A fossil unearthed in the Middle Atlas Mountains of Morocco is now officially the oldest-known plant-eating cerapodan dinosaur, pushing back the evolutionary timeline of this major herbivorous group by over two million years.
168-Million-Year-Old Femur Found in El Mers III Formation
According to Interestingengineering, an international team of paleontologists has discovered a fossilized upper limb bone—specifically a femur—in the El Mers III Formation, a Jurassic rock bed in Morocco’s Middle Atlas region.
The specimen dates back to the Bathonian stage of the Middle Jurassic, approximately 168 million years ago, making it the oldest skeletal evidence of a cerapodan ever recorded.
Cerapodans were small, bipedal herbivores, part of the larger ornithischian (“bird-hipped”) group of dinosaurs, and are related to well-known genera such as iguanodons and hadrosaurs.
Much like modern birds, they moved on two legs and thrived particularly during the Cretaceous Period—until now, their presence in earlier periods had remained largely speculative.
Anatomical Traits Confirm the Fossil’s Identity
Previous signs of Middle Jurassic cerapodans were limited to fossilized footprints, offering only indirect evidence. The newly discovered femur fills a critical void in the fossil record. Despite being fragmentary, the bone exhibits defining features of cerapodans:
- A distinctive groove on the posterior surface of the femur’s proximal end
- An offset femoral head on a clearly defined neck
- A constriction between the head and the greater trochanter
These characteristics led the researchers to conclusively place the specimen within the Cerapoda, excluding it from other neornithischians. The team—composed of scientists from the Natural History Museum (UK), University of Birmingham, and Sidi Mohamed Ben Abdellah University (Morocco)—published their findings in Royal Society Open Science.
Morocco Becomes a Hotspot for Jurassic Paleontology
The fossil was discovered near the same dig site that previously yielded the world’s oldest ankylosaur, an armored dinosaur with a club-like tail. The El Mers III Formation has also revealed one of the earliest stegosaurs, known for their iconic dorsal plates.
These finds collectively mark the region as a global center of dinosaur diversification during the Middle Jurassic. While fossil beds from this period remain rare across the globe, Morocco is rapidly becoming a key repository for unlocking evolutionary patterns in early dinosaurs—particularly ornithischians.
Evolutionary Implications and Global Context
Before this discovery, the oldest known cerapodan was a femur from the United Kingdom, dated roughly two million years younger. The Moroccan fossil shifts the origin timeline back significantly and supports long-held hypotheses that cerapodans diversified much earlier than previously confirmed.
The findings offer concrete support for evolutionary theories that had previously relied on indirect or incomplete data. With anatomical evidence now available, paleontologists can better trace the development of early herbivorous dinosaurs.
Interestingly, this discovery echoes recent breakthroughs in Asia. In 2024, Chinese researchers announced the unearthing of Archaeocursor asiaticus, the oldest and most primitive ornithischian found in Asia. Dated at 193 million years, that fossil was discovered in southwestern China and further broadens the known geographic distribution of early ornithischians.
A New Chapter in Jurassic Science
This discovery does more than add a new name to the fossil record—it reshapes our understanding of how and when some of the most successful plant-eating dinosaurs evolved.
As paleontologists continue to explore Morocco’s fossil-rich mountain ranges, further finds are likely to shed light on other ancient species that helped shape the ecosystems of the Jurassic world.
The Middle Atlas, long known for its striking landscapes, is now proving to be one of Earth’s most revealing time capsules of prehistoric life.
