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 a single, incomplete leaf, which displays a toothed margin and well-preserved cuticle. Despite the absence of teeth in over 2500 known species of fossil and extant Lauraceae, the fossil cuticle has a combination of traits that are lauraceous. These include the synapomorphy of stomata confined to small areoles, and also paracytic stomata with apparently embedded guard cells, simple, uniseriate trichomes with thickened, poral bases, slit-like stomatal apertures on the outer abaxial surface and persistent resin bodies. Leaf teeth could be a plesiomorphic trait in Lauraceae, as monimioid teeth occur throughout other lauralean families. However, the fossil teeth were evidently not glandular as in monimioid teeth, and thus are unlikely to be homologous with the teeth of other Laurales. Rather, the teeth are likely to have been apomorphic, having evolved in response to the physiological demands of the warm, wet, high latitude 'Greenhouse' environment.