Roughly 70 million years ago, during the Late Cretaceous, Hydrotherosaurus alexandrae glided through the waters of what is now California. This long-necked plesiosaur was a master of aquatic hunting, using its narrow, tooth-lined snout to snatch fish and squid with precision. While not a dinosaur, it was part of a lineage of marine reptiles that ruled the oceans while dinosaurs dominated the land.

Our Hydrotherosaurus skull kit captures the sleek, hydrodynamic design of this predator’s head—from its interlocking teeth built to grip slippery prey to the streamlined jaw that helped it cut through the water. Studying the skull reveals how this marine reptile paired speed and stealth to thrive in the ancient Pacific.