Chadronian insectivores of the Cypress Hills

Abstract

The Cypress Hills Formation of Saskatchewan preserves sediments of Uintan (middle Eocene) to Hemingfordian (middle Miocene) age, but the best-represented period is the Chadronian North American Land Mammal Age. The best-known site, with the richest biodiversity known for the area, is the middle Chadronian Calf Creek Locality, from which over 70 mammal and 25 non-mammal species are known. The majority of these taxa have been described in the literature, but the portion of the fauna which includes the "insectivores," members of the orders Leptictida, Apatotheria, and Lipotyphla, have not been formally described. The following thesis identifies and describes the insectivores and chiropterans of the Calf Creek Locality, together with the same groups from the nearby Chadronian-aged Horse Locality. The inclusion of the Horse Locality specimens serves three purposes: (1) to begin the formal description of material from the Horse Locality, (2) to compare the two faunas to identify possible differences between the two, and (3) to allow for analysis of the implications of any faunal differences in terms of age and environment of the two sites. The insectivore faunas of the two sites are found to be very similar, with the same genera and common species occurring at both localities. Six species-level differences are reported, all within relatively rare taxa; in most cases rare taxa were found at the Calf Creek but not at the Horse Locality. It seems likely that most of the specific differences result from the smaller collection size of the Horse Locality rather than from age-related species turnover. Although the non-insectivore taxa suggest that the Horse Locality dates from either later in the middle Chadronian or the Late Chadronian, an evolutionary change between the Calf Creek and the Horse localities could not be confirmed in the groups studied here.