Taxonomy and biostratigraphy of the Late AlbianActinoceramus sulcatuslineage (Early Cretaceous Bivalvia, Inoceramidae)

Abstract

TheActinoceramus sulcatuslineage (Parkinson, 1819) (Bivalvia: Inoceramidae) is a very distinctive and abundant component of late Albian (Early Cretaceous) molluscan assemblages that is found throughout Europe, Central Asia, Japan and the Far East of Russia, southern and western North America, South Africa, and possibly India, in a range of shallow- to deep-marine facies. The lineage encompasses a wide and continuous range of morphologies that provide evidence of phyletic evolution at varying rates combined with large ecophenotypic plasticity within populations. The evolution ofA. sulcatusmarks the oldest appearance of well-developed radial folds and sulci within the Inoceramidae. The range of morphological variation makes formal taxonomic subdivision of the group problematic. Here we use a combination of formal successional subspecies and informal morphotypes to subdivide the lineage into the following taxa:A. sulcatusformasulcatus, A. sulcatusformasubsulcatus(Wiltshire, 1869),A. sulcatusformamunsoni(Cragin, 1894), andA. sulcatus biometricusCrampton, 1996. Within these taxa and morphotypes, we synonymise a large number of earlier names that have been applied to variants within the lineage. Each of the forms recognized has biostratigraphic utility and we describe four new lineage biozones, in ascending order:A. concentricus parabolicus, A. sulcatus, A. sulcatusformamunsoni, andA. sulcatus biometricusbiozones. The lowest occurrence ofA. sulcatusis approximately coincident with the base of the upper Albian as currently defined, at least throughout most of Europe, and this datum provides a valuable tool in correlation. The nature of radial folds within theA. sulcatuslineage poses interesting but still unanswered questions regarding shell morphogenesis in bivalves and the functional significance (if any) of radial folds in the Inoceramidae.

Paleogene marine bivalves of the deep-water Keasey Formation in Oregon, Part II: The pteriomorphs

“…Moore 1984b, it is well represented and often abundant in Japanese deep-water facies. However, Paleocene occurrences in Australia (Darragh 1997) andArgentina (del Rio et al 2008) as well as Late Cretaceous pectinids with camptonectes sculpture from New Zealand and the Chatham Islands (Crampton 1988) are consistent with hypothesized long cosmopolitan history.…”

“…Fossils in these families are often poorly preserved. Independent origins of the multivincular ligament have been proposed by many authors (e.g., Cox 1954, Kauffman and Runnegar 1975, Fischer-Pietté 1976, Crampton 1988, Knight and Morris 2009. A brief comparative summary of each family follows.…”

“…Additional distinguishing features of the inoceramid ligament area include more numerous ligament pits and wider interspaces between pits. Crampton (1988) provides a detailed and well-illustrated comparison of diagnostic and differential characters of the two families, including a table with literature references and page numbers. Both families include a variety of shell shapes and both epibyssate and endobyssate species.…”

AN INSIGHT INTO THE SYSTEMATICS OF PLICATOSTYLIDAE (BIVALVIA), WITH A DESCRIPTION OF <em>PACHYGERVILLIA ANGUILLAENSIS</em> N. GEN. N. SP. FROM THE <em>LITHIOTIS</em> FACIES (LOWER JURASSIC) OF ITALY

“…(Benini & Loriga 1974;Accorsi Benini & Broglio Loriga 1982;Broglio Loriga & Posenato 1996). The former genus has been included in the family Isognomonidae by Cox (1969) (Crampton, 1988). However, the occurrence of teeth at the adult stage in Gervilleioperna prompted some authors (e.g., Damborenea 1987) to place it in the fam.…”

Ammonite Biostratigraphy of the Cretaceous—An Overview

“…Example for superb bivalve index fossils are members of the Actinoceramus concentricus-A. sulcatus lineage, characterizing the early Late Albian across Europe, many parts of Asia, South Africa and the Atlantic as well as Pacific coast of North America (Amédro and Robaszynski 2005;Crampton and Gale 2009). Here, Actinoceramus subsulcatus is figured from California, allowing a much better correlation with Europe than the associated desmoceratid ammonite that is endemic (Fig.…”