Hostname: page-component-76d6cb85b7-2r2wp Total loading time: 0 Render date: 2026-07-22T03:13:46.265Z Has data issue: false hasContentIssue false

Early orthoceratoid cephalopods from the Argentine Precordillera (Lower-Middle Ordovician)

Published online by Cambridge University Press:  14 July 2015

Björn Kröger
Affiliation:
Museum für Naturkunde, Institut für Paläontologie, Invalidenstraße 43, D-10115 Berlin, Germany, 〈bjoekroe@gmx.de〉
Matilde S. Beresi
Affiliation:
Cricyt-Ianigla, Departamento de Paleontología, Avda. Ruiz leal s/n, 5500 Mendoza, Argentina, 〈mberesi@lab.cricyt.edu.ar〉
Ed Landing
Affiliation:
New York State Museum, State Education Department, Albany, New York 12230, 〈elanding@mail.nysed.gov〉

Abstract

The Early and Middle Ordovician Orthocerida and Lituitida of Precordilleran Argentina are described, and their systematics and paleogeographic significance are revised. These cephalopods show a strong affinity to coeval faunas of North China, suggesting a location of the Precordillera at middle latitudes in the Southern Hemisphere east of the North China block and relatively close to the Gondwanan margin during the early Middle Ordovician. The descriptive terminology of characters of the septal necks, the position and shape of the siphuncule, and the shape of the connecting ring is improved. The distribution of these characters support an emendation of the Baltoceratidae, Sactorthoceratidae, and Proteoceratidae. Braulioceras n. gen. (Sactorthoceratidae) and Palorthoceras n. gen. (Orthoceratidae) are erected. The new species Braulioceras sanjuanense, Eosomichelinoceras baldisii, Gangshanoceras villicumense, and Rhynchorthoceras minor are proposed. Palorthoceras n. gen. from the Lower Ordovician Oepikodus evae Zone represents the earliest known orthocerid.

Information

Type
Research Article
Copyright
Copyright © The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable