Bothriolepis yeungae is an extinct placoderm of the Late Devonian period (~360 Mya). It had a heavily armoured body and distinctive spine-like pectoral fins and grew up to 500 mm in length.

Bothriolepis was a member of the order Antiarchi (gk. opposite anus).  Although antiarchs probably had limited upper body mobility it is clear they still had the ability to traverse widely through the water column as their remains have been found across the world.

Bothriolepis is also thought to have been anadromous - mostly living in a marine saltwater environment but spawning within sheltered fluvial freshwater environments (Downs et al. 2011) - similar to modern salmon. This would further explain its wide distribution.

Despite its heavy armour Bothriolepis is not considered to have been an overly active predator. This is because it had such a small ventral mouth. Instead it is thought to have been a benthic detritivore that ate plant material and small invertebrates by filtering sediment.

Bothriolepis anatomy from Paleozoo Evolutionary Models by Bruce Currie

The distinctive pectoral limbs of Bothriolepis were probably used to lift the body clear of the bottom or to sweep sediment over itself as camouflage. More contentiously it has been speculated that these fore-limbs could have been used to drag Bothriolepis out onto open tidal flats in much the same way as modern mudskippers. In support of this hypothesis, signs of ventral oesophageal sacs in some remains have been interpreted as possible rudimentary lungs (Janvier et al. 2010). However as almost all Bothriolepis fossils are associated with marine environments rather than tidal margins it is thought unlikely that they developed and used rudimentary lungs to venture onto land (Goujet, D. 2011).

Bothriolepis was the most successful genus of any placoderm and its remains have been found right around the world with some of the most notable deposits in Canowindra, NSW,Australia. 

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With thanks to Dr Alex Ritchie for assistance with anatomical detail.