Fig. 1 in Cranial morphology, systematics and succession of beavers from the middle Miocene Valentine Formation of Nebraska, USA

Fig. 1. Generalized stratigraphic section of the middle Miocene Valentine Formation in northern Nebraska (modified after Skinner and Johnson 1984: fig. 4 and Tedford et al. 2004: fig. 6.2). Striped area represents time gap of unconformity between members.