The Sahara was once a lush river system of giants

Ideas & Philosophy · Published 7 October 2026 Swipe more like this →

In short: Forget the arid dunes we know today. Roughly 100 million years ago, North Africa was a predator's paradise. A massive network of rivers supported a bizarre menagerie of giants, including a dinosaur even larger and more fearsome than the Tyrannosaurus rex.

Paleontologist Nizar Ibrahim, a researcher at the University of Chicago, has used geological and paleontological data to reconstruct a mid-Cretaceous ecosystem known as the 'River of Giants.' This ancient landscape, located in what is now the Moroccan Sahara, was far from a desert. Instead, it was a highly productive environment where animals from the water, land, and air coexisted, featuring 40-foot crocodiles, massive turtles, and enormous flying reptiles.

The centerpiece of this ecosystem was Spinosaurus aegyptiacus, a predator that reached lengths of 50 feet (15.2 meters). This makes it approximately nine feet (just under three meters) longer than the T. rex. Recent fossil findings published in Science magazine reveal that Spinos and its contemporaries were uniquely adapted to an aquatic lifestyle. Unlike the bipedal T. rex, Spinosaurus was 'front-loaded' and likely walked on all fours. Its anatomy—including a crocodilian snout, paddle-like feet, and dense bones to aid buoyancy—suggests it was the first dinosaur known to take to the water to hunt fish, such as the 25-foot (7.6-meter) sawfish.

The biodiversity of this period also included the Alanqa saharica, a new species of pterosaur discovered in 2010. This flying reptile possessed a 20-foot wingspan and represents the largest flying species ever found in Africa. Ibrahim notes that finding such specimens is rare because the bones of flying animals are incredibly fragile. By exploring previously unsearched desert regions, he has been able to piece together this lost world, providing a window into a period of significant evolutionary change.

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