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Large scaphitid ammonites (Hoploscaphites) from the Upper Cretaceous (upper Campanian-lower Maastrichtian) of North America : endless variation on a single theme. (Bulletin of the American Museum of Natural History, no. 441)

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dc.contributor.author Landman, Neil H.
dc.contributor.author Kennedy, W. J. (William James)
dc.contributor.author Grier, Joyce C.
dc.contributor.author Larson, Neal L.
dc.contributor.author Grier, James W.
dc.contributor.author Linn, Tom
dc.contributor.author Tackett, Lydia
dc.contributor.author Jicha, Brian R.
dc.date.accessioned 2020-09-14T21:47:47Z
dc.date.available 2020-09-14T21:47:47Z
dc.date.issued 2020-09-14
dc.identifier.issn 0003-0090
dc.identifier.uri http://digitallibrary.amnh.org/handle/2246/7243
dc.description 131 pages : illustrations (some color), map ; 26 cm. en_US
dc.description.abstract We describe three species of large scaphitid ammonites (Ammonoidea: Ancyloceratina) from the Upper Cretaceous (upper Campanian-lower Maastrichtian) of the Western Interior of North America. Each species occurs as two dimorphs, referred to as macroconch and microconch. All three species share a similar pattern of ornamentation consisting of long, thin, nonbifurcating ribs on the adoral part of the phragmocone, suggesting that they constitute a single monophyletic clade. Macroconchs of Hoploscaphites crassus (Coryell and Salmon, 1934) are characterized by a globose whorl section, with closely spaced ventrolateral tubercles on the body chamber, usually persisting to the aperture. Macroconchs of Hoploscaphites plenus (Meek and Hayden, 1860) differ from those of H. crassus in having a more subquadrate whorl section with flatter flanks, and fewer, larger, and more widely spaced ventrolateral tubercles. Macroconchs of Hoploscaphites peterseni, n. sp., closely resemble those of H. crassus, but differ in being nearly circular in side view with a more compressed whorl section. All three species lived at approximately the same time in the same general area and depositional environment. They are abundant in the Baculites baculus Zone but also occasionally occur in the B. eliasi Zone and possibly lower part of the B. grandis Zone. They are present in the Pierre Shale of east-central Montana and east-central Wyoming, the Lewis Shale of south-central Wyoming, and the Bearpaw Shale of northeast Montana. It is possible that these three species represent subspecies within a single species or a "flock" of very closely related species, similar to the "species flocks" observed in modern cichlid fishes. en_US
dc.language.iso en_US en_US
dc.publisher American Museum of Natural History. en_US
dc.relation
dc.relation.ispartofseries Bulletin of the American Museum of Natural History;no.441.
dc.subject Ammonoidea -- North America. en_US
dc.subject Ammonoidea -- West (U.S.) en_US
dc.subject Mollusks, Fossil -- North America. en_US
dc.subject Mollusks, Fossil -- West (U.S.) en_US
dc.subject Paleontology -- Cretaceous -- North America. en_US
dc.subject Paleontology -- Cretaceous -- West (U.S.) en_US
dc.subject Paleontology -- Cretaceous -- Pierre Shale. en_US
dc.subject Paleontology -- Cretaceous -- Bearpaw Formation. en_US
dc.title Large scaphitid ammonites (Hoploscaphites) from the Upper Cretaceous (upper Campanian-lower Maastrichtian) of North America : endless variation on a single theme. (Bulletin of the American Museum of Natural History, no. 441) en_US


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  • Bulletin of the American Museum of Natural History
    The Bulletin, published continuously since 1881, consists of longer monographic volumes in the field of natural sciences relating to zoology, paleontology, and geology. Current numbers are published at irregular intervals. The Bulletin was originally a place to publish short papers, while longer works appeared in the Memoirs. However, in the 1920s, the Memoirs ceased and the Bulletin series began publishing longer papers. A new series, the Novitates , published short papers describing new forms.

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