A new species of Spinosaurus has been discovered in Niger, which probably hunted fish as a wading predator along riverbanks between 100 and 95 million years ago. The species possesses a spectacular sabre-shaped bony crest on the skull and, according to the researchers, represents a third phase in the evolution of these enormous fish-eating dinosaurs (Science, 20 February). The international research team, led by evolutionary biologist Paul Sereno of the University of Chicago, based their findings primarily on fossils of the skull, upper and lower jaw, and several postcranial bone fragments, and has named the new species Spinosaurus mirabilis.
The fossils were found near the city of Agadez in the Sahara Desert of Niger, which during the mid-Cretaceous lay at least 1,000 kilometres inland from the Tethys Sea. They thus represent a third phase in the evolution of the three spinosaur species now known, the researchers speculate. They began as fish-catchers in rivers (Late Jurassic), subsequently evolved into dominant predators in the coastal waters of the Tethys Sea (Early Cretaceous), before ending up as ambush specialists in the shallow waters of North Africa and South America (mid-Cretaceous).