"Ancient Shark Fossil Unveils Dinosaur-Era Mystery"

Researchers have uncovered nearly complete fossils of the ancient shark genus Ptychodus in northeastern Mexico, providing new insights into its appearance, evolutionary history, and ecological role. These findings challenge previous assumptions about the shark's size, diet, and behavior, revealing it as a fast-swimming predator rather than a bottom-dweller. The discovery helps clarify the evolutionary lineage of mackerel sharks and offers a more comprehensive understanding of ancient marine ecosystems.