Some dinosaurs may have lived in herds as early as 193 million years ago

Fossils of long-necked Mussaurus suggest that the creatures stayed together through their lives

illustration of nine dinosaurs of differing ages

A herd of Mussaurus patagonicus, including hatchlings in nests, a group of juveniles and fully grown adults, are gathered together in this artist’s representation.

Jorge Gonzalez

A treasure trove of fossilized eggs, nests and skeletons represents the earliest evidence yet of dinosaurs traveling in herds, a study finds.