The Upper Miocene fish fauna of the Fortuna Basin, as observed in the surroundings of Abanilla (Murcia province, Spain)

Resumen

Fossil fishes are present at two different stratigraphical levels near Abanilla, in the Upper Miocene of the Fortune basin (Murcia, Spain). The first site corresponds to a monospecific fossiliferous horizon, late Tortonian in age, which was present at La Serretilla before recent levelling works destroyed this outcrop. This horizon has mainly yielded fish remains and, exceptionally, articulated skeletons of clupeid fishes belonging to the species Sardina? crassa (Sauvage). The second fossiliferous site, which is stratigraphically situated in the basal part of the “Chicamo cycles”, belongs to the lowermost Messinian. These strata, both marly and diatomaceous contain a juvenile fish fauna and correspond to a spawning area in which marine stenohaline fishes were breeding and where the newly hatched fishes were beginning their development. The diatoms of the fossiliferous horizons are clearly indicative of a fully marine salinity and exclude the possibility of hypo- or hyperhaline conditions. The composition of the Chicamo fish fauna looks very similar to that the Campos del Río site and characterizes marginal marine conditions that differ strikingly from those which, like the Columbares site, in the Murcia-Cartagena basin, are indicative of a connection to open sea