The mammal record of the succession of the Leffe Basin

The Plio-Pleistocene Leffe Basin (Northern Italy) has been known since the 19th century for the abundant fossil material, consisting of large mammals, turtles, molluscs and plant remains extracted from the brown coal mines. A careful restudy of the fossil mammals stored in the Civic Museum of Natural History of Milan and in the Museum “E. Caffi” of Bergamo, together with their scarce stratigraphic indications, allowed the identification of three reliable mammal associations: Mammal association #1 - from the main brown coal level (subunit #5) consists of Late Villafranchian species: Mimomys savini, Castor fiber, Mammuthus meridionalis, Stephanorhinus ex gr. etruscus, Leptobos cf. vallisarni, Capreolus sp., Pseudodama sp., Eucladoceros gr. ctenoides-dicranios and Megaloceros cf. obscurus. The age of this bank spans the end of the Tasso FU and the beginning of the Farneta FU. Mammal association #2 - from the subunit #6 (consisting of Pachycrocuta brevirostris, S. ex gr. etruscus and Pseudodama eurygonos) and from the subunit #7 (consisting of S. ex gr. etruscus and Cervalces cf. carnutorum) do not provide precise biochronological information, but could span the time interval between the latest part of the Farneta FU and the end of the Pirro FU. Mammal association #3 - from the subunit #9 consists of M. meridionalis vestinus and Megaloceros verticornis, that co-existed throughout the Colle Curti FU and following Slivia FU. Subunit #9 sediments bear a normal polarity interval (MUTTONI et al. in press), which is correlated to the Jaramillo Subchron, hence, the fauna from this subunit is assigned to the Colle Curti FU, which roughly correlates to the Jaramillo. Palaeoloxodon antiquus from the red palaeosoils overlying the Leffe Formation belongs to a generic time interval, which spans the early Middle Galerian–Late Aurelian Mammal Ages, i.e., from the Slivia FU to the Last Interglacial. The red palaeosoils are younger than the Gandino Formation, which is dated to nearly the entire period between the end of the Jaramillo Subchron and the beginning of the Brunhes Chron (RAVAZZI 2003). The elephant remains are therefore younger than 0.8 Ma BP and older than 0.1 Ma BP