~99 million years ago (Cretaceous)Reputable sourceDebated
Spinosaurus, the River Predator
On the timeline · around ~99 million years ago (Cretaceous) · The Cretaceous
What happened
Spinosaurus, a huge sail-backed predator from Cretaceous North Africa, was even longer than Tyrannosaurus rex. A remarkably complete skeleton found in Morocco in 2014 revealed dense bones, paddle-like feet and a fin-shaped tail, suggesting it hunted fish in rivers.
Why it matters
It may be the most water-adapted large dinosaur known — but exactly how aquatic Spinosaurus really was remains hotly debated among palaeontologists.
How we know
The 2014 Moroccan skeleton, and the later discovery of its tail, led some scientists to propose Spinosaurus was a swimming, fish-hunting predator; others argue it was a semi-aquatic wader. The debate is unresolved.