Rare evidence of a giant Jurassic pliosaur from Switzerland

7 november 2019

Life reconstruction of the pliosaur from Switzerland with a diver for scale.

An exceptionally rare fossil jaw from a giant Jurassic pliosaur has been found in Switzerland, and recently identified by an international team of scientists. Pliosaurs were huge marine reptiles that dominated the oceans during the Age of Dinosaurs. They had massive crocodile-like heads, and four powerful flipper-like limbs that would have been used to swim in a manner very similar to modern day sea turtles.

Pliosaurs are estimated to have reached lengths of up to 15 m, which exceeds the size of the largest toothed whales today. “Pliosaurs were amongst the largest marine animals of their time, and were at the top of the food chain”, said Sven Sachs of the Natural History Museum Bielefeld in Germany, and lead author on the study.

The fossil remains were initially discovered by the Swiss fossil enthusiast and collector, Dr. Hans Holenweg near the town of Arisdorf, in the foothills of the famous Jura Mountains in the canton of Basel-Land in Switzerland.

Only the rear section of the fossil jaw was recovered, but this alone is over 50 cm long. The originally complete lower jaw of the Arisdorf pliosaur could have reached about 1.5 m in length. “At around 170 million years old, the Arisdorf jaw represents one of the oldest occurrences of very large pliosaur apex predators in the fossil record, and may have come from an animal that was around 9 m long”, said co-author Dr Benjamin Kear of Uppsala University in Sweden.

Pliosaurs were top predators in the oceans for over 80 million years, and are known to have hunted other marine reptiles, including long-necked plesiosaurs, fish-like ichthyosaurs, and early sea turtles.

"The Arisdorf pliosaur is the first find of its kind from Switzerland, and comes from a geological timeframe with a hitherto very sparse fossil record of pliosaurs and their relatives, said co-author Dr Christian Klug from the University of Zurich in Switzerland.

The Arisdorf pliosaur is permanently housed in the collections of the Palaeontological Museum of the University of Zurich.

Publication:
Sachs, S., Klug, C. & Kear, B. P. (2019) Rare evidence of a giant pliosaurid-like plesiosaur from the Middle Jurassic (lower Bajocian) of Switzerland. Swiss Journal of Palaeontology.