The dwarfed 'giant deer' Megaloceros matritensis n.sp. from the Middle Pleistocene of Madrid - A descendant of M. savini and contemporary to M. giganteus

摘要

The Irish elk or Megaloceros giganteus is an emblematic species of the Pleistocene, but its relatives are much less known and were believed to have gone extinct when the Irish elk dispersed into Europe. The species Megaloceros matritensis n. sp. is described here on the basis of material from ten localities and levels in a terrace of the Manzanares river, South of Madrid. It must have been a common species when it lived there some 300-400 ka ago, being contemporary of M. giganteus. This species acquired features, such as enlarged premolars, very thick molar enamel, and a low mandibular condyle, which are masticatory adaptations to an, as yet, unknown diet. The species itself formed part of the diet of people which lived in the area. Megaloceros matritensis fossils are found associated to stone tools of late Acheulean and early Mousterian type. If found in other areas, this species could be indicative for this transitional period. Giant deer might be expected to be good examples of Cope's rule, which holds that species tend to evolve larger body sizes. However, M. matritensis is the last member of a lineage which gradually decreased in size during the Middle Pleistocene. Contrary to what one might expect, size decrease is not un-common in the giant deer.