A few vertebrae and the upper arm bone of a previously unknown species of stegosaurus have been found in the Middle Atlas Mountains of Morocco. And despite the lack of a complete skeleton, scientists say that at 168 million years old it's the oldest known stegosaurus yet found.
In particular, the neck vertebrae and the humerus were incredibly similar to those of other stegosaurus fossils that have been recovered in the past, said Susannah Maidment, team leader and paleontologist at London's Natural History Museum.
The research team named it Adratiklit boulahfa, which translates to "mountain lizard" in the Berber language. Boulahfa describes the area where it was found.
"The discovery of Adratiklit boulahfa is particularly exciting as we have dated it to the middle Jurassic," Maidment said. "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."
The herbivorous dinosaur was known for the bony plates marching down its back, ending in a spiked tail. It was one of a larger group of armored dinosaurs known as thyreophorans. Previously, they have been discovered in North America, Asia, Europe and southern Africa, but this is the first to be found in North Africa.
The research team analyzed the fossils in order to determine how it compares with other stegosaurs. Their results published last week in the Gondwana Research journal.
"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 Tom Raven, study co-author and PhD student at the museum.
Previously, many of the threophoran dinosaur fossils have been attributed to rock formations associated with the former supercontinent, Laurasia. The other supercontinent was Gondwana. The theory suggested that the armored dinosaurs were more common and diverse on the Laurasian continent.
This new discovery changes that.
"Most stegosaurs we know of, including the Natural History Museum's Sophie, the most complete stegosaur discovered, have been found in Laurasian rock formations," 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."
More efforts to search for fossils in former Gondwana could help researchers find a complete skeleton of the newly discovered type of stegosaurus as well as showcase the diversity of armored dinosaurs that once lived on the continent.
"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 said.