''Melanorosaurus'' (meaning "Black Mountain Lizard", from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''melas/'', "black", ''oros/'', "mountain" + ''/'', "lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had l ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

that lived during the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

period. A

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthp ...

from

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...

, it had a large body and sturdy limbs, suggesting it moved about on all fours. Its limb bones were massive and heavy like the limb bones of true

sauropods Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

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

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

had four teeth on each side, a characteristic of primitive sauropodomorphs. The

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...

had 19 teeth on each side of the jaw. ''Melanorosaurus'' was around long, with a weight of .

Discovery and species

The

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...

syntype In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part of ...

s SAM 3449 and SAM 3450, were discovered, described and named in 1924 by Sidney H. Haughton. They were collected from the Triassic Lower

Elliot Formation The Elliot Formation is a geological formation and forms part of the Stormberg Group, the uppermost geological group that comprises the greater Karoo Supergroup. Outcrops of the Elliot Formation have been found in the northern Eastern Cape, south ...

, dating to the early

Norian The Norian is a division of the Triassic Period. It has the rank of an age ( geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic ...

, on the north slope of the Thaba 'Nyama (Black Mountain) in

Transkei Transkei (, meaning ''the area beyond he riverKei''), officially the Republic of Transkei ( xh, iRiphabliki yeTranskei), was an unrecognised state in the southeastern region of South Africa from 1976 to 1994. It was, along with Ciskei, a Ba ...

, South Africa. The first complete skull referred to ''Melanorosaurus'', NM QR3314, was described in 2007.Yates, Adam M., "The first complete skull of the Triassic dinosaur ''Melanorosaurus'' Haughton (Sauropodomorpha: Anchisauria)". In Barrett & Batten (eds.), ''Evolution and Palaeobiology'' (2007), pp. 9–55. However, this specimen comes from the Upper Elliot, unlike the ''Melanorosaurus'' type material and NM QR1551, rendering its referral to the genus untenable. ''Melanorosaurus thabanensis'' was named in 1993 by Gauffre, based on

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

MNHN LES-16, a

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

found in the Upper Triassic lower Elliot Formation. However, a recent review of the material demonstrated that the femur, along with six other bones, can't be referred to the genus ''Melanorosaurus'', and a new combination ('' Meroktenos thabanensis'') was created.

Classification

''Melanorosaurus'' was once classified as a

prosauropod Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had ...

, but Prosauropoda no longer appears to be a natural group. According to some definitions of

Sauropoda Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their ...

, ''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'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...

'' than ''Melanorosaurus''). This definition would allow Sauropoda to retain its traditional concept. The following cladogram shows the position of ''Melanorosaurus'' within Massopoda, according to Oliver W. M. Rauhut and colleagues, 2020:

References

Bibliography

* {{Taxonbar, from=Q132584 Melanorosauridae Late Triassic dinosaurs of Africa Triassic South Africa Fossils of South Africa Fossil taxa described in 1924 Taxa named by Sidney H. Haughton