Last updated June 20, 2017 at 1:21 pm
Understanding the prehistory of Antarctica is an important aspect of knowing why this continent is like it is today. For most of its long history it was a verdant continent teaming with a diverse range of life. It began its ‘big freeze’ going from ‘paradise to polar ice’ immediately after the last remnants of East Gondwana split up. This event occurred about 38 million years again as Australia split from Antarctica.
The rift shut down Antarctica’s life-supporting warmer currents from the north. Once the circum-Antarctic current locked around it, it began getting colder and colder until it ended up as it is today. The last forests on the mainland of Antarctica vanished about 7 million years ago. You can read more on the prehistory of Antarctica in this recent book.
I’ve been down there now three times searching for the remains of ancient fishes that once lived in large river and lake system in Antarctica about 390 million years ago (the Devonian period). The first two expeditions were with New Zealand support, back in 1988 and 1991, and last summer I was working with team of US scientist supported by the NSF program.
We spent 3 months there on the 1991/92 deep field expedition, after being air-lifted by C130 Hercules to land on the Darwin Glacier at 80S. From there we sledged with skidoos through remote parts of the Transantarctic Mountains mapping the geology and exploring for fossils. Much of the terrain we traversed was unknown territory, never before visited by people, so we had a lot of challenges pioneering a new route up the McCleary Glacier and climbing mountains for the first time to map the geology and search for fossil fishes.
At times we faced challenges that threatened our survival. There were avalanches in the mountains, and at times we found ourselves sledging into dangerous crevasse fields. Every day was either a high of scientific discovery or one of serious challenges to get to where we needed to be. Furious katabatic storms would halt our travel on some days, or keep us tent bound for several days on end at some camp sites. I wrote a memoir on these expeditions outlining the day to day activity of a deep field scientist working in Antarctica.
We emerged with an excellent collection of ancient fish fossils belonging to a great diversity of fish types, from jawless fishes through to powerful lobed finned bony fishes. The majority of finds were of extinct armoured fishes called placoderms. Many of these turned out to be new species that show close links to the ancient drainage systems of Australia, as the two continents were joined at the time in a region called ‘East Gondwana’. These included a range of new species of fossil sharks, studied from their teeth and fin spine remains, and these were amongst the largest sharks known at this time anywhere (some might have been 3 m long).
In the mid1990s, I participated on a series of expeditions collecting Devonian fishes South Africa and was able to find a similar fauna of fossil sharks there, linking southern Africa to the East Gondwana fish assemblage.
The most recent trip (2016/17) was supported by United States Antarctic program (USAP) through a grant awarded to Prof Neil Shubin at the University of Chicago. Today things have changed a lot with respect to safety and logistical support. We were air-lifted by helicopters to our field sites, then moved by helicopter to new sites when we were finished collecting.
We explored the upper Dry Valleys Devonian outcrops at Mt.Fleming and the type section for the Aztec Siltstone at Mt. Aztec and Mt.Maya over 3 weeks. Again we collected many fine fossil specimens, most are now awaiting preparation and further detailed study. The trip was much safer overall and was run smoothly through the many courses and preparations now required before being dropped into the remote field localities. For a taste of the scenery the New York Times have a fantastic 360 degree video to replicate the experience of a helicopter ride through the McMurdo Dry Valleys, one of the most extreme environments on Earth.
Join Prof John Long, along with Director of the Royal Institution and Antarctic eco-tourism guide Dr Paul Willis and author and 2017 Antarctic Arts Fellowship recipient Sean Williams, as they share their perspectives on the continent that has captured the minds of explorers for generations at a free event Antarctica: Past, Present and Future at The Science Exchange Wednesday 21 June 2017, Bookings essential.
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