Jurassic Mammals Underwent Record-Setting Evolution

It turns out that despite what Hollywood would have you thinking, it wasn't dinosaurs who were evolving in the Jurassic world. New research has determined that by the end of that iconic period, mammals were evolving at ten times the average rate, leading to an explosion of new adaptation and species.

That's at least according to a study recently published in the journal Current Biology, which details how a team led by Oxford University researchers did the first large-scale analysis of skeletal and dental changes recorded in mammals from the Mesozoic era (252-66 million years ago).

It was once thought that most early mammals were tiny, living off plants and insects as they hid away from their scaly overlords. However, with a better understanding of the fossil record, researchers have determined that near the end of the Jurassic period in particular, mammals suddenly began to grow and change in wildly varied ways.

"This is characteristic of other 'adaptive radiation' events of this kind, such as the famous 'Cambrian explosion," lead author Roger Close , a researcher with Oxford University, explained in a statement. "In the Jurassic we see a profusion of weird and wonderful bodies suddenly appear and these are then 'winnowed down' so that only the most successful survive."

According to the study, most of these adaptations had to do with feeding and locomotion, including new ways to achieve gliding, digging, and swimming - many of which led to the body shapes we see today.

"We don't know what instigated this evolutionary burst," Close said. "It could be due to environmental change, or perhaps mammals had acquired a 'critical mass' of 'key innovations' - such as live birth, hot bloodedness, and fur - that enabled them to thrive in different habitats and diversify ecologically."

"What we may have identified in this study is mammals' own 'Cambrian explosion' moment," he added, when evolutionary experimentation ran wild and the future shape of mammals was up for grabs."

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