A fossil wood remain of par-autochthonous origin was found in Paleocene sedimentary rocks of the Moose Channel Formation in the Big Fish River area in Yukon, close to the Northwest Territories border, during the CASE 15 expedition. The fossil wood was recovered from overall medium to coarse-grained units of sandstone of an inferred fluvial-deltaic origin. This contribution summarizes the current knowledge primarily on the taxonomy and paleoecology of the protopiceaceous wood specimen. The fossil wood specimen turned out to be without a relationship to extant taxa: Protopiceoxylon yukonense sp. nov. as a taxon of the fossil wood genus Protopiceoxylon Gothan 1907 belongs to the extinct family of Protopinaceae Kraeusel, 1949. The holo- and paratypes of the generotypus Protopiceoxylon extinctum Gothan, 1907 from the King Charles Land (Gothan, 1907) and from Green Harbour/Spitsbergen (Gothan, 1910), were available for this investigation from the Natural History Museum Berlin (NHMB). Although most of samples characteristics are comparable to be extinct genus Protopiceoxylon, it is differentiated by some extinct anatomical features that are intermediate between the extinct Protopiceoxylon and the extant Piceoxylon Gothan, 1905. These features manifest within the radial bordered pits, which are protopinoid in Protopiceoxylon and abietoid in Piceoxylon. Most other features demonstrate a close relationship between both fossil taxa.
