A few vertebrae and an upper arm bone are all it has taken for palaeontologists at London’s Natural History Museum to announce a new species of stegosaur. Moreover, the discovery from the Middle Atlas Mountains in Morocco is the oldest example we’ve found of the dinosaurs famous for their spiny backs, replacing the Chinese Huayangosaurus taibaii.
Dr Susannah Maidment determined the bones are consistent enough with other stegosaurs to be placed in the same suborder, but sufficiently different to require a new genus, leading her to name the find Adratiklit boulahfa. The genus name means “mountain lizard” in Berber, while the species refers to the location where the find was made.
“The discovery of Adratiklit boulahfa is particularly exciting as we have dated it to the middle Jurassic. Most known stegosaurs date from far later in the Jurassic period, making this the oldest definite stegosaur described and helping to increase our understanding of the evolution of this group of dinosaurs,” Maidment said in a statement.
Besides its age, A. boulahfa is notable for being the first stegosaur found from North Africa. Stegosaurs have been found both in Southern Africa and across North America, Europe, and Asia (which made up the supercontinent Laurasia in the Jurassic), so it is not surprising to discover one in Morocco. On the other hand, the place the bones put A. boulahfa in the stegosaur family tree was less expected.
“Despite being from the African continent our phylogenetic analysis indicated that, surprisingly, Adratiklit is more closely related to European stegosaurs than it is to the two genera known from southern Africa,” said University of Brighton PhD student Tom Raven, co-author with Maidment of the Gondwana Research paper describing the find. The paper names Dacentrurus and Miragaia as the European stegosaurs that most closely resemble Adratiklit.
Stegosaurs were one of the main groups of thyreophorans, or armored dinosaurs. They thrived throughout Laurasia in the late Jurassic and early Cretaceous, but few have been found in Gondwana. The paper proposes the relative absence of stegosaurs from the Gondwanan record does not reflect true scarcity, but a combination of limited sites suited to preserving them, and less excavation of those that exist. The fact A. boulahfa predates any known Laurasian stegosaur is evidence for this.
“What is exciting about this is that there could be many more thyreophoran dinosaurs to find in places that until now have not been excavated,” Maidment added.
As interesting and scientifically significant as this all is, the discovery sheds no light on the question that has puzzled dinosaur experts and the public alike: How did stegosaurs have sex without one getting impaled on the other’s sharp bits?