A diverse assemblage of Late Eocene woods from Oregon, western USA

Abstract

Well-preserved silicified woods from a site near the town of Post, Oregon, western USA, provide insights into the late Eocene vegetation and climate ca. 36 million years and data for comparing with both older and younger wood floras regionally and globally. The composition of this wood flora, taken into consideration along with taxa identified from silicified fruits and seeds of the same locality, provides a more complete picture of the former vegetation. We recognize woods belonging to the families Anacardiaceae (Pistacia terrazasae sp. nov.), Cannabaceae (Celtis popsii sp. nov.), Cercidiphyllaceae (Cercidiphyllum cf. alalongum R.A.Scott et E.A.Wheeler), Fagaceae (Fagus dodgeii sp. nov., Lithocarpoxylon ashwillii sp. nov., Lithocarpoxylon sp., Quercus sp.), Hamamelidaceae (Hamamelidoxylon crystalliferum sp. nov., H. cf. suzukii E.A.Wheeler et T.A.Dillhoff), Juglandaceae (Pterocaryoxylon sp.), Malvaceae (Wataria kvacekii n. sp.), Platanaceae (Platanoxylon cf. haydenii (Felix) Süss et Müll.-Stoll, Platanus sp.), Sapindaceae (Acer, 2 spp.), Trochodendraceae (Trochodendron beckii (Hergert et H.K.Phinney) R.A.Scott et E.A.Wheeler). This assemblage, which we refer to as the Post Hammer flora (UF 279), is comparable in age to the nearby Teater Road flora known mainly from fossil leaf impressions. Comparing the functional traits of the Hammer woods to the older Clarno Nut Beds woods attests to changing climate in the region, including an increase in seasonality.