RECREATING AN UPPER CRETACEOUS DINOSAUR ASSEMBLAGE WITH GIS
CHADWICK, A. V., Dept of Geology,
TURNER, L. E., Dept. of Mathematics and
Physical Sciences, Southwestern Adventist University, Keene, TX 76059;
SPENCER, L., EHRC, 4754 Carberry Ck. Rd., Jacksonville, OR 97530
Using ArcGIS 8.2, and data from digital photographs and high-resolution GPS
coordinates of the bones we have recreated precise virtual maps of the
distribution of all bones, bone fragments, ossified tendons and teeth in
quarries operated in an extensive Upper Cretaceous (Lance Formation) bed in
eastern Wyoming. The process of mapping the bones, photographing and
georectifying over 2000 items has been a rich learning experience. Thanks
to recent changes in the ESRI product, it is now possible to carry out this
process without compromising data in the process.
The bones are field prepared and photographed and GPS data are retrieved in
situ. The bones are then stripped from background using a "smart edge"
feature in Paintshop Pro. The photos are converted to TIF files on a white
background. The ArcMap module of ArcGIS is used to georeference the TIF file
of each bones with the GPS data. When the bones have been rectified, they
can be taken into the ArcScene 3-D viewer and examined in three space.
Because of continuing and as yet unexplored limitations in the number of
layers displayable in the ArcScene viewer, we have found it convenient to
group the bones in clusters by year or by bone type or elevation in the
quarry to develop larger exported georeferenced assemblages of bones that
can be treated as single layers in ArcScene. This allows us to break the
data down and query with respect to distribution in vertical or horizontal
space. As a consequence of applying these techniques to the taphonomic
data, virtually all of the data with respect to location of the bones are
preserved intact, and the assemblage can be visualized as it appeared in the
ground. The finished files can be exported as VRML files for broad
paper presented at the SVP 2003 meeting, St. Paul, MN, Oct 2003.