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1 Dipartimento di Scienze della Terra, Università degli studi di Roma ‘La Sapienza’ and CNR-Istituto di Geologia Ambientale e Geoingegneria, Piazzale A. Moro 5, I-00185 Roma, Italy mariarita.palombo{at}uniromal.it
2 Dipartimento STAT, Università degli Studi del Molise, Via Mazzini 8, I-86170 Isernia, Italy
3 Dipartimento di Scienze della Terra, Università degli Studi di Roma ‘La Sapienza’, Piazzale A, Moro 5, I-00185 Roma, Italy Istituto Italiano di Paleontologia Umana, Piazza Mincio 2, I-00100 Roma, Italy
The late Early and Middle Pleistocene mammal fossil record of Italy has been revised by grouping faunal lists into discrete faunal complexes, termed cluster units, by means of bootstrapped cluster analysis which allows the evaluation of group partition sharpness. These complexes have been compared with previously erected Italian biochrons and then analysed for their body size (by cenogram analysis) and diversity trends. Some considerations about changes in predator-prey ratios are made. It is shown that diversity increased sharply at the onset of the middle Galerian mammal age, coincident with the well-known shift from 40 to 100 ka glacial-interglacial periodicity. This increased diversity was entirely driven by the concurrent arrival in Italy of some large ungulates. Cenograms reveal that the climate became wetter and markedly cooler following the arid conditions that characterize the late Early Pleistocene. Wetter environments are generally expected to sustain a higher proportion of large herbivore species. Because carnivore species did not respond in the same way, the predator-prey ratio changed in favour of prey. In summary, the transition from Early to Middle Pleistocene faunas (from early to middle Galerian mammal ages) represents a major reorganization in the large-mammal complexes from the Italian peninsula. This was reflected in both the diversity and trophic structure of large-mammal communities.
