[N] 2005 A new specimen of Apatosaurus ajax
Upchurch, P., Tomida, Y. and Barrett , P.M. (2004) A new specimen of Apatosaurus ajax (Sauropoda, Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA. National Science Museum Monographs No.26 ISSN 1342-9574 National Science Museum, Tokyo December, 2004
Abstract: In 1993, a nearly complete postcranial skeleton of Apatosaurus was recovered from the Morrison Formation (Upper Jurassic: Kimmeridgian - Tithonian) near Thermopolis, Wyoming (USA). This specimen was purchased by the National Science Museum, Tokyo, where it has been mounted for public display. Description of this new Apatosaurus material has yielded additional anatomical data that have been used to revise the generic diagnosis and species-level taxonomy of the genus. A specimen-level cladistic analysis of individuals referred to Apatosaurus identifies hitherto unrecognized phylogenetic structure and indicates the presence of four valid species: A. ajax (the type species), A.excelsus, A.louisae, A.parvus (comb. nov.). The latter species is based on material of ‘Elosaurus’ parvus from the Morrison Formation of Sheep Creek, Wyoming (USA). The cladistic analysis indicates that the Tokyo Apatosaurus can be referred to A. ajax, which makes the current study the most detailed description of this genotype species. Revised generic and specific diagnoses have allowed re-evaluation of various Specimens that have previously been assigned to Apatosaurus, including juvenile material from Oklahoma.