Antarctic Science

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

a1 Departamento de Ciencias Geológicas, Universidad de Buenos Aires. Ciudad Universitaria, Pabellón II (C1428EGA), Buenos Aires, Argentina,
a2 (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas. Rivadavia 1917 C1033AAJ, Buenos Aires, Argentina
a3 Laboratorio de Anatomía Comparada y Evolución de los Vertebrados. Museo Argentino de Ciencias Naturales Bernardino Rivadavia. Ángel Gallardo 470 (C1405DJR), Buenos Aires, Argentina
a4 Instituto Antártico Argentino. Cerrito 1248, C1010AAZ Buenos Aires, Argentina

Article author query
cichowolski m   [PubMed][Google Scholar] 
ambrosio a   [PubMed][Google Scholar] 
concheyro a   [PubMed][Google Scholar] 


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.

(Received September 2 2004)
(Accepted January 11 2005)

Key Words: Campanian; embryonic conch; Eutrephoceras; Maastrichtian; palaeoecology; Seymour Group.