Ohmdenosaurus (meaning "Ohmden lizard") is the name given to a genus of herbivorous dinosaur from the Early Jurassic. It was a very small (4 m (13 ft) long) perhaps vulcanodontid sauropod which lived in Germany. Only a couple of fragmentary leg bones were found.
Temporal range: Early Jurassic, Toarcian
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 recognised to be a dinosaur fossil instead. The museum, founded in the years 1936/37 and privately run by the Hauff fossil collector family, displays fossils from the Early Jurassic around the villages Holzmaden and Ohmden, an important lagerstätte (fossil site with exceptional preservation) that exposes sediments of the famous Posidonia Shale. These marine sediments contain abundant fossils of marine life, including numerous specimens of ichthyosaurs and plesiosaurs, although fossils of land-living species are rare, and no other dinosaur remains have been found. Asked about the dinosaur bone, which had been on exhibit since several years, Bernard Hauff junior explained that it had been part of the Hauff collection since decades, stemming from one of the early quarries near Ohmden that had been refilled since. Although its exact provenance is unknown, rock attached to the lower end of the fossil shows that it stems from the unterer Schiefer ("lower slate"), the lowermost (and oldest) part of the Posidonia Shale. It is therefore middle Toarcian in age (182.0 to 175.6 million years ago).
Further study determined that the fossil belonged to a new genus and species of early sauropod, which Wild named as Ohmdenosaurus liasicus in a 1978 publication. The name Ohmdenosaurus refers to Ohmden, the village were the remains were probably found; the second part, saurus, is Ancient Greek meaning "lizard". The specific name, liasicus, refers to the Lias, an old name for the Early Jurassic. The fossil, which lacked 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 its bones were washed into the sea. The tibia is only 405 millimetres long, indicating a remarkably small individual for a sauropod.
The shape of the fourteen centimetres wide astragalus, like that of a sandal and not convex on top as with the derived Neosauropoda, proves that Ohmdenosaurus is a very basal sauropod. In 1990 John Stanton McIntosh classified Ohmdenosaurus in the Vulcanodontidae but that concept then functioned as a waste-basket taxon for all kinds of unrelated basal sauropods. It has not been confirmed by an exact analysis as a vulcanodontid in the modern sense.
Apatosaurinae is the name of a subfamily of diplodocid sauropods that existed between 157 and 150 million years ago in North America. The group includes two genera for certain, Apatosaurus and Brontosaurus, with at least five species. Atlantosaurus and Amphicoelias might also belong to this group.Below is a cladogram of apatosaurinae interrelationships based on Tschopp et al., 2015.Cetiosauridae
Cetiosauridae is a family of sauropod dinosaurs. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural clade. Additionally, at least one study has suggested that the mamenchisaurids may represent a sub-group of the cetiosaurids, which would be termed Mamenchisaurinae.Daxiatitan
Daxiatitan is a genus of titanosaur dinosaur from the Lower Cretaceous of Lanzhou Basin, Gansu Province, northwestern China. It is known from fossils including several neck vertebrae, a shoulder blade, and a thigh bone.It was a very large dinosaur, estimated at 23–30 meters (75–98 feet). Like both Euhelopus and Huanghetitan, it had an enormously long neck.Diplodocinae
Diplodocinae is an extinct subfamily of diplodocid sauropods that existed from the Late Jurassic to Early Cretaceous of North America, Europe and South America, about 161.2 to 136.4 million years ago. Genera within the subfamily include Tornieria, Supersaurus, Leinkupal, Galeamopus, Diplodocus, Kaatedocus and Barosaurus.Cladogram of the Diplodocidae after Tschopp, Mateus, and Benson (2015).Eomamenchisaurus
Eomamenchisaurus (meaning "dawn Mamenchisaurus") is a genus of mamenchisaurid sauropod dinosaur from the Middle Jurassic of Yuanmou, Yunnan, China. The type species is E. yuanmouensis, described by Lü Junchang et al. in 2008.Ferganasaurus
Ferganasaurus was a genus of dinosaur first formally described in 2003 by Alifanov and Averianov. The type species is Ferganasaurus verzilini. It was a sauropod similar to Rhoetosaurus. The fossils were discovered in 1966 in Kyrgyzstan from the Balabansai Formation and date to the Callovian stage of the Middle Jurassic.Flagellicaudata
Flagellicaudata is a clade of Dinosauria. It belongs to Sauropoda and includes two families, the Dicraeosauridae and the Diplodocidae.Gravisauria
Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.Huangshanlong
Huangshanlong is a genus of mamenchisaurid dinosaurs native to the Anhui province of China. It contains a single species, Huangshanlong anhuiensis. H. anhuiensis represents, along with Anhuilong and Wannanosaurus, one of three dinosaurs fround in Anhui province.Jiutaisaurus
Jiutaisaurus is a genus of sauropod dinosaur from the Quantou Formation of China. Jiutaisaurus was a sauropod which lived during the Cretaceous. The type species, Jiutaisaurus xidiensis, was described by Wu et al. in 2006, and is based on eighteen vertebrae.Kaijutitan
Kaijutitan (meaning "Kaiju titan" after the type of Japanese movie monsters) is a genus of basal titanosaur dinosaur from the Sierra Barrosa Formation from Neuquén Province in Argentina. The type and only species is Kaijutitan maui.Kotasaurus
Kotasaurus ( KOH-tə-SAWR-əs; meaning "Kota Formation lizard") is a genus of sauropod dinosaur from the Early Jurassic period (Sinemurian–Pliensbachian). The only known species is Kotasaurus yamanpalliensis. It was discovered in the Kota Formation of Telangana, India and shared its habitat with the related Barapasaurus. So far the remains of at least 12 individuals are known. The greater part of the skeleton is known, but the skull is missing, with the exception of two teeth. Like all sauropods, it was a large, quadrupedal herbivore with long neck and tail.Microcoelus
Microcoelus is a dubius genus of small Titanosaurian sauropod dinosaur native to Argentina. It is known from only a single dorsal vertebra. A left humerus was formerly referred to this species, but it is now considered to belong to Neuquensaurus. This species may be a synonym of the contemporary sauropod Neuquensaurus australis.It was described by British paleontologist Richard Lydekker in 1893.Oceanotitan
Oceanotitan is a genus of titanosauriform sauropod known from the Upper Jurassic Praia da Amoreira-Porto Novo Formation of Portugal. It contains one species, Oceanotitan dantasi.The holotype consists of the scapula, almost all of the pelvis, a complete leg sans the toes, and nine caudals.Pilmatueia
Pilmatueia is a diplodocoid sauropod belonging to the family Dicraeosauridae that lived in Argentina during the Early Cretaceous.Tambatitanis
Tambatitanis is an extinct genus of titanosauriform dinosaur from the Early Cretaceous (probably early Albian) of Japan. It is known from a single type species, Tambatitanis amicitiae. It was probably around 14 meters long and its mass was estimated at some 4 tonnes. It was a basal titanosauriform and possibly belonged to the Euhelopodidae.Tastavinsaurus
Tastavinsaurus is a genus of sauropod dinosaur belonging to the Titanosauriformes. It is based on a partial skeleton from the Early Cretaceous of Spain. The type species is Tastavinsaurus sanzi, named in honor of the Rio Tastavins in Spain and Spanish paleontologist José Luis Sanz.Tengrisaurus
Tengrisaurus (meaning "Tengri lizard") is a genus of lithostrotian sauropod, from the Early Cretaceous (Barremian-Aptian), of the Murtoi Formation, Russia. It was described in 2017 by Averianov & Skutschas. The type species is T. starkovi.Vulcanodontidae
The Early Jurassic sauropod dinosaurs Zizhongosaurus, Barapasaurus, Tazoudasaurus, and Vulcanodon may form a natural group of basal sauropods called the Vulcanodontidae. Basal vulcanodonts include some of the earliest known examples of sauropods. The family-level name Vulcanodontidae was erected by M.R. Cooper in 1984. In 1995 Hunt et al. published the opinion that the family is synonymous with the Barapasauridae. One of the key morphological features specific to the family is an unusually narrow sacrum.