Biochronology of the Plio-Pleistocene Terrestrial mammals of Sardinia : The state of the art *

On the basis of currently available data, two main mammalian faunal complexes can be recognised in Sardinia from the Pliocene to the Late Pleistocene-Holocene: the “Nesogoral” a n d “ M i c r o t us (Tyrrhenicola)” faunal complexes. Notable faunal renewal characterises the transition between the two major complexes, while individual appearance and disappearance bioevents permit the recognition of less important renewals, which however allow one to distinguish, in the sphere of the two major complexes, subcomplexes of biochronologically-distinct fauna. The occurrence of endemic bovids, suids and archaic micromammals typified the earliest Sardinian LFAs. This faunal complex was present during the Pliocene and the beginning of the Early Pleistocene and was probably characterised by local evolution of some lineages, by a reduced extinction rate and by a moderate immigration rate. Two subcomplexes may be detected within this complex. In the earliest Mandriola faunal sub-complex, descendants from endemic pre-existing taxa (Tyrrhenoglis) are associated with new settlers that entered during the Messinian (murids, suids and bovids) and micromammals suggesting an early Middle Pliocene age. Very modest faunal renewal marks the transition to the following faunal subcomplex (“Capo Figari/Orosei 1”) (late Middle? , Late Pliocene-Early Pleistocene). The latter is typified by the occurrence, among others, of micromammals which evolved from pre-existing taxa, of an endemic predator, the Hyaenidae Chasmaporthetes melei, and strongly modified bovids, possibly present in Sardinia from the late Messinian, as well as mustelids that may have entered Sardinia during the Middle Pliocene regression. Marked faunal renewal indicates the transition to the subsequent Microtus (Tyrrhenicola) faunal complex (? latest Early Pleistocene/Early Holocene), within which two faunal subcomplexes can be recognised. In the older “Orosei 2” faunal subcomplex (latest Early Pleistocene/early Middle Pleistocene), an archaic endemic vole (Microtus (Tyrrhenicola) sp. ), Cynotherium sp. , a large megalcerine (“Praemegaceros” n. sp.) and possibly a new caprine first occurred, together with some pre-existing taxa such as Rhagamys minor. The younger “Dragonara” faunal sub-complex (latest Middle Pleistocene-Early Holocene), corresponding to classic endemic Sardinian fauna, is characterised by the presence, among others, of advanced voles (Microtus (Tyrrhenicola) henseli) and murids (Rhagamys orthodon), Cynotherium sardous, megacerines more or less reduced in size (“Praemegaceros” c a z i o t i) and, occasionally, endemic elephants (M a mmuthus lamarmorai). These faunal complexes testify to the evolution of mammalian fauna in the Sardinian insular domain towards progressively more unbalanced and impoverished fauna, and document colonisation phases from the mainland and faunal turnovers/renewals, followed by periods of more noteable insularity conditions. Key-words: Plio-Pleistocene, Sardinia, Mammals. ΠEPIΛHΨH: Βασιζόμενοι στα πρόσφατα δεδομένα, στη Σαρδηνία μπορούμε να αναγνωρίσουμε δύο κύρια πανιδικά συμπλέγματα από το Πλειόκαινο μέχρι το Ανώτερο Πλειστόκαινο-Ολόκαινο: το πανιδικό σύνολο “N e s o g o r a l” και το πανιδικό σύνολο “M icrotus (Tyrrhenicola)”. Η μετάβαση από το ένα πανιδικό σύνολο στο άλλο χαρακτηρίζεται από αξιοσημείωτα γεγονότα ανανέωσης της πανίδας, ενώ ιδιαίτερα γεγονότα εμφάνισης και εξαφάνισης επιτρέπουν την αναγνώριση φάσεων λιγότερο σημαντικής ανανέωσης, τα οποία όμως επιτρέπουν τη διάκριση πανιδικών υποσυνόλων εντός κάθε κύριου πανιδικού συνόλου. Τα παλαιότερα τοπικά πανιδικά σύνολα της Σαρδηνίας χαρακτηρίζονται από την παρουσία ενδημικών Bovidae, Suidae και αρχαϊκών μικροθηλαστικών. Aυτό το πανιδικό σύνολο ήταν παρόν κατά τη διάρκεια του Πλειοκαίνου και κατά την αρχή του Κατωτέρου Πλειστοκαίνου και χαρακτηριζόταν πιθανόν από την τοπική εξέλιξη ορισμένων φυλογενετικών γραμμών, από το μικρό ρυθμό εξαφάνισης και από το μέτριο ρυθμό μετανάστευσης. Εντός αυτού του συνόλου μπορούμε να διακρίνουμε δύο