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Najash
''Najash'' is an extinct basal snake from the Late Cretaceous Candeleros Formation of Patagonia.〔Apesteguía, S. and H. Zaher (2006). "A Cretaceous terrestrial snake with robust hindlimbs and a sacrum." Nature 440: 1037-1040.〕 Like a number of other Cretaceous and living snakes it retained hindlimbs, but ''Najash'' is unusual in having well-developed legs that extend outside the rib cage, and a pelvis connected to the spine. Fossils of ''Najash'' were found in the terrestrial Candeleros Formation, in Rio Negro Province, Argentina, and date to roughly 90 million years ago. The skull and spine of ''Najash'' both show adaptations for a subterranean existence, consistent with the hypothesis that the long bodies and reduced limbs of snakes are an adaptation for burrowing.
This burrowing creature had not lost its sacrum, the pelvic bone composed of several fused vertebrae, nor its pelvic girdle which are absent in modern snakes, and in all other known fossil snakes as well.〔Other known fossil snakes with developed hindlimbs, ''Haasiophis'', ''Pachyrhachis'' and ''Eupodophis''—all found in marine environments— all lack a sacral region.〕 Several phylogenetic analysis place ''Najash'' as either the most primitive known snake,〔 or near the base of the snake radiation, but outside of all living snakes.〔Longrich, N. R., B.-A. S. Bhullar, et al. (2012). "A transitional snake from the Late Cretaceous period of North America." Nature 488: 205-208.〕
This discovery does not support the hypothesis, first offered by the nineteenth-century paleontologist Edward Drinker Cope, that snakes share a common marine ancestry with mosasaurs. The marine origin hypothesis received new impetus with the discovery in the 1990s of basal snakes with vestigial limbs in marine sediments in Lebanon.
The generic name comes from the biblical legged snake of Genesis, Nahash, who tempted Adam and Eve to eat from a forbidden fruit tree.
==References==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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