Some of the most extraordinary body transformations in evolution have occurred in animals that adapted to life in water from land-living ancestors, such as modern whales, turtles and seals. During the Mesozoic, from 252 to 66 million years ago, while the dinosaurs stomped about on land, many groups of reptiles took to the seas, such as the iconic ichthyosaurs, plesiosaurs, crocodiles and mosasaurs.
In a new paper, published in the journal Palaeontology, a Bristol team of paleobiologists used state-of-the-art statistical methods to perform a large-scale quantitative study, the first of its kind, on the locomotion of Mesozoic marine reptiles.
The researchers collected measurements from 125 fossilized skeletons, and used these to explore changes in swimming styles within lineages and through time, discovering that there was no explosive radiation at the beginning of the Mesozoic, but a gradual diversification of locomotory modes, which peaked in the Cretaceous period.