Millions of years ago, theropods lived in Switzerland. There is a replica outside the Jurassica Museum in Porrentruy. Photo: Stéphane Herzog Émosson, the name of the first dam built in the valley. Georges Bronner took some photos with his daughter Sylvie. The Alsace native’s attention was suddenly drawn to a slab half-submerged in snow. These were not merely holes: they were tracks. News of this discovery travelled around the world and the site would become – and remain – the location of the Vieux Émosson dinosaurs. Why were they thought to be dinosaur tracks? The first reason, the Geneva journalist explains, was that the tracks were very numerous but they were of mediocre quality. They suggested the presence of three-toed footprints, characteristic of dinosaurs. In reality, all the footprints are five-toed. Another difficulty was that the sedimentary rock did not contain any fossils, which made precise dating impossible. The pioneers of this discovery had put their faith in the tracks being 230 million years old. However, the rock itself is 240 million years old, and dinosaurs had only just started appearing in the southern hemisphere at that point. So, the received wisdom is no longer dinosaurs but pentadactyl (five-toed) animals, upright crocodilians almost three metres long and with powerful jaws, belonging to the division of Pseudosuchia. The other division of the clade was Avemetatarsalia, the division of the dinosaurs. Frick and its perfect skeletons In his book, Pierre-Yves Frei mentions another legendary location in the history of dinosaurs in Switzerland: the quarries at Frick (Aargau), where, in 1976, Swiss palaeontologist Ben Pabst discovered the fossilised remains of dinosaurs around 210 million years old, Plateosauruses, in the clay. These herbivores were eight metres long and weighed four tonnes. The museum in Frick hosts a complete skeleton of the animal. This corner of Aargau is believed to contain around 500 fossils per hectare. Why are there so many? “During the Triassic, the bodies of water on this large plain became mud pools in the dry season. The bigger dinosaurs were driven by thirst to wade in regardless and they could not always escape,” the author explains. “I’d hate to imagine getting trapped there, but it leaves valuable evidence,” the Geneva native adds. The most well-known dinosaur fossil site in Switzerland stems from a misunderstanding. Swiss Review / July 2026 / No. 3 23
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