More than 200 million years ago, rock layers covered the seabed, but the folding of the Alps caused them to end at an altitude of 2,800 meters. Hence the unusual finding of marine fossils at such a high altitude.
Now, a team of paleontologists has discovered three new sets of enormous ichthyosaur fossils, they report in their research published in the peer-reviewed Journal of Vertebrate Paleontology . The 205-million-year-old ichthyosaurs were discovered in the Swiss Alps by a team from the University of Zurich, who described the find as “exciting”.
Known as the Kössen Formation, the rocks from which these fossils are derived were once at the bottom of a shallow coastal area, a very wide lagoon.
The longest ichthyosaur in the world
Discovered between 1976 and 1990, this find includes ichthyosaur vertebrae that were nearly 20 meters long and weighed 80 tons , as well as the largest ichthyosaur tooth ever discovered. The width of the tooth root is twice that of any known aquatic reptile, the latter related to the largest ichthyosaur found at 15 meters long.
“It is difficult to tell whether the tooth is from a large ichthyosaur with giant teeth or from a giant ichthyosaur with average-sized teeth,” the authors write.
“It is the longest ichthyosaur in the world; with the thickest tooth found to date and the largest trunk vertebra in Europe,” explains Heinz Furrer, retired curator of the Paleontological Institute and Museum of the University of Zurich.
Other incomplete skeletal remains include Europe’s largest trunk vertebra from another ichthyosaur that is the largest currently known marine reptile fossil, Shastasaurus sikkeniensis, another extinct genus of 21-meter-long ichthyosaur. Comparison of vertebrae from one set suggests, experts say, that they might have been the same size or slightly smaller than those of S. sikkanniensis.
These huge creatures moved through Panthalassa , an ocean that surrounded the supercontinent Pangea during the Late Triassic (the origin of the oceans).
Could there be even bigger ichthyosaurs hiding under the glaciers?
It’s a question scientists are asking in light of this discovery, as these huge creatures also made inroads into the shallow seas of the Tethys Sea on the eastern side of Pangea, the team found. ( Tethys can be considered the origin of the Mediterranean Sea ).
“Bigger is always better,” experts say. “There are clear selective advantages to large body size. Life would go there if it could. There were only three groups of animals whose mass exceeded 10-20 metric tons: the long-necked dinosaurs (sauropods); Whales; and the giant ichthyosaurs of the Triassic”.
Ichthyosaurs first arose in the wake of the Permian extinction event about 250 million years ago, when around 95% of marine species became extinct . Some species persisted into the Cretaceous, but so little is known about these giants that they remain mere ghosts in the fossil record.
These new specimens likely represent the last of the leviathans , experts conclude.
Referencia: Giant Late Triassic ichthyosaurs from the Kössen Formation of the Swiss Alps and their paleobiological implications, Journal of Vertebrate Paleontology (2022). DOI: 10.1080/02724634.2021.2046017
