Palaeoclimatic implications of continental saline and fresh water mollusc communities of the Cenozoic Iberian Peninsula

Abstract

Spatio-temporal distribution pattern of continental saline and fresh water mollusc palaeocommunities of the Cenozoic Iberian Peninsula were investigated in order to detect palaeo- climatic implications. Several thermophilous representatives of the Cerithioidea, which indicate a warm subtropical climate, are absent from the extant Iberian fauna and restricted to North Africa, the SE Mediterranean and Asia Minor. The fossil re- cord suggests that the different continental aquatic ecosystems were colonised at different times in the Cenozoic: distribution pattern of Melanoides palaeocommunities (Oligocene, Ebro Basin; Miocene, Albacete; Pliocene, Barcelona; Lower Pleis- tocene, Guadix Baza Basin) and Potamides palaeocommunities (Oligocene Ebro Basin; Miocene, Duero Basin, Ebro Basin; Early Pleistocene, Guadix Baza Basin) and their successive disappearance since the mid- to Late Miocene in the northern Spain basins refl ect the global Late Cenozoic temperature coo- ling. Potamides palaeocommunities in playa lake-environments of the Guadix Baza Basin indicate a semi-arid climate context, similar to the modern North African climate. Humid intervals are indicated by syntopic Melanoides palaeocommunities that colonised hyposaline environments, similar to the colonisation of aquatic ecosystems during the Holocene more humid climate episodes in North Africa. Melanopsis palaeocommunities are characterised by a greater temperature tolerance compared to the investigated Melanoides and Potamides palaeocommunities. The extant species Melanopsis praemorsa is distributed in Spain south of the 42 nd degree of latitude, roughly coinciding with the +10°C-January-Isotherme, while the area of distribution of the Miocene congeners extended the northern Spain basin systems.