OXFORD, England, July 16 (UPI) — In surveying fossil records and analyzing the scientific literature, a team of scientists calculate that mammal lineages in the middle of the Jurassic period featured a higher rate of evolutionary changes.
Over several million years, scientists from England’s Oxford University and Australia’s Macquarie University plotted all major mammalian adaptions — changes in body shape and anatomy — throughout the Mesozoic era (252-66 million years ago).
The period of accelerated change afforded mammals the opportunity to experiment with different anatomical techniques, developing specialized jaws and teeth, claws and limbs, to find a niche in the environment and securing enough food and mates to persist.
During the middle of the Jurassic (200-145 million years ago), researches calculated eight changes per million years per mammal lineage — some 10 times the rate of change witnessed before and after this period.
“This period of radical change produced characteristic body shapes that remained recognizable for tens of millions of years,” Roger Close, a researcher with Oxford University’s Department of Earth Sciences, explained in a press release.
Close is the lead author of a new study on the subject, published this week in the journal Current Biology.
Researchers can’t explain what triggered the explosion of adaptation, but similar events can be found throughout the evolutionary timeline. The Cambrian Explosion (542-512 million years ago) famously featured a burst of speciation.
“This is characteristic of other ‘adaptive radiation’ events of this kind, such as the famous ‘Cambrian explosion,’” Close said. “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. What we may have identified in this study is mammals’ own ‘Cambrian explosion’ moment, when evolutionary experimentation ran wild, and the future shape of mammals was up for grabs.”
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