Myotis thysanodes pahasapensis!
A rare bat. Narrow skull, large ears (1 inch) and a wingspan of 10-12 inches. Reddish to dark brown fur on its back, paler underneath. This is the only myotis with a conspicuous fringe of hairs along the back edge of the interfemoral membrane (bottom of wing).
Habitat:
Lives only in only in certain mountainous areas of South Dakota and Wyoming, primarily in caves in the Black Hills and Badlands. Lives there year-round but is only active from April to September. Roosts during the day in caves, mines and buildings. In winter, it hibernates in the same spots.
Puncture-resistant wings protect this bat while it feeds on insects on the ground or near thick or thorny vegetation. Females gather in large maternity colonies, producing one young per year in June or July.
http://www.npwrc.usgs.gov/resource/distr/others/sdrare/species/myotthys.htm
seems to think this bat's gestation period is 5060 days. I choose to believe it's 50-60.