An articulated phyllolepid fish (Placodermi) from the Devonian of central Australia: implications for non-marine connections with the Old Red Sandstone continent

摘要

A second species of the placoderm genus Placolepis (Pl. harajica sp. nov.), based on a single articulated specimen from Givetian–Frasnian strata in the MacDonnell Ranges, demonstrates the occurrence of this taxon across the Australian craton. Placolepis (order Phyllolepida) is endemic to east Gondwana, and other phyllolepids are widespread in the Givetian and younger of Gondwana (Australia, Antarctica, Turkey, Venezuela), but do not occur until Late Devonian (Famennian) time in the Northern Hemisphere (Europe, Russia, Greenland, North America). The disjunct space–time distribution of the Phyllolepida is inconsistent with palaeomagnetic evidence indicating a wide equatorial ocean between Gondwana and Laurussia in Late Devonian time. This new species provides additional evidence supporting a Gondwana origin for the group, and later access to northern landmasses resulting from closure of the ocean between Gondwana and Laurussia and continental connection at or near the Frasnian–Famennian boundary.