Featured Article Summary #70

Ohmdenosaurus is a genus of sauropod dinosaur that lived in Germany during the Early Jurassic epoch. The only known specimen, a tibia and ankle, was originally thought to be a plesiosaur but was later identified as a sauropod. It is displayed in a local museum. Ohmdenosaurus was one of the earliest sauropods and had four legs and columnar limbs. It was small for a sauropod, measuring about 3-4 meters in length. Its relationships to other sauropods are uncertain due to the limited remains. The Posidonia Shale, where the specimen was found, is known for its well-preserved fossils of marine reptiles. Ohmdenosaurus was a terrestrial animal and its remains were likely transported by predators or water currents from the shoreline to its burial site. It is the only dinosaur fossil found in the shale. The Posidonia Shale in Germany is a significant fossil deposit that contains many well-preserved marine reptiles. Bernhard Hauff discovered the fossils and opened a museum to display them. In the 1970s, Rupert Wild identified a fossil as a dinosaur and named it Ohmdenosaurus liasicus. The fossil is from the Lower Jurassic period and is one of the earliest sauropods known. Ohmdenosaurus was a relatively small sauropod with a body length of 3-4 meters. The tibia, astragalus, and calcaneus bones found suggest that it was a quadrupedal herbivore with a long neck and tail. There were also small elements near the ankle that may have been preserved cartilage or sesamoids embedded within tendons. Ohmdenosaurus is classified as a sauropodomorph dinosaur based on its limb characteristics, showing a mix of primitive and derived features. Its exact placement within sauropodomorphs is uncertain due to the incompleteness of the fossil specimen. Different studies have suggested various relationships, with some including it in the Vulcanodontidae family and others placing it within Eusauropoda alongside genera like Amygdalodon and Spinophorosaurus. The taphonomy of the Ohmdenosaurus specimen suggests that it was transported and deposited twice. The first transport took place near the coast where weathering occurred, indicating a site of sedimentation. The second transport to its final deposition site could have been through strong currents or by scavengers.