A handful of fossil teeth has added five shark species to an ancient Egyptian seafloor, pointing to a rich marine ecosystem that once covered part of northern Africa.
Paleontologists found the teeth in the Duwi Formation on the Abu-Tartur Plateau in Egypt. The finds bring the total number of shark species identified from that layer to at least seven, according to a paper led by Cairo University paleontologist Tarek Yassin and published in Cretaceous Research.
“Collectively, this assemblage highlights a nutrient-enriched, high-productivity marine ecosystem along a phosphogenic shelf margin,” the team wrote.
The site dates to the Cretaceous period, about 145 to 66 million years ago, when higher sea levels left much of northern Africa underwater. The Duwi Formation is known for extensive phosphate deposits, which commonly form where marine productivity is high and phosphorus is heavily cycled and concentrated.
In earlier work, Yassin and colleagues had identified two shark species from a small number of teeth at the site. They returned to Abu-Tartur and found 14 more teeth, representing five additional shark species that had not previously been identified there.
The researchers identified the teeth as Cretalamna cf. maroccana, Scapanorhynchus cf. raphiodon, Serratolamna cf. serrata, Squalicorax bassanii, and Squalicorax pristodontus.
All five are new records for Abu-Tartur. Two, Serratolamna cf. serrata and Squalicorax bassanii, are new records for Egypt. Scapanorhynchus cf. raphiodon may represent the first known occurrence of that species in Africa, and the researchers said it could also be the most recent example in the fossil record.
The teeth varied sharply in form. Some were long and slender, others broad and serrated. One was strongly curved, and some had small side projections called cusplets while others did not.
The researchers said those differences point to sharks occupying different ecological niches rather than directly competing in the same way.
“The presence of Squalicorax could suggest an input from nearshore/inner shelf settings, while the occurrence of Scapanorhynchus reflects deeper-water conditions on the outer shelf and slope,” the researchers wrote. “Lamniform taxa such as Cretalamna and Serratolamna further support stable open-shelf conditions.”
The team said upwelling may explain the richness of the ecosystem, with nutrient-rich deep waters rising to the surface and driving strong primary productivity.
The phosphate bed does not mean all seven shark species lived there at the same time. The researchers said sediment built up only slowly, so the teeth represent a time-averaged accumulation from multiple ecological niches.
The findings were published in Cretaceous Research.
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