Teysachaux (1,909 m) is a mountain of the Swiss Prealps, overlooking Les Paccots in the canton of Fribourg.

[2] Teysachaux lies at the south end of the Moléson ridge, west of the Sarine river valley.

They have been built during the 18th and 19th century, showing the evidence of a progressive expansion of farming (mainly milk and cheese) towards higher meadows.

In 1870, on the foothills of the west side of Teysachaux, a 2-meters long fossilised ichthyosaurus has been discovered.

It dates from the Jurassic period (175 to 183 million years), when dinosaurs walked the Earth.