A new study reveals that fossils found in Morocco's El Mers III Formation are the oldest known Cerapodan dinosaurs, dating back to the Middle Jurassic, around 163 to 174 million years ago. This discovery helps shed light on the evolution of Cerapodans and their rise as dominant plant-eaters in the Northern Hemisphere. Morocco is home to the world's oldest Cerapodan dinosaurs, a group of plant-eating dinosaurs, a new study has revealed. Fossils unearthed in Morocco's El Mers III Formation, a geological formation in the Middle Atlas Mountains, provide evidence for this conclusion, as featured on March 12 by a group of palaeontologists from Fes Sidi Mohammed Ben Abdellah University and the UK Natural History Museum. The study, titled «The World's Oldest Cerapodan Ornithischian Dinosaur from the Middle Jurassic of Morocco», explains that Cerapodan dinosaurs evolved by the Middle Jurassic, around 163 to 174 million years ago. Before the Morocco discovery, only one fossil from that time—a femur from the UK—has been found. To further understand how Cerapodans evolved and clarify confusion about their family tree, more fossils, especially from less studied regions, are needed. This is now possible thanks to the cerapodan femur found in Morocco's El Mers III Formation, near Boulemane. Dominant plant-eaters of their time Although the fossil is incomplete, its features identify it as part of the Cerapodan group, making it the oldest known specimen of its kind. The same formation also holds the oldest ankylosaur and one of the oldest stegosaurs, according to the researchers. The earliest Cerapodans were bipedal (walking on two legs) and had grasping front limbs. Later, some evolved to become quadrupedal (walking on four legs) with advanced chewing systems, which helped them become the primary plant-eaters in the Northern Hemisphere. Cerapoda consists of two main groups: Ornithopoda and Marginocephalia. The Morocco fossils belong to Ornithopoda, a group that includes both non-duck-billed dinosaurs, like iguanodontians, and duck-billed dinosaurs (hadrosaurids). The Morocco specimen, which is the proximal end of a left femur, is described as «the world's oldest cerapodan and only the second recorded from the Middle Jurassic globally», the researchers explained. Studying the Moroccan specimen, the researchers suggest that the Middle Jurassic was a key period for the rise of dinosaur-dominated ecosystems. Further research into this period will help us understand what allowed ornithischians to become the dominant plant-eaters of their time.
