Since Miguasha fossils were first discovered, they have been universally recognized for the remarkable quality of their fossilization. This feature was a supporting argument for granting Miguasha the title of UNESCO World Heritage Site, and is in large part due to the extraordinary environment of preservation that prevailed in this Devonian estuary.

The environment was characterized by two crucial factors: fairly oxygen-poor water and a large amount of sediment deposited on the estuary floor. Once settled on the bottom, any organism – a fish or plant, for example – would quickly be covered by a thin layer of sediment. This rapid burial had two favourable consequences for fossilization. First, it swiftly isolated the organism from its environment, making it inaccessible to scavengers and the action of water currents. Next, the already oxygen-poor conditions were made even more so because of the reduced gas exchange between the sediments and the water above. And so began the process of fossilization in this environment of exceptional preservation.

Direct evidence for the low oxygen content of the sediments also comes from the abundance of pyrite in Read More
Since Miguasha fossils were first discovered, they have been universally recognized for the remarkable quality of their fossilization. This feature was a supporting argument for granting Miguasha the title of UNESCO World Heritage Site, and is in large part due to the extraordinary environment of preservation that prevailed in this Devonian estuary.

The environment was characterized by two crucial factors: fairly oxygen-poor water and a large amount of sediment deposited on the estuary floor. Once settled on the bottom, any organism – a fish or plant, for example – would quickly be covered by a thin layer of sediment. This rapid burial had two favourable consequences for fossilization. First, it swiftly isolated the organism from its environment, making it inaccessible to scavengers and the action of water currents. Next, the already oxygen-poor conditions were made even more so because of the reduced gas exchange between the sediments and the water above. And so began the process of fossilization in this environment of exceptional preservation.

Direct evidence for the low oxygen content of the sediments also comes from the abundance of pyrite in the sedimentary layers. This mineral, commonly known as “fool’s gold”, consists of sulphur and iron, and only forms in oxygen-poor environments. At Miguasha, pyrite is often found on the bodies of fossilized organisms.

© Miguasha National Park 2007

Juvenile fish in the Escuminac Formation

The young fish of several Miguasha species were discovered in large numbers within a layer of the Escuminac Formation in 2006. A school of alevins was trapped by the sudden arrival of sediment in a turbulent current. E: Eusthenopteron foordi; S: Scaumenacia curta.

Miguasha National Park
2006
© Miguasha National Park


Blood vessels

These blood vessels left their mark on the ventral internal surface of the thorax in a specimen of Bothriolepis canadensis, a placoderm fish. The blood vessels converge toward a dark central zone that represents the heart region.

Miguasha National Park
2003
© Miguasha National Park


<i>Bothriolepis</i>

Bothriolepis

Miguasha National Park

© Miguasha National Park


Learning Objectives

The learner will:
  • identify and classify different types of fossils;
  • explain the stages of fossilization and the best conditions to create and preserve fossils;
  • make assumptions about the evolution of living beings;
  • make assumptions as to the explanation of the disappearance of some species.

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