Cairo University paleontologists have uncovered the fossilized teeth of five extinct shark species within Egypt’s Abu-Tartur Plateau. The Late Cretaceous marine fossils indicate that the region was once submerged beneath a warm, nutrient-enriched tropical sea driven by active upwelling currents.
Modern arid landscapes often conceal ancient marine histories, but few discoveries rival the geological transformation revealed by recent fossil finds in Egypt. Beneath the dry expanses of the Abu-Tartur Plateau, researchers exploring the Duwi Formation have unearthed stark physical evidence that northern Africa once lay submerged beneath a thriving, sunlit ocean.
Cairo University Paleontologists Expand Abu-Tartur Fossil Record
Previous excavations led by Cairo University paleontologist Tarek Yassin identified two shark species from a small collection of teeth recovered from the plateau. Seeking to understand whether a complex food web could sustain multiple large predators, the research team returned to the site and recovered 14 additional fossilized teeth.
Published in Cretaceous Research, the findings bring the total number of distinct shark species identified in the rock layer to at least seven. Among the newly recovered specimens are five extinct shark groups previously undocumented at the Abu-Tartur Plateau: Cretalamna cf. maroccana, Scapanorhynchus cf. raphiodon, Serratolamna cf. serrata, Squalicorax bassanii, and Squalicorax pristodontus.
Rare Needle Teeth and Geographic Milestones in Cretaceous Strata
The morphology of the recovered teeth varied significantly across the assemblage, pointing to specialized ecological niches rather than direct competition for food. Researchers noted that some teeth were long and slender like needles, while others appeared broad and serrated for slicing, and one specimen exhibited a curved, karambit-like shape. Some had small, fang-like side projections, called cusplets; others did not.
Two of the identified species—Serratolamna cf. serrata and Squalicorax bassanii—represent the first documented occurrences of their kind in Egypt. Most notably, the needle-toothed Scapanorhynchus cf. raphiodon may represent the first known occurrence of its species in Africa, while also standing out as a potential most recent example found in the fossil record compared to significantly older specimens elsewhere.
Upwelling Currents and Nutrient-Rich Waters of the Late Cretaceous
During the Cretaceous period, spanning from roughly 145 to 66 million years ago, greenhouse climates driven by tectonic activity generated warmer global temperatures with little to no polar ice and higher sea levels. Phosphate deposits preserved within the black and yellow layers of the Duwi Formation serve as indicators of intense marine productivity where phosphorus was intensively cycled and concentrated.
カイロ大学の古生物学者であるタレック・ヤッシン氏が率いる研究チームは、「Cretasious Research」誌に発表した論文の中で、この化石群全体がリン酸塩を豊富に含む棚縁に沿った、栄養塩が豊富で生産性の高い海洋生態系を際立たせていると述べている。
Tarek Yassin, Cairo University
Researchers believe this aquatic abundance was due to upwelling, where nutrient-rich waters rising from deeper in the ocean lifted phosphorus and other nutrients toward sunlit surface waters. This nutrient delivery fueled dense populations of plankton, sustaining a food chain that supported small fish, invertebrates, marine reptiles, and predatory sharks like Squalicorax and Cretalamna, with Cretoxyrhina higher up the food web.
Ecological Niches Across Marine Depth Zones
The distribution of the shark teeth within the same sedimentary layers allows scientists to map where different predators may have occupied different ecological niches within the prehistoric marine environment. Different tooth designs and anatomical adaptations indicate that various species preferred distinct habitats ranging from nearshore settings to the open ocean.
研究者らは、スクアリコラックスの存在が近岸や内側大陸棚環境からの流入を示唆している可能性がある一方で、スカパノリンクスの出現は外側大陸棚や斜面におけるより深い水深の環境を反映していると記している。
Research team led by Tarek Yassin
Lamniform taxa such as Cretalamna and Serratolamna further support stable open-shelf conditions that once prevailed across the northern perimeter of the African continent before millions of years of geological change reshaped the landscape into desert sand.