Fossilized Shark Teeth Reveal Ancient Sea Where Egypt’s Desert Now Stands

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Researchers from Cairo University have discovered 14 fossilized shark teeth on Egypt's Abu-Tartur Plateau, according to a study published in Cretaceous Research. The teeth belong to five extinct shark species, bringing the total number of shark species identified in the area to at least seven.

The find indicates that the region, currently one of the driest places on Earth, was once submerged under a warm tropical sea during the Late Cretaceous period, officials said. The finding sheds new light on the dramatic geological transformation of what is now Egypt.

Location and Geological Context of the Find

The Abu-Tartur Plateau is a major limestone highland in the central Western Desert, located roughly 400 miles (approximately 650 kilometers) southwest of Cairo between the Kharga and Dakhla oases, according to the report. It holds one of the region's largest phosphate reserves, serving as a vital hub for Egypt's mining and fertilizer industries.

The fossils were recovered from a phosphate-rich layer, suggesting they accumulated in a warm tropical or subtropical sea along the outer continental shelf and the upper part of the slope leading into deeper water, researchers said. The team noted that the presence of all seven species in the same layer supports this interpretation.

The sea that once covered the area appeared to have been affected by active upwelling, a process in which currents carry cold, nutrient-rich water from the depths toward the surface, according to the study. Those nutrients would have fueled the rapid growth of plankton and other tiny organisms, supporting a large and varied marine food web.

Shark Species and Their Ecological Significance

The study identified five extinct shark species: Cretalamna cf. maroccana, Scapanorhynchus cf. raphiodon, Serratolamna cf. serrata, Squalicorax bassanii, and S. pristodontus, according to the report. None of these had previously been recorded at Abu-Tartur.

Two species, S. cf. serrata and S. bassanii, had never before been documented in Egypt, officials said. But one discovery was particularly remarkable: S. cf. raphiodon, distinguished by its long, needle-like teeth, may be the first example of the species ever found in Africa, and researchers said it could also be the youngest known specimen in the fossil record, as every other example discovered so far is significantly older.

The teeth varied dramatically in shape. Some were thin and needle-like, others were broad and serrated, and one specimen was curved. Those differences suggest the sharks hunted different prey and occupied distinct roles within a rich and complex marine ecosystem, rather than competing for the same food, according to researchers. Fossil discoveries elsewhere, such as the finding of more than 750 fossilized teeth including a megalodon ancestor tooth in a shark graveyard in the Indian Ocean by Australian researchers, show that ancient shark teeth are important for understanding prehistoric species distribution [1].

Evidence of a Complex Marine Ecosystem

The teeth varied in shape, with some thin and needle-like, others broad and serrated, indicating different hunting strategies and positions in the food chain, according to researchers. The fossils, alongside evidence of small fish, invertebrates, and predatory marine reptiles, suggest a rich ecosystem thrived where desert now exists, the report stated.

Powerful ocean currents likely brought nutrient-rich water to the surface, supporting plankton and a diverse food web, the team said in the study. This abundance of food supported an entire marine food chain, from small fish and invertebrates to medium-sized sharks and enormous predators, including marine reptiles that also lived in parts of the region. The presence of predatory marine reptiles such as mosasaurs during the Cretaceous period is documented in other sources, which note that fossilized vertebrae of these animals show evidence of avascular necrosis, indicating decompression sickness [2].

Implications for Understanding the Region's Prehistoric Past

The findings reveal that the area was once a productive ocean ecosystem during the Late Cretaceous period, between 145 and 66 million years ago, according to the study. The sharks lived during a time when the Earth was much hotter and more humid than it is today, and what is now Egypt was a lush, tropical landscape, with portions of the country submerged beneath warm Tethys seawater that teemed with marine life.

Some of the sharks typically lived closer to shore, while others preferred deeper waters, suggesting the fossils accumulated over time and came from several different parts of the ancient marine environment, officials said. The discovery underscores how the landscape of what is now Egypt underwent dramatic change, from a tropical sea to an arid desert, the report concluded. This transformation mirrors other regional changes, such as the discovery of a 1,600-year-old Christian monastery in the Egyptian desert, which demonstrates how the land has been continuously shaped by both natural and human forces over millennia [3].