FIVE YEARS EXPERIENCE USING GIS FOR DATA COLLECTION AND ANALYSIS IN AN UPPER CRETACEOUS DINOSAUR QUARRY IN THE LANCE FORMATION.

CHADWICK, A. V., Dept of Geology,

TURNER, L. E., Dept. of Mathematics and Physical Sciences, Southwestern Adventist University, Keene, TX 76059, and

SPENCER, Lee, EHRC, 30 Panorama Rd., Running Springs, CA 92382

We have pioneered techniques for data analysis using GPS-based GIS analysis in an active dinosaur quarry site in the Upper Cretaceous Lance Formation in eastern Wyoming. After five years, massive amounts of spatial data have been accumulated, necessitating the development of methods of analysis for handling these data. We are currently able to display the data for successive years as composite georeferenced images, without losing the ability to display bones individually by type or by vertical distribution within the quarry. We will describe and illustrate these techniques.

Field and post-field analysis using the GPS/GIS tools have enabled us to determine that the bone bed represents a single unit dominated by the disarticulated bones of Edmontosaurus, with smaller contributions from Triceratops and other ornithischian dinosaurs, and Nanotyrannus, Tyrannosaurus, and other smaller theropods. The bed exhibits a three degree regional dip to the west. The deposit accumulated as a massive graded bed over an area of at least a square kilometer. Densities of 20 to 30 bones per square meter are common. Several estimates based on the distribution of individual skeletal elements in the areas quarried suggest as many as 10,000 individual dinosaurs may have been represented in the deposit.

Aerial distribution of bones by type or by species can be generated in the computer, permitting a variety of taphonomic analyses to be carried out. The distribution of individual skeletal elements appears to be random across the three quarry sites for which we have extensive data. Analysis of the vertical distribution reveals the bones are normally graded, and shows a pervasive and curious sorting by bone type that may be explainable in terms of different bone densities. Many other kinds of analyses critical to taphonomic studies are now possible from the computer console.