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Melanorosaurus; Temporal range: Late Triassic; ~216.5–201 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Life restoration of M. readi
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Family:	†Melanorosauridae
Genus:	†Melanorosaurus; Haughton, 1924
Type species
	†Melanorosaurus readi; Haughton, 1924

Melanorosaurus (meaning "Black Mountain Lizard", from the Greek melas/μέλας, "black", oros/ὄρος, "mountain" + sauros/σαῦρος, "lizard") is a genus of basal sauropodomorph dinosaur that lived during the Late Triassic period. An omnivore^[1] from South Africa, it had a large body and sturdy limbs, suggesting it moved quadrupedally. Its limb bones were massive and heavy like the limb bones of true sauropods.

Description

Size comparison

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 had four teeth on each side, a characteristic of primitive sauropodomorphs. The maxilla had 19 teeth on each side of the jaw.^[2]

Melanorosaurus was around 8 metres (26 ft) long, with a weight of 1.3 metric tons (1.3 long tons).^[3]

Discovery and species

The type specimens, syntypes 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, dating to the early Norian, on the north slope of the Thaba 'Nyama (Black Mountain) in Transkei, South Africa.^[4] The first complete skull referred to Melanorosaurus, NM QR3314, was described in 2007.^[2] However, this specimen comes from the Upper Elliot, unlike the Melanorosaurus type material and NM QR1551, rendering its referral to the genus untenable.^[5]

Melanorosaurus thabanensis was named in 1993 by Gauffre, based on holotype MNHN LES-16, a femur found in the Upper Triassic lower Elliot Formation.^[6] 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.^[7]

Classification

Melanorosaurus was once classified as a prosauropod, but Prosauropoda no longer appears to be a natural group. According to some definitions of Sauropoda, 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.^[8]

The following cladogram shows the position of Melanorosaurus within Massopoda, according to Oliver W. M. Rauhut and colleagues, 2020:^[9]

Massopoda

	Eucnemesaurus

	Riojasaurus

Sarahsaurus

Massospondylidae

Yunnanosaurus

	Jingshanosaurus

	Seitaad

Coloradisaurus

	Glacialisaurus

	Lufengosaurus

Massospondylus

	Adeopapposaurus

	Leyesaurus

Sauropodiformes

Xingxiulong

	Anchisaurus

	Leonerasaurus

Melanorosaurus

	Antetonitrus

	Ingentia

	Tazoudasaurus

	Sauropoda

References

^ "Melanorosaurus". www.nhm.ac.uk. Retrieved 12 May 2024.
^ ^a ^b 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.
^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 170
^ S.H. Haughton, 1924, "The fauna and stratigraphy of the Stormberg Series", Annals of the South African Museum 12 : 323-497
^ McPhee, B.W., Bordy, E.M., Sciscio, L., and Choiniere, J.N. 2017. The sauropodomorph biostratigraphy of the Elliot Formation of southern Africa: Tracking the evolution of Sauropodomorpha across the Triassic–Jurassic boundary. Acta Palaeontologica Polonica 62 (3): 441–465.
^ Gauffre, F.-X. (1993). "The most recent Melanorosauridae (Saurischia, Prosauropoda), Lower Jurassic of Lesotho, with remarks on the prosauropod phylogeny". Neues Jahrbuch für Geologie und Paläontologie - Monatshefte. 1993 (11): 648–654. doi:10.1127/njgpm/1993/1993/648.
^ Peyre de Fabrègues, C.; Allain, R. (2016). "New material and revision of Melanorosaurus thabanensis, a basal sauropodomorph from the Upper Triassic of Lesotho". PeerJ. 4: e1639. doi:10.7717/peerj.1639. PMC 4741091. PMID 26855874.
^ Yates, Adam M. (2010). "A revision of the problematic sauropodomorph dinosaurs from Manchester, Connecticut and the status of Anchisaurus Marsh". Palaeontology. 53 (4): 739–752. Bibcode:2010Palgy..53..739Y. doi:10.1111/j.1475-4983.2010.00952.x. S2CID 140535438.
^ Rauhut, O. W. M.; Holwerda, F. M.; Furrer, H. (2020). "A derived sauropodiform dinosaur and other sauropodomorph material from the Late Triassic of Canton Schaffhausen, Switzerland". Swiss Journal of Geosciences. 113 (1): 8. doi:10.1186/s00015-020-00360-8. S2CID 220294939.

Bibliography

Galton PM, Van Heerden J, Yates AM (2005). "Postcranial Anatomy of Referred Specimens of Melanorosaurus". In Carpenter, Kenneth, Tidswell, Virginia (eds.). Thunder Lizards: The Sauropodomorph Dinosaurs. Indiana University Press. pp. 1–37. ISBN 0-253-34542-1.