Quo Vadis? Paleoenvironmental and Diagenetic Constraints on Late Cretaceous Dinosaur Skin from Western North America

Upper Cretaceous sandstone deposits of the Western Interior Seaway include fossil skin (integument) associated with the skeletal remains of some dinosaurs. Skin preserves as thin pyrolusite (manganese oxide) coatings on sandstone molds and casts. Pyrolusite is an authigenic marine mineral used to map paleoshorelines, thus the dinosaur fossil is inferred to have been deposited in a nearshore marine environment. Rapid burial of the dinosaur remains in marginal-marine settings in the presence of seawater resulted in the inhibition of scavenging activity by other creatures. Seawater mixed with freshwater promoted the natural embalming of the corpse.Thus, it effected changes in the microbial consortia responsible for decay leading to an increase in pH allowing for preferential precipitation of pyrolusite as a replacement for dinosaur integument. Figure 1: Location of This Side of Hell Quarry in Elk Basin Anticline, Wyoming and Upper Cretaceous stratigraphy within Elk Basin. and is found in This Side of Hell Quarry, located in the Elk Basin Anticline in the northwestern Bighorn Basin in Park County, Wyoming (Figure 1). Dinosaur skin and skin impressions associated with lambeosaurine dinosaur bone (Figure 2) described herein occur in the second sandstone interval of the Lance Formation in Park County, Wyoming (Wegweiser, 2002). Specimens of dinosaur skin casts and molds (Figures 3) are reposited in the collections of the University of Wyoming.