Meet Adratiklit boulahfa, World’s Earliest Known Stegosaur
Stegosaurs were a widespread group with species of the armored (thyreophoran) dinosaurs found in Southern Africa, North America, Asia and Europe.
But the newly-discovered stegosaur, named Adratiklit boulahfa, is the first of the group to hail from North Africa.
Its fossilized remains — a handful of vertebrae and an upper arm bone — were found in the Middle Atlas Mountains of Morocco.
“The discovery of Adratiklit boulahfa is particularly exciting as we have dated it to the middle Jurassic,” said Dr. Susannah Maidment, a researcher at the Natural History Museum, London.
“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.”
To understand the evolutionary relationship of Adratiklit boulahfa with known stegosaurs, Dr. Maidment and her colleagues from the University of Brighton, the Natural History Museum, London, and the Université Sidi Mohamed Ben Abdellah conducted the phylogenetic analysis of the specimens.
“Despite being from the African continent our phylogenetic analysis indicated that, surprisingly, Adratiklit boulahfa is more closely related to European stegosaurs than it is to the two genera known from southern Africa,” said Tom Raven, a PhD student at the University of Brighton and the Natural History Museum, London.
When stegosaurs were alive, the world was divided into two supercontinents: Laurasia and Gondwana. Laurasia included the land masses that today make up most of the northern hemisphere’s continents, and Gondwana eventually split into land masses including Africa, South America, Australia and Antarctica.
Stegosaurs were diverse and abundant in Laurasia. In contrast, their remains are extremely rare in Gondwana.
The discovery of Adratiklit boulahfa now adds to the theory that the Gondwanan fossil record of armored dinosaurs is significantly biased by both geological factors and collection efforts.
“Most stegosaurs we know of have been found in Laurasian rock formations,” Dr. Maidment said.
“This, however may not mean that stegosaurs were not so common in Gondwana and in fact may be due to the fact that Gondwana rock formations have been subject to far fewer excavations and detailed studies.”
The team’s paper was published in the journal Gondwana Research.
Susannah C.R. Maidment et al. North Africa’s first stegosaur: Implications for Gondwanan thyreophoran dinosaur diversity. Gondwana Research, published online August 16, 2019; doi: 10.1016/j.gr.2019.07.007