Discovery of the fossil of a Triassic sea monster 17 meters long

Reconstitution de C. youngorum — © Stephanie Abramowicz / Natural History Museum of Los Angeles County (NHM)

The fossilized remains of one of the earliest known sea giants were recently discovered in Nevada. These reveal the incredibly rapid evolution of ichthyosaurs, reaching an impressive size in the space of just a few million years.

A dazzling evolution

Marine reptiles that populated the Earth’s oceans around 249 million to 90 million years ago, the ichtyosaures owned a morphology reminiscent of whales and dolphins modern. In the context of work recently published in the journal Science, researchers fromnashville university unearthed the remains of a previously unknown giant species. Baptized Cymbospondylus youngorum, this ichthyosaur might measure up to 17 meters.

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2 meters long, the fossilized skull described in the review Science was discovered in rocks some 246 million years old, only 3 million years following the appearance of the first and much smaller ichthyosaurs. This highlights the spectacular size gain of these creatures on an extremely reduced time scale.

If several whales modern technologies are now reaching gigantic sizes, their evolutionary path has been shown to be much longer. The first species appeared around 56 million years ago, and it took almost 50 million more years for them to become so massive. The rapid evolution of the ichthyosaur C. youngorum therefore highlights different evolutionary trajectories for these superficially similar animals.

The fossilized skull discovered by researchers – © Martin Sander / Natural History Museum of Los Angeles County (NHM)

« By studying completely extinct animal lines like ichthyosaurs, we can get a much richer picture of the complexity and commonalities in the history of terrestrial life. “, highlighted Neil Kelley, researcher atVanderbilt University and co-author of the study.

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“The whales did not benefit from such favorable conditions”

The ecosystem within which evolved C. youngorum was found to be very different from those seen in today’s oceans, with much shorter food chains, and a profusion of creatures, including former relatives of the squid called ammonoïdes, which would have made it possible to support the meteoric growth of these marine reptiles.

« This overabundance of food allowed large ichthyosaurs to evolve and endure, and patterns of energy flow in this ancient food web show that another giant ichthyosaur species might have survived within the same environment. », note Lars Schmitz, co-author of the study. ” Whales did not enjoy such favorable conditions and therefore took much longer to become the behemoths we know today.. »