High-Resolution GPS Mapping in a Vertebrate Taphonomic Quarry

TURNER, L. E., Dept. of Mathematics and Physical Sciences, turner@swau.edu; CHADWICK, A. V., Dept of Biology, Southwestern Adventist University, Keene, TX 76059, and SPENCER, L., EHRC, 4736 Carberry Ck. Rd., Jacksonville, OR 97530.

Taphonomic and related sedimentary studies depend upon precise information about field relationships for reconstruction of events in the history of burial and fossilization of organisms. Until recently, this meant overlaying the field relationships with a physical grid and sketching the details in two dimensions. While this technique has been satisfactory for preserving relationships in two dimensions, the procedure left three-dimensional relationships very difficult to reconstruct.

We have applied high-resolution GPS mapping and digital photography to a taphonomic quarry, and have satisfactorily reconstructed the field relationships in three dimensions using Arcview GIS software. Vertebrate fossils (principally dinosaur bones) were exposed in the quarry using standard field techniques. When bones were adequately exposed and pedestaled, they were photographed in their field relationships using a Nikon digital camera. A variable number of points (ranging from one for small fragments or teeth, to many for large bones) were then taken directly from the exposed bone using a Javad GPS having a resolution of 1 cm or less. The points and photographs were transferred to a laptop computer at the end of each day, and processed into individual bone files. These files were converted into three dimensional shape files and the photographs of the bones were overlaid on the three-dimensional GPS data in the computer and displayed in Arcview 3-D module. The resulting three-dimensional reconstruction was highly satisfactory for retaining field relationships and for data analysis.

The results give surprising insights into the processes of death and burial and enable predictions to be made about future discoveries. The procedure also enables us to preserve field relationships that might have been lost using older mapping techniques.

Presented at the GSA 2000 meeting, Reno, NV, Nov 2000.