Eucnemesaurus
Encyclopedia
Eucnemesaurus is a basal sauropodomorph
dinosaur
genus
usually considered to be a synonym of Euskelosaurus
. Recent study by Yates (2006), however, indicates that it is valid and the same animal as putative "giant herrerasaurid
" Aliwalia.
Eucnemesaurus was in 1920 named by Egbert Cornelis Nicolaas van Hoepen. The type species
is Eucnemesaurus fortis. The specific name means "strong" in Latin
. It is based on holotype
TrM 119, a partial skeleton including vertebrae, part of a pubis
, a femur
, and two tibia
e. The remains were found by Van Hoepen in the late Carnian
-early Norian
-age Upper Triassic Lower Elliot Formation
of the Slabberts district, Orange Free State
, South Africa
.
Yates assigned the genus to the new family Riojasauridae
, with Riojasaurus
, usually regarded as a melanorosaurid
.
, Aliwalia rex (the generic
name was taken from the Aliwal Park Reserve in the Union of South Africa
, where the first remains were found). The fossil
evidence of this species was comparably small, with for many years only femoral fragments and a maxilla
known.
The size of the femur led many palaeontologist
s to believe (along with the clearly carnivorous maxilla), that Aliwalia was a carnivorous dinosaur of remarkable size for the age in which lived. It would have been comparable to that of the large Jurassic
and Cretaceous
theropods, such as Allosaurus
, that evolved tens of millions of years after Aliwalia. The original material was believed to bear a strong similarity to the South America
n Herrerasaurus
, so much so that Aliwalia was originally classified in Herrerasauridae
by Peter Galton
.
However, recent re-evaluation of the material has shown that the maxilla assigned to Aliwalia does not, unlike the other material, belong to Eucnemesaurus, as it is clearly from a carnivore. In addition, new material clearly demonstrates this latter genus' sauropodomorph affinities.
Sauropodomorpha
Sauropodomorpha is an extinct clade of long-necked, herbivorous, saurischian dinosaurs which includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The...
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...
genus
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...
usually considered to be a synonym of Euskelosaurus
Euskelosaurus
Euskelosaurus was a semi-bipedal dinosaur from the Late Triassic. It was a prosauropod that lived in the Late Triassic Period, in present-day South Africa, Lesotho, and Zimbabwe. It was first described by Thomas Henry Huxley in 1866 as Euskelesaurus brownii based on holotype BMNH R1625, limb and...
. Recent study by Yates (2006), however, indicates that it is valid and the same animal as putative "giant herrerasaurid
Herrerasauridae
Herrerasaurids are among the oldest known dinosaurs, appearing in the fossil record 231.4 million years ago . They became extinct by the end of the Triassic period. Herrerasaurids were small-sized carnivorous theropods or basal saurischians...
" Aliwalia.
Eucnemesaurus was in 1920 named by Egbert Cornelis Nicolaas van Hoepen. 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...
is Eucnemesaurus fortis. The specific name means "strong" in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
. It is based on holotype
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...
TrM 119, a partial skeleton including vertebrae, part of a pubis
Pubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
, a femur
Femur
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...
, and two tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
e. The remains were found by Van Hoepen in the late Carnian
Carnian
The Carnian is the lowermost stage of the Upper Triassic series . It lasted from about 228.7 till 216.5 million years ago . The Carnian is preceded by the Ladinian and is followed by the Norian...
-early 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...
-age Upper Triassic Lower Elliot Formation
Elliot Formation
The Elliot Formation is a geological formation dating to roughly 210 to 190 million years ago and covering the Norian to Sinemurian stages. The Elliot Formation is found in South Africa and Lesotho and is a member of the Stormberg Group. It consists mainly of limestone, sandstone, and mudstone...
of the Slabberts district, Orange Free State
Free State
The Free State is a province of South Africa. Its capital is Bloemfontein, which is also South Africa's judicial capital. Its historical origins lie in the Orange Free State Boer republic and later Orange Free State Province. The current borders of the province date from 1994 when the Bantustans...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
.
Yates assigned the genus to the new family Riojasauridae
Riojasauridae
Riojasauridae is a family of sauropod-like dinosaurs from the Upper Triassic. It is known primarily from the genera Riojasaurus and Eucnemesaurus...
, with Riojasaurus
Riojasaurus
Riojasaurus was a herbivorous prosauropod dinosaur named after La Rioja Province in Argentina where it was found by José Bonaparte. It lived during the Late Triassic and grew to about long. Riojasaurus is the only known riojasaurid to live in South America.-Description:Riojasaurus had a heavy...
, usually regarded as a melanorosaurid
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...
.
Aliwalia
Fossil material now assigned to Eucnemesaurus was once placed in a separate genus and speciesSpecies
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, Aliwalia rex (the generic
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...
name was taken from the Aliwal Park Reserve in the Union of South Africa
Union of South Africa
The Union of South Africa is the historic predecessor to the present-day Republic of South Africa. It came into being on 31 May 1910 with the unification of the previously separate colonies of the Cape, Natal, Transvaal and the Orange Free State...
, where the first remains were found). The fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
evidence of this species was comparably small, with for many years only femoral fragments and a maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
known.
The size of the femur led many palaeontologist
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
s to believe (along with the clearly carnivorous maxilla), that Aliwalia was a carnivorous dinosaur of remarkable size for the age in which lived. It would have been comparable to that of the large Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
and Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
theropods, such as Allosaurus
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
, that evolved tens of millions of years after Aliwalia. The original material was believed to bear a strong similarity to the South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
n Herrerasaurus
Herrerasaurus
Herrerasaurus was one of the earliest dinosaurs. All known specimens of this carnivore have been discovered in rocks of late Ladinian age in northwestern Argentina...
, so much so that Aliwalia was originally classified in Herrerasauridae
Herrerasauridae
Herrerasaurids are among the oldest known dinosaurs, appearing in the fossil record 231.4 million years ago . They became extinct by the end of the Triassic period. Herrerasaurids were small-sized carnivorous theropods or basal saurischians...
by 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...
.
However, recent re-evaluation of the material has shown that the maxilla assigned to Aliwalia does not, unlike the other material, belong to Eucnemesaurus, as it is clearly from a carnivore. In addition, new material clearly demonstrates this latter genus' sauropodomorph affinities.