Mammals were adapted from tree life to live on the ground before killing dinosaurs, the study revealed

More mammals lived on the ground millions of years before the mass extinction event that wiped out dinosaurs, a new study led by the University of Bristol revealed.

The study, published in the Journal Palaeontology, provides fresh evidence that many mammals are already moving towards a more ground-based lifestyle that leads to asteroid effects.

By analyzing miniaturized bone fragments from marsupials and placental mammals found in western North America, particularly the edges of bones in the extremities, the only place with a conserved terrestrial fossil record from this point has discovered signs that these mammals are adapted to ground life. The edges of the limbs were analyzed to contain signatures of exercise habits that can be statistically compared to modern mammals.

Professor Christine Janice, the lead author of the Department of Earth Sciences at the University of Bristol, said, “It was already known that plant life changes towards the edge of the Cretaceous period, and flowering plants, called plants, create more diverse habitats on the ground.

“We also knew that the mammals living in the trees struggled after the asteroid impact. What was not documented was whether the mammals were more grounded along with habitat changes.”

Previous studies used full skeletons to study ancient mammal movements, but this study was one of the first to use small bone elements to track changes throughout the community. The team analyzed these small fossils using statistical data from the museum collection in New York, California.

Professor Janice added, “plant habitat was more important in the course of Cretaceous mammal evolution than in the influence of dinosaurs.”

Evidence was collected from bone joint fragments of treated mammals, including marsupials and placenta. The team’s methods were common at the time, as they were different bones.

Professor Janice said, “We have known for a long time that the articular surfaces of mammals in long bones can convey good information about their motility style, but I think this is the first study to use such small bone elements to study changes within the community, rather than just individual species.”

Although this study marks the end of the project, the findings provide new insights into how prehistoric mammals responded to changing environments.