Asoriculus
Asoriculus is an extinct genus of terrestrial shrews in the subfamily Soricinae and tribe Nectogalini, native to Europe West Asia and North Africa, from the Late Miocene until the late Holocene. The genus is closely related and probably ancestral to the also recently-extinct Balearic shrews, with their closest living relative being the Soriculus shrews native to the Himalayas and surrounding areas.
Taxonomy and evolution
The number of valid species in the genus is uncertain and subject to dispute. The best known species of Asoriculus, Asoriculus gibberodon, was widespread in Europe from the Late Miocene to the Early Pleistocene, and was also present in Anatolia and the Caucasus during the Pliocene. The youngest records of the species date to the end of the Early Pleistocene approximately 846,000 ± 57,000 years ago in the Iberian Peninsula. Another larger species, A. thenii, is sometimes also recognised in the Early Pleistocene of Europe. The species Asoriculus maghrebiensis is known from the Pliocene-Pleistocene boundary of Morocco in North Africa, making it the only known member of Soricinae to have been native to the African continent.Insular species are known from the Mediterranean islands of Sicily, and Corsica-Sardinia including A. corsicanus and A. similis. Asoriculus is closely related and likely ancestral to the genus Nesiotites, known from the Balearic Islands from the Early Pliocene to the Holocene, whose species have sometimes been included in Asoriculus. The Asoriculus species A. corsicanus and A. similis were formerly included in Nesiotites in its original circumscription, though they are usually no longer treated as part of the genus.
Based on DNA from Nesiotites, the closest living relatives of Asoriculus are considered to be the terrestrial Soriculus shrews known from the Himalayas and adjacent areas, belonging to a clade of terrestrial nectogaline shrews primarily known from Asia, also including the genera Episoriculus and Chodsigoa, rather than related to the nectogaline water shrews. A molecular clock analysis suggests that Himalayan shrews and Balearic shrews genetically diverged approximately 6.44 million years ago.
Phylogeny of Nectogalini based on DNA and morphological characters after Bover et al..
The Sardinian-Coriscan species A. similis appears to have survived into the Holocene, when it became extinct sometime after human settlement of the islands, with remains apparently being found in Mesolithic and Neolithic aged archaeological sites in Sardinia. Studies in the 1990s suggested that Asoriculus became extinct on Corsica between 393 and 151 BC during the Carthaginian or Roman period.
Description
The skulls of fossil shews are generally only known from fragments of the maxilla and sometimes the nasal-palate region due to the thinness of the rest of the skull bones. A relatively well preserved but crushed skull, one of only a handful of well-preserved skulls known for fossil shrews, of Asoriculus gibberodon from the Pliocene of Jradzor, Armenia, is overall closest in morphology to those of its closest living relatives Soriculus and Episoriculus. The skull has four antemolars in each side of the upper jaw, as in the aforementioned genera. The skull of Asoriculus gibberodon differs from Soriculus and Episoriculus in having the lachrymal foramen placed more forward and higher up on the skull.A. gibberodon has been estimated to weigh approximately. The insular species of Asoriculus are substantially larger than A. gibberodon and most other species of Nectogalini, with A. burgioi estimated to weigh and A. similis, which has been cited as an example of island gigantism.