Impressions of the attachment of the soft body to the shell in late Cretaceous pachydiscid ammonites from the Western Interior of the United States. American Museum novitates ; no. 3273

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dc.contributor.author Landman, Neil H. en_US
dc.contributor.author Lane, Jennifer A.
dc.contributor.author Cobban, William Aubrey, 1916-
dc.contributor.author Jorgensen, Steven D.
dc.contributor.author Kennedy, W. J. (William James)
dc.contributor.author Larson, Neal L.
dc.date.accessioned 2005-10-06T16:47:57Z
dc.date.available 2005-10-06T16:47:57Z
dc.date.issued 1999 en_US
dc.identifier.uri http://hdl.handle.net/2246/3045
dc.description 31 p. : ill. ; 26 cm. en_US
dc.description Includes bibliographical references (p. 30-31). en_US
dc.description.abstract "Late Cretaceous pachydiscid ammonites Menuites oralensis Cobban and Kennedy, 1993 and Menuites portlocki (Sharpe, 1855) complexus (Hall and Meek, 1856) from the Western Interior of the United States show four kinds of markings on the phragmocone and body chamber. These markings are preserved on internal molds that retain traces of the original shell, mostly the inner prismatic layer. (1) Transverse lines appear on the surface of the inner prismatic layer and extend adorally as far as midway onto the adult body chamber. They consist of a sequence of regularly spaced iridescent lines that usually cross the venter with a marked adoral projection, forming a chev-ronlike pattern. The transverse lines do not follow the shape of the apertural margin. Viewed in close-up, these lines appear as narrow bands of nacre; the adoral edge of each band is ragged and the adapical edge thins out and disappears. (2) A longitudinal band occurs on the flanks and extends from the umbilicus to about two--thirds whorl height. It appears on the surface of the inner prismatic layer. (3) A mid-ventral band extends for several tens of millimeters adoral of the ultimate septum and terminates in an unpaired scar. It appears on the internal mold and is visible below the inner prismatic layer. (4) A pair of dorsal scars occurs on the internal mold several millimeters adoral of the ultimate septum. Each scar is boomerang-shaped and extends from the dorsal margin to just ventral of the umbilical shoulder. We hypothesize that the transverse line formed at the adapical margin of the zone of nacreous secretion in the middle of the body chamber. They may have represented narrow bands of mantle attachment. The longitudinal band demarcated a broad area of nacreous secretion on the flanks, which may have represented an additional area of mantle attachment. During growth, both the transverse lines and the longitudinal band were overlain by the inner prismatic layer (and are thus now visible on the surface of this layer on partially exfoliated shells). The mid-ventral scar and dorsal scars just adoral of the ultimate septum are the sites of attachment of the soft body at the adapical end of the body chamber. These sites developed on the inside surface of the inner prismatic layer (and are thus now visible on the internal mold below the inner prismatic layer, if present)"--P. [1] - 2. en_US
dc.format.extent 11776353 bytes
dc.format.mimetype application/pdf
dc.language eng en_US
dc.language.iso en_US
dc.publisher New York, NY : American Museum of Natural History en_US
dc.relation.ispartofseries American Museum novitates ; no. 3273 en_US
dc.subject.lcc QL1 .A436 no.3273, 1999 en_US
dc.subject.lcsh Menuites oralensis. en_US
dc.subject.lcsh Ammonoidea -- South Dakota. en_US
dc.subject.lcsh Ammonoidea -- Wyoming. en_US
dc.subject.lcsh Ammonoidea -- Colorado. en_US
dc.subject.lcsh Mollusks, Fossil -- South Dakota. en_US
dc.subject.lcsh Mollusks, Fossil -- Wyoming. en_US
dc.subject.lcsh Mollusks, Fossil -- Colorado. en_US
dc.subject.lcsh Paleontology -- Cretaceous -- South Dakota. en_US
dc.subject.lcsh Paleontology -- Cretaceous -- Wyoming. en_US
dc.subject.lcsh Paleontology -- Cretaceous -- Colorado. en_US
dc.subject.lcsh Paleontology -- South Dakota. en_US
dc.subject.lcsh Paleontology -- Wyoming. en_US
dc.subject.lcsh Paleontology -- Colorado. en_US
dc.subject.lcsh Pierre Shale. en_US
dc.title Impressions of the attachment of the soft body to the shell in late Cretaceous pachydiscid ammonites from the Western Interior of the United States. American Museum novitates ; no. 3273 en_US
dc.type text 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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