Name: Gogo Formation.
Location: The Kimberley, NW Australia.
Age: Upper Devonian, Frasnian. 350 million years.
Fossil Lagerstatten title logo


Taphonomy

The Gogo Reef Formation fossils are found within calcareous nodules. In the Late Devonian the barrier reef had areas within the atoll, or on the periphery, which were deeper and slightly anaerobic (dysaerobic). After death the specimens settled down in these regions, away from scavenging creatures, and were slowly covered by sediment. These sediments are the shales within the Gogo Formation limestones. The carcasses acted as heterogeneities (areas of difference) within the sediments for fluids to move and form the calcareous concretions around the bones. These nodules are very hard compared to the surrounding fissile shale and the limestones of the reef. The nodules preserve the three dimensionality of the specimens. Acid etching of the nodules was used to extract the fossils. This lagerstatte preserved the palaeobiology of the placoderm head shields including nerve pathways and the olfactory systems.

 Fig 1.Fig 2.
 Fig 1. Dr J. Long in the Gogo formation surrounded by nodules. Fig 2. Close-up of a nodule prior to acid etching. Courtesy of Dr J. Long.


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