The remains of a huge ichthyosaur surprised researchers
The discovery of the skull of a giant marine reptile in the United States has revealed new theories about the rate of evolution and how quickly this process can lead to diversity.
A giant ichthyosaur fossil – with a skull nearly two meters long, an estimated body length of over 17 meters and weighing 45 tons – has been found in Nevada, CNN reported.
Ichthyosaurs are large, extinct marine reptiles that dominated the sea over 200 million years ago. Examination of the skull of this particular ichthyosaur fossil revealed a new species: Cymbospondylus youngorum.
The skull analysis was part of a larger study undertaken by an international team to understand how quickly body size changed in ichthyosaurs compared to the evolution of body size in whales – another group of originally four-legged terrestrial vertebrates that returned to life at sea, like ichthyosaurus, says CNN.
The study was published in the journal Science on Thursday.
“Ichthyosaurs reached gigantic body sizes in a very short period of time, evolutionarily speaking – only about 3 million years. By comparison, it took whales about 45 million years to reach their largest body sizes, says biologist Lars Schmitz, a member of the fossil research team. “This discovery shows that under favorable environmental conditions and a certain stability of the environment, evolution can occur very quickly.”
Schmitz worked with a group of international researchers to analyze the fossil, identify the found ichthyosaur as a new species, create a phylogenetic tree – a diagram that shows the evolutionary relationships between different species – and then performed computational analysis comparing the rate and type of evolution of ichthyosaur body size to size. whales.
Cymbospondylus youngorum was part of a group of reptiles that returned to the ocean during the Triassic period – the beginning of the dinosaur era – and fully adapted to marine life. Lars Schmitz describes him as a “fish lizard”.
An ichthyosaur fossil found in Nevada, which includes a preserved skull, shoulder and flipper-like limb, has been found in rocks that have preserved a cross-section of fauna that existed about five million years after the “Great Extinction.” It happened about 252 million years ago, when 81% of the world’s marine life became extinct, CNN tells CNN.
When the skull was discovered, the research team initially did not know how such a large animal could have evolved and survived so soon after the most severe extinction on Earth.
“The oceans of that period were very different from our modern oceans,” explained Lars Schmitz. – The modern marine ecosystems that feed today’s whales are composed of very large plankton that did not exist when Cymbospondylus youngorum lived. We found a giant ichthyosaur that lived in an era when the oceans were thought to be unable to support animals of this size. “
The discovery provided Schmitz and the research team with a new understanding of how fast evolution can occur and lead to diversity. “This fossil is an example of how rapid evolution can lead to diversity,” says the scientist. “You can go from zero to 100 in a few million years, which is very fast in terms of evolution.”
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