Did primitive cetaceans feed like marine reptiles?
Published:13 Sep.2022 Source:ScienceDaily
Did the first ancestors of whales pick up where the mosasaurs left off 66 million years ago, after the extinction of all the large predatory marine reptiles? A study has looked into the possible convergences in morphology and behavior that may exist between these two groups of large marine predatory animals.
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, notably the mosasaurs, a completely extinct group closely related to snakes and lizards. While cetaceans and mosasaurs initially had quite different ecological characteristics, this study found 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 necessary for large marine predators to evolve optimally. 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 examples of convergence. The results show what is called 'incomplete convergence', with differences remaining due to the mammalian or reptilian origin of each group.
Modern cetaceans are indeed a group that remains scientifically very interesting to study, it remains to be seen how diverse their morphology and ecology is compared to other fossil marine animals. This research is just the tip of the iceberg; further research into the convergence of marine animals through the fossil record will help us understand the constraints that evolution places on aquatic organisms and how they overcome them.