Paleontologists have uncovered fossilized teeth from seven distinct shark species—including five new to the region and two entirely new to Egypt—buried within the phosphate-rich Duwi Formation on the Abu-Tartur Plateau, revealing that the arid Western Desert was once a lush, nutrient-enriched marine ecosystem during the Cretaceous period.
The desert sands of Egypt have remained dry for thousands of years, preserving little outward trace of the ancient waters that once blanketed the northern perimeter of the African continent. Beneath the surface of the Abu-Tartur Plateau in Egypt’s Western Desert, however, the black and yellow layers of the Duwi Formation hold a remarkably preserved record of a vanished prehistoric sea.
A team of researchers led by Cairo University paleontologist Tarek Yassin returned to the region after earlier identifying two shark species from a handful of teeth found in the fossil bed. By collecting 14 newly unearthed teeth, the team expanded the local catalog to at least seven distinct shark species, according to findings published in Cretaceous Research. The discovery sheds new light on a tropical marine environment that flourished tens of millions of years ago before tectonic shifts and falling sea levels caused the waters to retreat permanently.
Extinct Species and Rare African Finds in the Duwi Formation
Because ancient sharks possessed skeletons made primarily of cartilage rather than bone, their remains rarely fossilize completely. Teeth serve as the primary indicator of ancient shark populations, and the subtle variations among the 14 newly collected specimens allowed researchers to identify five extinct species previously unrecorded on the plateau: Cretalamna cf. maroccana, Scapanorhynchus cf. raphiodon, Serratolamna cf. serrata, Squalicorax bassanii, and Squalicorax pristodontus.
Among those discoveries, Serratolamna cf. serrata and Squalicorax bassanii represent entirely new records for Egypt. Most striking to the research team was Scapanorhynchus cf. raphiodon, featuring needle-like teeth that may mark the first known occurrence of the species on the African continent. Paleontologists noted that the specimen could also represent the youngest known fossil record for the species, as all other known examples are significantly older.
Diverse Feeding Strategies and Ecological Niches
The physical characteristics of the recovered teeth varied widely across the assemblage, indicating that the predators did not directly compete with one another but instead occupied distinct ecological niches within the shallow sea. Some teeth appeared long and slender like needles, while others were broad and serrated for slicing through prey. One specimen displayed a prominent curve resembling a karambit, while others featured small, fang-like side projections called cusplets.
Researchers deduced the habitat preferences of these species from their dental morphology and global fossil comparisons.
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, Tarek Yassin et al., Cairo University researchers via ScienceAlert
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Lamniform taxa such as Cretalamna and Serratolamna further supported the presence of stable open-shelf conditions, operating alongside small fish, invertebrates, and marine reptiles higher up the food web.
Upwelling and High Marine Productivity in the Cretaceous Sea
The abundance of large predators required a robust underlying food web, which researchers attribute to active ocean upwelling during the Cretaceous period between roughly 145 million and 66 million years ago. Driven by a warmer greenhouse climate with little to no polar ice and higher global sea levels, rising currents lifted phosphorus and other nutrients from the deep ocean into sunlit surface waters.
This nutrient delivery sparked intense primary productivity, fueling blooms of plankton that sustained the entire marine ecosystem. Phosphorite deposits commonly form under such high-productivity conditions, explaining why the Duwi Formation preserved not only shark teeth but also a record of a productive shelf margin.
Collectively, this assemblage highlights a nutrient-enriched, high-productivity marine ecosystem along a phosphogenic shelf margin, Tarek Yassin et al., Cairo University researchers via Yahoo News
