Jurassic Park got it right: Triceratops lived in groups

Triceratops, the famous horned dinosaur. (Photo: Center for Biodiversity Naturalis)

For many years, Triceratops, the famous horned dinosaur, was depicted as a pack animal. This was no different in the world-famous Jurassic Park films. However, there was no evidence that the beast lived in herds yet. One researcher began working with fossils from Naturalis in Leiden and came to a groundbreaking result: Triceratops formed a team.

In the summer of 2013, a team from the Naturalis Research Institute and Museum of Natural History made a strange discovery. Five triceratops were found next to each other in the US state of Wyoming. In fact, the excavation team was looking for Tyrannosaurus, a giant carnivore. Instead, they found a Triceratops: the famous herbivorous dinosaur with three horns and a large sternum.

Not one, not two, but five specimens were found underground in America. At least 1,200 bones and bone fragments were recovered from the rock and examined.
“What were all those dead dinosaurs doing there together?” asked paleontologist Jimmy de Rooij. Eleven years after the discovery, his research was complete and the result was surprising: the animals lived together and died together.

Sinking
“It's very good material,” de Rooij says of dinosaur detective work in his thesis. “This made it possible, for example, to show that these triceratops grow very slowly.” Details of the bone bed indicate that the five dinosaurs must have died together, perhaps by drowning in the swamp. It is located in a thin layer of rock, without the bones of other species.

Dental examination indicates the presence of a wanderer. “These types of dinosaurs lived in groups at least sometimes. “This of course raises all new questions,” says de Rooij. “How complex was this social behavior?” Jimmy de Rooij’s study has not resulted in a thesis for which he hopes to earn a degree. Not only did he complete his PhD on Wednesday, but it also led to an entire voyage of discovery surrounding his research.

Bones
The finds will be shown separately first – this summer they can be seen for free in five cities in the Netherlands – and in October at Naturalis. “There they are arranged as they lived and died 67 million years ago: together,” states the Natural History Museum in Leiden.

Leiden Association