USING GIS TO DOCUMENT ICHNOLOGICAL RESOURCES OF FIELD SITES FOR FUTURE RESEARCH

The ichnological resources of a given field site can provide important clues for interpreting the geologic history of an area. One example is the Willow Creek Anticline (WCA) area west of Choteau, Montana, with its outcrops of the Two Medicine Formation (Late Cretaceous). Although the WCA is paleontologically more famous for its abundant dinosaur bones and eggs, it also contains a diverse suite of invertebrate and vertebrate trace fossils, such as crayfish burrows, insect burrows and cocoons, dinosaur tracks and coprolites, and probable small vertebrate burrows. In July 2014, one of us (Martin) recorded ichnological data at 77 GPS waypoints in the WCA area. In 2018, another of us (Bradford) uploaded GPS waypoints as point features in a feature dataset using ArcMap. Data recorded in the field were then stored at each waypoint, with additional features that allowed waypoints to be categorized by trace type (general descriptions) and probable tracemaker, while also noting incidental body fossils. For example, dinosaur fossils were recorded at 16 waypoints, with bones (n = 4), tracks (n = 11), and coprolites (n = 2), with two types at one site. By far the most abundant trace fossils were those attributed to insects, recorded at 62 waypoints, with burrows as the most commonly represented (n = 45) and then cocoons (n = 19), with multiple trace fossil types at some sites. Waypoints were projected on 8-bit NAIP orthoimagery georeferenced to the coordinates of the field area and may be explored by an online user; field photos of the trace fossils were also linked to waypoint localities. These methods allow for the projection of field-derived ichnological data onto a field area that can be reviewed by trace fossil type (such as ichnogenera), interpreted tracemaker, and/or location in space. Further research into the trace fossils of the area, including the nature of the fossil cocoons and their tracemakers, is better facilitated by the creation of such maps and searchable databases, which also can be corrected or updated with new information. We hope the methods outlined in this study might prove useful for mapping ichnological resources of other field sites.