cool name... don't stake your future happiness on it sticking around forever. Though 2010 was the Year of the Ceratopsian, a simple calendar change won't shut the book. There's going to be plenty of work to mull over in 2011 and beyond.

Update: As brought up by Matt Martyniuk on the Dinosaur Mailing List, this is a pre-publication announcement of an accepted paper, so rather than the last new ceratopsian taxa of 2010, Titanoceratops might end up being the first of 2011. Bill Parker has posted about the issue of pre-publication announcements like this on taxonomy at Chinleana. I'll expand more on this in this week's Mesozoic Miscellany roundup.

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