Andrea Savorelli

Independent water vole (Mimomys savini, Arvicola: Rodentia, Mammalia) lineages in Italy and Central Europe

Abstract

Water voles are important key fossils of the Quaternary. Given their wide distribution, regional differences were expected to exist in different areas. Early hints on possible independent evolutionary trends of water voles in Italy came from palaeontology and specifically from the comparison of enamel differentiation (SDQ value) of the first lower molars between specimens from Italy and Germany. The data available at that time indicated that in the early Middle Pleistocene there were only minor enamel differences between first lower molars of water voles from these two geographical regions, whereas from the late Middle Pleistocene onwards, two lineages were clearly distinguished. Examination of mitochondrial DNA of extant Arvicola populations from across Europe by Wust-Saucy led to a similar conclusion that Arvicola populations from the Italian Peninsula had undergone independent evolution during the last 0.2 million years.

The inclusion of new fossil and extant Arvicola samples from Italy and Central Europe, together with the examination of additional morphological parameters of the occlusal surface (so-called van der Meulen indexes), have provided further support for the proposed evolutionary pattern. The combined analysis of length, SDQ and A/L index reveal a certain degree of intercorrelation and indicate an essentially continuous evolutionary trend. However, variations are discernible, related to the age and geographical origins of the samples, and become more clearly seen at least since the beginning of the Late Pleistocene. Italian samples have a characteristic tendency to grow larger, elongate the anteroconid, and have less derived SDQ. This corroborates the suggestion that Italian water voles underwent an evolutionary history distinct from that of their Central European counterparts. The differences in morphology may be related to a combination of etho-/ecological (aquatic or terrestrial habits) and palaeobiogeographical factors.

Key words

water voles, first molars, Europe, evolution, Pleistocene, morphometrics

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New light on Parasorex depereti (Erinaceomorpha: Erinaceidae: Galericini) from the Late Messinian (MN 13) of the Monticino Quarry (Brisighella, Faenza, Italy)

Abstract

A large-sized species of Parasorex is common in the MN 13 mammal assemblages from the uppermost Messinian sandy-marly fissure fillings within the Gessoso Solfifera Formation at Brisighella (Northern Apennine). This erinaceid has been classified as Galerix sp. in the first papers on the Brisighella fauna. Later, it was described in detail in an unpublished Ph.D. dissertation by Fanfani (1999), who referred it to Galerix depereti. Van den Hoek Ostende (2001) included G. depereti in the genus Parasorex, Parasorex depereti has been described by Crochet (1986) on scarce material from a few Early Pliocene (MN 14–15) localities of southern France and Spain. Parasorex cf. depereti has been reported from the Early Pliocene fauna of Capo Mannu (Mandriola, Sardinia; Furió and Angelone 2010). The species seems actually distributed in south-western Europe, where it represents the youngest occurrence of the genus Parasorex. The very abundant sample of P. depereti from fissure filling BRS 25 enables a more accurate and comprehensive description of the species. It also permits inspection of the mesial elements of the dentition, which were lacking in the material examined by Crochet (1986). The systematic position of the species has been revisited and compared with those of other Galericini of the Parasorex group.

Key words

Parasorex, Messinian, taxonomy, biometry, emended diagnosis

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