About 250 million years ago, life on Earth went through serious trials - climatic changes, volcanic eruptions and the rise in the level of the World Ocean contributed to the mass extinction of living beings. But the worst of all natural disasters affected marine life - 96 percent of all marine species then disappeared from the face of the earth.
For a long time, scientists believed that the first marine reptiles that appeared after the mass extinction evolved slowly. But the recent discovery of a rather unusual fossil casts doubt on this claim.
In their study, published in Scientific Reports, paleontologists described a new marine reptile, Sclerocormus parviceps, similar in structure to the ichthyosaurus. Similar, but still seriously different from them.
To be clear, the ichthyosaurs were a huge group of marine reptiles that lived during the early dinosaurs. Most of them were somewhat similar to modern dolphins - streamlined bodies, a long beak-shaped muzzle and powerful tail fins. We add that ichthyosaurs in their mass are very similar to each other.
But recently discovered fossils of S. parviceps are clearly different from their "relatives." The creatures of this species had a short muzzle (the name of the species contains the words "small skull"). In addition, instead of a triangular-finned tail, it had a long, whip-like tail, without a large fin at the end.
There is one more significant difference: many ichthyosaurs had tapered teeth for catching prey, while Sclerocormus was completely toothless. How did he get his food? Scientists suggest that his short muzzle was probably used: he created pressure and absorbed food just like a syringe sucks liquid.
Thus, this species was really different from most of its relatives. This makes the new discovery very important for the theory of evolution.
“The discovery of fossils of the genus Sclerocormus tells us that ichthyosaurids evolved and changed rapidly at the end of the Lower Triassic. We do not have many marine reptile fossils from this period, so this specimen is very important because it points to a variety that scientists have never known before,”says Olivier Rieppel, Field Museum of Natural History.
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The way in which this new species rapidly evolved into such a different form sheds light on how evolution actually works. “Darwin's evolutionary model speaks of small and gradual changes over a long period of time. But this is not at all like what we see here now. These ichthyosaurids seem to have evolved very quickly and in short periods of time,”says Rippel.
In addition, according to paleontologists, animals such as Sclerocormus, which lived after the mass extinction, show how life responds to significant changes in the environment.