On Brancoceras STEINMANN, 1881 (Brancoceratidae) and Pseudobrancoceras gen. nov., (type species Ammonites versicostatus MICHELIN, 1838: Lyelliceratinae) from the Albian (Cretaceous) of the western Paris Basin and Provence, France

Abstract

A re-examination of the type material of Ammonites senequieli D'ORBIGNY, 1841, the type species of Brancoceras STEINMANN, 1881, shows D'ORBIGNY'S original figures to be a chimaera, based on specimens of two species, while the other specimens in his collection belong to several other species, many of them named by COLLIGNON (1949), all of which are revised. The following species are described: Brancoceras senequieli (D'ORBIGNY, 1841), B. magneti COLLIGNON, 1949, B. helcion (REYNES, 1876), B. subcompressum COLLIGNON, 1949, B. paronai COLLIGNON, 1949, B. retrorsum COLLIGNON, 1949, B. alternatum sp. nov., B. flexuosum sp. nov., and B. multicostatum sp. nov. Ammonites versicostatus MICHELIN, 1838, referred to Brancoceras by some authors, belongs to Lyelliceratinae, as proposed most recently by LATIL (1995), and is a brancoceratid homeomorph referred to Pseudobrancoceras gen. nov., of which it is the type species, and to which a second species, P transiens sp. nov., is also referred.