Ohmdenosaurus

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Ohmdenosaurus
Temporal range: Early Jurassic, Toarcian
Ohmdenosaurus.JPG
Fossil tibia and astragalus
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Family: Vulcanodontidae
Genus: Ohmdenosaurus
Species:
O. liasicus
Binomial name
Ohmdenosaurus liasicus
Wild, 1978

Ohmdenosaurus (meaning "Ohmden lizard") is a genus of herbivorous dinosaur from the Early Jurassic. It is currently one of the only sauropods described from the Toarcian of the northern hemisphere, along with Tazoudasaurus which may be a relative. Ohmdenosaurus lived on an island series in what is now Germany.

Description

Ohmdenosaurus' tibia is 40-42 cm long, with an estimated femur length of at least 70 cm. This yields an estimated total body length of 6.2–6.7 metres (20–22 ft) and an estimated weight of 1.1–1.3 tonnes (2,400–2,900 lb). This is relatively small for a sauropod.[1]

History of discovery

In the 1970s, German palaeontologist Rupert Wild, visiting the Urwelt-Museum Hauff at Holzmaden in Baden-Württemberg, noticed a fossil in a display labelled as a upper arm bone of a plesiosaur which he recognized as a misidentified dinosaur fossil.[1] The bone had been collected from one of the early quarries near Ohmden that was later refilled. Although the exact discovery site is unknown, rock attached to the lower end of the fossil comes from the unterer Schiefer ("lower slate"), the oldest part of the Posidonia Shale.[1] It is therefore Middle Toarcian in age (182.0 to 175.6 mya).[2]

Further study determined that the fossil belonged to a new genus and species of early sauropod, which Wild named Ohmdenosaurus liasicus in a 1978 publication. The fossil, which lacks an inventory number, consists of a right tibia (shinbone) together with the upper bones of the ankle, the astragalus and the calcaneus. The bones, disarticulated in the fossil, show signs of weathering, evidence that the animal died on land and that only later were its bones washed into the sea.

Classification

The shape of the astragalus - which is not convex on top as it is in derived members of Neosauropoda - suggests that Ohmdenosaurus was a very basal sauropod. In 1990 John Stanton McIntosh included Ohmdenosaurus in the Vulcanodontidae; however, this clade later became a waste-basket taxon for many unrelated basal sauropods. Ohmdenosaurus has not been confirmed by an exact analysis as a vulcanodontid in the modern sense.

It has been suggested that Ohmdenosaurus is a more basal gravisaurian, closely related to the Australian genus Rhoetosaurus.[3]

Literature

  • Wild, R. (1978). "Ein Sauropoden-Rest (Reptilia, Saurischia) aus dem Posidonienschiefer (Lias, Toarcium) von Holzmaden". Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie) 41: 1-15.

References

  1. ^ a b c Wild, R. (1978). "Ein Sauropoden-Rest (Reptilia, Saurischia) aus dem Posidonienschiefer (Lias, Toarcium) von Holzmaden". Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie) (in German). 41: 1–15.
  2. ^ "Ohmdenosaurus liasicus Wild 1978 (sauropod)". paleobiodb.org. Paleobiology Database. Retrieved 2019-08-04.
  3. ^ Stumpf, S., Ansorge, J., & Krempien, W. (2015). Gravisaurian sauropod remains from the marine late Early Jurassic (Lower Toarcian) of North-Eastern Germany. Geobios, 48(3), 271-279.≈
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