THE OLDEST TABULATE CORAL AND THE ASSOCIATED ARCHAEOCYATHA, LOWER CAMBRIAN, FLINDERS RANGES, SOUTH-AUSTRALIA

The oldest known tabulate, Flindersipora bowmani LAFUSTE gen. et sp. nov. from the Flinders Ranges of South Australia, is described for the first time. The new genus presents all morphological and structural characteristics of Tabulate : cerioid shape, septal ridges, tabulae, wall pores. Its microstructure is nevertheless new, formed by "platelets". Specimens have been found associated with archaeocyaths and calcified cyanobacteria in Lower Cambrian shelf margin buildups in the Oraparinna Shale and Moorowie Formation, in two different localities : Ten Miles Creek, where they are associated with solitary archaeocyaths, and Moorowie Mine, where they built complex bioconstructions associated with colonial archaeocyaths. The archaeocyaths, comprising 11 species, indicate a middle Botomian age. One species Robertocyathus brenti DEBRENNE is new. The buildups were among the last to flourish prior to widespread regression in the Early Cambrian in South Australia. With this discovery, the present opinions on the phylogeny of Tabulate Corals must be modified. In comparison with some Cambrian or even Ordovician forms which have been supposed to have affinities with corals, Flindersipora has a less rudimentary morphology and could not be said more primitive than these previously known genera. Because of its advanced favositid architectural type Flindersipora reinforce the idea that the origin of Tabulate is very ancient and must be looked for in the Precambrian.