A Chinese horned dinosaur, a relative of Triceratops, walked on two feet

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Artistic representation of auroraceratops shows its biped posture and the beak and the wheel that characterize it as a member of the horned dinosaurs. Penn's paleontologists led a characterization team for this species discovered in China. Credit: Robert Walters

Many species of dinosaurs are known for their rare remains. Some estimates suggest that 75% of these are known for five or fewer individuals. Auroraceratops rugosus was typical in this regard when he was named in 2005 based on a single skull from the Gobi Desert in northwestern China. But this is no longer the case.

In the meantime, scientists have recovered fossils of more than 80 Auroraceratops, bringing this little plant eater into the ranks of the most famous dinosaurs. It is now one of the few very early horned dinosaurs known from complete skeletons. In a collection of articles appearing in Brief 18 of the Journal of Vertebrate Paleontology This week, researchers from the University of Pennsylvania, Indiana University of Indiana, Chinese Academy of Sciences, Gansu Agricultural University and other institutions have described the anatomy, age, conservation, and evolution of this vast collection of Auroraceratops.

Their analysis places Auroraceratops, who lived about 115 million years ago, as the first member of the group Ceratopsia, or horned dinosaurs, of the same group as Triceratops. Unlike the Triceratops, Auroraceratops is small, about 49 inches (1.25 meters) long and 17 inches (44 cm) tall, and weighs an average of 15.5 kilograms. While Auroraceratops has a small flying and beak that characterizes it as a horned dinosaur, it lacks the "real" horns and the vast cranial ornamentation of Triceratops.

"When I saw this animal for the first time in 2004, I immediately understood that it was a new type of fish and that it was a good thing. he was very excited about it, "said paleontologist Peter Dodson, lead author of the work and professor at Penn's. School of Veterinary Medicine and School of Arts and Sciences. "This monograph on Auroraceratops is long overdue."

In 2005, Dodson and his alumni, Hai-Lu You and Matthew Lamanna, named Auroraceratops (Latin, "the horned face of dawn") in honor of Dodson's wife. , Dawn Dodson. Together with your Chinese scientist colleague Da-Qing Li – the two authors of the current work – and your collaborators, you followed up on the discovery by identifying over 80 additional examples of the species, near-new born to adults.

Scientists were lucky enough to have a solid set of fossils of auroraceratops use to characterize the dinosaur, including almost complete skeletons. More than 80 individuals of the species have been identified since his name was named 15 years ago. Credit: Scott Hartman

Eric Morschhauser, senior author who is currently a professor at the University of Indiana, Pennsylvania, has completed his Ph.D. under Dodson at Penn, he's focused on characterizing Auroraceratops with the help of this robust data set.

Auroraceratops is the only horned dinosaur in the Neoceratopsia group (the line leading to large ceratopsians such as Triceratops), including Triceratops, from the lower Cretaceous with a complete skeleton. Researchers say this exclusivity is important because the horned dinosaurs, which were once bipeds, have become large rhinoceros-like quadruple animals that most people consider horned dinosaurs in the later parts of the Cretaceous.

"Before this study," says Morschhauser, "we had to rely on Psittacosaurus, a more distant and unusual cera- topsian, for our image of what the last bipedal ceratopsian looked like."

Auroraceratops preserves many skeletal features, such as a curved femur and long, slender claws, unequivocally associated with bipedal walking in some dinosaurs.

"This can now give us a better idea of the starting point of the changes between bipedal and quadrupedal ceratopsia," adds Morschhauser.

Peter Dodson is Professor of Anatomy at the Department of Biomedical Sciences of the School of Veterinary Medicine at the University of Pennsylvania and Professor of Paleontology at the Department of Earth Sciences and Environmental Sciences. School of Arts and Sciences.