Dinosaurs Likely Started Living in Herds About 190 Million Years Ago; Formed Groups Based On Age, Body Size

In 1993, Steven Spielberg's Jurassic Park introduced the world to dinosaurs like never before. While researchers were interested in the reptile that occupied Earth hundreds of millions of years ago, the movie made people curious about it. Since then, technological advancements have let scientists uncover deep-buried facts about dinosaurs. Today, whatever we know about them, we know through fossils. There still remained one area where fossil studies were unable to reveal much about — the social behaviour of dinosaurs. However, a set of recently discovered fossils has provided a rare insight into the social lives of one dinosaur — the herbivore Mussaurus patagonicus.

After studying the fossils, found in a sag basin in southern Patagonia (Argentina, South America), scientists concluded that the occurrence of many fossils of dinosaurs at different life stages within a square kilometre suggests they lived in herds nearly 190 million years ago (the fossils have been dated to 192 million years ago). The researchers also think the social cohesion of the Mussaurus may have helped it survive longer.

“Most specimens were found in a restricted area and stratigraphic interval, with some articulated skeletons grouped in clusters of individuals of approximately the same age. Our new discoveries indicate the presence of social cohesion throughout life and age-segregation within a herd structure, in addition to colonial nesting behaviour,” the researchers said.

The researchers studied the skeletal specimens of 80 individuals, ranging from embryos to eggs and infants to fully-grown adults. They also found evidence of individuals having formed age-based subgroups within the community. This was not unique, however.

Many existing animals with notable differences in body size segregate themselves based on age. Living in a tightly knit group of the same body size allows animals to better arrange for their food and other behaviour.