A toothed Lauraceae leaf from the early Eocene of Tasmania, Australia

Abstract

Bandulskaia aestuaria gen. et sp. nov. is described from Early Eocene estuarine sediments in Tasmania. It is represented by an incomplete leaf with a finely toothed margin and well-preserved cuticle. Despite the absence of such teeth in more than 2500 known species of fossil and extant Lauraceae, the fossil cuticle exhibits traits that in combination are found only in the family. These include the derived characters of sunken, paracytic stomata with small, apparently embedded guard cells, stomata confined to small areoles, and stomatal positions that are marked by slitlike abaxial surface apertures, as well as the presence of persistent resin bodies and simple, uniseriate trichomes with thickened, poral bases. Although monimioid teeth occur widely in other lauralean families, the teeth in B. aestuaria are not monimioid, and it is most parsimonious to infer that the teeth were derived independently within Lauraceae, possibly in response to the physiological demands of a warm, waterlogged, high-latitude “greenhouse” environment.