Barwickosteus antarcticus was named by Young and Long (2014) [A phlyctaeniid of small size with a trunk-armour characterised by a broad pectoral embayment, spinal margin length ~65% of AVL width, and angle between ventrolateral ridge and spinal margin of nearly 50
; spinals diverging ~30
from the midline in the restored armour, slender and curved, with 5–9 recurved denticles on inner margin of spines, which reach almost as far back as the end of the ventral armour. AVLs and PVLs of similar length; AVL with B/L index of ~127; PMV deeply separating PVLs anteriorly; subanal lamina of PVL relatively narrow. ADL triangular, with angled dorsolateral ridge, pointed dorsal margin and narrow overlap for MD plate; posterior angle of ADL situated ventral to lateral line sensory groove. Ornament of fine crowded tubercles on all dermal bones.]. Its type specimen is ANU V886, a partial skull (associated ADL, AVL, AMV, PVL and SP plates presumed to come from one individual), and it is a 3D body fossil. Its type locality is Young et al 1992 Devonian Fish Locality 8, which is in a Givetian marine siltstone in the Aztec Siltstone Formation of Antarctica.