How they dealt with changes in climate remains a mystery. ‘Mammals just took advantage of the opportunity and started to evolve really fast,’ Dr Brusatte said. Although the first mammals originated at the same time as the early dinosaurs – more than 200 million years ago – they remained small, about the size of badgers, when they co-existed.Ī few hundred thousand years after dinosaurs disappeared, there were much larger, cow-sized species.

The team was surprised to learn how quickly mammals evolved after the extinction. ‘There was probably chance and randomness involved because things changed so quickly after the asteroid hit.’ ‘There isn’t one magic reason why some of them lived and others died,’ he said. Smaller mammals seemed to be better equipped to survive since they could hide more easily, for example, and those with a diverse diet were able to adapt more quickly, Dr Brusatte said. The work supports a growing body of research showing that when the dinosaurs were wiped out, it wasn’t simply a case of one group of animals dying off and another taking over as was previously thought. ‘Some of today’s familiar mammals, like the groups that later evolved into horses or bats, got their start soon after the extinction and probably as a direct result of it,’ Dr Brusatte said. The specimens that they analysed are also providing an insight into how mammals living right after the extinction are linked to modern ones. The team also visited museums to explore fossil collections, which allowed them to describe the features of several important mammal species in detail, such as a type of Periptychus, one of the first mammals to prosper after the asteroid struck. They collected several new fossils, including the previously unknown Kimbetopsalis simmonsae, a beaver-like species that lived during the first few hundred thousand years after the extinction.

They hunted for fossils in New Mexico, US, which is known to have the best record of vertebrate specimens from this period. His work revealed that while many mammals were wiped out with the dinosaurs, there was also an increase in the diversity and abundance of those that did survive.Īs part of the four-year BRUS project which ended in March, Dr Brusatte and his team collected new fossils dating back to the first million years after the extinction, which is thought to have lasted about 60,000 years, and put together a family tree of early mammals. ‘I wanted to find out where mammals were living, what were their habits … and how this exciting period of evolution set the stage for the great diversity of mammals that exists today,’ he said. Dr Steve Brusatte, a palaeontologist at the University of Edinburgh, UK, who previously studied the dinosaurs’ extinction, sought to understand exactly how this event affected mammals and their evolution.

Dino survival