A team of researchers has identified a new extinct shark species from dozens of isolated teeth found in 2024 in Morocco's Sidi Chennane quarry, one of the world's richest Maastrichtian fossil sites. The species is distinguished by unusually variable serrations, offering new insights into shark evolution just before the end of the dinosaur era. A team of researchers has identified a new species of extinct shark in Morocco's fossil-rich Upper Cretaceous phosphates. The species, Pseudocorax heteroserratus, was described from a large sample of isolated teeth found in 2024 in the upper Couche III layer of the Sidi Chennane quarry in the Oulad Abdoun Basin (Khouribga Province), one of the world's most important sites for Maastrichtian marine fossils. According to the authors, the new species differs from all previously known Pseudocorax sharks due to three key features: a mesiodistally elongated tooth base, a broad crown, and exceptionally variable serrations, ranging from completely smooth to finely or even coarsely serrated cutting edges. This striking variability inspired the species name heteroserratus, meaning «differently serrated». The researchers say the wide range of serration patterns «raises new questions about how serrations evolved in the genus», including whether they developed gradually or emerged multiple times independently. The unusually large number of teeth, rare for Pseudocorax, allowed scientists to document the full spectrum of shapes and features, something that is usually difficult for shark species known only from isolated teeth. A Fossil-Rich Setting Morocco's newly identified shark species also helps refine the biostratigraphy of the Oulad Abdoun Basin and sheds new light on shark diversity in the million years leading up to the end-Cretaceous extinction. The Oulad Abdoun Basin, about 150 km south of Rabat, is the largest of Morocco's phosphate basins and part of the wider Mediterranean Tethyan phosphogenic province. Couche III, where the shark teeth were collected, dates to the latest Maastrichtian, just before the mass extinction that ended the age of dinosaurs. The study notes that this layer also contains mosasaurs, plesiosaurs, crocodilians, turtles, actinopterygians, and even rare dinosaur remains, offering a detailed snapshot of a warm, shallow marine ecosystem thriving at the end of the Cretaceous. It is worth noting that the discovery, published this November by Cambridge University Press on behalf of the Paleontological Society, was made through a collaboration involving state-licensed Moroccan fossil collector Boubker Chaibi and his daughter Ikhlass Chaibi, who excavated and sieved the in-situ sediments, along with other local collectors using the same methods. The fossils were later studied and accessioned into the Mississippi Museum of Natural Science (USA) as part of ongoing research on Moroccan selachians.
