Biggest find of Triceratops fossils proves they were social dinosaurs

A haul of 1,200 bones and bone fragments of at least 5 Triceratops horridus individuals has been dug up over the course of 10 years at a quarry in Wyoming, US.

The palaeontologists were looking for Tyrannosaurus rex bones in 2013, but instead unearthed the largest group of Triceratops fossils ever found.

Triceratops are often depicted as the arch nemesis of T. rex. Both species lived right at the end of the Cretaceous period (145–66 million years ago), becoming extinct when an asteroid spelled the end of the reign of the dinosaurs. Evidence suggests that these ancient herbivores were a food source for the “king of the dinosaurs.”

But Triceratops were no push overs.

These animals are known for their menacing 3-horned heads and frilled necks. In fact, the Triceratops skull is among the longest of any terrestrial animal extinct or living, measuring about 2.5 m from the tip of the frill to the end of its beaked snout. Sitting above each eye are horns measuring about 1 metre, with a smaller horn on its nose.

Overall, Triceratops were big animals. They could grow to 9 metres long and weighed between 6 and 12 tonnes – up to double that of a large bull African elephant.

Nevertheless,  palaeontologists have long suggested that these plant eaters would have lived together in herds for protection.

The trove of fossils in Wyoming supports this hypothesis.

Among the fossils are hundreds of teeth. Chemical analysis shows that the animals were migratory and that all 5 individuals took the same path. It suggests that they travelled in a herd.

“And that of course leads to all kinds of new questions,” says PhD candidate and lead researcher Jimmy de Rooij from Utrecht University in the Netherlands: “How complex was this social behaviour, exactly?” The study forms de Rooij’s doctoral thesis. Analysis of the fossils was conducted in collaboration with the Naturalis Biodiversity Center in the Netherlands.

The fossils are so well preserved they reveal other details about the ancient creatures’ lives.

“This enabled us to show that these Triceratops grew really slowly, for instance,” de Rooij adds. The group died together, possibly stuck in a swamp. Their remains were found alongside those of other species.

“Naturalis, the national natural history museum of the Netherlands, now has the biggest triceratops find in the world, and Utrecht University has the first ‘Dr Triceratops’ in the Netherlands,” says de Rooij’s supervisor Professor Anne Schulp.

“De Rooij’s work didn’t just result in research papers, but also in an exhibition about his findings. As of October, the exhibition will kick off at Naturalis – and kick off the world tour – where the five triceratops are shown as they lived and died 67 million years ago: together.”

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