5.The oceanward edge of the Sibumasu terrane is probably marked by a cyclopygid biofacies fauna in Malaysia, that is, this edge should line up with marginal sites on other plates
There is thus a difference between earlier and later Ordovician biogeographic signals, the former providing apparently strong evidence for similarity between North China and Australia (and suggesting a placement of Sibumasu next to Western Australia), the latter rather indicating a close relationship with the South China plate. The North and South China plates have been placed far apart on Ordovician continental re- constructions (e.g., Burrett et al., 1990). This leads to a paradox. How can Sibumasu appar- ently switch. between one and the other? Three explanations can be considered with regard to the biogeographic history of Sibumasu: