Evolution of jaws first occurred in fishes within the group called

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The group called gnathostomes includes all jawed vertebrates, which includes fishes, amphibians, reptiles, birds, and mammals. Therefore, the evolution of jaws first occurred in this group, and not in other groups such as hagfishes or cartilaginous fishes. While coelacanths and ray-finned fishes are both gnathostomes, the evolution of jaws occurred earlier in the history of this group, before the split between these two subgroups.

Evolution of Jaws First Occurred in Fishes Within the Group