Lommiswil tracksite
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The Lommiswil tracksite preserves fossil tracks of sauropod dinosaurs from the Late Jurassic epoch. The tracksite is located in the Jura Mountains in Switzerland, north of the village of Lommiswil and near the city of Solothurn, in limestones of the Reuchenette Formation. The site consists of around 450 individual tracks on a steeply inclined (70°) surface measuring 7,000 m2 (75,000 sq ft) in area. Discovered in 1988 in an active quarry, it was the first Jurassic dinosaur tracksite to be discovered in Switzerland. The tracks provided evidence that the area, which was thought to have been a shallow sea, was above sea level. The site was scientifically documented by rock climbing and the use of a helicopter. The tracks are large, with hind foot impressions up to 1 m (3 ft 3 in) in length. At least 10 trackways can be seen, one of which showing a pronounced right turn. The site is protected as a geoheritage site (geotope) and accessible to the public.
The tracksite is located in the Steingrueben quarry, c. 1 km north of the village of Lommiswil, in the canton of Solothurn, Switzerland. Geologically, it is part of the Weissenstein anticline, a major fold in the southernmost extent of the Swiss Jura mountains. The sediments are part of the Reuchenette Formation and date to the late Kimmeridgian.[1] The track surface is inclined by about 70°. The Steingrueben quarry extracted packstones that contained a large amount of snail shells (Nerineidae) for use as building stones. The tracks were located directly beneath this packstone layer and were exposed as the stone was quarried away. Besides the abundant snail shells, macroscopic fossils are rare in the quarry, but the hermit crab Orhomalus virgulinus, a tooth of the fish Macrodon, fragments of turtle shells (Plesiochelys), tooth plates of sharks (Asteracanthus), and fragments of the marine crocodile Steneosaurus have been discovered.[2]
The tracks were discovered by the palaeontologist Christian Meyer in February 1988,[3] having previously been overlooked by geologists who studied the quarry.[2][1] They were the first discovered dinosaur tracks from the Late Jurassic of Switzerland.[1] The scientific study was complicated by the steep inclination of the surface and the danger of rock fall. To allow every individual track to be reached by climbing, the entire surface was equipped with bolts. In order to produce a sitemap, the track outlines were traced with black paint and photographed perpendicular to the surface from a helicopter. Artificial casts of selected tracks were made in 1988 and 1990, and stored in the Museum of Nature in Solothurn.[3]
Meyer published a preliminary report in 1990, which noted more than 200 individual tracks,[2] and an additional account in 1993, in which more than 380 tracks were recognised.[3] In 2003, Meyer and Basil Thüring reported that 450 tracks are visible, with new tracks being exposed due to continued quarrying.[1] The site has been protected as a geoheritage site (geotope), and was the first designated geotope of Switzerland.[4] An observation platform with interpretive signs was installed to make the site accessible to visitors.[5]
