Kangnasaurus

Kangnasaurus Temporal range: Campanian-Maastrichtian ~80–66  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Thigh bone of cf. Kangnasaurus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Clade:	† Ornithischia
Clade:	† Ornithopoda
Clade:	† Elasmaria
Genus:	† Kangnasaurus Haughton, 1915
Species:	†K. coetzeei
Binomial name
†Kangnasaurus coetzeei Haughton, 1915

Kangnasaurus (meaning "Farm Kangnas lizard") is a genus of elasmarian ornithopod dinosaur found in Late Cretaceous rocks of South Africa. It is known from a tooth and possibly some postcranial remains dating between the middle-Campanian to Maastrichtian Kalahari Deposits Formation. ^[1]

Discovery and naming

Holotype tooth of K. coetzeei (SAM 2732) as seen from three different angles; figured from Haughton (1915)

Kangnasaurus was named in 1915 by Sidney H. Haughton. The type species is Kangnasaurus coetzeei. The generic name refers to the Kangnas farm; the specific name to the farmer, Coetzee. Kangnasaurus is based on holotype SAM  2732, a tooth found at a depth of 34 metres in a well at Farm Kangnas, in the Orange River valley of northern Cape Province, South Africa. ^[2] The age of these rocks, conglomerates in an ancient crater lake, was once suggested to date to the Early Cretaceous (probably early-Aptian) due to the original phylogenetic position of the taxa as a dryosaurid. ^[3] But a Late Cretaceous age between the Campanian and Maastrichtian is more likely due to sedimentological analyses. ^[4] Haughton thought SAM 2732 was a tooth from the upper jaw, but Michael Cooper reidentified it as a lower jaw tooth in 1985. ^[5] This had implications for its classification: Haughton thought the tooth was that of an iguanodontid, ^[2] while Cooper identified it as from an animal more like Dryosaurus , a more basal ornithopod. ^[5]

Haughton described several other fossils as possibly belonging to Kangnasaurus. These include five partial thigh bones, a partial thigh bone and shin bone, a partial metatarsal, a partial shin and foot, vertebrae, and unidentified bones. Some of the bones apparently came from other deposits, and Haughton was not certain that they all belonged to his new genus. ^[2] Cooper was also not certain, but described the other specimens as if they did belong to Kangnasaurus. ^[5] Like other basal iguanodontians, it would have been a bipedal herbivore. ^[6]

Classification

Kangnasaurus was originally regarded as dubious, ^{[7] [6]} although a 2007 review of dryosaurids by Ruiz-Omeñaca and colleagues retained it as potentially valid, differing from other dryosaurids by details of the thigh bone. ^[3]

The differences in interpretation between Haughton and Cooper regarding the placement of the tooth had implications for the taxon's classification: Haughton thought the tooth was indicative that of an iguanodontid when interpreted as a maxillary position, ^[2] while Cooper classified it as coming from an animal more like Dryosaurus based on his assignment of the tooth to the dentary. ^[5] However, more recent studies have separately uncovered a position nested within the elasmarian group. ^{[8] [9] [10]}

References

1. "Table 19.1," in Weishampel, et al. (2004). Page 417.
2. Haughton, Sidney H. (1915). "On some dinosaur remains from Bushmanland". Transactions of the Royal Society of South Africa. 5 (1): 259–264. Bibcode:1915TRSSA...5..259H. doi:10.1080/00359191509519723.
3. Ruiz-Omeñaca, José Ignacio; Pereda Suberbiola, Xavier; Galton, Peter M. (2007). "Callovosaurus leedsi, the earliest dryosaurid dinosaur (Ornithischia: Euornithopoda) from the Middle Jurassic of England". In Carpenter Kenneth (ed.). Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Bloomington and Indianapolis: Indiana University Press. pp. 3–16. ISBN   978-0-253-34817-3.
4. Forster CA, de Klerk WJ, Poole KE, Chinsamy-Turan A, Roberts EM, Ross CF (2022). "Iyuku raathi, a new iguanodontian dinosaur from the Early Cretaceous Kirkwood Formation, South Africa". The Anatomical Record. 306 (7): 1762–1803. doi:10.1002/ar.25038. PMID   35860957. S2CID   250730794.
5. Cooper, Michael R. (1985). "A revision of the ornithischian dinosaur Kangnasaurus coetzeei Haughton, with a classification of the Ornithischia". Annals of the South African Museum. 95 (8): 281–317.
6. Norman, David B. (2004). "Basal Iguanodontia". In Weishampel, D.B.; Dodson, P.; Osmólska H. (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 413–437. ISBN   0-520-24209-2.
7. Sues, Hans-Dieter; Norman, David B. (1990). "Hypsilophodontidae, Tenontosaurus, Dryosauridae". In Weishampel, David B.; Dodson, Peter; Osmólska Halszka (eds.). The Dinosauria (1st ed.). Berkeley: University of California Press. pp. 498–509. ISBN   0-520-06727-4.
8. Rozadilla, Sebastián; Agnolín, Federico Lisandro; Novas, Fernando Emilio (2019-12-17). "Osteology of the Patagonian ornithopod Talenkauen santacrucensis (Dinosauria, Ornithischia)". Journal of Systematic Palaeontology. 17 (24): 2043–2089. Bibcode:2019JSPal..17.2043R. doi:10.1080/14772019.2019.1582562. ISSN   1477-2019. S2CID   155344014.
9. Dieudonné PE, Cruzado-Caballero P, Godefroit P, Tortosa T (2020). "A new phylogeny of cerapodan dinosaurs". Historical Biology. 33 (10): 2335–2355. doi: 10.1080/08912963.2020.1793979 .
10. Fonseca, A.O.; Reid, I.J.; Venner, A.; Duncan, R.J.; Garcia, M.S.; Müller, R.T. (2024). "A comprehensive phylogenetic analysis on early ornithischian evolution". Journal of Systematic Palaeontology. 22 (1) 2346577. doi:10.1080/14772019.2024.2346577.