Mammal diversity expedited following dinosaur extinction: study

Mammals evolved a greater variety of forms in the first few million years after the dinosaurs went extinct than in the previous 160 million years of mammal evolution, according to a study published Wednesday by the University College London (UCL).

New analysis of the fossil record shows that placental mammals became more varied in anatomy during the Paleocene epoch, the 10 million years immediately following the event. Placental mammals, the group that today has nearly 5,000 species, include elephants, sloths, cats, dolphins and humans.

Placental mammal fossils from this period have been previously overlooked as they were hard to place in the mammal tree of life because they lack many features that help to classify the living groups of placental mammals.

Through recent work by a team at UCL, this issue was resolved by creating a new tree of life for placental mammals.

"When dinosaurs went extinct, a lot of competitors and predators of mammals disappeared, meaning that a great deal of the pressure limiting what mammals could do ecologically was removed. They clearly took advantage of that opportunity, as we can see by their rapid increases in body size and ecological diversity," said Dr Anjali Goswami from UCL, who participated in the study.

The team are now investigating rates of evolution in these mammals, as well as looking at body size more specifically, according to UCL. Further work will involve building data from DNA into these analyses, to extend these studies to modern mammals. Endit