Diverse fossil epacrids (Styphelioideae; Ericaceae) from early Pleistocene sediments at Stony Creek Basin, Victoria, Australia

Abstract

There is currently intense interest in the radiation of the scleromorphic groups that dominate the Australian flora, but at present, only Proteaceae and Casuarinaceae have fossil records detailed enough to provide useful evidence on the timing of these radiations. This article records a diverse assemblage of fossil leaves of another major scleromorphic group, the epacrids (subfamily Styphelioideae of Ericaceae, formerly known as Epacridaceae). The fossils are from Stony Creek Basin, in the western uplands of Victoria, Australia, and are of earliest Pleistocene age (ca. 1.6 million years old). They include 19 forms sufficiently distinct as to constitute different species. This diversity is considerably greater than the extant diversity of epacrids in the region. Published taphonomic data are used to argue that the actual diversity of the source vegetation of the fossil flora may have been significantly greater and comparable to the current local species richness of the centers of diversity. Ten of the fossil species are assigned to the largest extant tribe (Styphelieae), eight are assigned to Epacrideae or Archerieae, and one is assigned to Cosmelieae. This evidence is used to argue that substantial radiation of the epacrids had occurred by the beginning of the Pleistocene.