Scientists have uncovered evidence of a lost underwater world buried beneath Egypt's desert for more than 70 million years, after finding 14 fossilized teeth belonging to five now-extinct shark species on the Abu-Tartur Plateau in the Western Desert.
The discovery brings the number of shark species identified in the area to at least seven and shows that one of the driest places on Earth was once submerged beneath a warm tropical sea teeming with life, according to a study published in the journal Cretaceous Research.
The teeth varied dramatically in shape. Some were thin and needle-like, others broad and serrated, and one specimen was curved. Researchers said the differences suggest the sharks hunted different prey and occupied separate positions in the food chain. Together with evidence of small fish, invertebrates and predatory marine reptiles, the fossils point to a rich ecosystem that once thrived where only desert exists today.
A phosphate-rich desert plateau
Abu-Tartur Plateau is a major limestone highland in the central Western Desert, located roughly 400 miles southwest of Cairo between the Kharga and Dakhla oases. It holds one of the region's largest phosphate reserves and serves as a key hub for Egypt's mining and fertilizer industries.
Currents that fed a marine food web
The research team said powerful ocean currents likely carried nutrient-rich water toward the surface, helping plankton and other small organisms thrive. That abundance of food supported an entire marine food chain, from small fish and invertebrates to medium-sized sharks and enormous predators. Marine reptiles also lived in parts of the region, according to the study.
Some of the sharks typically lived closer to shore, while others preferred deeper waters, suggesting the fossils accumulated over time from several different parts of the ancient marine environment. The sharks lived during the Cretaceous period, between 145 and 66 million years ago, when the Earth was much hotter and more humid than it is today. What is now Egypt was a lush, tropical landscape, with parts of the country submerged beneath the warm Tethys seawater that teemed with marine life.
Five species, one a first for Africa
By comparing the teeth with fossils found elsewhere in the world, the researchers, led by Cairo University, linked them to five extinct shark species: Cretalamna cf. maroccana, Scapanorhynchus cf. raphiodon, Serratolamna cf. serrata, Squalicorax bassanii and Squalicorax pristodontus.
None of the five had previously been recorded at Abu-Tartur, and two of them, Serratolamna cf. serrata and Squalicorax bassanii, had never before been documented anywhere in Egypt.
One find stood out. Scapanorhynchus cf. raphiodon, distinguished by its long, needle-like teeth, may be the first example of the species ever found in Africa. Researchers said it could also be the youngest known specimen of the species in the fossil record, since every other example discovered so far is significantly older.
A sea shaped by upwelling
Together, the five species reveal more than the simple presence of sharks. Their differently shaped teeth suggest they hunted separate prey and occupied distinct roles within a complex marine ecosystem, rather than competing for the same food.
The team said finding all seven species known from the site in the same phosphate-rich layer means their remains accumulated in a warm tropical or subtropical sea, probably along the outer continental shelf and the upper part of the slope leading into deeper water. The sea also appeared to have been affected by active upwelling, a process in which currents carry cold, nutrient-rich water from the depths toward the surface. Researchers said those nutrients would have fueled the rapid growth of plankton and other tiny organisms, supporting a large and varied marine food web.
