A conifer wood assemblage from the Late Jurassic-Early Cretaceous, Fontana Lake area, Chubut Province, Argentine Patagonia

An assemblage of 22 silicified wood specimens collected from the Cerro Grande and Arroyo Blanco localities (Lago La Plata and Tres Lagunas formations, Late Jurassic-Early Cretaceous), in the Fontana Lake area (Chubut Province, Argentine Patagonia), is described. The specimens consist of decorticated secondary xylem. Thirteen specimens have araucarian pits in the radial walls of tracheids and araucarioid cross-fields, allowing their assignment to Agathoxylon Hartig, a fossil-genus related to the Araucariaceae Henkel & W. Hochst. Two specimens, with non-contiguous pits in the tracheid radial walls, are assigned to an ‘indeterminate abietinean type’. The remaining seven specimens could not be identified taxonomically due to poor preservation, although they have general conifer anatomical features. The size of the specimens and the curvature of their growth rings indicate that they came from large trees. Distinct growth ring boundaries observed in most specimens suggest annual seasonality. In addition, some specimens have false rings and patterns of wood decay. The wood assemblage suggests a forest dominated by Araucariaceae in the Fontana Lake area near the Jurassic-Cretaceous boundary.