THE FIRST REPORT OF PLANOLITES IN THE MOJADO FORMATION, CERRO DE CRISTO REY, SUNLAND PARK, NEW MEXICO

Current fieldwork in the lowermost Albian-Cenomanian Mojado Formation (Sarten member) has produced several new invertebrate trace fossil discoveries. Reported here is the second documented occurrence of Planolites isp. in the Washita Group at Cerro de Cristo Rey Sunland Park, New Mexico. Planolites is a simple, sub-horizontal, cylindrical trace with fill that is different than the host rock. It is interpreted as a domichnia (dwelling trace) or fodichnia (feeding trace) with several possible tracemakers, is preserved from most environmental settings including marine and continental, from the Ediacaran to Recent. At this locality this trace cross-cuts Thalassinoides and Curvolithus and these are associated with Arthrophycus, so we tentatively assign this ichnoassemblage to the Cruziana ichnofacies. Although ichnoassemblages attributed to the Cruziana ichnofacies have been described a few meters below in the Mesilla Valley Formation, these differ from the low-diversity ichnoassemblage in the Mojado Formation. This change in ichnoassemblage may in the future be used to define the lower contact of the Mojado Formation at Cristo Rey.