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The Ojo Alamo Formation is a geologic formation spanning the Mesozoic/Cenozoic boundary. Dinosaur remains are among the fossils that have been recovered from the formation, though all dinosaur remains come from the lowest part of the formation, the Naashoibito member (sometimes considered part of the Kirtland Formation, which dates to the late Maastrichtian stage of the Cretaceous period.〔Williamson, T.E. and Weil, A. (2008). "Metatherian mammals from the Naashoibito Member, Kirtland Formation, San Juan Basin, New Mexico and their biochronologic and paleobiogeographic significance. ''Journal of Vertebrate Paleontology'', 28: 803-815.〕 The Ojo Alamo formation is divided into two subunits separated by a large unconformity—a gap in the geologic record. The lower Naashoibito member (sometimes considered part of the Kirtland Formation) was deposited during the Maastrichtian age of the Cretaceous period, specifically between about 69-68 million years ago. It overlies the De-na-zin member of the Kirtland formation, though the two are separated by another large unconformity that spans 73-69 million years of geologic time.〔Sullivan, R.M., and Lucas, S.G. 2006. "(The Kirtlandian land-vertebrate "age" – faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America )." New Mexico Museum of Natural History and Science, Bulletin 35:7-29.〕 All dinosaur fossils probably come from this unit.〔 The upper unit of the Ojo Alamo Formation is the Kimbeto Member, which was deposited mainly during the earliest Cenozoic (Danian age of the Paleogene period), between 66 and 64 million years ago.〔 Some researchers have claimed to find isolated non-avian dinosaur remains in this younger unit. If this is the case, it would represent the only known instance of a non-avian dinosaur population persisting after the Cretaceous–Paleogene extinction event. However, most scientists consider these to have been stratigraphically misinterpreted or reworked from the older Naashoibito member. ==Alamo Wash Fauna== The following species are known to be present in the Naashoibito Member "Alamo Wash Fauna".〔Jasinski, S. E., Sullivan, R. M., & Lucas, S. G. (2011). Taxonomic composition of the Alamo Wash local fauna from the Upper Cretaceous Ojo Alamo Formation (Naashoibito Member) San Juan Basin, New Mexico. Bulletin, 53, 216-271.〕 * Lizards * * Peneteius * Fish * * ''Myledaphus'' sp. * * ''Squatirhina'' sp. * * cf. ''Lepisosteus'' sp. * * ?Osteichthyes indet. * Amphibians * * Caudata indet. * Turtles * * ''Aspideretoides'' * * ''Compsemys'' * * cf. ''Hoplochelys'' sp. * * ''Neurankylus'' * * ''Plastomenus'' * * ''Adocus''? * * ''Basilemys''? * Theropods * * Dromaeosauridae sp. * *''Ojoraptorsaurus boerei'' * * Ornithomimidae indet. * * ''Richardoestesia'' sp. * * Troodontidae indet. * * Tyrannosauridae indet. * * aff. ''Tyrannosaurus rex'' * Sauropods * * ''Alamosaurus sanjuanensis'' * Ankylosaurs * * ''Glyptodontopelta mimus'' * * Ankylosauridae indet. * Hadrosaurids * * Saurolophinae indet. * * Lambeosaurinae indet. * Ceratopsians * *''Ojoceratops fowleri'' * Mammals * * cf. ''Alphadon marshi'' * * Alphadontinae indet. * * ''Essonodon browni'' * * cf. ''Glasbius'' sp. * * ''Mesodma formosa'' * * cf. ''Meniscoessus'' sp. * * Multituberculata indet. * * cf. Pediomyidae indet. 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「Ojo Alamo Formation」の詳細全文を読む スポンサード リンク
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