Systematic Affinities And Paleoenvironment Of Eocene Petrified Woods From Southwestern Wyoming, USA

Petrified woods from the late Early Eocene in southwestern Wyoming, BridgerFormation of Big Sandy Reservoir and Green River Formation of Parnell Draw, wereexamined to assess their diversity and systematic affinities. The lower diversity in petrifiedwoods from Big Sandy Reservoir include Palmoxylon macginitiei Tidwell, Simper et Medlyn(Palmae), Edenoxylon parviareolatum Kruse (Anacardiaceae), Laurinoxylon stichkai sp. nov.(Lauraceae), Wilsonoxylon edenense gen. et sp. nov.(Canellaceae), and one unnameddicotyledonous species of uncertain familial affinity. Edenoxylon and Palmoxylon arerepresented by multiple samples and appear to have been dominant in the local vegetation atthe time of deposition. The floristic diversity shown in petrified woods from Parnell Draw ishigher, they are assigned to Cupressinoxylon sp.(Cupressaceae), Pinus sp.(Pinaceae),Palmoxylon sp.(Palmae), Edenoxylon sp.(Anacardiaceae), cf. L. stichkai (Lauraceae),cf. Mastixia sp.(Cornaceae), Welnotopoxylon multiseriata gen. et sp. nov.(Moraceae),Platanoxylon sp.(Platanaceae), cf. Fagaceoxylon sp., Parnelloxylon dicheri gen. et sp. nov.,and other seven unknown taxa (Dicotyloxylon spp.) possibly related to families includeAnacardiaceae, Apocynaceae, Araliaceae, Combretaceae, Leguminosae, Oleaceae, Meliaceae,Moraceae, Rosaceae, Rutaceae. These findings augment the data from fossil leaves and fruitssuggesting that the affinities of floristic diversity from the two studied sites are consistent with other indicators and evidence that late Early Eocene climate of this region wassubtropical, in contrast to the present semi-arid and temperate climate conditions.