Early Cretaceous non‐marine Ostracoda from theNorthFalklandBasin,SouthAtlantic

Abstract

AbstractTwenty‐seven species of well‐preserved and abundant Early Cretaceous non‐marine ostracod crustaceans were recovered from the North Falkland Basin. The assemblage is unusually diverse for a non‐marine palaeoenvironment and is sourced from cuttings samples collected during 2011 drilling of wells by Desire and Rockhopper Exploration, in the northern and southern areas of the basin. Ostracoda are entirely undocumented in published accounts from this basin, and all but one species appear to be new to science. For the new taxa, one new family (Alloiocyprideidae; type genusHourcqia) is proposed and includesHourcqia woodisp. nov. Four new genera are erected:Falklandicyprisgen. nov.; type speciesF. petrasaltatasp. nov.,Gangamoncytheregen. nov.; type speciesG. colinisp. nov.,Paraplesiocyprideagen. nov.; type speciesP. alloiossp. nov., andMusacchiocytheregen nov.; type speciesM. sarunata(Musacchio,). Nine other species are described as new and areFalklandicypris desiderata,Clinocypris epacrus,Cypria poietes,Ilhasina? leiodermatus,Looneyellopsis tuberculatus,Theriosynoecum petasmathylacus,Theriosynoecum ballentae,Timiriasevia fluitans,andVecticypris samesi. The remainder are left in open nomenclature due to paucity of material. The ostracod assemblage is largely restricted to the southern part of the basin (wells 25/5‐1 and 26/6‐1). In the northern part of the basin only four species, dominated byVecticypris samesi, are present and with one possible exception are restricted there. There appears to have been little or no interchange of species suggesting that a barrier probably existed between the northern and southern regions. The more diverse southern assemblage indicates that more favourable conditions existed to the south. Stratigraphically, a distinct change in faunal composition recorded in both southern wells is likely to be an isochronous event correlatable across the southern area, and of an age no younger than Hauterivian.