A new kind of fin-winged fruit is recognized from lacustrine shales of the early Eocene Tepee Trail Formation of northwestern Wyoming and from the middle Eocene Clarno Formation of central Oregon, USA. The fruits are obovate with five thick lateral wings, borne on a thick pedicel and bearing scars of hypogynous perianth and disk. The fruit surface is covered with small circular dots interpreted as glands. This combination of characters leads us to infer affinities with the Rutaceae, although no identical modern genus is known. We establish the new genus and species, Quinquala obovata.
winged fruits, Tertiary, Wyoming, Oregon, Clarno Formation, Tepee Trail Formation
Shales of the early middle Eocene Parachute Creek Member of the Green River Formation in Utah, western USA, have yielded a large number of fossil plant remains with abundant Platanaceae, Salicaceae, and Ulmaceae, but many of the constituents of this flora remain indeterminate. Here we present a new fruit type based on distinctive sedimentary molds investigated by reflected light and μCT scanning. The structures are oblate woody fruits, about 18–26 mm wide but only 2–4 mm high, but partially flattened by compression within the sediment. In transverse view they are rounded-polygonal, with 5–6 sides. In lateral view the locule is dome-shaped with 7 to 11 obpyriform grooves radiating from the center of the basal wall. Three-dimensional imaging and both physical and digital sections indicate that the fruits were circumscissile capsules. Although analogous fruits occur in the Lecythidaceae A.RICH., Bonanzacarpum sprungerorum sp. nov. fruits are much smaller and lack the prominent woody pedicel and corresponding basal scar that characterizes that family. Hence, the systematic position of B. sprungerorum remains uncertain.
fossil fruits, circumscissile capsules, Palaeogene, extinct, micro-CT scanning