Melanorosaurus
Encyclopedia
Melanorosaurus is a genus
of basal
sauropodomorph
dinosaur
that lived during the Late Triassic
period. A herbivore
from South Africa
, it had a large body and sturdy limbs, suggesting it moved about on all fours. Limb bones were massive and weighty, like sauropod limb bones.
s SAM 3449 and SAM 3450, were described and named in 1924 by Sidney Henry Haughton. They were collected from the Triassic Lower Elliot Formation, dating to the early Norian
, on the north slope of the Thaba 'Nyama (Black Mountain) in Transkei
, South Africa. The first complete skull of Melanorosaurus was described in 2007. Two species are known: M. readi, the type species
, and M. thabanensis named in 1993 by François-Xavier Gauffre, based on holotype
MNHN LES-16, a femur
found in the Jurassic Upper Elliot Formation
.
, Melanorosaurus is an early sauropod. However, these definitions also take in many other former "prosauropods," and Adam Yates has proposed a definition of Sauropoda that will specifically exclude Melanorosaurus (Sauropoda as all sauropodomorphs closer to Saltasaurus
than Melanorosaurus). This definition would allow Sauropoda to retain its traditional concept.
had four teeth on each side, a characteristic of primitive sauropodomorphs. The maxilla
had 19 teeth on each side of the jaw.
Melanorosaurus was around 8 metres (26.2 ft) long, with a weight of 1.3 metric tons (1.3 LT).
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
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...
that lived during 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...
period. 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...
from 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...
, it had a large body and sturdy limbs, suggesting it moved about on all fours. Limb bones were massive and weighty, like sauropod limb bones.
Discovery and species
The type specimens, syntypeSyntype
In biological nomenclature, a syntype is a term used to indicate a specimen with a special status.In zoological nomenclature, a syntype is defined as "Each specimen of a type series from which neither a holotype nor a lectotype has been designated [Arts. 72.1.2, 73.2, 74]. The syntypes...
s SAM 3449 and SAM 3450, were described and named in 1924 by Sidney Henry Haughton. They were collected from the Triassic Lower Elliot Formation, dating to the 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...
, on the north slope of the Thaba 'Nyama (Black Mountain) in Transkei
Transkei
The Transkei , officially the Republic of Transkei , was a Bantustan—an area set aside for members of a specific ethnicity—and nominal parliamentary democracy in the southeastern region of South Africa...
, South Africa. The first complete skull of Melanorosaurus was described in 2007. Two species are known: M. readi, 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...
, and M. thabanensis named in 1993 by François-Xavier Gauffre, 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...
MNHN LES-16, 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...
found in the Jurassic Upper Elliot Formation
Upper Elliot Formation
The Upper Elliot Formation is a geological formation dating to roughly between 200 to 190 million years ago and covering the Hettangian to Sinemurian stages. The Upper Elliot Formation is found in South Africa and Lesotho and is a member of the Stormberg Group. It consists mainly of limestone,...
.
Classification
Melanorosaurus was once classified as a prosauropod, but Prosauropoda no longer appears to be a natural group. According to some definitions of SauropodaSauropoda
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...
, Melanorosaurus is an early sauropod. However, these definitions also take in many other former "prosauropods," and Adam Yates has proposed a definition of Sauropoda that will specifically exclude Melanorosaurus (Sauropoda as all sauropodomorphs closer to Saltasaurus
Saltasaurus
Saltasaurus is a genus of titanosaurid sauropod dinosaur of the Late Cretaceous Period. Relatively small among sauropods, though still massive by the standards of modern creatures, Saltasaurus was characterized by a diplodocid-like head...
than Melanorosaurus). This definition would allow Sauropoda to retain its traditional concept.
Description
Melanorosaurus had a skull which measured approximately 250 mm. The snout was somewhat pointed, and the skull was somewhat triangular when seen from above or below. The premaxillaPremaxilla
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....
had four teeth on each side, a characteristic of primitive sauropodomorphs. The 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...
had 19 teeth on each side of the jaw.
Melanorosaurus was around 8 metres (26.2 ft) long, with a weight of 1.3 metric tons (1.3 LT).