Problems of Antiquity presented in Gypsum Cave, Nevada

Strikingly real as the material evidence of the life record of the past frequently is the vividness of that reality is in large measure dependent upon the satisfaction which one experiences in apprehending organisms of a remote period as once living creatures. Nowhere is this better exemplified than in those noteworthy occurrences where remains of mammalian types, presumably long extinct, have come down through time, exhibiting not only skeletal parts but also the epidermal structures, excrement and occasionally the viscera in a remarkable state of preservation. Curious though it may seem our views regarding the geologic antiquity of this type of material are frequently but dimly defined.