Palynoflora of the Insect Limestone, late Eocene, UK

The latest Eocene (late Priabonian; c. 34 Ma) Insect Limestone, that outcrops on the Isle of Wight, UK, is known for its exceptional preservation and diversity of fossil insects. The fauna and flora from the Insect Limestone has the potential to provide a unique window into the paleoenvironment, biodiversity, and plant-insect interactions near the end of the Eocene. Much of the earlier Eocene was characterized by a hot and humid climate with paratropical conditions, even at mid to high latitudes. The Insect Limestone macroflora has been described but, in order to acquire a more complete representation of the plants thriving in the Isle of Wight area during the latest Eocene, we investigated dispersed spores and pollen from the Insect Limestone using combined light- and scanning electron microscopy. Our study so far has revealed spores from six different fern taxa, representing Osmundaceae, Polypodiaceae, Pteridaceae, and Schizaeaceae. Various pollen of gymnosperms includes Cupressaceae (both papillate and ulcerate types), Pinaceae (Cathaya, Picea, Pinus, Tsuga), Sciadopityaceae (Sciadopitys), and Ephedraceae (Ephedra). The angiosperm component is by far the most diverse, with about 115 different pollen types assignable to at least 40 families. These include various basal angiosperm/monocot pollen of Arecaceae, Chloranthaceae, Lemnaceae, and Typhaceae, as well as an overwhelming number of dicot pollen types demonstrating the presence of, among others, Adoxaceae, Apocynaceae, Araliaceae, Clethraceae, Ericaceae, Euphorbiaceae, Icacinaceae, Loranthaceae, Malvaceae, Moraceae, Nyctaginaceae, Oleaceae, Rosaceae, Rutaceae, Santalaceae, Sapotaceae, and Thymelaeaceae. This first account attempts to describe and assign the spores and pollen taxonomically. Future work will focus on comparing the previously described macroflora with the microflora, reconstructing the vegetation units around the accumulation site, and evaluating the paleoclimate under which the respective plants and insects lived during the latest Eocene in the Isle of Wight region.