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Asprosaurus
Asprosaurus (lit. 'white lizard') is an extinct genus of anguimorph lizard from the Late Cretaceous (Campanian) of South Korea. The genus contains a single species, A. bibongriensis, which is the first Mesozoic lizard to have been discovered on the Korean peninsula. Discovery and namingThe holotype of Asprosaurus (KDRC-BB4) is an associated specimen consisting of partial cranial and postcranial material. Initially interpreted as a turtle fossil, it was discovered in 2000 from the Seonso Conglomerate, one of the rock units that form the Boseong Bibong-ri Dinosaur Egg Site which also yielded the fossils of an ornithischian dinosaur Koreanosaurus and over 200 dinosaur eggs.[2] The generic name means "white lizard", named so because the fossil bones of the holotype were light in color, while Mesozoic fossil bones of the Korean peninsula are usually dark. The specific name is in reference to "bibongri", the type locality where the holotype was found. Because Asprosaurus is known only from fragmentary material, its relationships with other lizards are uncertain. However, features of the lower jaw suggest that it is an anguimorph, and it is tentatively classified as cf. Monstersauria, a clade which includes the living Gila monster.[2] In 2016, a potential second specimen (KDRC-BB5) was identified as Asprosaurus sp. This specimen is a partial skull donated in 2008 from an uncertain stratigraphic level within the same locality where the holotype of Asprosaurus was discovered. The specimen exhibits synapomorphies of Varanoidea and Monstersauria, and is the only known lizard skull fossil with preserved teeth in South Korea.[3] DescriptionAsprosaurus is among the largest Late Cretaceous terrestrial lizards from Asia described to date, with an estimated skull length of 18–20 cm (7.1–7.9 in).[2] It is probably larger than Chianghsia,[4] whose skull length is estimated up to 17.5–18 cm (6.9–7.1 in) in total and the snout-vent length around 1–1.25 m (3 ft 3 in – 4 ft 1 in).[5] PaleobiologyVarious genera of large anguimorph lizards from the Late Cretaceous including Asprosaurus have been found in close proximity to the dinosaur eggs, so it is possible that these lizards are nest raiders. Asprosaurus might have been able to dig into nests using powerful forelimb muscles, which is inferred based on the morphology of the scapulocoracoid and humerus.[2] References
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