Original paper

Marking the Kimmeridgian-Tithonian transition with a bivalve Protocardia gigantea sp. nov. (Bivalvia: Cardiidae) and its relatives from the Lusitanian Basin (Portugal)

Schneider, Simon; Fürsich, Franz T.; Werner, Winfried

Abstract

The cardiid Protocardia gigantea sp. nov., which is newly described herein, represents the largest member of this globally distributed genus of shallow-water Mesozoic bivalves. It is found throughout the central Lusitanian Basin (Central Portugal) and may be utilised as a stratigraphic marker for the Kimmeridgian-Tithonian transition in this area, which is confirmed by Sr-isotope data. Its frequent occurrence, large size, and characteristic features make Protocardia gigantea a valuable tool for field stratigraphy. Its taxonomy, systematic position, and ontogenetic as well as intra-population morphological variability are outlined. Possible ancestry in and outside the Lusitanian Basin is discussed, and four other species of Protocardia from the Upper Jurassic of Portugal are taxonomically treated.

Keywords

protocardiacardiidaestratigraphylate jurassicportugaltaxonomymorphometryfourier shape analysis