A team of paleontologists has discovered fossils of three impressive new ichthyosaurs — ancient marine reptiles — in rocks located 2,743.20 m above sea level.
The ichthyosaurs were found in excavations that took place between 1976 and 1990, but the remains were very fragmentary. Since then, more comparative research on ichthyosaurs has been produced, and now a team of paleontologists has finally been able to assess the alpine fossils to a greater level of detail.
Among the superlative finds were ribs, the largest tooth yet attributed to an ichthyosaur (the width of its root is twice that of any other aquatic reptile), and vertebrae larger than a human head. The team’s research is published today in the Journal of Vertebrate Paleontology.
“The new finds show an interesting diversity of very big ichthyosaurs at the end of the Triassic, just before the mass extinction 201 million years ago,” said Heinz Furrer, a paleontologist at the University of Zürich and co-author of the paper, in an email to Gizmodo. “Together with a nearly time-equivalent find in British Columbia, they were the biggest marine reptiles that ever lived on Earth.”
To get these fossilized ichthyosaur bones off the mountain, Furrer said he and his team had to carry hundreds of pounds of bones on their backs and in a Jeep loaned to them from the Swiss Army. They schlepped the vertebrae across a glacier to a mountain hut, and the fossils were finally brought down the mountain in a cable car ordinarily used for food transport.
Just over 200 million years ago, the rocks atop the Swiss Alps were sediments on the floor of a lagoon or shallow basin on the rim of Tethys, part of the ocean surrounding the supercontinent Pangea. It was there that the ichthyosaurs — aquatic reptiles with bodies that looked similar to whales and dolphins — fed on cephalopods, fish, and smaller ichthyosaurs. Most ichthyosaurs were smaller than these behemoths.
The British Columbian ichthyosaur, Shastasaurus sikkanniensis, was nearly 21.34 m long and toothless; it is thought to have effectively inhaled its prey, according to National Geographic. Martin Sander, a paleontologist at the University of Bonn in Germany and the paper’s lead author, said that “bigger is always better” and that “life will go there if it can” in a press release. Sander noted that sauropod dinosaurs, modern whales, and the Triassic ichthyosaurs are the only animal groups with masses that exceed 20 metric tons.
The ichthyosaur teeth uncovered by the paleontologists are curved similarly to marine mammals that feed on boneless cephalopods, hinting at their food of choice. But “it is hard to say if the tooth is from a large ichthyosaur with giant teeth or from a giant ichthyosaur with average-sized teeth,” Sander said.
In an email to Gizmodo, Sander noted that the ichthyosaur teeth have deep grooves along their roots, a pattern similar to those observed in modern monitor lizards. But the two animals are not related, so exactly what purpose the tooth grooves served remains a mystery.
The researchers know that the remains do not belong to any known ichthyosaur. Based on the measurements of the various specimens — though distorted by the tectonic shifts that upheaved the fossils from the seafloor to the mountaintops — they suspect fossils represent three different species, but it’s possible there are fewer.
But the team did not assign new species names to the fossils, stating that they were too fragmentary to warrant such a move; sometimes, animals that are too hastily identified as a new species are later found to be part of a previously known species, and their species has to be ‘sunk’ into the existing fossil record.
The discovery of ichthyosaurs in the Alps expands considerably the geographic footprint of the swimming reptiles. “Vertebrate evolution in general is impacted by the realisation that giant ichthyosaurs were globally distributed in the Late Triassic,” Sander said.
With such behemoths prowling the prehistoric seas around the world, smaller denizens of the Triassic oceans had a lot to worry about, as even the toothless ichthyosaurs were fearsome predators.