Newly-Identified Mosasaur Species Challenges Understanding of Ancient Marine Reptiles

• 18 Dec 2023

Mosasaurs, formidable marine predators from the Late Cretaceous epoch, are back in focus with the discovery of a unique species, Megapterygius wakayamaensis, challenging existing knowledge about their anatomy and swimming capabilities.

Key Points

• Ancient Marine Predators: Mosasaurs, large predatory marine reptiles, once inhabited global oceans during the Late Cretaceous epoch, coexisting with well-known dinosaurs like Tyrannosaurus rex.
• Extinction Event: These creatures faced extinction, alongside most dinosaurs, due to a mass extinction event triggered by an asteroid impact in the Gulf of Mexico.
• Relation to Monitor Lizards: While the exact relationship to other reptiles is uncertain, mosasaurs are believed to be closely related to monitor lizards.
• Unusual Flippers and Dorsal Fin: Megapterygius wakayamaensis had disproportionately long rear flippers, exceeding the length of its front flippers, and a dorsal fin similar to a shark's, suggesting extraordinary swimming abilities.
• Fossil Discovery in Japan: The fossilized skeleton was discovered in 2006 in the Hasegawa Muddy Sandstone Member of the Toyajo Formation in Wakayama prefecture, Japan, making it the most complete mosasaur specimen found in the region.
• Challenges to Understanding: The discovery challenges existing understanding of mosasaur swimming behaviour, with speculation about the purpose of the unusual flippers and their role in rapid manoeuvring and diving.