Expedition Greenland: chasing evolution

Approximately 370 million years ago, land-living vertebrates, so-called tetrapods, left the oceans for a life on land as their fins evolved into hind- and forelegs. Around 120 million years later, those same legs once again gave way to fin-like structures, and so the tetrapods returned to a life fully aquatic.

‘Both these evolutionary adaptations can be directly traced in the fossil record, and they have taught us much about how structural and functional changes correlate with varying environmental conditions. But we are still largely in the dark as to what ecological mechanisms underpin these extensive changes’, Henning Blom says, senior lecturer at the Department of Organismal Biology at Uppsala University, and one of four members of the expedition (which will also include colleagues from the same department, the Museum of Evolution at Uppsala University and the Swedish Polar Research Secretariat).

The expedition enjoys operative support from the Swedish Research Council and the Swedish Polar Research Secretariat, and the goal is to examine and collect material from new and classic sites on Greenland over two seasons. Swedish researchers discovered the fossilised remains of early land-living tetrapods there in the 1930’s.

The project, entitled (in Swedish) “Onto land and back in the water: a study of the ecosystems of aquatic tetrapods in Greenland”, concerns itself with East Greenland, one of the scant few areas in the world where fossils of the aforementioned and usually temporally separated groups of aquatic vertebrates can be found, both fish and tetrapods. These sites are also suitable for studies on how changes in biological diversity relate to the ecosystem at large.

‘This includes the mass extinctions between the Devonian and the Carboniferous and between the Permian and the Triassic, two of the most catastrophic events in natural history’, Henning Blom says.

Follow the expedition online

The researchers will write about their work in a blog, where everybody can follow the progress of the expedition. Update 5 August: The expedition is having some technical difficulties with its satellite connection, making blogging difficult at the moment. However, the expedition members remain hopeful that the issue will be resolved soon.

More on the expedition

The group will fly out from Sweden on 28 July, first to Iceland, then Greenland using specially chartered Twin Otters aircraft, which are able to land at relatively inaccessible locations. For the final stretch to Kap Stosch at Hold With Hope, travel by helicopter is required. The expedition will make camp for around two weeks, before the journey goes on to Celsius Bjerg on Ymer Ø. The researchers will return to Sweden on 28 August.

At Kap Stosch, as-of-yet unexamined findings of marine amphibians and amniotes have been described. There, a detailed sampling of the sedimentary layers will be carried out in order to examine the connection between body shape and ecology, as well as investigate how fauna were affected by the succession of extinctions. The fossil gathering will focus on performing geochemical analyses and the correlation between body shape and ecology in the earliest marine tetrapods.

At Celsius Bjerg, the researchers will conduct systematic sampling and detailed studies of trace fossils as well as methodically collect tooth elements for geochemical studies of the various natural environments. In addition, sea sediments that are unique in their representation of the transition between the Devonian and the Carboniferous will also be analysed.