Abstract

Prolagus michauxi López-Martínez, 1975 (Prolagidae, Lagomorpha) is one of the best known and most widespread species of its genus. It was described from Sète, a karst filling located in southern France that has yielded a rich fauna of micromammals. Its age is estimated between 3.5–3.0 Ma. This study provides as complete as possible a picture of the cranial and dental morphology by the analysis of the characters and their variation. Usually, the cranial and postcranial material is poorly represented in the fossil record, and thus little studied. Abundance of cranial and dental remains in Sète is an exception and allows for a better characterisation of P. michauxi. Detailed comparisons with contemporary species show its great resemblances with P. sorbinii Masini, 1989 from Italy with regard to dental features, but it differs by the characters of the cranium and the mandible. It is well known that the Alpine uplift and the progressive aridification of the Mediterranean region since the terminal Miocene (Messinian) have led to the fragmentation of habitats and, as far as the genus Prolagus is concerned, to the occurrence of numerous speciations. To adapt to these new conditions, some Mio-Pliocene species of Prolagus, in particular P. michauxi, have developed an enlarged premolar foramen next to upper cheek teeth and numerous foramina on the hard palate that allow for better thermoregulation. The fragmentation of habitats may also explain a great variation in dental morphologies in various Pliocene species whose geographical range extends from Portugal to Ukraine and Asia Minor, and also to North Africa. Indeed, P. michauxi is abundantly represented in the Iberian Peninsula and the Maghreb. Also, it was reported from several sites in Greece and Asia Minor, but the material is scarce, which makes the identifications uncertain.

Key words

Lagomorpha, Prolagidae, Prolagus, Sète, Pliocene, systematics, dispersal, adaptation

Abstract

The vertebrate locality of Dorkovo yielded a rich mammalian assemblage of which some large mammals have been studied, but not smaller mammals. The previous investigations correlated this fauna to the early Pliocene (early Ruscinian, MN 14). The present paper describes lagomorph remains which consist of one fragment of mandible and 106 isolated teeth. Four species are identified: Ochotona cf. antiqua, Prolagus sorbinii, Alilepus spassovi n. sp. and Trischizolagus crusafonti. The new species is characterised by the derived pattern of its p3 which has trigonid more stretched, enamel infolding stronger than in any other species of Alilepus, and the p3 lacks anteroflexid. The presence of four species of lagomorphs at Dorkovo is in agreement with the diversity dynamics of lagomorphs toward the end of late Miocene and during the early Pliocene in Eurasia, and in particular in Eastern Europe. The time range of the Dorkovo lagomorphs encompasses the Miocene/Pliocene boundary, and this is in agreement with the previous age assignments, i.e., earliest Pliocene, or early part of MN 14 mammalian zone.

Key words

Lagomorpha, Ochotonidae, Prolagidae, Leporidae, early Pliocene, Bulgaria, dispersal