A sea monster who lived in the beginning dinosaur the age is unexpectedly so colossal, it reveals that his species have grown to gigantic sizes extremely quickly, at least evolutionarily speaking.
The discovery suggests that these ichthyosaurs – a group of fish-shaped marine reptiles that inhabited dinosaur-era seas – grew to enormous sizes in just 2.5 million years, according to the new study. To put this in context, it took whales about 90% of their 55 million year history to reach the enormous sizes to which ichthyosaurs evolved in the first 1% of their 150 million year history, have said the researchers.
“We discovered that ichthyosaurs evolved to gigantism much faster than whales, at a time when the world was recovering from devastating extinction [at the end of the Permian period]Study principal investigator Lars Schmitz, associate professor of biology at Scripps College in Claremont, Calif., told Live Science in an email. resilience of life – if environmental conditions are right, evolution can happen very quickly and life can bounce back. “
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Researchers first noticed the ancient ichthyosaur fossils in 1998, embedded in the rocks of the Augusta Mountains of northwestern Nevada. “Only a few vertebrae protruded from the rock, but it was clear that the animal was large,” Schmitz said. But it wasn’t until 2015, with the help of a helicopter, that they were able to fully search the individual – whose surviving fossils include a skull, shoulder, and fin-like appendix – and the airlift to the Los Angeles Museum of Natural History. county, where it was prepared and analyzed.
The team named the new species Cymbospondylus youngorum, they reported online Thursday (December 23) in the newspaper Science. This large jawed marine reptile lived 247 million years ago during the Triassic period. Like other creatures of that time, it was strange. “Imagine an animal resembling a sea dragon: a streamlined, fairly long body with limbs modified into fins and a long tail,” Schmitz said. With a skull nearly 6.5 feet long (2 meters), this adult C. youngorum would have measured over 55 feet (17 m), or longer than a semi-trailer, the researchers found.
When the 45 tons (41 metric tons) C. youngorum was alive, C. youngorum reportedly lived in the Panthalasic Ocean, a so-called superocean, off the west coast of North America, Schmitz said. Depending on its size and the shape of its teeth, C. youngorum probably ate smaller ichthyosaurs, fish and possibly squid, he added.
There are many huge beasts that lived in the days of the dinosaurs, but C. youngorum stands out for several reasons. For example, C. youngorum lived only 5 million years after “the Great Die”, a mass extinction event that occurred 252 million years ago at the end of the Permian, which killed about 90% of the world’s species. This makes the ichthyosaur’s enormous size all the more impressive, as it took approximately 9 million years for life on Earth to recover from this extinction, a 2012 study in the journal Geosciences of nature find.
However, there was a boom in the diversification of marine molluscs known as ammonoids within 1 to 3 million years of mass extinction, according to the 2012 study. Ichthyosaurs in gigantism are partly due to the consumption of ammonites in the early Triassic, as well as jawless eel-like conodonts that filled the ecological void after the mass extinction, the researchers of the new study said. . In contrast, whales grew up eating highly productive primary producers, such as plankton; but these were absent from the food webs of the dinosaur era, said Eva Maria Griebeler, co-author of the study, an evolutionary ecologist at Johannes Gutenberg University in Mainz, Germany, in a statement.
Despite the different paths and time frames for whales and ichthyosaurs to reach gigantism, the groups show some similarities. For example, there is a link between large size and raptor hunting, just as sperm whales dive to hunt giant squid, and a link between large size and tooth loss, just like giant filter-feeding whales that are toothless, according to the researchers. noted.
“This new fossil impressively documents the rapid evolution of gigantism in ichthyosaurs,” Schmitz said. On the other hand, the whales “have taken a different route towards gigantism, much more prolonged and slower.
“The history of the ichthyosaurs tells us that ocean giants are not guaranteed features of marine ecosystems, which is a valuable lesson for all of us in the Anthropocene,” wrote paleontologists Lene Delsett and Nicholas Pyenson, who did were not involved in the research from a published perspective. in the same number Science.
Originally posted on Live Science.
