Ichthyosaurs were, along with plesiosaurs and mosasaurs, something like the marine version of dinosaurs , colossi that ruled the Earth’s oceans until about 90 million years ago. The cause of their extinction, which occurred 25 million years before that of the “dinos”, is not yet clear, but a new study published in the journal Nature Communications sheds new light on this open case.
Known as “sea dragons”, ichthyosaurs looked similar to modern dolphins and could reach a length of fifteen meters. Agile hunters, they reached their peak in the Jurassic, although something abruptly killed them . Commonly, it was thought that their diet was impoverished due to ruthless competition from sharks and bony fish.
Without underestimating this factor, the new study, carried out by paleobiologists from Belgium, the United Kingdom, France and Russia, points to another culprit: global warming , a phenomenon that also did its thing at the time.
The geological record shows that, indeed, there was a rather sudden rise in temperature and sea levels, which in turn changed the directions of currents, migratory routes, and the availability of food. Ichthyosaurs probably did not adapt quickly enough to the new circumstances , while other animals did manage to cope.
” During the last 50 million years of his reign, the evolution of ichthyosaurs was very slow, ” summarized Valentin Fischer, from the University of Oxford, the main person in charge of the study.
