SMU Earth Sciences, Antarctica

Earth Sciences master’s student Chris Strganac, doctoral student Yosuke Nishida and Professor Louis Jacobs are part of a team traveling to Antarctica to discover 120 million-year-old mammal fossils from Livingston Island and other places around the Antarctic Peninsula.
They hope to link the evolutionary history of mammals across South America to Africa and Australia through ancient Antarctica when climates were warmer. So far in their journey, as chronicled by Chris, they have found ancient plants, but mammal remains have been elusive. They are still looking…

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On to Seymour Island

Chris-photo4.jpgThe weather seemed to get clearer and nicer as we left Livingston Island. As we approached Seymour Island, the increasing ice in the sea slowed the LMG’s progress, but the weather still seemed fair.

Seymour Island is just east of James Ross Island in the Weddell Sea and is nearly surrounded by sea ice for most of the year.

Unlike Livingston Island, the fossil-bearing rocks record younger times on Earth, just before the K-T boundary at 65 million years ago to the opening of the Drake Passage between 40 million and 30 million years ago.

Prior field work on Seymour has yielded collections and publications on mammal fossils from this island. These mammals were preserved in offshore sediments, not the typical place you would find terrestrial mammals. We realize finding a mammal fossil will take work and much luck.

Strong winds and snow
We reached Seymour Island the afternoon of December 11. Most of Seymour Island’s coast was bound by sea ice, making landing possible only on the northern coast.

We approached Seymour by Zodiac with strong headwinds blowing in our faces (of course!). These winds send subfreezing water, thanks to high salinity, in our face with each splash. It didn’t take long for our cheeks to feel numb. As we reached the island, the winds became stronger, and the haze turned to snow. After our landing we embarked on a 3-mile hike to find the mammal sites.

The rock exposures, once bare when we were in the Zodiacs, quickly were being covered by snow. As we hiked, the weather seemed to get worse. After a mile or so we stopped to prospect for fossils. Despite the weather and snow cover, this was the best opportunity to find fossils thus far, and we did find fossil bones.

Chris%20-photo7.jpgFossils! …
Chris Denker found a fossil toe bone within minutes of our stop. At first, we thought Chris had found a mammal bone. After a few more bones were recovered, we realized the fossils were not from mammals, but very large penguins. Bird bones typically are hollow, but penguins, being land and sea bound, do not have hollow bones.

After a few hours of collecting and pretty poor weather conditions, we headed back. A mummified crab eater seal was testimony to the typically dry and harsh conditions.

The next few days the weather improved. We had sunny days … days in which the burns on some were good testament to the hole in the ozone layer. The scenery around us included completely ice-choked seas to James Ross Island, beautiful cirrus clouds and the Antarctic Peninsula mountains off in the distance. After a climb up, the bright-orange LMG looked bite-size to the floating ice around.

.. Or penguin bones and shells
Each day, we left the LMG by Zodiac and hiked 3 miles to potential sites (where mammals had been found by prior expeditions). A troop of Adelie penguins would greet us on the return to the shore after the hard day. Each day we returned to the LMG with more penguin bones that we tried (and hoped) to see as mammal bones.

Chris-photo5.jpgWe had only a few days of field work left and no mammal bones to show yet. Surface prospecting was complicated on Seymour – not by snow as on Livingston, but by the tremendous volume of broken mollusk and bivalve shells eroding out. With each step on Seymour we saw numerous bone-looking shell fragments. We needed to be able to reduce the amount of shells, which we did by screen washing.

On our last day we collected 15 large sample bags of matrix. After washing the matrix through screens (and dried in the sediment dry sauna on the LMG), these will be shipped to SMU. We will slowly look through the matrix, grain by grain, with the aid of microscopes, for rodent-sized mammal bones and teeth. The discovery of ancient mammals in Antarctica may be done at SMU.

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