What paleontologists long believed were long spines on the aptly named Alienacanthus turn out to be an extended lower jaw. By Jack Tamisiea Some 375 million years ago, armored fishes ruled a watery ...

The arrangement of the bones that form the joint (the articulation) between the lower jaw and the skull is a key hallmark of vertebrates. Their configuration has long been used to draw a line in the ...

A random selection of lower jaw shapes from among the world's vertebrate animals. All are mammal jaws consisting of a single bone except for those in orange, which are from vertebrates that have lower ...