This contribution presents descriptions of 14 fossil woods from the Piedra Chamana Fossil Forest in Peru, an assemblage of fossil woods and leaves dated at 39 Ma (late Middle Eocene). It is part two of the descriptions of the non-monocot angiosperm fossils from the site (see Woodcock et al. 2017). The woods are assigned to the subfamilies Bombacoideae, Bombacoideae/Malvoideae, Byttneroideae, Grewioideae, and Sterculioideae of Malvaceae and the families Melastomataceae, Muntingiaceae, Rubiaceae, Rutaceae, and Sapindaceae. Malvalean taxa make up around one-third of the wood types. Many of the woods are identifiable to modern-day genera or groups, including genera with species counted among the hyperdominant trees of the New World forests. Represented vegetation types include mixed freshwater swamp with Avicennia, seasonally flooded forest, and lowland tropical forest with a dry aspect. The assemblage shows floristic similarities to extant South American lowland tropical forest, particularly the seasonally flooded forests growing along white water rivers (várzea); however, the dry forest association has a less clear analog in the present-day tropics.
The fossil woods and leaves of the Fossil Forest Piedra Chamana represent a diverse assemblage of plants dating to 39 Ma (late Middle Eocene). The fossils are preserved in an ashfall and overlying lahar deposits near the small village of Sexi in the northern Peruvian Andes (central Cajamarca). The assemblage includes dicot wood types and leaf morphotypes, as well as a diversity of monocot material. The ~30 dicot wood types are referred to the families Acanthaceae, Anacardiaceae, Apocynaceae, Combretaceae, Cordiaceae, Dipterocarpaceae, Euphorbiaceae, Fabaceae, Lechythidaceae, Lythraceae, Malvaceae, Melastomataceae, Muntingiaceae, Rubiaceae, Rutaceae, and Sapindaceae. Described herein are descriptions of the first 17 wood types that have been assigned to the families Acanthaceae through Lythraceae; descriptions of the additional wood types will appear in a later paper. The paleovegetation can be characterized as lowland tropical forest with a dry aspect based on preliminary analysis of floristic affinities and wood anatomical characteristics of the fossils.