'Trigonal' Discocyclina sp. from the Pondicherry formation, Pondicherry, South India

Abstract

A rare and unusual type of 'trigonal' @iDiscocyclina@@ sp. is noticed in the uppermost Discocyclinid limestone and the Upper marlstone units of the Pondicherry formation (F horizon - Nerinea beds - of Pondicherry area). The faunal association of this species is chiefly planktonic, and transitional from the Discocyclinid limestone unit to the Upper marlstone unit, as seen by a lesser degree of abundance. The 'trigonal' shape of the test may be due either to specialisation or degeneration in the changed conditions of the regressive phase of the Cretaceous transgression in South India. The faunal assemblage indicates a middle to outer neritic environment