Pluridens serpentis, a new mosasaurid (Mosasauridae: Halisaurinae) from the Maastrichtian of Morocco and implications for mosasaur diversity

Nick Longrich, Nathalie Bardet, Fatima Khaldoune, Oussama Khadiri Yazami, Nour Eddine Jalil

Research output: Contribution to journalArticlepeer-review

Abstract

Mosasaurids (Mosasauridae) were specialized marine lizards that evolved and radiated in the Late Cretaceous. Their diversity peaked in the Maastrichtian, with the most diverse faunas known from Morocco. Here we describe a new species of mosasaurid from this fauna. Pluridens serpentis sp. nov. is described based on two complete skulls and referred jaws. It is referred to Pluridens based on the elongate and robust jaws, small teeth, and specialized tooth implantation. Pluridens is referred to Halisaurinae based on the posteriorly expanded premaxilla, long premaxilla-maxilla suture, broad premaxillary facet on the maxilla, closed otic notch, and small, striated, hooked teeth. The orbits are reduced relative to other halisaurines while the snout is robust and flat with a broad, rounded tip. The jaws bear numerous small, hooked, snake-like teeth. Skulls imply lengths of 5–6 m; referred material suggests lengths of ≥9 m. Pluridens’ specialized morphology – especially the contrasting large size and small teeth - suggests a distinct feeding strategy. Small orbits imply that P. serpentis relied on nonvisual cues including touch and chemoreception during foraging, as in modern marine snakes. Numerous neurovascular foramina on the premaxillae are consistent with this idea. The small teeth suggest proportionately small prey. The dentary becomes massive and robust in the largest individuals, suggesting sexual selection and perhaps sexual dimorphism, with the mandibles possibly functioning for combat as in modern beaked whales and lizards. The new mosasaur emphasizes how Maastrichtian mosasaurids were characterized by high species richness, high functional diversity, and high endemism, i.e. geographic specialization. It appears mosasaurids continued diversifying until the end of the Cretaceous, just prior to the K-Pg extinction.
Original languageEnglish
Article number104882
JournalCretaceous Research
Volume126
Early online date8 May 2021
DOIs
Publication statusE-pub ahead of print - 8 May 2021

Keywords

  • Pluridens
  • Mosasauridae
  • Squamata
  • Cretaceous
  • Maastrichtian
  • Morocco
  • Africa
  • Evolution
  • Paleontology
  • Extinction
  • Mass Extinction

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