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Why was the hyostylic jaw important in the evolution of modern sharks and rays?
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chondrichthyan
Southern stingrays (Dasyatis americana or Hypanus americanus) are found in the western Atlantic Ocean.
The hyostylic jaw is a significant evolutionary development in modern sharks and rays (class Chondrichthyes). In this jaw arrangement, the articulation between the cranium and the jaws is mediated by the hyoid bone.12
This structure is important because it provides greater mobility to the jaws compared to the more primitive amphystylic jaw condition found in earlier ancestors. This increased flexibility allows for more effective and varied methods of predation, serving as a key feature in the evolutionary success and diversification of modern selachians—the group that includes ground sharks, mackerel sharks, and skates and rays.1