Spiky, Scaly New Species of Ankylosaur Discovered in New Mexico

The remains of an unusual armored dinosaur found in New Mexico may “fill the gap” in the fossil record of the lumbering, plated beasts known as ankylosaurs, paleontologists say.

Its distinctive horns and scales prove it to be a new species to science, and adds to the evidence that the ankylosaurs that roamed what’s now the American Southwest were related to, but clearly distinct from, their northern cousins commonly found in Montana and Alberta.

“We were really excited by both its familiarity and its distinctiveness—we were pretty sure right away we were dealing with a new species that was closely related to the ankylosaurs we find in Alberta,” said Dr. Victoria Arbour of the University of Alberta, in a press statement.

Ziapelta sanjuanensis
An artist’s reconstruction of Ziapelta sanjuanensis, a new species of ankylosaurid dinosaur discovered in New Mexico. (Illustration by Sydney Mohr)

Arbour and her colleagues, experts in ankylosaurs, were called in to help investigate the fossil when it was first discovered in the Bisti/De-Na-Zin Wilderness of northwestern New Mexico in 2011.

(Read about a different kind of find in New Mexico: “New Mexico’s ‘Atari Dump,’ a Midden of Video Games, to Be Excavated“)

The animal’s complete, intact skull allowed scientists to identify several unique traits, including unusually tall spikes along the back of its neck, and unusually shaped scales on its face and nose.

“The horns on the back of the skull are thick and curve downwards, and the snout has a mixture of flat and bumpy scales—an unusual feature for an ankylosaurid,” Arbour said.

“There’s also a distinctive large triangular scale on the snout, where many other ankylosaurids have a hexagonal scale.”

That big nasal scale inspired the name for the new dinosaur: Ziapelta, “zia” for the traditional sun symbol of the Pueblo, and “pelta,” Latin for “small shield.”

The ancient sediments where Ziapelta was found date back about 73 million years, a span of the Late Cretaceous from which, so far, no northern ankylosaurs have ever been found.

Ziapelta fossil
Top, bottom, and side views of Ziapelta’s complete skull. (Courtesy Arbour et al., PLOS One)

“The rocks in New Mexico fill in this gap in time, and that’s where Ziapelta occurs,” Arbour said.

As a result, the discovery of Ziapelta could provide crucial new information about the evolution and dispersal of the Ancient West’s armored dinosaurs.

“Could Ziapelta have lived in Alberta, in the gap where we haven’t found any ankylosaur fossils yet?

“It’s possible, but in recent years there has also been increasing evidence that the dinosaurs from the southern part of North America—New Mexico, Texas, and Utah, for example—are distinct from their northern neighbors in Alberta.”

Arbour and her colleagues report their findings in the open-access journal, PLOS One.


ResearchBlogging.org

Arbour, V., Burns, M., Sullivan, R., Lucas, S., Cantrell, A., Fry, J., & Suazo, T. (2014). A New Ankylosaurid Dinosaur from the Upper Cretaceous (Kirtlandian) of New Mexico with Implications for Ankylosaurid Diversity in the Upper Cretaceous of Western North America PLoS ONE, 9 (9) DOI: 10.1371/journal.pone.0108804

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