Paleontologists Are Discovering Ancient Sharks—in the Sandy Egyptian Desert

4 min readHere’s what you’ll learn when you read this story:Paleontologists have discovered the teeth of five extinct species of shark in Egypt, bringing the total known prehistoric shark species in the region to seven. The teeth of these sharks ranged from short to long, broad to slender, and smooth to serrated, allowing them to bite down on different types of prey. While these species might have not all coexisted at the same time, their diverse tooth morphologies suggest they found different niches to hunt in. During the Cretaceous period, Egypt wasn’t the endless ocean of sand that pyramids rise out of and mummies emerge from. Instead, much of Northern Africa was submerged beneath a tropical sea that thrived with diverse forms of life ranging from plankton to fearsome marine reptiles. Lurking in this underwater paradise were also many pairs of toothy jaws, snapping up fish left and right in the rich underwater environment. When the sea eventually transformed into arid desert over the years, the remains of these creatures stayed put, which is parts of Egypt are actually swarming with long-deceased sharks.In a new study published in the journal Cretaceous Research, paleontologist Tarek Yassin of Cairo University and his research team reported finding those remains—teeth, teeth, and more teeth—while excavating on the Abu-Tartur plateau in Egypt’s Western Desert. The fossilized teeth of seven distinct species that lived between 66 and 145 million years ago were embedded in what was once a seafloor sprawling with life. Back then, Earth was a warmer planet, its climate influenced by tectonic activity that led to the release of carbon dioxide, trapping heat in the atmosphere. The Cretaceous Hot Greenhouse climate reached paleotemperatures anywhere from 42.8 °F to 57.2 °F (6 °C to 14 °C) higher than current global temperatures, and polar ice was either rare or nonexistent. It was a breeding ground for life.The Abu-Tartur plateau is especially known for teeth that once belonged to lamniform species, from which today’s mackerel sharks are descended. Abu-Tartur has yielded one of the most diverse assemblages of fossil shark teeth in Egypt, though the specimens come from an active phosphate mine, where heavy machinery has fractured many of them. Yassin and his team discovered five of the seven species known to have existed in this region (including one that’s new to Africa and others new to the region) in the plateau’s Duwi Formation, once a tropical haven of shallow waters over a bed of marine rocks that included phosphorites. These rocks, high in phosphate minerals, provided an abundance of nutrients through frequent upwellings from the bottom to the surface. Teeth found in these phosphorite deposits suggest that several species coexisted at the same time, some competing for prey and others occupying different niches.“[Phosphates drove] intense primary productivity that sustained a diverse trophic web,” the researchers wrote in their study. “This could be supported by the presence of small fishes, some invertebrates at the base of the unit, mid-level predators…[and] large apex predators, with also the presence of predatory marine reptiles in some areas.”Joining the two species already known to have stalked these ancient waters, the five new species were Cretalamna maroccana, Scapanorhynchus raphiodon, Serratolamna serrata, Squalicorax bassanii, and Squalicorax pristodontus. No fossilized remains of these sharks had ever surfaced at Abu-Tartur before. S. raphiodon wasn’t previously known to have lived in the prehistoric Egyptian sea, and the specimen found by Yassin may be the youngest known for this species. The scientists found an array of tooth morphologies. Their colors range from sandy yellows and browns to gray and black. Like a collection of daggers, some were broader and shorter, some narrower and longer, straight or curved, with smooth or serrated edges. C. maroccana had curved teeth so similar to its relative Cretalamna biauriculata that it may be a morphological variant instead of its own species.S. raphiodon may have been small in size, but flashed long and slender teeth not unlike vampire fangs. The teeth of S. serrata had shorter, sharp points that protruded from asymmetrical roots. This species was widespread, with tooth fossils emerging not just in Africa, but also Madagascar, the Middle East, and the Caribbean along with North and South America. S. bassani had a mouthful of serrated teeth that could have easily starred in a horror movie. While some teeth from these species were more serrated than others, the less serrated specimens are thought to have been more lethal before millions of years in Egyptian rock and sand partially eroded them. S. pristodontus teeth were broad and flat, but still dangerously serrated. Fossils from that species have also been found in Jordan, Morocco, Madagascar, and Palestine.“The Abu-Tartur plateau is a locality with one of the most diverse assemblages of shark teeth fossils in Egypt,” said Yassin, adding that “[what we discovered] also sheds new light on the paleodiversity, stratigraphic, chronological and paleoenvironmental context of extinct lamniforms inhabiting tropical seas during the Late Cretaceous in North Africa.”Watch Our Science VideosElizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.