Caption 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 ...

Bird has one large cavern, with all bars between ... dentary is single bone on each side of the lower jaw. ii. With loss of bones, switch to bones articulating hinge between upper and lower jaw.

1, the evolution of stronger, more effective jaw mechanisms ... In snakes, the upper bar has been lost as well, leaving the whole cheek clear of dermal bone. Icthyosaurs and plesiosaurs have a ...