Tropical trilobites from frozen Greenland

Collecting fossils in the snow
Collecting fossils in the snow. 1950s.
Aerial Photo of Greenland
Aerial Photo of Greenland: The fossils were collected from the area shaded in red.
Large fossilised eye
The large fossilised eye of Carolinites, a trilobite which swam in the open ocean searching for food.
The tail of the trilobite <em>Acidiphorus</em> has an impressive spine.
The tail of the trilobite Acidiphorus has an impressive spine.

The Museum's extensive holding of fossils include a collection of Ordovician age (470-490 million years old) trilobite fossils from Greenland. Although the continent is now cold and icy, it was not always so.

British explorers in the icy north

Greenland is a very difficult place in which to study and collect fossils. Most of it remains ice-covered throughout the year, and rock outcrops are readily accessible only in coastal areas during the summer months.

Expeditions to explore the geology of Greenland began in the late nineteenth century, and continue to the present day. These have been organised by the Greenland Geological Survey, based in Copenhagen.

In the 1990s, the Museum was presented with a collection of Cambrian and Ordovician trilobites from central east Greenland made between 1950 and 1954 by Dr John Cowie, formerly of the University of Bristol, and a colleague, Dr Peter Adams.

Globe-trotting Greenland

Today, we are familiar with Greenland as a cold, icy place, but this has not always been the case. The tectonic plates that make up the Earth's lithosphere have moved around throughout its history, and geologists have demonstrated that during the Ordovician Period Greenland lay close to the equator, and together with North America and Spitsbergen formed the ancient continent of Laurentia.

At this time, Wales lay far away in cool, high southern latitudes, close to the vast continent of Gondwana. The fossil faunas of the shallow Ordovician seas around Laurentia and Gondwana are very different, and no trilobite species is common to Greenland and Wales.

Earth during the early Ordovician Period, 490 million years ago
Earth during the early Ordovician Period, 490 million years ago

Tropical trilobites new to science.

The Ordovician trilobites of Greenland are preserved in limestone which accumulated on the floor of warm, shallow sub-tropical seas. Around forty different species have been identified in our Greenland collection, and several are new to science. Research has confirmed they are common to, or closely related, to those from other parts of Laurentia.

Features of different trilobite species provide clues as to how they lived. Most were probably benthic (living on the sea floor), and were either scavengers or deposit feeders. Others have features such as very large eyes, showing that they were pelagic (swimmers); such forms were widely distributed in the Ordovician oceans, and found in other tropical regions apart from Laurentia.

Article by: Lucy McCobb, Senior Curator, Palaeontology

Article Date: 5 August 2009

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Glossary

Lithosphere
The outer part of the earth, consisting of the crust and upper mantle

Trilobite
An extinct group of arthropods that lived in the seas from the Cambrian Period (520 million years ago) to the end of the Permian Period (250 million years ago). Their name comes from division of their body into three lobes.

Limestone
A sedimentary rock made mostly of calcium carbonate (lime), and often containing the shells of marine organisms.

Tectonic plates
The large rigid blocks that make up the Earth's lithosphere. These move around very slowly relative to each other, changing the map of the world over hundreds of millions of years.

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