Aristonectes (meaning "best swimmer") is an extinct genus of large elasmosaurid plesiosaurs that lived during the Maastrichtian stage of the Late Cretaceous. Two species are known, A. parvidens and A. quiriquinensis, whose fossil remains were discovered in what are now Patagonia and Antarctica. Throughout the 20th century, Aristonectes was a difficult animal for scientists to analyze due to poor fossil preparation, its relationships to other genera were uncertain. After subsequent revisions and discoveries carried out from the beginning of the 21st century, Aristonectes is now recognised as the type genus of the subfamily Aristonectinae, a lineage of elasmosaurids characterized by an enlarged skull and a reduced length of the neck.
Measuring more than 10 m (33 ft) long, Aristonectes is a notably imposing plesiosaur. A referred specimen discovered in Antarctica has an estimated size of more than 11 m (36 ft) long, which would make this genus one of the largest known plesiosaurs. The paddle-like limbs of Aristonectes are unusually large for an elasmosaurid, reaching almost 3 m (9.8 ft) in length, suggesting a total wingspan of around 7 m (23 ft) for the animal. The skull is ogival-shaped and is flattened, possessing sharp forward-facing teeth. According to estimates, 13 teeth would have been present in each premaxilla, 50 teeth in the maxilla and 50 to 63 or more teeth in the lower jaw.
According to its morphology, mainly cranial, Aristonectes fed by mixing prey and sediment in the benthic zones, like the modern gray whale. As in other plesiosaurs, gastroliths (stomach stones) would have been used by Aristonectes either to help digest its food or to aid in buoyancy, although there is little support for the first hypothesis. According to its geographical distribution in the fossil record, Aristonectes would have regularly migrated between Patagonia and Antarctica.
distribution in the fossil record, Aristonectes would have regularly migrated between Patagonia and Antarctica. The first Aristonectes fossil was discovered long...
Morturneria to be so similar to Aristonectes, they found it most likely that it was merely a juvenile A. parvidens. Since Aristonectes was named first, they concluded...
conglomerates of the formation were deposited in a marine environment. Aristonectes quiriquinensis Australobaena chilensis Neogaeornis wetzeli Belonostomus...
; Martin, J.E.; Fernandez, M.S. (2003). "The elasmosaurid plesiosaur Aristonectes Cabreta from the Latest Cretaceous of South America and Antarctica"....
elasmosauroids; the type vertebra was recognized as potentially belonging to Aristonectes parvidens by José O'Gorman and colleagues in 2013. Another was E. haasti...
of plesiosauroids. Kaiwhekea was reclassified to Leptocleididae, and Aristonectes was transferred to Elasmosauridae. Cladogram based on Ketchum and Benson...
Zealand. Kaiwhekea has been placed as an aristonectine plesiosaur close to Aristonectes (O'Keefe and Street, 2009). In 2010, Kaiwhekea was transferred to Leptocleididae...
remains are among the fossils that have been recovered from its strata. Aristonectes parvidens Ptychoceratodus sp. Flora Plesiosaur stratigraphic distribution...
Other Antarctic marine reptiles included elasmosaurid plesiosaurs like Aristonectes and another indeterminate elasmosaurid. The fish assemblage of the López...
that some Cryptocleididae were suspension feeders, filtering plankton. Aristonectes e.g. had hundreds of teeth, allowing it to sieve small Crustacea from...
placement has varied. They were once considered to be close relatives of Aristonectes in the family Cimoliasauridae or Aristonectidae, but later assigned to...
Pliosauroidea are usually short-necked. The largest known plesiosauroid is Aristonectes, with a body length of 10–11.86 metres (32.8–38.9 ft) and body mass of...
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