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The Fossils

Bothriolepis yeungae Johanson 1998

Pronunciation: Both-ree-oh-lee-pis young-ee
Translation: "Yeung's pitted scale"
Named after the pitted ornament of the bony plates, and after Monica Yeung, Gondwana Dreaming Canberra, who helped to organise volunteer groups to prepare the Canowindra fossil discoveries.
Period: Late Devonian (360-70 million years ago)
Description - small mud-eating armoured fish
Length - up to 50 cm

Class - Placodermi ('plated-skin' - the armoured fishes)
Order - Antiarchi (armoured pectoral fins)
Family - Bothriolepidae ('the family of Bothriolepis')
Genus - Bothriolepis
Species - Bothriolepis yeungae

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In the Devonian

Bothriolepis was the most successful of all the placoderms. More than 100 species have been described and the genus is found on every continent. Bothriolepis seems to have spent most of its life in fresh-water rivers and lakes, as most fossils are found in fresh-water sediments, but some Bothriolepis species lived in marine conditions and have been found in Late Devonian reef deposits (eg. at Gogo in the Kimberleys of Western Australia) which helps explain their world wide distribution.

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Bothriolepis yeungae was a very common fish in Canowindra's ancient lake - more than 1700 specimens have been counted so far. The weak structure its mouth suggests that it fed on algae and other microorganisms. Its long, stiff bony fins may have provided enough hydrodynamic lift for the animal to 'take-off' from the lake-bottom and regularly swim in mid water. Its bony armour probably provided Bothriolepis with some protection from the lake's predatory fish, at least when more fully grown.

Superficially, smaller placoderms like Bothriolepis resemble modern 'armoured' cat-fishes from South America (although the two are not related). These bottom-dwelling catfish live on nutrient rich muds and algae, but the resemblance is indeed superficial and is probably a result of similarity in ecology and lifestyle.