Irish Elk

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{{Taxobox | color = pink | name = Irish Elk | status = Template:StatusPrehistoric | image = Irish Elk.jpg | image_width = 250px | image_caption = Skeleton at the National Museum of Natural History | regnum = Animalia | phylum = Chordata | classis = Mammalia | ordo = Artiodactyla | familia = Cervidae | genus = Megaloceros | species = M. giganteus | binomial = Megaloceros giganteus | binomial_authority = (Blumenbach, 1799) }} The Irish Elk (Megaloceros giganteus or Megaceros, more properly a subgenus<ref>Template:Cite book</ref>) is an extinct deer that lived in Eurasia, from Ireland to China, during the Pliocene, Pleistocene, and Holocene epochs. It is famous for its formidable size (about two meters (6½') at the shoulders), and in particular for having the largest antlers of any known cervid (a maximum of 13 feet or 4 metres from tip to tip). Its name is misleading: although large numbers of skeleton have been found in Irish bogs, the animal was not exclusively Irish, and neither was it closely related to either of the living species currently called “elk”; for this reason, the name “Giant Deer” is sometimes preferred.

The latest known remains of the Irish elk have been carbon dated to about 5700 BC.

The size of the Irish Elk's antlers is remarkable, and several theories have arisen as to their evolution. One theory was that the Elk's antlers, under constant sexual selection, increased in size because males were using them in combat for access to females; it was also suggested that they eventually became so unwieldy that the Elks could not carry on the normal business of life and so became extinct. However, Stephen Jay Gould's important essay on Megaloceros demonstrated that for deer in general, species with larger body size have antlers that are more than proportionately larger, a consequence of allometry, or differential growth rate of body size and antler size during development. In fact, Irish Elk had antlers of exactly the size one would predict from their body size and no special theory of natural selection is required.

The antlers do seem to have played a role in the animal's eventual extinction, however. Recent research has determined that due to the high amounts of calcium and phosphate compounds required to form these massive structures, the Irish Elk males had to deplete these compounds partly from their bones, replenishing them from foodplants when the antlers were grown. Thus, in the growth phase, males were suffering from a condition similar to osteoporosis. When the climate changed at the end of the last Ice Age, the vegetation in the animal's habitat also changed towards species that could not deliver sufficient amounts of the required minerals. Thus, the delicate balance between the animal and its environment was broken, the probable cause of this animal's extinction. Some have suggested hunting by man is a contributing factor in the demise of Megaloceros giganteus, but most paleontologists now believe that the last animal died off about 10,600 years ago, over a millennium before the first humans arrived.

A significant collection of Irish Elk skeletons can be found at the Natural History Museum in Dublin.

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