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Finding Frozen Fossils in Antarctica

By John Long

Antarctica throws up some challenges to paleaontologists attempting to excavate and return fossils that may tell us if tetrapods first evolved in Gondwana.

On the eve of my third fossil-collecting expedition to Antarctica, which departs for McMurdo Station in December, I thought I’d reflect on the daily routines and hazards of working as a palaeontologist on the frozen continent.

My last expedition there was over the summer of 1991–92. I went with a New Zealand party, aided by US air logistics. We searched the mountains around the Darwin Glacier, then moved north to the Skeleton Névé, where earlier expeditions had recovered very well preserved Devonian fish fossils.

The trip was fraught with unexpected hazards, mostly because we traversed some 700 km of largely unexplored territory, using skidoos pulling Nansen sledges loaded with our camping gear, food and supplies. At times we found ourselves caught in the midst of crevasse fields, and had to slowly pace our way out using a crevasse probe to determine a safe path out of the immediate danger. Other times we were subjected to minor avalanches from the snow-laden cliffs above us, or near misses stepping over crevasses covered by thin ice bridges. Luckily we all survived.

Such exploits were also commonplace for the early heroic explorers on their first deep-field ventures into the remote heart of the continent. But we go there to explore areas and find fossils where few people ever get the chance to venture. This gives us access to extraordinarily rich sites where no soil or plant covering hides the fossil beds, so it’s a matter of selecting which fossils are worth collecting, and which can be carried down the mountains on our backs.

Collecting fossils in Antarctica can be somewhat of a challenge compared with regular dig sites. First, the rocks and fossils are generally exposed in high mountainous regions that sit above or beside the high polar plateau, which is up to 2.7 km thick in places. Access can be difficult, requiring the services of a trained mountaineering guide to find safe routes from the base camp up the mountain to reach the fossil sites. Then we need time to search the exposed rocky outcrops to find the most significant fossils.

This requires good weather, and it’s always at the back of our minds how the weather can change for the worse quickly. This means that emergency preparations are necessary if the sites are a 3–4-hour hike away from the base. In such cases we would hike up the mountain with a spare tent, extra food, stove and fuel in case an overnight emergency camp is required should storms suddenly close in.

Finally, once we find our prize fossils, we need time to excavate them from the rock using hammers and chisels. As we are dealing with rocks at subzero temperatures, regular glues and consolidants may not set, so care must be taken not to break the specimens. As with Murphy’s Law, often the best specimens are in the centre of large slabs of very hard sandstone or shale. The art of excavating such fossils comes down to having the patience and good sharp tools to slowly dig them out.

Our expedition this year is led by Prof Neil Shubin of The University of Chicago, whose team announced to the world the tetrapod-like fish Tiktaalik in 2006. We will be searching for Tiktaalik-like ancestors of the first land animals in the Devonian rocks of Antarctica, and hope to test the idea that tetrapods may have first evolved in Gondwana.

We are funded for two field seasons, and will be returning to the central Transantarctic Mountains again in late 2018. Hopefully what we find there will add new knowledge to our current theories about tetrapod origins and the ancient environments where they lived.

More to come, after the field work.

John Long is Strategic Professor in Palaeontology at Flinders University, and current President of the Society of Vertebrate Paleontology.