Giant Marine Reptiles Over the Alps

Giant Marine Reptiles Over the Alps
Reconstructed discovery of a partial incomplete skeleton of Shastasauridae sp. (field top view). A, PIMUZ A/III 744, East side of the Fil da Stidier ridge, Filisur, Grisons, Switzerland. Single major vertebra exposed posteriorly upwards. Most of the associated ribs are right ribs and are seen in anterior view.

Among the fossils unearthed in the Swiss Alps between 1976 and 1990 is the largest ichthyosaur tooth ever found. Ichthyosaurs were found in the world's oceans for millions of years during the Triassic, Jurassic, and Cretaceous periods. They had an elongated body and a relatively small head. But most evolved into gigantic forms shortly before they went extinct 200 million years ago. Only the familiar dolphin-like species survived until 90 million years ago.

"With an estimated weight of 80 tons and a length of more than 20 m, these prehistoric giants would have rivaled a sperm whale," said Professor Martin Sander, a researcher at the Institute of Geosciences at the University of Bonn.

“However, they left almost no fossil remains; The reason for this remains a great mystery to this day.”

The finds are between 210 and 200 million years old and include a very large tooth devoid of most of the crown, a very large vertebra and a postcranial bone association of ten rib fragments, and a fusion of seven very large vertebral centers.

Paleontologists compared this material with the two largest known ichthyosaurs from partial skeletons, Shonisaurus popularis (15 m long) and Shastasaurus sikkanniensis (21 m) from Nevada and British Columbia, respectively.

The missing tooth in the Kössen Formation confirms that at least some giant ichthyosaurs had teeth, according to the team.

Due to their proportional differences, the two groups of skeletal remains may represent two different species of Shastasaurus-like ichthyosaurs.

Let us share the ABSTRACT information about the study with you.

During the Late Triassic, it was inhabited by the largest ichthyosaurs known to date, exceeding 20 m in length. Recent discoveries include the remains of giant ichthyosaurs from the Austroalpine nappes of the eastern Swiss Alps. The finds come from the lower two members of the Kössen Formation (late Norian to Rhaetian). The material consists of a very large tooth devoid of most of the crown from the Rhaetian Schesaplana Member, a postcranial bony junction of a very large vertebra, and an assemblage of ten rib fragments from the Schesaplana Member, and seven very large vertebral centers from above.

Norian will drop the Rhaetian Alplihorn Member. These groups represent the only published partial skeletons of large to giant ichthyosaurs younger than middle Norian. We compare the material with the two largest ichthyosaurs known from partial skeletons, Shonisaurus popularis (15 m) and Shastasaurus sikkanniensis (21 m), Nevada's late Carnian (about 230 Ma) and middle Norian (about 218 Ma) British Columbia, respectively. The missing tooth confirms that at least some giant ichthyosaurs had teeth. Due to their proportional differences, the two bone associations may represent two different taxa of Shastasaurus-like ichthyosaurs. The larger and geologically younger specimen may be nearly the size of S. sikkanniensis and the smaller S. popularis. These giant ichthyosaurs in the eastern Swiss Alps indicate that such ichthyosaurs also colonized western Tethys. The finds also definitively document the persistence of giant ichthyosaurs into the last Triassic.

If we go back to our article;

The missing tooth in the Kössen Formation confirms that at least some giant ichthyosaurs had teeth, according to the team.

Due to their proportional differences, the two groups of skeletal remains may represent two different species of Shastasaurus-like ichthyosaurs.

The larger and geologically younger specimen may be nearly the size of Shastasauru sikkanniensis and the smaller Shonisaurus popularis.

“Bigger is always better,” Professor Sander said.

“Large size has obvious selective advantages. If possible, life will go there.”

There were only three groups of animals with a mass greater than 10-20 tons: long-necked dinosaurs (sauropods); whales; and the giant ichthyosaurs of the Triassic.”

“These monstrous reptiles patrolled the world ocean Panthalassa, which surrounded the supercontinent Pangea during the Late Triassic about 205 million years ago.”

"They also raided the shallow seas of Tethys on the eastern side of Pangea."

A paper on the findings was published in the Journal of Vertebrate Paleontology.

Source: sci-news

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