New molluscan records and palaeoecology of the Late Pleistocene marine assemblage from La Coronilla (Rocha, Uruguay)

Abstract

The Late Pleistocene marine molluscan assemblage from La Coronilla is one of the richest Quaternary marine deposit from Uruguay. This contribution represents an update of the bivalve and gastropod species composition of this deposit and includes a palaeoecological analysis of the molluscan fauna. The ecological preferences of the recorded species allowed the reconstruction of the palaeoenvironmental conditions of the eastern Uruguayan coast and the palaeobiogeographic scenario of the area during the Late Pleistocene. The fossil assemblage of La Coronilla contains 91 bivalve and gastropod taxa of which 28 are new to this deposit and 11 are first reported for the Uruguayan Quaternary marine assemblages. The latest are Turbonillaabrupta, Turbonillacf. farroupilha, Turbonillabrasiliensis, Turbonillacf. deboeri, Turbonillapenistoni, Turbonillaturris, Olivella defiorei, Eurytellinaangulosa, Kelliasp., Paraleptopectenbavayi,and Pandorasp. Almost all recorded species from the assemblage are marine and livein soft bottoms, although hard/consolidated substrate species and microgastropods that live in ecological interaction with other invertebrate taxa were also found. The high percentage of tropical-subtropical species, the absence of cold-water species, andthe record of extralimital warm water northern species, adds new evidence for the inference of warmer than present conditions in the Uruguayan coast during the Late Pleistocene.