A giant predatory lizard swam in Antarctic seas near the end of the dinosaur age
Date: Source: Summary:
November 7, 2016 University of Chile
Kaikaifilu is a new species of giant sea lizard (mosasaur) discovered in 66millionyearold rocks of Antarctica. At about 10 meters long, it is the largest known top marine predator from this continent. It lived near the end of the dinosaur age, when Antarctica was a much warmer ecosystem, and fed on filterfeeding marine reptiles.
Upper left. Kaikaifilu was found in late cretaceous rocks from Seymour island, Antarctica. Upper right. An estimated size comparison of Kaikaifilu with a human. The size of the skull remains suggest it could have been as long as 1214 mt. Bottom left: The terrain where the remains of Kaikaifulu were found turns mostly into mud under bad weather conditions like those encountered by the Chilean expedition (bottom right).
Credit: Image courtesy of University of Chile
Kaikaifilu is a new species of giant sea lizard (mosasaur) discovered in 66millionyearold rocks of Antarctica. At about 10 m long, it is the largest known top marine predator from this continent. It lived near the end of the dinosaur age, when Antarctica was a much warmer ecosystem, and fed on filterfeeding marine reptiles.
Because of its harsh conditions, Antarctica is probably one of the toughest places to work for palaeontologists. However, precisely because of this, information is scarce, and new discoveries can be highly rewarding. In 2010, an expedition of Chilean scientists to Seymour Island encountered particularly bad weather. Only during their last days in the field, after dreadful walks through kneedeep mud, they made a truly exciting discovery in 66 million yearold rocks: The fossil remains of a particularly large skull of a Mosasaur, a giant sea lizard.
Mosasaurs were not dinosaurs, but close relatives of modernday lizards, that thrived in the seas during the Cretaceous period of the dinosaur age. Unlike modern lizards, however, mosasaurs evolved paddlelike limbs, and a long, deep tail for swimming. Some of them were top predators that attained truly gigantic size, like the fearsome Tylosaurus (regularly featured in books of prehistoric animals). Prior to this find, the largest known mosasaur from the Antarctic continent was represented by Taniwhasaurus antarcticus, a predator with a skull about 70 cm long. Interestingly, the new species is found to be a 5 million year younger, close relative of Taniwhasaurus. It is also a close relative of the the North American Tylosaurus, however, the new Antarctic mosasaur lived ca. 20 million years after, in the opposite Hemisphere. Its skull is estimated to be a about 1.2 m long, being the largest southern mosasaur to date, suggesting a body length close to 10 mts. And while it is similar to north American giants like Tylosaurus, it shows other completely unique traits, that justify a new scientific name. The scientists called it Kaikaifilu hervei after the cosmology of the Mapuche, the native people from southern Chile and Argentina. KaiKai filú is the almighty giant reptile owner of the seas, rival of TrengTreng filú, the land reptile, both creators of the lands through their continuous fight that causes the earthquakes, volcanoes, tsunamis and all the events that shaped the earth where we live. The species name hervei is after Dr. Francisco Hervé, a worldrenowned Chilean geologist and pioneer earthscience Antarctic explorer.
According to Rodrigo Otero, one of the authors of the study, "The increasing diversity of endemic Cretaceous marine reptiles in the southern hemisphere are slowly changing an historical paradigm. Since the 19th century many southern fossil reptiles had been assigned to species from the northern hemisphere. In this sense, Kaikaifilu adds to this paradigm shift. 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."
Previous to the discovery of Kaikaifilu, isolated teeth had been frequently found in Late Cretaceous rocks of Antarctica. Anatomical features led scientists to refer them to several mosasaur species previously known in the Northern Hemisphere. Remarkably, the jaws of Kaikaifilu now reveal that many of these teeth coexisted as different tooth types in the mouth of this species, a condition known as heterodonty. Therefore, in all probability, the diversity of Antarctic mosasaurs has been overestimated. The case nicely illustrates the difficulties that palaeontologists may encounter when discovering unique but isolated body parts.
During the dinosaur age, antarctic climate was much warmer and the continent harboured a diverse ecosystem, that included several unusual reptiles. Kaikaifilu probably fed on an abundant "buffet" of contemporaries, especially the unique aristonectine plesiosaurs, robust, longnecked forms that did not feed on fish but rather were filterfeeders of much smaller prey, using fine, narrow teeth and whalelike adaptations in their skulls.
"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 latest Cretaceous" says Otero.
These ecosystems existed shortly before the ultimate demise of the dinosaurs, a time in which temperatures and sea levels experimented significant changes. Scientists continue to discuss how these changes may have affected extinction and evolution in these southernmost marine ecosystems. Without a doubt, they will continue to explore for new data as Antarctica, an entire continent,