A new ( Hovenia) and an old ( Chadronoxylon) fossil wood from the Late Eocene Florissant Formation, Colorado, U.S.A.

摘要

A fossil wood with features similar to those of the Oligocene Hovenia palaeodulcis Suzuki (Rhamnaceae) from Japan is described from the late Eocene Florissant Fossil Beds National Monument, Colorado, U.S.A. This is the first report of fossil wood of this Asian genus in North America and is further documentation of Tertiary exchange between East Asia and North America. The affinities of Chadronoxylon florissantensis, the most common angiosperm wood at Florissant, are reevaluated; its combination of features suggests relationships with two families in the Malpighiales, the Salicaceae and Phyllanthaceae. Chadronoxylon is compared with Paraphyllanthoxylon Bailey. The Eocene P. hainanensis from China has notable differences from the original diagnosis of Paraphyllanthoxylon, but shares features with Chadronoxylon warranting transfer of P. hainanensis to Chadronoxylon and the creation of Chadronoxylon hainanensis (Feng, Yi, Jen) Wheeler & Meyer, comb. nov.