Their find suggests that ichthyosaurs – a group of fish-shaped marine reptiles that inhabited ancient waters, reached their enormous sizes in a span of only 2.5 million years. In comparison, it took whales about 90 percent of their 55 million-year history to reach the huge sizes that ichthyosaurs evolved to in the first one percent of their 150 million-year history.
Lars Schmitz, an associate professor of biology at Scripps College in Claremont, California, said: “We have discovered that ichthyosaurs evolved gigantism much faster than whales, in a time where the world was recovering from devastating extinction [at the end of the Permian period].
“It is a nice glimmer of hope and a sign of the resilience of life – if environmental conditions are right, evolution can happen very fast, and life can bounce back.”
Experts first noticed the ancient fossils in 1998, embedded in the rocks of the Augusta Mountains of northwestern Nevada.
Prof Schmitz added: “Only a few vertebrae were sticking out of the rock, but it was clear the animal was large.”
In 2015, with the help of a helicopter, the team was able to full excavate the mammoth creature.
They airlifted the fossils of a skull, shoulder, and flipper-like appendage to the Natural History Museum of Los Angeles County.
They named the new species Cymbospondylus youngorum in their study, published in the journal Science.
They concluded that it lived 247 million years ago during the Triassic period.
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That makes the ichthyosaur’s huge size all the more impressive, as it took about nine million years for life on Earth to recover from that extinction, a 2012 study in the journal Nature Geoscience found.
It appears that ichthyosaurs’ venture into gigantism was, in part, due to chowing down on the early Triassic boom of ammonites.
Prof Schmitz added: “This new fossil impressively documents the fast-track evolution of gigantism in ichthyosaurs.”