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Centrosaurine sites in North America. From Rivera-Sylva et al., 2016.

Paleo Profile: Mexico’s Mystery Dinosaur

A few years back, while crashing at my apartment for the night during a long trip west, a friend of mine asked me “Haven’t paleontologists found all the dinosaurs already?” Museums from coast-to-coast seem well-stocked with primordial reptiles, and, really, when dealing with such giants, how many species could there possibly be? I had to chuckle at my friend’s question. Not only were there more dinosaur species than we ever imagined, but we’re still a long way from finding them all.

I can’t think of a place that better exemplifies the dinosaur boom than North America’s southwest. Hell, the fantastic new species coming out of the area from the four corners on south was half the reason I moved to Utah. New explorations in the western deserts have yielded an increasing array of new dinosaur species, and paleontologists already know that there’s more out there than has been formally identified. Take, for example, an animal represented by a smattering of bones found in northern Mexico.

There is no formal name for this dinosaur yet. There’s too little of it to justify a permanent identification. But, as described by paleontologist Héctor Rivera-Sylva and colleagues, the fossils appear to represent a horned dinosaur not seen before.

The bones were found in Coahuila, northern Mexico, between 2007 and 2011. And while paleontologists named another horned dinosaur – Coahuilaceratops – from this area in 2010, the bones described by Rivera-Sylva and coauthors are from something different. That’s because Coahuilaceratops is what experts call a chasmosaurine – the lineage that contains Chasmosaurus and Triceratops – while this new dinosaur belongs to a separate lineage called centrosaurines that includes Centrosaurus, Nasutoceratops, and their relatives. This makes CPC 274 the southernmost occurrence of a centrosaurine dinosaur yet found.

This is how some dinosaurs make their debut. Not as beautiful skeletons with names as awesome as their osteology, but as fragments and pieces that hint at what’s left to find. The recently-named tyrannosaur Timurlengia, for example, first came to paleontologists as a smattering of tantalizing fragments before a braincase tied everything together. Hopefully the Coahuila centrosaurine will follow the same pattern, new finds filling in the identity of what must have been a gnarly herbivore with its own splay of spikes and horns.

I look forward to the day that paleontologists will be able to organize an unveiling for Mexico’s mystery dinosaur, but that’s not the point of this post. I picked this unnamed enigma for my last Paleo Profile here at National Geographic because of what it represents. The unknown is what calls to scientists, both in the lab and in the layers of time laid out in the desert. For every fact or fossil we find, we get a bloom of new questions that itch at the brain and the soles of your boots. That’s the drive to seek out unknown dinosaurs in their remote, ancient tombs, and, truly, we are just getting started.

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Fossil Facts

Name: There is no genus and species name yet. For now the dinosaur is designated as specimen CPC 274.

Age: About 80 million years ago.

Where in the world?: Coahuila, Mexico.

What sort of critter?: A horned dinosaur related to Centrosaurus.

Size: Unknown.

How much of the creature’s body is known?: A partial skull and several pieces of the postcrania.


Rivera-Sylva, H., Hedrick, B., Dodson, P. 2016. A centrosaurine (Dinosauria: Ceratopsida) from the Aguja Formation (Late Campanian) of northern Coahuila, Mexico. PLOS ONE. doi: 10.1371/journal.pone.0150529

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