Abstract

Lacustrine shales of the Kishenehn Formation of northwestern Montana provide an important window to the local mid-Eocene (Lutetian) ecosystem including evidence from insects, molluscs, vertebrates and plants. However, little has been published on the macrofossils flora, which includes abundant compressed fruits and seeds as well as foliage. Here we provide a preliminary survey, with particular attention to reproductive remains from the Middle Fork Region. Identified families include Equisetaceae, Cupressaceae, Pinaceae, Betulaceae, Brassicaceae, Cercidiphyllaceae, Eucommiaceae, Juglandaceae, Oleaceae, Platanaceae, Rutaceae, Salicaceae, Sapindaceae, Simaroubaceae and Ulmaceae. With at least 107 entities, this is among the most diverse lacustrine megafossil floras in North America. This flora shares elements with the early to mid-Eocene Green River Parachute Creek Member flora of Colorado and Utah, the Thunder Mountain flora of Idaho and the Okanogan Highland floras of British Columbia and Republic, Washington, as well as some with the late Eocene Ruby flora of Montana. We estimate the mean annual temperature to have been between 8.91 and 12.10 °C and mean annual precipitation to have been between 945 and 1,204 mm using the Bioclimatic Analysis/Mutual Climate Range Technique. This summary of floral elements complements the faunal record of the Kishenehn Formation and fills a gap in prior knowledge of the paleofloristic distributions.

Key words

fossil plants, paleoclimate, Lutetian, shale, Lemnoideae, Brassicaceae

Abstract

Following on the seminal works of Reid and Chandler in 1933 and Chandler in 1961, morphology and anatomy of fossil mastixioid fruits from the early Eocene London Clay of southern England were reanalyzed with the benefit of new methods in comparison with extant genera of Mastixiaceae and with other fossil representatives from Europe and North America. The species named Mastixia cantiensis E.Reid et M.Chandler was based on a heterogeneous assemblage of specimens, all representing Mastixiaceae, some of which truly represent Mastixia whilst others correspond to Diplopanax and Mastixiopsis The holotype of M. cantiensis E.Reid et M.Chandler corresponds to extant Diplopanax rather than Mastixia. Therefore, this species is moved out of Mastixia and is treated as Diplopanax cacaoides (Zenker) comb. nov. Nine species of mastixioid fruits are currently recognized in the London Clay flora: Mastixia parva E.Reid et M.Chandler, M. cf. oregonensis (R.A.Scott) Tiffney et Haggard, Diplopanax cacaoides, Tectocarya grandis (E.Reid et M.Chandler) comb. nov., Mastixiopsis nyssoides Kirchh., Exbeckettia mastixioides (E.Reid et M.Chandler) gen. et comb. nov., Lanfrancia subglobosa E.Reid et M.Chandler, Portnallia bognorensis M.Chandler, and Langtonia bisulcata E.Reid et M.Chandler. These include the oldest known representatives of the genera Diplopanax, Tectocarya and Mastixiopsis and contribute to our understanding of the former morphological diversity and palaeobiogeography of the Mastixiaceae.

Key words

Beckettia, biogeography, Diplopanax, Exbeckettia, Lanfrancia, Langtonia, Mastixia cantiensis, Mastixiaceae, Mastixiopsis, Portnallia, taxonomy, Tectocarya grandis

Abstract

The early middle Eocene Wagon Bed fruit and seed flora of central Wyoming encompasses nine morphotypes that are assignable to extant genera (Alangium, Aphanathe, Canarium, Carya, Celtis, Iodes, Mastixia, Nyssa, Pleiogynium), four that are assignable to extinct genera in extant families (Chandlera, Menispermaceae; Coryloides, Betulaceae; Pentoperculum, Anacardiaceae; Saxifragispermum, Salicaceae) and one morphotype potentially assignable to an extant family (Pandanaceae). At least 11 morphotypes remain unidentified due to incomplete characters, although some exhibit features suggestive, but not definitive, of extant families (e.g., Euphorbiaceae, Lauraceae, Nymphaeaceae, Rosaceae). Individual taxa exhibit paleobiogeographic links with the Eocene floras of the west coast of North America, as well as with those of the Eocene of Europe. Together with previously described pollen and woods, these fruits and seeds indicate a mixed evergreen and deciduous forest, existing under moist circumstances, possessing primary taxonomic affinities with extant paratropical taxa of the Old World.

Key words

fossil fruit, fossil seed, Eocene, Wyoming, Cannabaceae, Carya, Juglandaceae, Mastixiaceae, Menispermaceae, ?Pandanaceae, Salicaceae, Spondioid Anacardiaceae

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.

Key words

John Day Formation, fossil wood, Anacardiaceae, Cannabaceae, Cercidiphyllaceae, Fagaceae, Hamamelidaceae, Juglandaceae, Malvaceae, Platanaceae, Sapindaceae, Trochodendraceae

Abstract

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.

Key words

winged fruits, Tertiary, Wyoming, Oregon, Clarno Formation, Tepee Trail Formation

Abstract

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.

Key words

fossil fruits, circumscissile capsules, Palaeogene, extinct, micro-CT scanning