Abstract of paper presented at the 2001 annual meeting of the Geological Society of America:

A remarkable vertebrate assemblage from the Lance Formation, Niobrara County, Wyoming. SPENCER, L., EHRC, 4736 Carberry Ck. Rd., Jacksonville, OR 97530, lspencer@bco.com; TURNER, L. E., Dept. of Mathematics and Physical Sciences, CHADWICK, A. V., Dept of Geology, Southwestern Adventist University, Keene, TX 76059.

During the process of an on-going taphonomic study of the Lance vertebrates, a small quarry was opened up on a sandstone ridge abutting a calcareous cemented cobbly sandstone bone bed one meter in thickness. The deposit concerned here occurs in a poorly cemented well-sorted immature white sandstone that appears to be a lag deposit on the trailing edge of the larger mass of the bone bed itself. Transport of the entire unit appears to have been to the south, based upon imbrication of the flat pebble clasts contained in the unit. The bone bed contains bones in all size categories, ranging from small bone chips and ossified tendons to whole femurs. The lag deposit contains a variety of bones, but all of them tend to be smaller than those of the main bone bed, and the entire thickness of the lag deposit is less than 20 cm. The profile of the lag tails and disappears in the white sandstone over a distance of two meters proximal to the bone bed. The materials described below were recovered from 20 cm depth in an area of a little more than one square meter in this lag.

The lag deposit contained a variety of bones of Edmontosaurus, fragments of turtle bones and fish scales, and numerous teeth. While the majority of the teeth were those of Edmontosaurus, and a dentary of a juvenile Edmontosaurus was recovered, teeth of at least six other species of dinosaur were recovered, including Triceratops horridus, Tyrannosaurus rex, Nannotyrannus sp., and Troodon formosus. Associated with the dinosaur teeth were teeth from crocodiles, fish, multituberculates and other forms still under study. The accumulation of such a variety of species in such a small area is consistent with the lag developing downstream from a high energy debris accumulation

2001 L. Spencer, L. Turner and A.V. Chadwick, A remarkable vertebrate assemblage from the Lance Formation, Niobrara County, Wyoming. Geological Society of America. Abstracts with Program 33:A499.