Hybodonta

Hybodonta is an extinct order of cartilaginous fishes that lived from the Devonian period to the Cretaceous period. These ancient sharks were a diverse group, exhibiting a wide range of sizes and forms. They are distinguished by their dentition, which often featured flattened, crushing teeth suitable for processing hard-shelled prey like mollusks and crustaceans. Some hybodonts possessed prominent dorsal spines, which may have served defensive purposes or aided in locomotion. Fossil evidence suggests they inhabited both marine and freshwater environments, with various species adapting to different ecological niches. Their distribution was widespread across the globe during their existence. The hybodonts were a successful lineage for a long period, outliving many other early fish groups. However, they eventually declined and disappeared by the end of the Cretaceous period, likely facing competition from the increasingly dominant teleost fishes. Their fossil remains, particularly teeth and fin spines, are important indicators of ancient aquatic ecosystems.