A walrus rostrum (upper jaw bone) with tusks used in the study. It can be dated to c.1200-1400 CE based on the characteristics of a runic inscription in Old Norse. It is from the collections of ...

In the Chondrichthyes, the skull consists of chondrocranium and upper jaw. In the Osteichthyes through mammals, the skull is a fused unit in which the braincase is added to and welded together by a ...