Social mammals evolved faster than solitary ones, new study of ancient skulls says

Research has shown that mammals who require a lot of parental care, such as apes and gorillas evolve slower than those who do not, Mustafa Qadri reports

The last common ancestor of placental mammals was likely to have a shrew-like skull, researchers say (Creative Commons)

Researchers say they have discovered a ‘new model’ for mammalian evolution by analysing the skulls of hundreds of animals.

A new study looks at the remains of more than 300 species, including extinct creatures and living placental mammals to look at their common ancestors.

Among the many findings, the research suggests that social mammals that live in groups evolved faster than solitary ones, and that herbivores evolved faster than carnivores.

They also found that mammals that require a lot of parental care, such as apes and gorillas evolve slower than those that do not.

The research predicted what the skull of the ancestors of placental mammals would have looked like - a diverse group that includes humans, whales and armadillos.

Published in the journal Science, the study states: “Mammals have the greatest degree of morphological variation among vertebrate classes, ranging from giant whales to the tiny bumblebee bat.

“How they evolved this level of variation has been a persistent question, with much debate being centered around the timing and tempo of evolutionary change.”

A sample of the diversity of mammal skulls used in the study (R. Felice/UCL & NHM)

The earliest mammals existed alongside dinosaurs and were relatively constrained in their diversity, with the largest mammals of the Mesozoic Era growing to be the size of a small dog.

However, when dinosaurs became extinct around 65 million years ago that diversity increased significantly.

Up until that point, the ancestors of today’s placental mammals all had similar-shaped skulls but the research claims that soon changed.

Lead author Professor Anjali Goswami of the Natural History Museum said: “We see that there is a huge boom, in terms of mammal diversification, right after the boundary, or right around that boundary.

“This research will transform how we understand the incredible radiation of placental mammals, a group that includes our own species, and how that critical period after the last mass extinction 66 million years ago has shaped over evolution ever since.”