Acanthoceras Neumayr, 1875
publication ID |
https://doi.org/ 10.5252/geodiversitas2018v40a20 |
publication LSID |
urn:lsid:zoobank.org:pub:ED6A1495-51C7-4586-91FF-111E2DBF4267 |
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https://treatment.plazi.org/id/03D28793-F615-FFB7-9B1D-FAE45A50FD11 |
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Marcus |
scientific name |
Acanthoceras Neumayr, 1875 |
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Genus Acanthoceras Neumayr, 1875 View in CoL
Acanthoceras rhotomagense ( Brongniart, 1822) ( Fig. 3 View FIG H-J)
MATERIAL. — Six phosphatised internal moulds, one of them with a glued indication (463). Original label: Nº 463/ Ammonites rhotomagensis (Lamarck), Andar 20º Cenomaniense, Terreno Cretaceo, Localidade Rouen (Seine inf. re). See Figs 1D; 3K. View FIG
DESCRIPTION
Relatively large-sized, evolute and ornamented ammonites with subpoligonal whorl section.Tabular venter, conspicuous ventrolateral margins, arched flanks and wide umbilici with bended walls. Ornamentation formed by 24-28 straight ribs per whorl, with umbilical, inner ventrolateral, outer ventrolateral and siphonal tubercles. During ontogeny, whorl section changes from depressed subrounded to compressed subpolygonal. Relatively simple acanthoceratid suture lines.
DISCUSSION
Already cited in the Sainte-Catherine Mountain of Rouen by d’Orbigny (1840: 348), as characteristic of “des craies chloritées, des craies tufau [sic], ou des grès verts supérieurs” of France. This morphologically highly variable middle Cenomanian species, type of the genus, was attributed to Lamarck by some authors, such as d’Orbigny (1850, p. 146). Wright & Kennedy (1987) included within its synonymy numerous taxa proposed by different authors, as detailed by Barroso-Barcenilla (2004). Among the morphologically closest forms of the genus, the stratigraphically overlaying species A. jukesbrownei ( Spath, 1926) has less numerous and more distant ribs with strong umbilical bullae, and weak inner ventrolateral tubercles that decline to give a characteristic trapezoidal (rather than polygonal) whorl section. In the last years, A. rhotomagense has been studied by some authors, such as Kennedy & Juignet (1993), Kaplan et al. (1998), Fischer & Gauthier (2006) andKennedy et al. (2011).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Acanthoceras Neumayr, 1875
Barroso-Barcenilla, Fernando, Antunes, Miguel Telles, Brandão, José Manuel, Callapez, Pedro Miguel, Santos, Vanda Faria dos & Segura, Manuel 2018 |
COILOPOCERATIDAE
Hyatt 1903 |