Biogeographic significance of some Ordovician faunas in relation to east Australian Tasmanide suspect terranes

The continental platform-shelf remnants of the Australian sector of Gondwana, have varied Ordovician marine invertebrate faunas. Biogeographically they are low-latitude faunas. The suspect terranes of the adjacent, major Tasmanide fold belt of eastern Australia also contain some biogeographically useful Ordovician faunas which are also low-latitude faunas. They provide low-latitudinal constraints for these structural blocks. The corals of the most easterly-place Tamworth terrane seem to have the closest affinities to North America. Major strike-slip movements are not detectable on faunal evidence, though one earliest Ordovician trilobite fauna is anomalous in having an influx of "higher latitude' Argentinian immigrants. The Late Ordovician, low-latitude island-arc faunas of central New South Wales are regarded as biogeographically distinct from equivalents in the continental shelf remnant of Tasmania. This seems consistent with a separation of the two regions by a marginal sea. -from Author