01 March 2011

Fossil Vertebrate of the Month: Megaloceros giganteus

As my readers are no doubt aware, St. Patrick's Day is this month, and in honor of that March's fossil vertebrate is the extinct animal most strongly associated with Ireland: Megaloceros, the Irish elk.  It's common name, as famously observed by Stephen J. Gould, is a double misnomer, as Megaloceros was not exclusively Irish (it's remains have been found across Eurasia) and while it is a cervid (the largest ever known, in fact), it is not particularly closely related to elk.  However, the earliest specimens to be described were uncovered from Irish bogs, which still yield some of the most impressive Megaloceros fossils.  Because of this, the Irish elk remains something of a national symbol of Ireland, with its remains adorning museums, universities (such as the pair at left from Dublin's Trinity College), and castles alike.  The outsized antlers of Megaloceros males have, unsurprisingly, been the focus of a great deal of research.  Whether they were the product of sexual selection, allometric growth, or some combination of the two has been an area of debate, as has been their role in the animals' extinction.  A long-standing (but somewhat fanciful) hypothesis held that Irish elk went extinct when forests overtook the more open habitats to which they were adapted and that their large bodies and antlers made life in a closed environment impossible.  A more likely culprit is changing climate that ushered in flora that were nutritionally insufficient to support healthy populations of large, antlered animals such as Megaloceros.

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