Saturday, March 16, 2013

Megaloceros: Prehistoric Animal of the Week

Today, in honor of Saint Patrick's Day, we shall be getting familiar with a prehistoric mammal that once called Ireland home.  Megaloceros giganteus, or as its commonly referred to, the "Irish Elk", was the largest deer to ever walk the earth, measuring almost seven feet tall at the shoulder and having antlers measuring twelve feet wide.  They lived not only in Ireland but across most of Europe and Asia during the Pleistocene era alongside mammoths and early humans.  The youngest known Megaloceros specimen is 7,700 years old.  Despite its common name, Megaloceros is more more closely related to modern deer than to elk.

Life reconstruction of Megaloceros giganteus by Christopher DiPiazza.

There is much debate surrounding why the Irish Elk's antlers were so large.  The most likely answer is probably sex (Honestly, when has sex ever not complicated things?).  Like most species of animals with antlers, it is likely that only male Megaloceros had them  (Only exception is the modern Reindeer where both males and females have them).  Sexual selection probably pressured the males to evolve more impressive antlers over time to attract the females and intimidate rival males.

Megaloceros skeleton at the Natural History Museum in Dublin, Ireland.

Some scientists proposed that the huge antlers may have been the animal's ultimate demise as well.  This was proposed for a few reasons.  The first is that the antlers were believed to be too wide and thus, towards the end of the ice age when there were more trees and foliage growing, made it difficult for male Megaloceros to maneuver in their environments.  Another hypothesis is that the antlers became too expensive to maintain.  Allow me to explain.  Antlers, unlike horns which are part of an animal's skull, are shed off and regrown every year.  In order to grow such large structures within a period of just a few months, the animal must consume more nutrient-rich food.  Modern deer have even been observed and documented killing and eating other animals (yup, predatory deer) to supplement their diets during this rapid growth stage.  Don't believe me?  Check out this video.  Also notice that the deer is in the process of growing a new set of antlers.



So imagine how much nutrient rich food, plant or animal, Megaloceros must have needed to get in order to maintain itself during this time.  Now imagine the dilemma it must have faced when its environment, including its food sources, suddenly changed at the end of the ice age.  Uh oh!  The bigger they are the harder they fall.  The last hypothesis about their extinction is common for most large animals that lived during the end of the Pleistocene; over hunting by humans.  We know that our ancestors must have hunted them sometimes thanks to Megaloceros appearing in cave paintings but there is really no solid evidence that humans were the cause of their extinction.  In fact, nobody still knows for a fact why Megaloceros went extinct.  It may have been none of these theories or it may have been a combination of more than one of them.

Cave painting of Megaloceros.  Must have been by one of Tim Burton's early ancestors. 

Thats all for this week!  Happy Saint Patrick's Day!  As always if you have a request just comment below or on our facebook page!

References

Gould, Stephen J. (1974): Origin and Function of 'Bizarre' Structures - Antler Size and Skull Size in 'Irish Elk', Megaloceros giganteus. Evolution 28(2): 191-220. doi:10.2307/2407322 (First page text)

 Moen, R.A.; Pastor, J. & Cohen, Y. (1999): Antler growth and extinction of Irish Elk. Evolutionary Ecology Research 1: 235–249. HTML abstract

Stuart, A.J.; Kosintsev, P.A.; Higham, T.F.G. & Lister, A.M. (2004): Pleistocene to Holocene extinction dynamics in giant deer and woolly mammoth. Nature 431(7009): 684-689. PMID 15470427 doi:10.1038/nature02890 PDF fulltext Supplementary information. Erratum in Nature 434(7031): 413, doi:10.1038/nature03413

 "Scottish Deer Are Culprits in Bird Killings." National Geographic. National Geographic Society, n.d. Web.

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