Ngwevu

Ngwevu Temporal range: Early Jurassic Pliensbachian–Toarcian PreꞒ Ꞓ O S D C P T J K Pg N
Holotype skull
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Family:	†Massospondylidae
Genus:	†Ngwevu Chapelle et al., 2019[1]
Species:	†N. intloko
Binomial name
†Ngwevu intloko Chapelle et al., 2019[1]

Ngwevu is a genus of massospondylid sauropodomorph dinosaur from the Lower Jurassic of South Africa. The genus contains one species, Ngwevu intloko.

Discovery and naming

The genus Ngwevu is known from only one specimen, BP/1/4779, which is stored in the Environmental Studies Institute of the University of the Witwatersrand, in Johannesburg, South Africa. The holotype specimen was discovered in 1978 by James William Kitching in the Tevrede Farm, located in Fouriesburg district, South Africa. The strata which preserved the specimen was located in the Clarens Formation,^[2] which is Pliensbachian-early Toarcian in age.^[3] The specimen was initially considered a specimen of the genus Massospondylus^[4][5] but in 2019 was designated as a new genus and species Ngwevu ntloko (pronounced "'Ng-g'where-voo" IPA: [ŋ.gəˈweːvuː]; directly from Xhosa 'ngwevu' and 'intloko' meaning "grey skull").^[1]

Description

Ngwevu can be distinguished from other sauropodomorphs based on a unique combination of 16 traits, including one unique feature: a ridge on the lateral surface of the backside of the jugal. Previously, the specimen was noted to share some different traits compared to other Massospondylus specimens but the differences were considered a result of deformation.^[4] In the description of the new genus, it was revealed that these differences cannot be attributed to deformation, and in fact the specimen is well intact. Another hypothesis presumed the differences found in Ngwevu could be attributed to a less advanced ontogenetic stage, with some paleontologists considering it to be a younger specimen of Massospondylus.^[5] However, histological study of the holotype of Ngwevu suggests it was an adult (about 10 years old) when it fossilized, rejecting this hypothesis as well. The describing authors of Ngwevu also noted that Ngwevu was proportionately more robust than specimens of Massospondylus.^[1]

Phylogeny

Despite the fact that Ngwevu could be distinguished from Massospondylus, there are several shared features between the two genera. A phylogenetic analysis conducted in the describing paper corroborates this, placing Ngwevu intloko in the Massospondylidae. A portion of the analysis is reproduced below.^[1]

Massopoda	Anchisaurus Jingshanosaurus Seitaad Massospondylidae Massospondylus carinatus BP/1/5241 Massospondylus carinatus BP/1/4934 Adeopapposaurus mognai Leyesaurus marayensis Ignavusaurus rachelis Sarahsaurus aurifontanalis Coloradisaurus brevis Massospondylus kaalae Lufengosaurus huenei Ngwevu intloko Sauropodiformes

Paleobiology

The snout of Ngwevu is wider than that of Massospondylus carninatus, and the describing authors propose that it signifies a more generalist rather than selective diet. The holotype's robust jaw and skull features, including a broad palate and short snout, may have given it a stronger bite than M. carinatus, suggesting niche partitioning between these two species.^[1]

References

1. Chapelle, Kimberley E. J.; Barrett, Paul M.; Botha, Jennifer; Choiniere, Jonah N. (August 5, 2019). "Ngwevu intloko: a new early sauropodomorph dinosaur from the Lower Jurassic Elliot Formation of South Africa and comments on cranial ontogeny in Massospondylus carinatus". PeerJ. 7: e7240. doi:10.7717/peerj.7240. PMC 6687053. PMID 31403001.
2. Viglietti, P.A.; McPhee, B.W.; Bordy, E.M.; Sciscio, L.; Barrett, P.M.; Benson, R.B.J.; Wills, S.; Chapelle, K.E.J.; Dollman, K.N.; Mdekazi, C.; Choiniere, J.N. (2020-06-01). "Biostratigraphy of the Massospondylus Assemblage Zone (Stormberg Group, Karoo Supergroup), South Africa". South African Journal of Geology. 123 (2): 249–262. Bibcode:2020SAJG..123..249V. doi:10.25131/sajg.123.0018. ISSN 1996-8590. S2CID 225859330.
3. Bordy, Emese M.; Abrahams, Miengah; Sharman, Glenn R.; Viglietti, Pia A.; Benson, Roger B.J.; McPhee, Blair W.; Barrett, Paul M.; Sciscio, Lara; Condon, Daniel; Mundil, Roland; Rademan, Zandri (April 2020). "A chronostratigraphic framework for the upper Stormberg Group: Implications for the Triassic-Jurassic boundary in southern Africa". Earth-Science Reviews. 203: 103120. Bibcode:2020ESRv..20303120B. doi:10.1016/j.earscirev.2020.103120. ISSN 0012-8252. S2CID 213646670.
4. Gow, Chris E. (1990). "Morphology and growth of the Massospondylus braincase (Dinosauria Prosauropoda)" (PDF). Palaeontologia Africana. 27: 59–75. hdl:10539/16145 – via CORE.
5. Sues, Hans-Dieter; Reisz, Robert R.; Hinic, Sanja; Raath, Michael A. (30 December 2004). "On the skull of Massospondylus carinatus Owen, 1854 (Dinosauria: Sauropodomorpha) from the Elliot and Clarens formations (Lower Jurassic) of South Africa". Annals of Carnegie Museum. 73 (4): 239–257. doi:10.5962/p.316084. S2CID 251542198 – via ResearchGate.