Ichthyosaurs were similar to cetaceans in body shape but descended from an as yet unknown group of reptiles and breathed air. These animals appeared 249 million years ago and inhabited the oceans for the next 150 million years. And they are some of the largest fossil reptiles known to science long before the dinosaurs. Today, such giants are whales. They evolved to larger sizes about 56 million years ago. Despite outward similarities, the evolutionary path of ichthyosaurs and whales to gigantism was different.
In 2011, scientists extracted part of the spine, shoulder and some other bones of an ichthyosaur from the Rocky Hill rock formation near Mount Augusta, Nevada (USA), and then found the skull of the animal. The age of the find is 247.2-237 million years old. So the remains belong to early ichthyosaurs. It turns out that ichthyosaurs developed gigantism only three million years after their appearance. And this, according to researchers, is a very surprising fact, which was found out thanks to comparative modeling of the evolution of ichthyosaurs and cetaceans. Perhaps the high competition in the Triassic seas and the "explosion" of life after the Permian extinction contributed to the large size of the ichthyosaurs. Ammonites and conodonts filled the vacated ecological niches.
You must be logged in to post a comment.