14 DAY TRIAL // A group of researches from the University of Lyon in France recently discovered that ancient marine reptiles were significantly different from the fish that lived at the same time. They are not talking just about body shape and size, but also about the ability that some creatures had to retain their bodily temperatures constant. The conclusions belong to a new study they conducted on ancient fossils, that reportedly lived between 251 million and 65 million years ago, LiveScience reports.
Fish are unable to maintain a constant body temperature, and neither are modern-day crocodiles and alligators. Some sharks are, however, capable of doing this and the research team believes these animals may be descendants of the reptiles they discovered in the fossil record. The thing that distinguished them from the rest of the creatures living at the same time was the fact that they were able to maintain their bodily temperature at relatively constant levels, with the direct consequence that they were able to maintain muscular effort for prolonged periods of time.
This added to their existing advantages (sharp, serrated teeth and large bodily sizes), to produce some of the most vicious and efficient predators that lived. They reigned for portions of the Mesozoic era, but ended up being destroyed in the same extinction event – the Cretaceous–Tertiary dying – that saw the disappearance of all dinosaurs, and which laid the foundation for the rise of mammals. “The only way to maintain a constant and high body temperature is that the animal is able to produce internal heat by its organs. It was probably very useful for them to dive in deep waters to track prey and also to have access to environments where normal reptiles cannot go,” says study researcher Christophe Lecuyer.
Speaking about some of the largest species that lived at the time, the researchers estimate that icthyosaurs and plesiosaurs, for example, had bodily temperatures reaching 24 degrees Celsius, or roughly 75 degrees Fahrenheit. These levels are comparable to the ones found today in common fish such as tuna. On the other hand, mosasaurs had temperatures closer to that of humans – about 36 degrees Celsius, or 97 degrees Fahrenheit. The team believes that the creatures may have used blubber or advanced, specialized circulatory systems to maintain their temperatures.