2-meter sea skull reveals first giant living being known to date

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Paleontologists have discovered the fossil of a new species of aquatic reptile, as large as a sperm whale. Baptized Cymbospondylus youngorum, the creature is an ichthyosaur dating from the early stages of the dinosaur era and which grew to gigantic proportions very quickly. The analysis of its fossil allows us to better understand the evolution of these marine reptiles, but also of current cetaceans, which resemble them in many ways.

Ichthyosaurs were marine reptiles that dominated the oceans for about 150 million years, from the Lower Triassic to the Upper Cretaceous, or for most of the dinosaur reign. The archetypes resembled dolphins, with an elongated snout and fins, averaging 2-4 meters in length. But some ichthyosaurs were veritable “giants of the seas”, measuring more than 20 meters in length.

First giant creature, the size of a sperm whale

The fossil of Cymbospondylus youngorum – a previously unknown ichthyosaur species – was discovered in the Augusta Mountains of Nevada. It features a well-preserved skull measuring 2 meters in length (currently on display at the Los Angeles Museum of Natural History) as well as part of the spine, a shoulder and a forelimb.

With an estimated length of 17 meters (like an average sperm whale), this new species living around 244 million years ago represents the first case of ichthyosaur to have reached such proportions. In fact, it is the first giant creature to inhabit Earth to our knowledge.

crane cymbospondylus youngorum nhm
The skull of C. youngorum, with a volunteer from the Dinosaur Institute at the Los Angeles County Museum of Natural History (NHM). © Martin Sander / NHM

« We first had to describe in detail the anatomy of the giant skull and determine how this animal is related to other ichthyosaurs. », Explain lead author of the study, Dr. Lars Schmitz. ” We didn’t stop there, as we wanted to understand the significance of this new discovery in the context of large-scale ichthyosaur and whale size evolution, and how the Fossil Hill Fauna Fossil Ecosystem – in Nevada – could work ».

Very rapid growth

Its discoverers suggest that the creature managed to reach this size thanks to a “boom” in prey. About six million years earlier, the Earth experienced the worst extinction in its history, on the border between the Permian and the Triassic. By the time the ichthyosaurs appeared, many ecological gaps were filled by animals such as fish, squid, ammonites, and conodonts (eel-like). This new abundance of food may have fostered the rapid growth of predatory species such as C. youngorum.

In fact, ichthyosaurs and whales are examples of convergent evolution, where natural forces guide unrelated species into the same forms and strategies for survival. Besides similar body shapes, the two groups indeed seem to have evolved to gigantic sizes after mass extinctions and by exploiting food niches to develop. They did so at different rates, however: ichthyosaurs grew to impressive sizes very quickly before becoming on average smaller thereafter, while whales took much longer to reach their current size, but are still the largest known animals of all time.

« Another interesting aspect is that C. youngorum and the rest of the Fossil Hill fauna bear witness to the resilience of ocean life after the worst mass extinction in Earth history. Concludes Dr. Jorge Velez-Juarbe, associate curator of marine mammals at the Los Angeles Museum of Natural History. “ We can say that this is the first major stroke of the tetrapods in the oceans ».

Source : Science

⇧ [VIDÉO] You might also like this partner content (after the ad) Paleontologists have discovered the fossil of a new species of aquatic reptile, as large as a sperm whale. Baptized Cymbospondylus youngorum, the creature is an ichthyosaur dating from the early stages of the dinosaur era and which grew to gigantic proportions very quickly.…

⇧ [VIDÉO] You might also like this partner content (after the ad) Paleontologists have discovered the fossil of a new species of aquatic reptile, as large as a sperm whale. Baptized Cymbospondylus youngorum, the creature is an ichthyosaur dating from the early stages of the dinosaur era and which grew to gigantic proportions very quickly.…

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