The evolution of jaws represents one of the most transformative innovations in vertebrate history, fundamentally reshaping both animal anatomy and ecological dynamics. At the core of this innovation lies the neural crest, a unique vertebrate cell population whose molecular and developmental properties enabled the formation of articulated jaws. This review explores how neural crest cells, as multipotent stem cells, contributed to jaw development through their extraordinary capacity to form cartilage, bone, and associated tissues. Beyond the developmental perspective, we examine how the emergence of jawed vertebrates dramatically altered marine ecosystems, leading to new predator-prey relationships and driving an unprecedented diversification of feeding strategies. This innovation triggered an evolutionary arms race that shaped marine biodiversity and established new trophic relationships that persist in modern oceans. Understanding this ancient innovation provides crucial insights into both developmental mechanisms and ecological dynamics that defined vertebrate evolution.