Ouranosaurus niger was a plant-eating dinosaur that lived in what is now Niger during the Early Cretaceous Period, about 125 to 112 million years ago. It belonged to the ornithopods, a group of mostly bipedal herbivores related to iguanodontians and later duck-billed dinosaurs. Its most famous feature was a row of tall neural spines along its back, which may have supported a sail or a thick ridge.
Studying Ouranosaurus helps paleontologists understand dinosaur diversity in ancient African ecosystems.
Key Facts
- Scientific name: Ouranosaurus niger.
- Age: Early Cretaceous, about 125 to 112 million years ago.
- Location: fossils are known from the Elrhaz Formation of Niger in northern Africa.
- Diet: herbivore, with teeth and jaws adapted for cropping and processing plants.
- Length estimate: about 7 m from head to tail.
- Speed relation: speed = distance / time, useful for estimating trackway movement when fossil footprints are preserved.
Vocabulary
- Ornithopod
- An ornithopod is a plant-eating dinosaur from a group that includes iguanodontians and hadrosaurs.
- Neural spine
- A neural spine is the upward projection from a vertebra that can support muscles, ligaments, or special body structures.
- Cretaceous Period
- The Cretaceous Period was the final period of the Mesozoic Era, lasting from about 145 to 66 million years ago.
- Formation
- A formation is a named body of rock layers that formed in a particular place and time and can contain fossils.
- Reconstruction
- A reconstruction is a scientifically informed model or illustration of an extinct organism based on fossils and comparisons with related species.
Common Mistakes to Avoid
- Calling Ouranosaurus a carnivore is wrong because its teeth, jaws, and body plan show it was adapted for eating plants.
- Assuming the back structure was definitely a thin skin sail is wrong because the tall spines could also have supported a thicker hump or ridge, and soft tissues rarely fossilize.
- Treating Ouranosaurus as a type of hadrosaur is wrong because it was an iguanodontian ornithopod related to, but not the same as, later duck-billed dinosaurs.
- Using modern Africa to describe its habitat without caution is wrong because Cretaceous Niger had different climate patterns, rivers, floodplains, plants, and animal communities.
Practice Questions
- 1 If an Ouranosaurus was about 7 m long and a scale drawing shows it as 14 cm long, what scale is being used in centimeters per meter?
- 2 A fossil layer containing Ouranosaurus is estimated to be 115 million years old. How many million years before the present did this dinosaur live, and how many million years before the end of the Cretaceous at 66 million years ago is that?
- 3 Explain why paleontologists cannot be completely certain whether the tall spines of Ouranosaurus supported a thin sail or a thicker ridge.