Logging Tasks and Introduction

This Earthcache brings you to the National Museum of Ireland - Natural History. When you walk in the entrance you will be greeted by 3 giants. Choose any one of these as your specimen for the following tasks - which you will send to me.

1. These specimens are all found in Ireland. Given that fossils need to be at least 10,000 years old, could you consider these specimen fossils? Why?
2. Are you looking at body fossils, cast/mold fossils or trace fossils?
3. Are the fossils here petrified via permineralisation or replacement?
   • Can you see any "meat" being petrified? Where?
4. Attach a photo to your log to prove your visit in case of unsatisfactory answers.

Giant Irish Deer

The Irish elk (Megaloceros giganteus), also called the giant deer or Irish deer, is an extinct species of deer in the genus Megaloceros and is one of the largest deer that ever lived. Its range extended across Eurasia during the Pleistocene, from Ireland (where it is known from abundant remains found in bogs) to Lake Baikal in Siberia. The most recent remains of the species have been radiocarbon dated to about 7,700 years ago in western Russia. Its antlers, which can span 3.5 metres (11 ft) across are the largest known of any deer. It is not closely related to either living species called the elk, with it being widely agreed that its closest living relatives are fallow deer (Dama).

The earliest fossil record of the giant deer is from 400,000 years ago and the last fossil record is from 8,000 years ago. It is thought the species probably slowly died out due to a changing climate. 

The first wave of extinction for the giant deer was around 12,000 years ago when it disappeared from Ireland, Britain and most of Europe. During this time, at the end of the Ice Age, the climate became very cold and severe, and food for the deer would have been very scarce.

The added pressure of having to find enough food to grow their enormous antlers might have made it difficult for the deer to adapt and survive.

But this period wasn't the end of the story for the giant deer. After carbon dating a fossil bone collected from Central Russia, researchers found that there was one remaining enclave of this species living there until around 8,000 years ago.

Turning into Stone (Fossilisation)

Strictly speaking, a fossil needs to be at least 10,000 years old. There are a variety of fossil classifications:

1. The actual organism (body fossils)
2. A hollow imprint or one that is later filled in (cast/mold fossils)
3. Evidence of the organism (Trace fossils, these can be nests, footprints etc.)

There are also many ways that a fossil can be created, for this Earthcache let us focus on petrification, which is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals. Petrified wood typifies this process, but all organisms, from bacteria to vertebrates, can become petrified (although harder, more durable matter such as bone, beaks, and shells survive the process better than softer remains such as muscle tissue, feathers, or skin).

Two types of petrification:

1. Permineralisation - a process where minerals fill in the spaces and cavities of the organic matter.

2. Replacement - a process where the organic matter is slowly replaced by another mineral.