New phyllolepids (placoderm fishes) from the Middle-Late Devonian of southeastern Australia

Phyllolepid placoderms from the Devonian Boyd Volcanic Complex on the south coast of New South Wales are described as Cobandrahlepis petyrwardi, gen. et sp. nov., and Yurammia browni, gen. et sp. nov. Both are more primitive than other described phyllolepids in retaining a posterior dorsolateral plate in the trunk armor. Cobandrahlepis resembles Placolepis Ritchie, 1984, in the shape of the nuchal plate in the skull, and Austrophyllolepis Long, 1984, in the more lateral position of the sensory groove on the paranuchal plate. Yurammia, gen. nov., differs from all other phyllolepids in lacking ridged ornament on the dermal bones. These new taxa add to the diversity of early members of the order Phyllolepida from East Gondwana, before the appearance of the genus Phyllolepis in the Northern Hemisphere during the last stage of the Late Devonian (Famennian). Phyllolepid placoderms, only recorded from non-marine deposits, have a unique disjunct distribution in both time and space between the Southern and Northern hemispheres. They document a major dispersal event indicating continental connection between Gondwana and Laurussia near the Frasnian-Famennian boundary, at about the time of the Late Devonian mass extinction.