The desert sands of Egypt have been dry for thousands of years. However, as difficult as it is to imagine now, much of that desert was once submerged beneath a sea that covered much of the northern perimeter of the African continent. Nor was it a dead sea; Evidence suggests that, during the Cretaceous period, it may have been a tropical paradise, where rising currents lifted nutrients into the water column to fuel a thriving ecosystem. Now, buried at what was once the bottom of that ancient sea, on the Abu-Tartur Plateau, paleontologists have found evidence of its exuberance: shark teeth that would have thrived amid the abundance of fish. And not just a shark. The total number of different species found in that layer of the Duwi Formation now stands at least seven, offering a glimpse of the rich marine ecosystems that once flourished along Africa’s northern edge. The 14 teeth represented five species. (Yassin et al., Cretac. Res., 2026) “Taken together, this assemblage highlights a highly productive, nutrient-enriched marine ecosystem along a phosphogenic shelf margin,” writes a team led by paleontologist Tarek Yassin of Cairo University in a paper published in Cretaceous Research. During the Cretaceous period, approximately 145 to 66 million years ago, our Earth was a very different place. Under a greenhouse climate driven by tectonic activity, the world was warmer, with little or no polar ice; Higher sea levels meant that much of the land we inhabit today was underwater, including North Africa. We know this, at least in part, thanks to phosphate. Phosphorite deposits commonly form where marine productivity is high and phosphorus is intensely recycled and concentrated. A diagram illustrating how the oceans once covered the region. (Yassin et al., Cretac. Res., 2026) The extensive phosphate deposits of the Duwi Formation therefore preserve not only the remains of this ancient sea, but also clues to how productive its waters once were. In previous research, Yassin and his colleagues had identified two species of sharks in a handful of teeth found in the fossil bed, an intriguing sign, since a community capable of supporting multiple large predators requires a productive food web beneath them. So they returned to Abu-Tartur. to see if they could discover more. And the black and yellow layers of Duwi phosphate covered the merchandise. They found another 14 shark teeth, representing five other shark species, none of which had been identified at Abu-Tartur. When all you have are teeth (and with ancient sharks, that’s often the case), subtle differences may be the only metric on which species diagnosis depends. With Duwi’s teeth, the differences weren’t always subtle. Several of the teeth were long and thin, like a needle. Others were wide and serrated, probably better suited for cutting than penetrating. One tooth had a prominent curve like a karambit. Some had small fang-like lateral projections, called cusps; others did not. frameborder=”0″ enable=”accelerometer; autoplay; writing on clipboard; encrypted media; gyroscope; picture in picture; web-share” referrerpolicy=”strict-origin-when-cross-origin” enablefullscreen> Based on other fossil records from around the world, the researchers identified these teeth as belonging to five extinct species: Cretalamna cf. maroccana, Scapanorhynchus cf. raphiodon, Serratolamna cf. serrata, Squalicorax bassanii and Squalicorax pristodontus. All five are new records for Abu-Tartur.Two were completely new to Egypt: Serratolamna cf. serrata and Squalicorax bassanii. One stood out as extraordinary, Scapanorhynchus cf., the one with pointed teeth, may represent the earliest known case in Africa, the researchers said; interesting that “lots of sharks.” As their teeth might suggest, they may not have been competing directly, but rather occupying different ecological niches in a rich marine environment. “The presence of Squalicorax could suggest an entry from nearshore/inner shelf environments, while the emergence of Scapanorhynchus reflects deeper water conditions on the outer shelf and slope,” the researchers write. “Lamniform taxa such as Cretalamna and Serratolamna further support the conditions. stable open-shelf waters.” Nutrient-rich waters rising from the deep ocean would have delivered phosphorus and other nutrients to the sunlit surface waters, driving intense primary productivity: plankton coming to feast. That would have supported small fish and invertebrates, then predators like Squalicorax and Cretalamna, with Cretoxyrhina and marine reptiles further up the food web. But this is where the shark “graveyard” becomes interesting. Sharks lived, so the phosphate bed represents a more condensed time span than you might find somewhere with more mud. Related: The world’s largest shiny vertebrate may be using its own light as a hunting tool. Consequently, the teeth are a time-averaged accumulation of multiple ecological niches, there is no evidence that seven species of sharks lived at the same time and all died there together. But it does add to the evidence that these ecosystems were common. in the far north of Africa during the Late Cretaceous. Other phosphate deposits from places like Morocco and Syria record large numbers of shark species roaming around, suggesting that the entire region was a great place to do business with sharks. Today, few remains of that shark paradise have disappeared, the seabed has become a desert and the predators that roamed its waters disappeared millions of years ago. embedded in a rock can evoke an entire lost world. Published in Cretaceous Research This article was fact-checked by Rebecca Dyer. While we take pride in our process, we’re human. If you spot an error, please let us know.
