Wednesday 9 October 2013

A new species of Red Toothed Shrew from the Early Pleistocene of Poland.

Shrews (Soricidae) are small insectivorous or omnivorous Mammals found across much of the world, the only major landmasses from which they are absent being Australia, New Zealand and New Guinea, though they are restricted to the northwest of South America, suggesting they are recent arrivals in that continent. They are small animals, superficially resembling Mice, though they are not closely related to Rodents, with the largest species reaching only about 15 cm. Shrews are notoriously verocious eaters, consuming around 80-90% of their bodyweight each day. They also reproduce extremely rapidly, with females of many species able to produce up to ten litters of young a year, though they seldom live more than 30 months. Red Toothed Shrews are found in North and South America, Europe and parts of Asia. They get their name from an iron pigment in the tips of their teeth, which hardens the cutting edges of the teeth, as well as giving them a reddish tinge.

In a paper published in the journal Palaeontologia Electronica on 4 May 2013, Barbara Rzebik-Kowalska of the Institute of Systematics and Evolution of Animals at the Polish Academy of Sciences describes a new species of Shrew from the Early Pleistocene Żabia Cave in the Częstochowa Upland in southern Poland, as part of a wider study into the Mammalian fauna of the cave.

The new species is placed in the genus Sorex and given the specific name bifidus in reference to the structure of the upper first incisor. The species is described from  a fragmentary jaw remains with some attached teeth (describing Mammal species from their teeth alone is not unusual, as Mammal teeth are regarded as sufficiently distinctive to allow this). Sorex bifidus appears to have been a large Shrew, but not exceptionally so.

Sorex bifidu. (1) Left mandible buccal view. (2) The same in lingual view. (3) Condyloid process in posterior view. (4) Right mandibular fragment in buccal view. (5) Right maxillary fragment in occlusal view. (6) The same in buccal view. (7) The same in anterior view. Rzebik-Kowalska (2013).

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