EXPLORING MINIMUM GEOGRAPHIC RANGES OF CRETACEOUS WESTERN INTERIOR AMMONITES USING GEOGRAPHIC INFORMATION SYSTEMS, PALEOGIS, SPREADSHEETS, AND TOPOGRAPHIC SOFTWARE

Maps displaying the minimum geographic ranges for all Cretaceous Western Interior ammonites have been constructed from a digital inventory using GIS techniques. The inventory was compiled from over 200 sources including several museum collections, published databases, and relevant publications to provide information on over 20,000 individual ammonite occurrences in over 2,000 different localities. The inventory is divided into three sections each providing a required type of information needed to construct an ammonite's minimum geographic range. Fossil identification contains all available information on an ammonite specimen's identity including specie variations. Contained in this section is also information on the publication or museum collection the information was collected from, and the identifier of the fossil. Geospatial information is completed down to the highest level available including Global Positioning System (GPS) data with less than 0.5 meter resolution. This section also contains coordinates indicating the current geospace where the fossil was discovered, and the paleo-geospace where it came to rest postmortem to the highest resolution obtained by the collector. All localities were mapped in current geospace using ArcView GIS 3.2 software, and were rotated to their paleocontinental position using PaleoGIS. Temporal data is recorded to the highest level provided including current standard biozones and sub-zones. Also provided in this section are lithologic data if included in the source. The inventory was constructed using a simple spreadsheet format with EXCEL 2003 providing easy sorting and modification using standard EXCEL queries. It is hoped that this inventory and subsequent bioigeographic range maps will provide information on morphologic variation in geospace, geographic range variation comparison with an ammonite's origination and extinction rates, and the geography of mass extinction and recovery.