Fossil Bonanza reveals first evidence of dinosaurs living in herds

Mussaure is a type of dinosaur called a sauropodomorph, and it has been known to science since the 1970s, based on 11 fossils found in the Laguna Colorada formation in Argentina. Other sites around the world have alluded to the social behavior of Mussauresauropodomorphic cousins. Sites in Germany preserve assemblages containing multiple fossils of Plateosaurus, while sites in South Africa preserve nesting sites and eggs of the related dinosaur Massospondyle.

But Kimi Chapelle, a postdoctoral researcher at the American Museum of Natural History who was not involved in the new study, points out how the Mussaure the last lots of fossils on the site really are.

“You have the eggs, [and] individuals — and it’s not just people of the same age, but people of different ages. It’s just crazy, ”she said. “To have all this in a square kilometer and a thickness of three meters [rock] section? Unbelievable.”

Advantages and disadvantages of breeding

Many of today’s large herbivores move in herds, and the basic evolutionary calculation today is the same as it would have been for Mussaure over 190 million years ago.

Breeding has advantages and disadvantages, notes Temple University paleontologist Timothy Myers, who was not involved in the new study. On the one hand, moving in large groups offers more protection against predators, allowing each individual in that group to spend less time monitoring and more time eating. On the other hand, groups have to share food, and there is a higher risk of diseases and parasites.

For herds to function well, Myers adds, the animals within the herd must be in sync, which can be tricky for animals that change size dramatically as they age. In MussaureIn the case of, the newborns were the size of a human palm, reached 20 pounds and two feet tall at the hip by one year of age, and weighed over 3,300 pounds as adults. , nearly twice the mass of an adult moose.

This is where age segregation comes in. “The costs, basically, of having to synchronize your behavior increase as you get increasing differences in body size,” Myers explains. “For things like sauropods and sauropodomorphs, it is certainly more practical for them to train those herds of immature individuals that are separated from the adults.”

That said, deducing this type of social behavior – or any type of social behavior – from the fossil record is tricky. Fossil traces such as trail sites can help, and for some dinosaurs much newer than Mussaure, these preserved footprints showed signs of multigenerational herds.

Skeletal evidence can also hint at social behavior, if paleontologists find groups of skeletons that were buried at the same time. Without this crucial evidence, two skeletons in the assemblage could have come from animals that lived and died years apart.

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