New prehistoric sea lizard discovered

Researchers in Chile have discovered a new species of giant sea lizard that existed near the end of the Cretaceous period that has forced them to rethink how the species is classified. 

The skull of Kaikaifilu hervei was discovered in 66 million year old Antarctic rock. It is the largest southern mosasaur (sea lizard) ever found and fed on filter-feeding marine reptiles.

Rodrigo Otero, from the University of Chile and co-author of the study said: “Prior to this research, the known mosasaur remains from Antarctica provided no evidence for the presence of very large predators like Kaikaifilu, in an environment where plesiosaurs were especially abundant. The new find complements one expected ecological element of the Antarctic ecosystem during the late Cretaceous period.”

Mosasaurs were not dinosaurs, instead close relatives of modern-day lizards that existed during the Cretaceous period of the dinosaur age. They evolved paddle-like limbs and a long, deep tail for swimming. Kaikaifilu’s skull is estimated to be more than a metre long with a body length of almost 10 metres

Before this discovery,  mosasaur teeth were frequently found in Late Cretaceous rocks of Antarctica. The anatomical features led scientists to believe they were from several mosasaur species known to exist in the Northern Hemisphere. However, the recent find of the skull has shown that one skull can include different tooth types – known as heterodonty. This suggests that the diversity of Antarctic mosasaurs could have been overestimated.

Otero, a palaeontologist, said: “Since the 19th century many southern fossil reptiles had been assigned to species from the northern hemisphere. The southern record has scarce informative mosasaur skulls, most of them found in New Zealand. However, in southern South America and Antarctica, mosasaur remains are especially scarce. Hence the relevance of the new specimen, which shows a distant kinship with respect to the northern hemisphere mosasaurs.”

Kaikaifilu hervei, was named after Dr Francisco Hervé, an Earth scientist and Antarctic explorer. Until its discovery, the largest mosasaur from the Antarctic continent was Taniwhasaurus antarcticus, a predator with a skull length about 70cm. The research can be viewed in Cretaceous Research.