Acanthoceras Neumayr, 1875

Barroso-Barcenilla, Fernando, Antunes, Miguel Telles, Brandão, José Manuel, Callapez, Pedro Miguel, Santos, Vanda Faria dos & Segura, Manuel, 2018, The d’Orbigny Palaeontological Collection of the National Museum of Natural History and Science, Lisbon, Portugal: Historical perspective and revision of Cretaceous Cephalopoda, Geodiversitas 40 (20), pp. 505-519 : 512

publication ID

https://doi.org/ 10.5252/geodiversitas2018v40a20

publication LSID

urn:lsid:zoobank.org:pub:ED6A1495-51C7-4586-91FF-111E2DBF4267

persistent identifier

https://treatment.plazi.org/id/03D28793-F615-FFB7-9B1D-FAE45A50FD11

treatment provided by

Marcus

scientific name

Acanthoceras Neumayr, 1875
status

 

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).

Family COILOPOCERATIDAE Hyatt, 1903 View in CoL

Kingdom

Chromista

Phylum

Ochrophyta

Class

Bacillariophyceae

Order

Chaetocerotales

Family

Acanthocerataceae

Loc

Acanthoceras Neumayr, 1875

Barroso-Barcenilla, Fernando, Antunes, Miguel Telles, Brandão, José Manuel, Callapez, Pedro Miguel, Santos, Vanda Faria dos & Segura, Manuel 2018
2018
Loc

COILOPOCERATIDAE

Hyatt 1903
1903
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