Efraasia

Efraasia (pronounced "E-FRAHS-ee-A") is a genus of basal sauropodomorph dinosaur. It was a herbivore which lived during the middle Norian stage of the Late Triassic, around 210 million years ago, in what is now Germany. It was named in 1973 after Eberhard Fraas, who during the early twentieth century collected what were the original type specimens.

The specimens were at first assigned to three already existing genera and so became divided among three separate species: Teratosaurus minor, Sellosaurus fraasi and Paleosaurus diagnosticus. In 2003 these were combined into a single valid species: Efraasia minor.

Efraasia was a lightly built, medium-sized sauropodomorph, about 6 to 7 metres (20 to 23 ft) long.

Efraasia
Temporal range: Late Triassic, 210 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Genus: Efraasia
Galton, 1973
Type species
Efraasia minor
(von Huene, 1907–1908 [originally Teratosaurus minor])
Synonyms

Discovery and naming

WeißerSteinbruchSandsteinformation
The Weiße Steinbruch site

Efraasia has had a complicated taxonomic history involving several genera and species. Material now known under Efraasia first came to light after Albert Burrer, Hofsteinmetzmeister ("Court master stonemason") at Maulbronn, in 1902 began to exploit the Weiße Steinbruch, a quarry near Pfaffenhofen in Württemberg. To reach the layer of hard white sandstone Burrer wanted to use for his building projects a 6 metres (20 ft) thick overburden of softer marl had to be removed. Many vertebrate fossils proved to be present in it. This stratum was part of the Stubensandstein Member of the lower Löwenstein Formation, dating to the Norian. From 1906 until 1914 when the quarry closed, Burrer donated the finds to paleontologist Professor Fraas of the königliche Stuttgarter Naturalienkabinett.

A specimen of a basal sauropodomorph, SMNS 11838, was first described by Friedrich von Huene in 1907–1908 and named as a new species of Teratosaurus: T. minor. At the time, Teratosaurus was thought to be a theropod dinosaur; it was only established as a rauisuchian non-dinosaur in the 1980s. The specific name referred to the fact that the specimen was smaller than Teratosaurus suevicus. The fossils consisted of a few vertebrae from the hip, the right hindlimb, and a pubic bone. Elsewhere in the same publication he gave the name Sellosaurus fraasi to a partial skeleton, SMNS 12188-12192, from slightly older rocks of the same formation, as a second species of his new genus Sellosaurus (the genus is today considered to be a synonym of Plateosaurus).[1]

In 1912, Eberhard Fraas reported on two partial skeletons, SMNS 12667 and SMNS 12684 collected in 1909, which he assigned to a new species of Thecodontosaurus: T. diagnosticus.[2] He would never describe them due to his failing health, and thus this name remained a nomen nudum. Von Huene adopted the specific name years later, after Fraas' death, redescribing Fraas' specimens as Paleosaurus (?) diagnosticus in 1932.[3] The question mark indicates that von Huene considered the reference as provisional only. In 1959 Oskar Kuhn pointed out that the name Paleosaurus Riley & Stutchbury 1836 was preoccupied and renamed the genus Palaeosauriscus.[4] Allen Charig in 1967 was the first to use the combination Palaeosauriscus diagnosticus for the German material.[5] However, the new generic name was itself a junior homonym of Palaeosauriscus fraserianus Cope 1878.

Peter Galton reassigned Fraas' specimens to the new genus Efraasia in 1973, because Palaeosaurus, apart from the homonymy problems, was a nondiagnostic tooth genus. The generic name was a contraction of "E. Fraas". The new species name combination thus became Efraasia diagnostica.[6] However, Galton and Robert Bakker later (1985) recommended that Efraasia be considered a junior synonym of another prosauropod, Sellosaurus gracilis.[7][8]

In 2003, Adam Yates published a study incorporating these and other fossils from the Late Triassic of Germany.[9] He found that the "Sellosaurus" material fell into two clusters. One included the original Sellosaurus gracilis, which he assigned to Plateosaurus as P. gracilis. The other included "Teratosaurus" minor, "Sellosaurus" fraasi, and "Palaeosaurus" diagnosticus. Efraasia was the oldest valid generic name for these fossils. The specific name could not be determined as simply, as both Teratosaurus minor and Sellosaurus fraasi had first appeared in von Huene's 1908 book. Because the former name had page priority, Yates chose minor as the specific name, providing for the type species Teratosaurus minor the new combination Efraasia minor, which is thus the single valid species name of the taxon.[8] Yates did not take into account two other species based by von Huene on very fragmentary German basal sauropodomorph material, Teratosaurus trossingensis and Thecondontosaurus hermannianus, though Galton had considered them junior synonyms of Efraasia diagnostica in 1990.[10]

Apart from the specimens mentioned above, mostly consisting of rather complete skeletons preserved in large slabs, though not fully prepared from the rock matrix, several other fossils have been found. Together they allow for a good impression of what the animal looked like.

Description

Efraasia was once thought to be a relatively small dinosaur, about 2 to 3 metres (6.6 to 9.8 ft) long, but this was because the most complete known fossils are from juvenile animals. Yates in 2003 has estimated the adult length at 6.5 metres (21 ft); the largest specimen is SMNS 12843 with a femur length of 627 millimetres (24.7 in). Efraasia was lightly built for its size, with gracile hands and feet. Like many "primitive" sauropodomorphs, Efraasia might have been partially bipedal and partly quadrupedal. It had long fingers and mobile thumbs, with which it would have been able to grasp food, but the shape of its wrists might have allowed it to walk easily on all fours.[11] Some researchers however, contend that the lower arm did not allow pronation, a rotation of the radius around the ulna, so that the hand could not be directed downward, making the animal an obligate biped.

The skull is small, pointed and triangular. There are four teeth in the premaxilla. The neck is only moderately elongated but thin. The neural spines of the tail are low. The second finger is longer than the third finger. The first toe is not strongly reduced. Von Huene identified a cluster of stomach stones (gastroliths) in association to specimen SMNS 12667.

Yates identifies two unique derived traits (autapomorphies): the presence of a raised crescent-like ridge on the upper part of the inner side of the pubis shaft; and the presence of a vaulted bony web between two lower extensions of a braincase bone, the processus basipterygoidei, with a raised central bony platform on top of the vault.

Classification

Von Huene continued interpreting these forms as predatory dinosaurs, in 1932 assigning them to a separate family Palaeosauridae as part of the Carnosauria. Only in 1965 Charig established they were plant-eating sauropodomorphs.[12]

In 1973 Galton assigned Efraasia to the Anchisauridae, but he used this name as a paraphyletic group encompassing all "prosauropods" that were not melanorosaurids. Modern phylogenetic analysis has indicated that Efraasia is a basal sauropodomorph, somewhat more derived than Thecodontosaurus, but less than either the Prosauropoda (including Plateosaurus) or the Sauropoda. The genus is sometimes recovered as the sister taxon to the last common ancestor of both larger groups.

References

  1. ^ F. v. Huene, 1908, Die Dinosaurier der Europäischen Triasformation mit berücksichtigung der Ausseuropäischen vorkommnisse. Geologische und Palaeontologische Abhandlungen Suppl. 1(1): 1-419
  2. ^ E. Fraas, 1912, "Die schwäbischen Dinosaurier", Jahreshefte des Vereins für Vaterländische Naturkunde in Württemberg 68: 56-57
  3. ^ Huene, F. von, 1932, Die fossile Reptil-Ordnung Saurischia, ihre Entwicklung und Geschichte: Monographien zur Geologie und Palaeontologie, 1e Serie, Heft 4, pp. 1-361
  4. ^ Kuhn, O., 1959, "Ein neuer Microsaurier aus dem deutschen Rotliegenden", Neues Jahrbuch für Geologie und Palaeontologie. Monatshefte 9: 424-426
  5. ^ Appleby, R.M.; Charig, A.J., Cox, C.B.; Kermack, K.A. & Tarlo, L.B.H., 1967, "Reptilia", In: (Harland, B. e.a. ed.) The Fossil Record, Geological Society of London, pp 695-731
  6. ^ P.M. Galton, 1973, "On the anatomy and relationships of Efraasia diagnostica (Huene) n.gen., a prosauropod dinosaur (Reptilia: Saurischia) from the Upper Triassic of Germany", Paläontologische Zeitschrift 47(3/4): 229-255
  7. ^ Galton, P.M. & Bakker, R.T., 1985, "The cranial anatomy of the prosauropod dinosaur "Efraasia diagnostica", a juvenile individual of Sellosaurus gracilis from the Upper Triassic of Nordwürttemberg, West Germany", Stuttgarter Beiträge zur Naturkunde B, 117: 1-15
  8. ^ a b Glut, Donald F. (2006). "Efraasia". Dinosaurs: The Encyclopedia. 4th Supplement. Jefferson, North Carolina: McFarland & Company, Inc. pp. 327–328. ISBN 0-7864-2295-5.
  9. ^ *A.M. Yates, 2003, "The species taxonomy of the sauropodomorph dinosaurs from the Löwenstein Formation (Norian, Late Triassic) of Germany", Palaeontology 46(2): 317-337
  10. ^ Galton, P.M. 1990. "Basal Sauropodomorpha-Prosauropoda". Pp. 320-344 in: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.), The Dinosauria. University of California Press, Berkeley
  11. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 123. ISBN 1-84028-152-9.
  12. ^ Charig, A.J.; Attridge, J. & Crompton, A.W., 1965, "On the origin of the sauropods and the classification of the Saurischia", Proceedings of the Linnaean Society of London 176: 197-221

External links

Arcusaurus

Arcusaurus is an extinct genus of sauropodomorph dinosaur from the Early Jurassic (Hettangian to Sinemurian stages) of South Africa.

Arcusaurus was first named by Adam Yates, Matthew Bonnan and Johann Neveling in 2011 and the type species is Arcusaurus pereirabdalorum. The generic name is derived from Latin arcus, "rainbow", a reference to the Rainbow Nation. The specific epithet honours Lucille Pereira and Fernando Abdala who discovered the fossils .

Arcusaurus is known from two fragmentary skeletons collected in March 2006 at the Spion Kop Heelbo site from the upper Elliot Formation in Senekal in Free State. The holotype, BP/1/6235, consists of a partial skull. Some limb bones and vertebrae are included in the material. Both specimens represented juvenile individuals. From detailed features the describers concluded these were not the young of either Aardonyx or Massospondylus.

A phylogenetic study of Arcusaurus found it to be a basal sauropodomorph, placing it as the sister taxon of Efraasia and all of the more derived sauropodomorphs. Since Efraasia is known from the Norian stage of the Late Triassic, the close relationship with Arcusaurus implies that there was a 35-million-year ghost lineage of sauropodomorphs stretching from Late Triassic forms to Arcusaurus. However, Arcusaurus possesses many features unique to more advanced groups included in the clade Plateosauria, raising doubts about the results of the phylogenetic analysis.

Averostra

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Avetheropoda

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Bagualosaurus

Bagualosaurus is a genus of sauropodomorph dinosaur from the Santa Maria Formation of Brazil, dating to around 230 million years ago in the Carnian of the Late Triassic. It includes one species, Bagualosaurus agudoensis.

Cerapoda

Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.

Eberhard Fraas

Eberhard Fraas (26 June 1862 – 6 March 1915) was a German scientist, geologist and paleontologist. He worked as a curator at the Stuttgarter Naturaliensammlung and discovered the dinosaurs of the Tendaguru formation in then German East Africa (now Tanzania). The dinosaur Efraasia is named after him.

Jeholosauridae

Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.

Jingshanosaurus

Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.

Melanorosauridae

The Melanorosauridae were a family of sauropodomorph dinosaurs which lived during the Late Triassic and Early Jurassic. The name Melanorosauridae was first coined by Friedrich von Huene in 1929. Huene assigned several families of dinosaurs to the infraorder "Prosauropoda": the Anchisauridae, the Plateosauridae, the Thecodontosauridae, and the Melanorosauridae. Since then, these families have undergone numerous revisions. Galton and Upchurch (2004) considered Camelotia, Lessemsaurus, and Melanorosaurus members of the family Melanorosauridae. A more recent study by Yates (2007) indicates that the melanorosaurids were instead early sauropods.

Nambalia

Nambalia is a genus of basal sauropodomorph dinosaur. It lived during the Late Triassic period (late Norian to earliest Rhaetian) in what is now Andhra Pradesh, central India. It is known from the holotype ISI R273, parts 1-3, partially articulated postcranial material and from the paratypes ISI R273, parts 4-29, including partial postcrania of at least two individuals of different sizes found closely associated and one of them is nearly the same size as the

holotype. ISI R273 was discovered and collected from the Upper Maleri Formation within the Pranhita–Godavari Basin,

north of Nambal village. It was first named by Fernando E. Novas, Martin D. Ezcurra, Sankar Chatterjee and T. S. Kutty in 2011 and the type species is Nambalia roychowdhurii. The generic name is derived from the Indian village of Nambal which is close to the type locality. The specific name honors Dr. Roy Chowdhuri, for his research on the Triassic vertebrate faunas of India. A cladistic analysis by Novas et al. found that Nambalia is basal to Efraasia, Plateosauravus, Ruehleia and Plateosauria, but more derived than Thecodontosaurus, Pantydraco, and Guaibasauridae. Nambalia was found along with the plateosaurid Jaklapallisaurus, a guaibasaurid, and two basal dinosauriforms.

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Orionides

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Orodrominae

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Palaeosaurus

Palaeosaurus (or Paleosaurus) is a genus of indeterminate archosaur from the Magnesian Conglomerate of Bristol, England. It has had a convoluted taxonomic history.

Richard Owen's mistake of associating prosauropod skeletal remains with the carnivorous teeth which Riley and Stutchbury called Palaeosaurus, combined with von Huene's Teratosaurus minor, which was also a combination of carnivore and prosauropod remains, led paleontologists to view prosauropods as carnivorous animals for quite a long time. This error made it into several textbooks and other dinosaur reference works.

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Unaysauridae

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Xixiposaurus

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