Did primitive cetaceans feed like marine reptiles? –ScienceDaily

Did the first ancestors of whales pick up where the mosasaurs left off 66 million years ago, after the extinction of all large predatory marine reptiles? A study conducted by Rebecca Bennion, a doctoral student at the EDDyLab of the University of Liège (Belgium), looked at the possible convergences in morphology and behavior that may exist between these two groups of large marine predators. This research was published in the journal Paleobiology.

Many of us are familiar with modern whales and dolphins. However, the extinct ancestors of these modern marine mammals bear an uncanny resemblance to earlier forms of marine life, including mosasaurs, a completely extinct group closely related to snakes and lizards. “Superficial similarities have been noted for a long time, but the idea that these two groups could be functionally similar has never been rigorously tested”, explains Rebecca Bennion, doctoral student at ULiège’s EDDyLab and first author of the study.

The research, which has just been published in the journal Paleobiology and was carried out by an international team of scientists based in Europe, the United States and New Zealand, investigated the potential for convergent evolution in skull morphology between ancestral cetaceans and mosasaurs. To do this, a range of functional and biomechanical characteristics were recorded from high-resolution three-dimensional (3D) scans of skulls from both groups. “Our laboratory has built up an extensive library of 3D scans of fossils, allowing us to explore in detail questions about large-scale evolution”, explains Prof. Valentin Fischer, paleontologist and director of the EDDy Laboratory at ULiège.

While cetaceans and mosasaurs initially had quite different ecological characteristics, this study revealed that several species had nevertheless acquired quite similar morphology and thus showed evolutionary convergence. “This convergence between early cetaceans and mosasaurs tells us more about the physical characteristics needed for large marine predators to evolve optimally,” says EDDyLab researcher Dr Jamie MacLaren, “Many members of these groups become very similar in their ecological characteristics, suggesting similar selective pressures on these animals despite being separated by tens of millions of years. Nevertheless, important differences remain between the two groups despite these instances of convergence.” results show what is called ‘incomplete convergence’, with differences remaining due to mammalian or reptilian origin. of each group,” continues Rebecca Bennion.

Modern cetaceans are indeed a group that remains scientifically very interesting to study, it remains to be seen how diverse their morphology and ecology are compared to other fossil marine animals. This research is just the tip of the iceberg; Further research on the convergence of marine animals through the fossil record will help us understand the stresses that evolution places on aquatic organisms and how they overcome them.

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