A new hadrosaurid dinosaur from the late Maastrichtian Phosphates of Morocco provides evidence for an African radiation of lambeosaurines

In the Late Cretaceous, continental fragmentation and high sea levels created a series of island continents, leading to the evolution of endemic dinosaur faunas on these isolated land masses. Laramidia saw the emergence of faunas dominated by ornithischian herbivores and tyrannosaurid predators whereas Gondwanan continents were dominated by titanosaurian sauropods and abelisaurid predators. However, the end of the Cretaceous also saw exchange between northern and southern assemblages, with titanosaurs immigrating into Laurasia, and hadrosaurids invading Gondwana. Recently, the lambeosaurine hadrosaurid Ajnabia odysseus was reported from the late Maastrichtian Phosphates of Morocco, providing evidence of dispersal by duckbill dinosaurs into northwest Africa. A second lambeosaurine, Minqaria bata, has since been documented from the same strata in Morocco. Both belong to the lambeosaurine tribe Arenysaurini. Here we report a third species of arenysaurin, Taleta taleta gen. et sp. nov., also from the uppermost Maastrichtian Phosphates of Morocco. Taleta, known from two associated maxillae, differs from Ajnabia and Minqaria in the dorsally positioned ectopterygoid ridge, straight toothrow, large, obliquely oriented maxillary tooth crowns, and prominent primary ridge of the maxillary teeth. The striking variation in jaw and tooth morphology seen in African arenysaurins suggests a dispersal-driven adaptive radiation, with lambeosaurines rapidly diversifying to occupy new niches following dispersal from Europe into North Africa. The African radiation coincided with lambeosaurine decline in North America, emphasizing the highly regional nature of dinosaur evolution.