Efraasia
Encyclopedia
Efraasia 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 m (19.7 to 23 ft) long.
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 (19.7 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 rauisuchia
n 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
).
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. 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. 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
. Allen Charig in 1967 was the first to use the combination Palaeosauriscus diagnosticus for the German material. 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. However, Galton and Robert Bakker later (1985) recommended that Efraasia be considered a junior synonym of another prosauropod, Sellosaurus gracilis.
In 2003, Adam Yates
published a study incorporating these and other fossils from the Late Triassic of Germany. 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
. 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.
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.
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. 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 (gastrolith
s) 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.
. Only in 1965 Charig established they were plant-eating sauropodomorphs.
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.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
sauropodomorph dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
. It was a herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
which lived during the middle Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
stage of the Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
, around 210 million years ago, in what is now Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. It was named in 1973 after Eberhard Fraas
Eberhard Fraas
Eberhard Fraas was a German 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 ....
, who during the early twentieth century collected what were the original type specimens
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
.
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 m (19.7 to 23 ft) long.
Discovery and naming
Efraasia has had a complicated taxonomicTaxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
history involving several genera and species. Material now known under Efraasia first came to light after Albert Burrer, Hofsteinmetzmeister ("Court master stonemason") at Maulbronn
Maulbronn
Maulbronn is a city in the district of Enz in Baden-Württemberg in southern Germany.-History:Founded in 1838, it emerged from a settlement, built around a monastery, which belonged to the Neckar Community in the Kingdom of Württemberg. In 1886, Maulbronn officially became a German town and was an...
, in 1902 began to exploit the Weiße Steinbruch, a quarry near Pfaffenhofen
Pfaffenhofen
Pfaffenhofen is the name ofin Germany:* Pfaffenhofen an der Ilm, a town in Bavaria* Pfaffenhofen , in Bavaria* Pfaffenhofen an der Glonn, a municipality in Dachau, Bavaria* a part of the municipality of Altomünster in Dachau, Bavaria...
in Württemberg
Württemberg
Württemberg , formerly known as Wirtemberg or Wurtemberg, is an area and a former state in southwestern Germany, including parts of the regions Swabia and Franconia....
. To reach the layer of hard white sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
Burrer wanted to use for his building projects a 6 metres (19.7 ft) thick overburden
Overburden
Overburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...
of softer marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
had to be removed. Many vertebrate fossils proved to be present in it. This stratum
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
was part of the Stubensandstein Member of the lower Löwenstein Formation, dating to the Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
. 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
Friedrich von Huene
Friedrich von Huene was a German paleontologist who named more dinosaurs in the early 20th century than anyone else in Europe.-Biography:...
in 1907–1908 and named as a new species of Teratosaurus
Teratosaurus
Teratosaurus was a genus of rauisuchian known from the Triassic Stubensandstein of Germany...
: T. minor. At the time, Teratosaurus was thought to be a theropod dinosaur; it was only established as a rauisuchia
Rauisuchia
Rauisuchia is a group of predatory and mostly large Triassic archosaurs. As a clade, Rauisuchia includes these Triassic forms and all crocodylomorphs, which are descendants of Triassic rauisuchians. The group in its traditional sense is paraphyletic, because it does not include crocodylomorph...
n 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
Plateosaurus
Plateosaurus is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 216 to 199 million years ago, in what is now Central and Northern Europe. Plateosaurus is a basal sauropodomorph dinosaur, a so-called "prosauropod"...
).
In 1912, Eberhard Fraas
Eberhard Fraas
Eberhard Fraas was a German 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 ....
reported on two partial skeletons, SMNS 12667 and SMNS 12684 collected in 1909, which he assigned to a new species of Thecodontosaurus
Thecodontosaurus
Thecodontosaurus is a genus of herbivorous basal sauropodomorph dinosaur which lived during the late Triassic period ....
: T. diagnosticus. He would never describe them due to his failing health, and thus this name remained a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
. Von Huene adopted the specific name years later, after Fraas' death, redescribing Fraas' specimens as Paleosaurus
Palaeosaurus
Several very different genera of prehistoric animals have been named Palaeosaurus or Paleosaurus since the 1830s. Further confusing the matter, all of the species are poorly known or poorly preserved and both spellings have been used interchangeably, even by the same authors.The repeated recurrence...
(?) diagnosticus in 1932. The question mark indicates that von Huene considered the reference as provisional only. In 1959 Oskar Kuhn
Oskar Kuhn
Oskar Kuhn was a German palaeontologist.-Life and career:Kuhn was educated in Dinkelsbühl and Bamberg and then studied natural science, specialising in geology and paleontology, at the University of Munich, from which he received his D. Phil...
pointed out that the name Paleosaurus Riley & Stutchbury 1836 was preoccupied and renamed the genus Palaeosauriscus
Palaeosauriscus
Palaeosauriscus is a name that has been given to several different genera of reptiles between 1843 and 1959.Palaeosauriscus fraserianus, described by Edward Drinker Cope in 1878, is a nomen dubium included with Anchisaurus polyzelus. P. diagnosticus is a juvenile Sellosaurus. "P...
. Allen Charig in 1967 was the first to use the combination Palaeosauriscus diagnosticus for the German material. However, the new generic name was itself a junior homonym of Palaeosauriscus fraserianus Cope 1878.
Peter Galton
Peter Galton
Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...
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. However, Galton and Robert Bakker later (1985) recommended that Efraasia be considered a junior synonym of another prosauropod, Sellosaurus gracilis.
In 2003, Adam Yates
Adam Yates
Adam Paul Yates is an English footballer who plays for League Two side Port Vale as a full back. He is a former semi-pro international with England....
published a study incorporating these and other fossils from the Late Triassic of Germany. 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
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
Teratosaurus minor the new combination Efraasia minor, which is thus the single valid species name of the taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
. 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.
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 m (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 (21.3 ft); the largest specimen is SMNS 12843 with a femurFemur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
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. Some researchers however, contend that the lower arm did not allow pronation
Pronation
In anatomy, pronation is a rotational movement of the forearm at the radioulnar joint, or of the foot at the subtalar and talocalcaneonavicular joints. For the forearm, when standing in the anatomical position, pronation will move the palm of the hand from an anterior-facing position to a...
, a rotation of the radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
around the ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
, 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
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
. 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 (gastrolith
Gastrolith
A gastrolith, also called a stomach stone or gizzard stones, is a rock held inside a gastrointestinal tract. Gastroliths are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. The grain size depends upon the size of the animal and the gastrolith's...
s) in association to specimen SMNS 12667.
Yates identifies two unique derived traits (autapomorphies
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
): 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 CarnosauriaCarnosauria
Carnosauria is a group of large predatory dinosaurs that lived during the Jurassic and Cretaceous periods. While it originally contained a wide assortment of giant theropods that were not closely related, the group has since been defined to encompass only the allosaurs and their closest kin...
. Only in 1965 Charig established they were plant-eating sauropodomorphs.
In 1973 Galton assigned Efraasia to the Anchisauridae
Anchisauridae
The Anchisauridae were a group of early sauropodomorph dinosaurs first proposed by Othniel Charles Marsh in 1885. The clade consists of Anchisaurus and its nearest relatives. However, it is not clear which other genera are included in the family; many of the dinosaurs once included have since been...
, but he used this name as a paraphyletic group encompassing all "prosauropods" that were not melanorosaurids
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...
. Modern phylogenetic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
has indicated that Efraasia is a basal sauropodomorph, somewhat more derived than Thecodontosaurus, but less than either the Prosauropoda (including Plateosaurus) or the Sauropoda
Sauropoda
Sauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land...
. The genus is sometimes recovered as the sister taxon to the last common ancestor of both larger groups.
External links
- Sauropodomorpha from Palaeos.com