A Preliminary Analysis of Phytodebris Assemblages from the Liscomb Bone Bed Area, Prince Creek Formation, North Slope, Alaska

The Campanian-Maastrichtian Prince Creek Formation preserves one of the most complete records of high-latitude environmental change in polar terrestrial environments during the Late Cretaceous. The Prince Creek has been subject to intensive study of plant macrofossils, palynomorphs, and sedimentology, and is noteworthy for the occurrence of two diverse dinosaur localities. Here we describe an abundant and well-preserved record of phytodebris from Alaska's North Slope in a measured stratigraphic section that includes the Liscomb bone bed, currently placed near the Campanian-Maastrichtian boundary. Large amounts of dispersed cuticle occur in the samples, including angiosperms, conifers belonging to Metasequoia and other genera, and possible ferns. Mosses, seeds, and fragmentary arthropods are also present, including one arthropod with pollen preserved in the gut. A variety of non-cuticular plant tissues can occur with cuticle, including vitrinized wood, fusain, axial parenchyma, and periderm. Phytodebris assemblages reinforce evidence from plant macrofossils and sedimentology for extensive herbaceous flora and widespread marsh vegetation on the North Slope during the Campanian-Maatrichtian. Many assemblages are characterized by the absence of woody tissues and the overwhelming abundance of plant tissues with cells organized into longitudinal files, as is characteristic of herbaceous stems and the petioles and rachises of leaves. Phytodebris floras also reinforce evidence from plant macrofossils for woody deciduous plants through the occurrence of thin conifer cuticles with stomata. The stratigraphic density of phytodebris in the Prince Creek Formation far exceeds that of plant macrofossils, and the finer taxonomic resolution of cuticles relative to palynomorphs indicates that it can provide a more systematically refined interpretation of the woody flora, especially for conifers. This suggests that the phytodebris record of the Prince Creek Formation has the potential to make important contributions to an understanding of ecological and environmental change at polar latitudes during the latest Cretaceous.