North Africa's first stegosaur: Implications for Gondwanan thyreophoran dinosaur diversity

Abstract

Eurypoda, the major radiation of armoured dinosaurs, comprises the ankylosaurs and their sister group, the stegosaurs. As the earliest-branching major clade of ornithischian dinosaurs, the evolutionary history of Eurypoda is significant for understanding both the palaeobiology of bird-hipped dinosaurs and the composition of middle Mesozoic ecosystems. Eurypodans were diverse and abundant throughout the Late Jurassic and Cretaceous in Laurasia; in contrast, their remains are extremely rare in Gondwana. Herein, we describe a new genus and species of stegosaur from the Middle Jurassic of Morocco, Adratiklit boulahfa. Adratiklit is the first eurypodan from north Africa and the oldest definitive stegosaur from anywhere in the world. The genus is more closely related to the European stegosaurs Dacentrurus and Miragaia than it is to the southern African taxa Kentrosaurus and Paranthodon. Statistically significant correlations between the number of dinosaur-bearing formations, dinosaur-bearing collections, and eurypodan occurrences in Gondwana indicates that their fossil record is biased by both geological and anthropogenic factors. Tantalizing but fragmentary remains and trackways suggest that eurypodan diversity in Gondwana may have been as rich as that of Laurasia, and the prospects for future discoveries of new genera across Gondwana are therefore very good.