Fossils play an important role in our understanding of life on Earth. Studying past climate change and mass extinction events can tell us a lot about how species evolve and recover following dramatic change. For instance, Antarctica was not always the icy, inhospitable place it is today. The discovery of land-living, backboned animals in 251-million-year-old Triassic rocks tells us that a wide variety of life once existed on the continent. This has led to a deeper understanding of the evolution of life at high latitudes as well as how Antarctica’s climate has dramatically warmed and cooled.
Approximately 250 million years ago during the Triassic period, Antarctica was part of the supercontinent of Pangea.
During this time, all of the continents were assembled into a large and continuous land mass that was free of polar ice and all of the oceans were combined into one large oceanic mass (Panthalassa).
Pangea drifted slowly northwards during the Triassic until the supercontinent began to divide in the Early Jurassic (about 180 million years ago).
Collecting fossils in Antarctica
In December 2010, a team of paleontologists from the Burke Museum of Natural History and Culture in Seattle, Washington, traveled to Antarctica to collect 250-million-year-old fossils from the Triassic period. Antarctica can be a challenging place to collect fossils. The freezing temperatures mean that most glues don’t work and the plaster typically used to cover fossils during the removal process often won’t set. (The solution? Wrap the fossils in duct tape!) Some of the unique challenges of fieldwork in Antarctica start even before you arrive on the continent.
LC-130 Hercules by Brandon R. PeecookThe Burke Museum of Natural History and Culture
Months prior to the expedition, team members underwent rigorous equipment and survival trainings to prepare for the difficult conditions.
When departure day arrives, the team boards a U.S. Air Force Air National Guard plane in Christchurch, New Zealand, for the flight to Antarctica. This photo shows a LC-130 Hercules, which is a ski-equipped cargo plane that can land on a snow runway.
McMurdo Station by Brandon R. PeecookThe Burke Museum of Natural History and Culture
Most researchers working in the Transantarctic Mountains begin their journey at McMurdo Station, the primary base of the U.S. Antarctic Program. The population of McMurdo can reach upwards of 1,000 people during the austral summer, but goes down to about 200 during the long, dark polar winter.
CTAM camp by Roger M. H. SmithThe Burke Museum of Natural History and Culture
After leaving McMurdo Station, the team headed to the Central Transantarctic Mountain (CTAM) base camp where they were based for nearly two months. The CTAM base camp hosted up to 80 scientists researching a wide variety of subjects, such as geology, geophysics, glaciology, atmospheric sciences, and even microscopic organisms that are found exclusively near the south pole.
Start of fossil excavation by Roger M. H. SmithThe Burke Museum of Natural History and Culture
One of the biggest misconceptions about fieldwork in Antarctica is that paleontologists dig through snow and ice to get to rock—thankfully, this is not true! Depending on the time of year and prevailing winds, large areas of rock outcrops can be exposed. In this photo, Brandon Peecook is seen examining a fossil still in the rock.
Helicopter ride by Roger M. H. SmithThe Burke Museum of Natural History and Culture
Fossil and brush by Roger M. H. SmithThe Burke Museum of Natural History and Culture
The team spends each day recording the geology, searching for fossils, and excavating any important finds. The sun doesn’t set during December and January, so a day of work could last a long time!
This is what a fossil looks like at the moment of discovery. Would you be able to recognize it? The white area below the brush is part of the mandible of a giant temnospondyl. Once fully excavated and then prepared, these jaws turned out to be almost a meter long.
Fossil excavation by Roger M. H. SmithThe Burke Museum of Natural History and Culture
Antarctic rocks are especially hard due to the lack of liquid water that causes chemical weathering. For that reason, and to speed up the excavation process, the Burke team relied on a diamond-bladed rock saw to cut fossils out of the ground.
Each fossil discovery is recorded in a field notebook. These field notes are critical to capture details about where, when and how a fossil was discovered along with its extraction. This shows a Lystrosaurus fossil that was visible in the rock.
This is the Lystrosaurus fossil that was sketched in the field notebook. On the left is visible some of the vertebral column and ribs, whereas on the right are the forelimbs.
To remove the fossil, they cut a border around it with the rock saw and then drive large chisels underneath the fossil to “pop” it out (along with a slab of rock).
In this case, the “pop” didn’t go according to plan. It turns out that there was a skeleton of a completely different animal, Prolacerta, underneath the Lystrosaurus. We’ll go more into this interesting specimen later...
Transporting a fossil by Roger M. H. SmithThe Burke Museum of Natural History and Culture
All of the fossils and rock samples get carried back to the helicopter landing area, which can sometimes mean a long haul across difficult terrain. Having graduate students can come in handy—pictured are Brandon Peecook and Adam Huttenlocker.
At the museum: the real work begins
Collecting fossils can be exciting, but it’s really only the first step in a long process before a fossil can make a contribution to scientific knowledge. In most cases, the fossil will need to be freed from the rock encasing it. This process can take months, as a museum technician works under a high-powered microscope and uses a miniature jackhammer (known as an airscribe) to carefully remove the rock. After that, the fossil will typically be compared to other similar museum specimens to determine if it belongs to a previously recognized species, or if it represents a new species.
Lystrosaurus was a dog-sized herbivore and are the most common vertebrate remains found in the lower Fremouw Formation. Lystrosaurus fossils have also been discovered in South Africa, China, Russia and possibly Australia, meaning that the species was extremely widely dispersed. In fact, this broad geographic distribution is one of the pieces of evidence of the supercontinent of Pangea.
This illustration depicts what Lystrosaurus (top, right) and Thrinaxodon (bottom, left), a cat-sized animal that likely fed on insects and other invertebrates, might have looked like in life.
Lystrosaurus skull (2016-04-13) by Nikki MacgregorThe Burke Museum of Natural History and Culture
The space is where the eye would be in life. A recently published analysis suggests that, based on the size of the eye socket (orbit), Lystrosaurus was active during daylight hours.
Lystrosaurus teeth are often referred to as tusks, because like tusks in elephants, they are ever-growing, made entirely of dentine, and have a distinctive cone-in-cone structure.
Here you can see the tree ring-like structure of the tusk of Lystrosaurus. The alternating bands of light and dark represent periods of relatively fast and slow growth.
Prolacerta (2016-04-13) by Cathy MorrisThe Burke Museum of Natural History and Culture
This is a slightly jumbled skeleton of the second fossil that was found directly underneath the Lystrosaurus specimen in the earlier field excavation photos. It belongs to the early dinosaur relative, Prolacerta.
Prolacerta was lizard-like in its size and overall body shape, but details of its anatomy point to it being more closely related to crocodiles and dinosaurs.
The skull of Prolacerta was quite delicate and easily disarticulated. You can see some of the small, needle-like teeth in the jaws.
These small, rod-like elements are called gastralia, but are more commonly known as “belly ribs.” Living vertebrates, crocodilians and the lizard-like tuatara all have these gastralia.
These are the bones of the left hind limb, including the femur, tibia, fibula and ankle bones.
Today, the Antarctic fossils are part of the Burke Museum’s paleontology collection where we care for more than three million fossil vertebrates (animals with a backbone), invertebrates (animals without a backbone), plants, microfossils and trace fossils.
They are organized in large cabinets and are available to researchers around the world to study.
Beardmore Glacier region by Brandon R. PeecookThe Burke Museum of Natural History and Culture
The fossils discovered in the 2010-11 expedition help us to better understand what animals once thrived in Antarctica’s warmer climate and how they were affected by climate change and mass extinctions over time.
The Burke team is planning to return to Antarctica in 2017-18 to the Shackleton Glacier area, which was last explored by paleontologists more than 30 years ago. This is an exciting opportunity to uncover even more fossils that shed light on how animals relate to each other worldwide and diversified over time.
Christian Sidor’s research on the Antarctic fossil record has been supported by several grants from the National Science Foundation (NSF-PLR 0551163, PLR 0838762, PLR 1146399). Team members for the 2010-11 field season were Adam K. Huttenlocker, Brandon R. Peecook, and Roger M.H. Smith.
Exhibit created by Christian Sidor and Cathy Morris, Burke Museum of Natural History and Culture.