Dinosaurs lived in groups 200 million years ago

Artistic restoration of patagonia rat dragons. Image credit: Jorge Gonzalez

A new study has found that the suborder Sauropods, a fossil of a large, long-necked plant-eating dinosaur that lived in the Mesozoic Era, may provide the earliest evidence that dinosaurs lived in groups. The study was published online October 21 in Scientific Reports.

Diego Pol and colleagues at the Ferugoglio Museum of Paleontology in Argentina found fossils and 100 eggs of 69 dinosaur individuals from the Laguna Colorada Formation in the country, derived from Patagonia.

The researchers found that most eggs were lined up in groups of 8 to 30. X-ray imaging of 5 of these groups showed that the eggs contained embryos of Patagonian rats. They are stacked in ditches in 2 to 3 layers, indicating that they are placed in a breeding nest. The study analyzed the size and type of bone tissue in the bone remnants to determine the age of fossilized individuals. The scientists found a group of 11 juvenile individuals, younger than 1 year old, as well as two adult individuals found together, and 9 individuals between minors and adults.

The researchers believe that the presence of these age-specific groups of individuals at the same site indicates that Patagoniaratosaurus lived in groups throughout their lives, but mainly with people of the same age. They analyzed the rocks surrounding the fossil remains, which are about 193 million years old, advancing the earliest record of complex social behavior by more than 40 million years.

The researchers reasoned that the complex social behavior of the sauropod suborder evolved or coincided with the enlargement of its body shape, a process that occurred about 227 million to 208 million years ago. They believe that in order to meet the energy needs associated with larger bodies, Patagoniaratosaurus may need to coordinate their behavior and form communities to forage for food at greater distances. (Jinnan)

Source: China Science Daily