Boom and bust for ancient sea dragons

[Still Waters]

A new study by scientists from the University of Bristol's School of Earth Sciences, shows a well-known group of extinct marine reptiles had an early burst in their diversity and evolution—but that a failure to adapt in the long-run may have led to their extinction.

Ichthyosaurs were fish-like reptiles that first appeared about 250 million years ago and quickly diversified into highly capable swimmers, filling a broad range of sizes and ecologies in the early Mesozoic oceans. However, this rapid pace didn't last long and an evolutionary bottleneck 200 million years ago, through which only one lineage of ichthyosaurs survived, led to much slower evolution in much of their long history.

https://phys.org/news/2020-02-boom-ancient-sea-dragons.html

http://www.bristol.ac.uk/news/2020/february/ichthyosaur-evolution.html