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The La Quinta Formation is a Mesozoic geologic formation which crops out in the Cordillera de Mérida and Serranía del Perijá, Venezuela. At its type locality near La Grita, south of Lake Maracaibo, it consists of a basal dacitic tuff followed by interlayered sandstones, tuffs, siltstones and rare limestones.〔Barret, et al. (2008). p. 164.〕 Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.〔Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.〕 Fossil associations suggest that the La Quinta Formation is of Early - Middle Jurassic age.〔Barret, et al. (2008). p. 175.〕 A new dinosaur from the earliest Jurassic of the Venezuelan Andes is the first basal ornithischian recovered from terrestrial deposits directly associated with a precise radioisotopic date. In addition, Paul Barrett et al provide a well-constrained maximum radioisotopic age for the La Quinta Formation of the Venezuelan Andes, based on analysis of detrital zircon crystals found in direct association with the dinosaur specimens, thereby providing one of only a few absolute age estimates available for Late Triassic–Early Jurassic terrestrial faunas worldwide. The summer-wet equatorial belt of the La Quinta Formation played a pivotal role in theropod evolution across the Triassic–Jurassic boundary. ==See also== * List of dinosaur-bearing rock formations * * List of stratigraphic units with few dinosaur genera 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「La Quinta Formation」の詳細全文を読む スポンサード リンク
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