astragalus and the calcaneus (the upper bones of the ankle). It had long been part of the museum's collection, and was collected from one of the early quarries near the village of Ohmden that were later refilled; the exact discovery site is unknown. In a 1978 publication, Wild determined the dinosaur fossil belonged to a new genus and species, which he named Ohmdenosaurus liasicus. The generic name Ohmdenosaurus is derived from that of the village of Ohmden and from the Ancient Greek σαῦρος (sauros), meaning lizard or reptile. The specific name liasicus refers to the Lias, an old name for the Lower Jurassic of Europe. A chunk of rock – a gray-black, finely laminated slate containing small remains of fish – is still attached to the lower end of the fossil. This rock indicates that the fossil stems from the Unterer Schiefer ("lower slate"), the oldest part of the Posidonia Shale. It is therefore middle Toarcian in age (182.0 to 175.6 million years ago). This makes it one of the earliest sauropods known at the time. It also was, besides an undescribed femur (upper thigh bone) from Whitby, the only fossil of a terrestrial saurian known from the Toarcian. Between tibia and astragalus, the specimen also preserves a limestone geode that is rich in the mineral pyrite and contains fossils of the snail Coelodiscus. Description As all sauropods, Ohmdenosaurus was quadrupedal (four-legged) herbivore with a long neck and tail. Wild estimated the total body length at , which is relatively small for a sauropod. The tibia is long. The bone preserves projections that served as attachment sites for muscles, including the , which projects by about from the upper front of the bone, and the crista lateralis, which runs for about down the upper half of the shaft but is mostly broken off. The upper end of the tibia is oval in shape when viewed from above, with a width-to-length ratio of 1.4. The lower end of the tibia is rotated by 90° relative to the upper end. The lower end of the tibia was formed by two rounded, well-separated prominences, the medial (inner) and lateral (outer) condyles. The medial condyle was much larger than the (broken) lateral condyle and located ca. lower than the latter. The astragalus is in diameter, sandal-shaped, and rotated by 90° out of its original position, exposing its upper surface. This surface has two concavities,