The fossils from a 28-foot-long carnivorous marine reptile are giving paleontologists clues about how ecosystems recuperate and species emerge after mass extinctions. The fossils, recovered in 1997 from rocks in central Nevada, date back 244 million years ago. Under analysis by Martin Sander from the University of Bonn in Germany and other colleagues from around the world, they include most of the skull, the vertebrae, and pieces of the rear fins. They belong to a new species dubbed Thalattoarchon saurophagis, which translates to “lizard-eating ruler of the sea.” This monstrous reptile was almost dolphin-like in appearance, but much larger, and with 5-inch-long razor-sharp teeth. Thalattoarchon was a member of the ichthyosaurs, marine dinosaurs that evolved from land-dwelling dinosaurs and lived until 90 million years ago. During Thalattoarchon’s heyday, Nevada was under what is known as the Panthalassian Ocean and all Earth’s land was connected as the supercontinent Pangaea.

Most interesting is what these fossils tell us about species survival and extinction. T. saurophagis emerged 8 million years after the biggest mass extinction of all time—a relatively short period of time in the grand scheme of evolution. Scientists think that, due to the size, shape, and sharpness of its teeth, Thalattoarchon held its own at the very top of the food chain in the marine ecosystem of ancient Nevada, feeding on even the larger predators of the sea (See diagram below, from PNAS). Those species lower on the chain that provided sustenance for the upper echelons must have been around too, indicating that enough resources must have been readily available and marine ecosystems must have recuperated soon after the mass extinction, probably more quickly than did terrestrial habitats. This has implications for humans in this day and age, when ecosystems are declining at a rapid pace due to human activity.

Learn more at www.livescience.com.

The study on Thalattoarchon saurophagis is published in the journal Proceedings of the National Academy of Sciences.

The mid-Triassic Marine Food Chain

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Published On: January 15, 2013

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