Giant Triassic Ichthyosaur Found in Nevada Desert

Paleontologists have described a huge new species of ichthyosaur based on a 244-million-year-old fossil found in the Nevada desert in 2010.

Left: skull of Thalattoarchon saurophagis in dorsal and left lateral view, scale bar – 100 mm. Right: reconstruction of the skull, scale bar: 100 mm (Fröbisch NB et al)

The ichthyosaur, called Thalattoarchon saurophagis (means lizard-eating sovereign of the sea), was found in what is today Favret Canyon in Augusta Mountains, Nevada. Most of the creature was preserved, including the skull, parts of the fins, and the complete vertebral column up to the tip of the tail.

Thalattoarchon is an early representative of the ichthyosaurs, a group of marine reptiles that lived at the same time as dinosaurs and roamed the oceans for 160 million years. It was about 28 feet (8.6 m) in length, had a massive skull and jaws armed with large teeth with cutting edges used to seize and slice through other marine reptiles in the Triassic seas. Because it was a meta-predator, capable of feeding on animals with bodies similar in size to its own, Thalattoarchon was comparable to modern orca whales.

Only 8 million years prior to the appearance of Thalattoarchon, a severe extinction at the end of the Permian period killed as many as 80 to 96 percent of species in the Earth’s oceans. The rise of a predator such as Thalattoarchon documents the fast recovery and evolution of a modern ecosystem structure after the extinction.

“Everyday we learn more about the biodiversity of our planet including living and fossil species and their ecosystems,” said Dr Nadia Fröbisch of the Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung an der Humboldt-Universität zu Berlin, Germany, lead author of a paper describing Thalattoarchon in the Proceedings of the National Academy of Sciences.

Teeth of Thalattoarchon saurophagis, scale bar – 10 mm (Fröbisch NB et al)

“The new find characterizes the establishment of a new and more advanced level of ecosystem structure. Findings like Thalattoarchon help us to understand the dynamics of our evolving planet and ultimately the impact humans have on today’s environment,” she said.

“This discovery is a good example of how we study the past in order to illuminate the future,” said senior author Dr Olivier Rieppel of the Field Museum.

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Bibliographic information: Fröbisch NB et al. Macropredatory ichthyosaur from the Middle Triassic and the origin of modern trophic networks. PNAS, published online before print January 7, 2013; doi: 10.1073/pnas.1216750110