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Lower jaw of Spathites (Ammonoidea, Acanthoceratoidea) from the Upper Cretaceous (Turonian) of New Mexico. (American Museum novitates, no. 3925)

Show simple item record Landman, Neil H. Sealey, Paul L. Foley, Michael P. Lucas, Spencer G. 2019-04-23T19:38:16Z 2019-04-23T19:38:16Z 2019-04-24
dc.description 12 pages : illustrations (some color), color map ; 26 cm. en_US
dc.description.abstract A lower jaw was recently discovered in a limestone concretion in association with the Late Cretaceous (Turonian) ammonite Spathites puercoensis (Herrick and Johnson, 1900) from the Carlile Member of the Mancos Shale in Sandoval County, New Mexico. It is nearly complete and comprises the aptychus with a hinge along the midline. The better-preserved plate, the left (according to its position in life), is roughly triangular in shape with a broadly rounded lateral margin, a narrowly rounded posterior margin, and a weakly concave anterior margin. It is 26.2 mm wide and 33.0 mm long. Together, the left and right plates form an escutcheonlike shape that projects slightly forward at the apex. The ratio of jaw width to length (26.2 mm x 2 / 33.0 mm) equals 1.59. The aptychus consists of yellow-orange calcite and is covered with comarginal ribs that parallel the lateral and posterior margins and become more prominent toward the posterior end. It is likely that this jaw belongs to the associated ammonite and would have comfortably fit inside the body chamber, based on a comparison of the length of the jaw and the whorl height, suggesting that it functioned as a jaw, rather than as an operculum. It is the first report of an ammonite jaw in the genus Spathites and the first reported occurrence of an ammonite jaw from New Mexico. en_US
dc.language.iso en_US en_US
dc.publisher American Museum of Natural History. en_US
dc.relation.ispartofseries American Museum novitates;no.3925.
dc.subject Spathites puercoensis -- Anatomy. en_US
dc.subject Mandible. en_US
dc.subject Ammonoidea -- Anatomy. en_US
dc.subject Sandoval County (N.M.) en_US
dc.subject New Mexico. en_US
dc.subject Mancos Shale. en_US
dc.title Lower jaw of Spathites (Ammonoidea, Acanthoceratoidea) from the Upper Cretaceous (Turonian) of New Mexico. (American Museum novitates, no. 3925) en_US
dc.title.alternative Lower jaws of Spathites. en_US

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  • American Museum Novitates
    Novitates (Latin for "new acquaintances"), published continuously and numbered consecutively since 1921, are short papers that contain descriptions of new forms and reports in zoology, paleontology, and geology. New numbers are published at irregular intervals.

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