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Nautilids from the Upper Cretaceous of the James Ross Basin, Antarctic Peninsula

Published online by Cambridge University Press:  06 June 2005

MARCELA CICHOWOLSKI ,
ALFREDO AMBROSIO  and
ANDREA CONCHEYRO
MARCELA CICHOWOLSKI
Affiliation:
Departamento de Ciencias Geológicas, Universidad de Buenos Aires. Ciudad Universitaria, Pabellón II (C1428EGA), Buenos Aires, Argentina, mcicho@gl.fcen.uba.ar (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas. Rivadavia 1917 C1033AAJ, Buenos Aires, Argentina
ALFREDO AMBROSIO
Affiliation:
Departamento de Ciencias Geológicas, Universidad de Buenos Aires. Ciudad Universitaria, Pabellón II (C1428EGA), Buenos Aires, Argentina, mcicho@gl.fcen.uba.ar Laboratorio de Anatomía Comparada y Evolución de los Vertebrados. Museo Argentino de Ciencias Naturales Bernardino Rivadavia. Ángel Gallardo 470 (C1405DJR), Buenos Aires, Argentina
ANDREA CONCHEYRO
Affiliation:
Departamento de Ciencias Geológicas, Universidad de Buenos Aires. Ciudad Universitaria, Pabellón II (C1428EGA), Buenos Aires, Argentina, mcicho@gl.fcen.uba.ar (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas. Rivadavia 1917 C1033AAJ, Buenos Aires, Argentina Instituto Antártico Argentino. Cerrito 1248, C1010AAZ Buenos Aires, Argentina
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Abstract

To date, Cretaceous nautilids from the Antarctic Peninsula have received little attention and only a single species had been reported, Eutrephoceras simile Spath, from Seymour, Snow Hill, and James Ross islands. Currently, it is considered a synonym of Eutrephoceras subplicatum (Steinmann), which has also been described from the Upper Cretaceous of central Chile, southern Argentina and Angola. Here, we report and describe E. subplicatum in detail, based on specimens from the Lower Campanian–Maastrichtian of Vega, Seymour and James Ross islands, presenting, for the first time, embryonic conch features related to the palaeoecology of these organisms. The nauta of this species had a diameter of approximately 30 mm with 5–6 septa. In addition, we describe a new species, Eutrephoceras antarcticum, and one specimen assigned to the same genus in open nomenclature, both recovered from the Lower Campanian beds of James Ross Island.

Keywords

Campanianembryonic conchEutrephocerasMaastrichtianpalaeoecologySeymour Group
Type
Research Article
Information
Antarctic Science , Volume 17 , Issue 2 , June 2005 , pp. 267 - 280
Copyright
© Antarctic Science Ltd 2005

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