A New Phyllolepid Placoderm Occurrence (Devonian Fish) from the Dulcie Sandstone, Georgina Basin, Central Australia

Abstract

A new phyllolepid placoderm occurrence from a low level in the Dulcie Sandstone, Georgina Basin, Northern Territory, lies about 200 metres stratigraphically above an older fish assemblage containing Wuttagoonaspis. A new species Austrophyllolepis dulciensis is characterised by an unusually broad anterior ventrolateral plate. The stratigraphic range of other species in this genus from southeastern Australia and Antarctica suggest a Givetian-Frasnian age. Early members of the order Phyllolepida are endemic to east Gondwana, and other phyllolepids of similar age occur in Turkey and Venezuela. In the Northern Hemisphere (Europe, Russia, Greenland, North America) phyllolepids are restricted to the latest Devonian stage (Famennian). This disjunct space-time distribution for the group supports a Gondwanan origin for the Phyllolepida, and later access to northern landmasses resulting from closure of the ocean between Gondwana and Laurussia at or near the Frasnian-Famennian boundary.