Badgers of the genus Meles are found throughout temperate Eurasia. They are burrowing omnivores, primarily feeding on worms, insects and other invertebrates but also quite willing to take plant matter and small vertebrates (the proportion of the diet made up by each varies from place to place). Badger lifestyles are also varied - badgers in England may live in groups of up to thirty individuals, but in other parts of their range they are much more reclusive. Many authors recognise only a single modern species in the genus, Meles meles, but based on characters of the dentition, coloration and baculum morphology some authors have argued for the recognition of three species - M. meles in Europe and Russia west of the Volga river, M. leucurus in Asia east of the Volga (with M. meles and M. leucurus marginally overlapping in central Asia east of the Caspian), and M. anakuma (the smallest species) in Japan (Abramov & Puzachenko, 2005). However, both the two continental species include a number of subspecies, while genetic divergence overall is low, so this is an area that requires further investigation (Marmi et al., 2005).
The genus Meles probably divided from the ancestors of its current living sister taxon, the hog badger Arctonyx collaris of south-east Asia, some time around the beginning of the Pliocene* (Tedford & Harington, 2003). Meles gennevauxi from Montpellier in France is known from the Lower Pliocene, but opinions differ as to whether this should be included in Meles or Arctomeles (a fossil genus related to Arctonyx; Tedford & Harington, 2003; Arribas & Garrido, 2007). If M. gennevauxi loses its spot, the runner-up is the late Pliocene Meles thorali.
*Offhand, Meles and Arctonyx are now the only living members of the mustelid subfamily Melinae, which used to contain all the "badgers" except the honey badger Mellivora capensis. Recent studies have shown that "badgers" are a polyphyletic group, and they have been divided up accordingly (Koepfli et al., 2008). The south-east Asian stink badgers of the genus Mydaus are related to the American skunks (which have been excluded from the Mustelidae as a separate family, Mephitidae), the American badger Taxidea taxus is sister to all other mustelids, while the ferret badgers (Melogale) are closer to Mustela and otters.
Meles thorali was described from Saint-Vallier in France by Viret (1950; I haven't seen the original description), and has since been recorded from Bulgaria and Lesbos (Lyras & van der Geer, 2007). A subspecies, Meles thorali spelaeus, has been described from the south of France (Bonifay, 1971), but again I haven't seen the original description. Meles thorali was similar in size to modern Meles meles, but was distinguished by features such as the lesser lateral projection of the zygomatic arches (the cheekbones) and the presence of only two instead of three or more roots on the lower second molar (Arribas & Garrido, 2007).
Other badger species present in Europe during the latest Pliocene and early Pleistocene were the Spanish M. iberica, M. dimitrius of Greece and M. hollitzeri of Germany. On purely phenetic grounds, M. iberica appears to be the most divergent of the European badgers, while M. dimitrius and M. hollitzeri were closer to M. thorali and M. meles. Genetic studies confirm the identity of modern Iberian badgers with M. meles (Marmi et al., 2005), and nearly one and a half millions years (not to mention a couple of ice ages) separate M. iberica from the earliest known Iberian M. meles (Arribas & Garrido, 2007). M. thorali has been suggested to be the ancestor to the modern Meles species (Baryshnikov et al., 2003), but it is notable that M. thorali spelaeus seems to be even closer morphologically to M. meles than M. thorali thorali - a fused root on the upper second premolar and a second lower molar wider than long are derived features of the first two not shared with the third (Arribas & Garrido, 2007). Moreover, if one considers M. thorali proper and not M. spelaeus, I don't see from the characters described by Arribas & Garrido (2007) why M. thorali is necessarily any closer to modern badgers than M. dimitrius or (particularly) M. hollitzeri - M. hollitzeri, for instance, is closer to modern badgers in molar morphology. While Baryshnikov et al. (2003) derive modern east Asian badgers as well as M. meles proper from M. thorali*, I don't know whether they considered the relatively little-mentioned early Pleistocene Chinese badgers M. chiai and M. teilhardi (Xue et al., 2006).
*That is, if I've understood the abstract correctly. Funnily enough, the Russian Journal of Theriology doesn't seem to be readily available here in Perth.
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Arribas, A., & G. Garrido. 2007. Meles iberica n. sp., a new Eurasian badger (Mammalia, Carnivora, Mustelidae) from Fonelas P-1 (Plio-Pleistocene boundary, Guadix Basin, Granada, Spain). Comptes Rendus Palevol 6: 545-555.
Baryshnikov, G. F., A. Yu. Puzachenko & A. V. Abramov. 2003. New analysis of variability of cheek teeth in badgers (Carnivora, Mustelidae, Meles). Russian J. Theriol. 1 (2): 133–149.
Bonifay, M. F. 1971. Carnivores quaternaires du Sud-Est de la France. Mem. Mus. natl Hist. nat., Paris, n.s., Ser. C 21 (2): 1–377.
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Tedford, R. H., & C. R. Harington. 2003. An Arctic mammal fauna from the Early Pliocene of North America. Nature 425: 388-390.
Viret, J. 1950. Meles thorali n. sp. du loess villafranchien de Saint-Vallier (Drôme). Eclogae Geologicae Helvetiae 43 (3): 274–287.
Xue X., Zhang Y. & Yue L. 2006. Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the Chinese Loess Plateau since 8.0 Ma B.P. Science in China: Series D Earth Sciences 49 (5): 518—530.