Late Paleocene woods from Cherokee Ranch, Colorado, U.S.A.

Abstract

Fossil woods are common in the Late Cretaceous through early Eocene rocks of the Denver Basin, Colorado. The overwhelming majority of these woods are dicotyledonous angiosperms. A new locality for fossil woods, Cherokee Ranch, in the upper D1 stratigraphic sequence (Denver Formation) is described, and evidence for it being late Paleocene is reviewed. Most Cherokee Ranch woods resemble previously described Denver Basin angiosperm woods, but there is one new type of wood attributed to the family Lauraceae. A new genus, Ubiquitoxylon, is proposed for woods with the combination of features commonly seen in the Cherokee Ranch woods. Denver Basin Paleocene woods differ from Paleocene wood assemblages to the north (Wyoming and Montana), where conifer woods are common and angiosperms are rare. The width and spacing of the water-conducting vessels and the lack of distinct growth rings in almost all of the Cherokee Ranch woods suggest that these trees did not experience water stress, and there was no pronounced seasonality.

First fossil woods and palm stems from the mid‐Paleocene of Myanmar and implications for biogeography and wood anatomy

“…The genus Ubiquitoxylon Wheeler was instituted for fossil woods with a combination of features that occurs in multiple families, including the Anacardiaceae and Lauraceae. Wood‐type 1‐d shares most of the features of this genus, including the occurrence of enlarged marginal ray cells, but it does not have idioblasts amongst the fibers and axial parenchyma is rare to scanty paratracheal (Wheeler et al, 2019). However, given the poor state of preservation of sample MNHN.F.50231 (PPP6), it seems unwise to assign it to a genus.…”

“…The fossil record of the family is large, mostly dated from the Eocene or later (Dupéron‐Laudoueneix and Dupéron, 2005; Gregory et al, 2009; and references therein). A few Paleocene Lauraceae fossils are recorded in England (Crawley, 1989), the United States (Herendeen et al, 1994; Wheeler et al, 2019), Cameroon (Dupéron‐Laudoueneix and Dupéron, 2005), and in ancient islands of the Indian Ocean (Carpenter et al, 2010) and Australia (Vadala and Greenwood, 2001), attesting that the family was already widespread at this time.…”