New research on the systematic position of the enigmatic thyreophoran dinosaur Paranthodon africanus

A new article, by Thomas Raven and Susie Maidment, redescribes a very poorly known thyreophoran taxon, Paranthodon africanus Broom 1910, from the Lower Cretaceous Kirkwood Formation of South Africa, that has had uncertain taxonomical affinities since its discovery, in 1845. At the time, it was the first dinosaur to be found in Africa. Since then, it has been placed in different groups. Richard Owen (1876) identified it as pareiasaur, Anthodon serranius, then Broom (1910) reassigned it as the ankylosaur Palaeoscincus africanus, and then Nopcsa (1929) as the stegosaur Paranthodon oweni. More recently, Peter Galton & Walter Coombs (1981) agreed that the specimen is a member of the Stegosauria and coined Paranthodon africanus.

The new research shows that the phylogenetic positioning of P. africanus is highly labile and deeply dependent on the chosen taxonomic exemplifier. The material is limited to a left partial maxilla, premaxilla, nasal, and a dorsal vertebra. Therefore, additional material is also needed to fully assess its place within Thyreophora. Nonetheless, the authors conducted extensive phylogenetic analysis, comparing it with previous phylogenetic trees, and concluded that, with the available data, the most likely outcome is that P. africanus is indeed a stegosaur.

It is worth noting that one of the results of the analysis performed in this study is an improved resolution of the ankylosaurian phylogeny and more robust support of the previous analysis, by Arbour & Currie (2016), Arbour et al. (2016), and Thompson et al. (2012).

Full article: Raven, T. J., and S. C. R. Maidment. 2018. The systematic position of the enigmatic thyreophoran dinosaur Paranthodon africanus, and the use of basal exemplifiers in phylogenetic analysis.

Arbour, V. M., and P. J. Currie. 2015. Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs. Journal of Systematic Palaeontology, 14(5): 385-444.

Arbour, V. M., Zanno, L. E., and T. Gates. 2016. Ankylosaurian dinosaur palaeoenvironmental associations were influenced by extirpation, sea-level fluctuation, and geodispersal. Palaeogeography, Palaeoclimatology, Palaeoecology, 449: 289-299.

Broom R. 1910. Observations on some specimens of South African fossil reptiles preserved in the British Museum. Transactions of the Royal Society of South Africa, 2(1): 19-25.

Galton, P. M., and W. P. Coombs. 1981. Paranthodon africanus (Broom) a stegosaurian dinosaur from the lower cretaceous of South Africa. Geobios, 14(3): 299-309.

Nopsca FB. 1929. Dinosaurierreste Aus Siebenburgen V. Geologica Hungarica (Series Paleontology), 1: 1-76.

Owen, R. 1876. Descriptive and illustrated catalogue of the fossil Reptilia of South Africa in the collection of the British Museum. Order of the Trustees.

Thompson RS, Parish JC, Maidment SCR, Barrett PM. 2012. Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora). Journal of Systematic Palaeontology, 10(2): 301-312.