Dinosaurs engaged in herd living much earlier than expected

A new study published in the journal Nature Scientific Reports has found the earliest evidence of herd living among dinosaurs through the discovery of fossilized remains of sauropodomorphs, a species of large, long-necked herbivores living in the Mesozoic Era.

“Sauropodomorph dinosaurs dominated the herbivorous niches during the first 40 million years of dinosaur history (Late Triassic–Early Jurassic), yet palaeobiological factors that influenced their evolutionary success are not fully understood,” the study authors wrote. “For instance, knowledge of their behavior is limited, although herding in sauropodomorphs has been well documented in derived sauropods from the Late Jurassic and Cretaceous.”

A research team led by paleontologist Diego Pol from the Museum of Paleontology Egidio Feruglio discovered the fossilized skeletal remains of 80 individuals and over 100 eggs of the early sauropodomorph Mussaurus patagonicus in the Laguna Colorada Formation in Patagonia, Argentina.

By analyzing the size and type of bone tissue of the skeletal remains, the scientists identified a cluster of 11 juveniles of less than a year of age, nine specimens aged between a year old and adult, and two adults that were found closely together. These findings suggest that the presence of age-specific clusters of individuals in the same location could indicate that these dinosaurs lived in herds and primarily associated with others of their own age.

Since the rocks surrounding the remains appeared to be approximately 193 million years old, this is the earliest evidence of complex social behavior in dinosaurs, predating previous records by at least 40 million years.

According to the researchers, the evolution of complex social behavior among sauropodomorphs might have coincided with increases in body size that occurred between 227 and 208 million years ago. In order to meet the increased energy demands associated with larger body sizes, these dinosaurs might have needed to coordinate their behaviors by forming herds, and thus manage to forage over longer distances.

“The presence of sociality in different sauropodomorph lineages suggests a possible Triassic origin of this behavior, which may have influenced their early success as large terrestrial herbivores,” the authors concluded.

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By Andrei Ionescu, Earth.com Staff Writer