American Museum of Natural History

Don’t mess with this fish! For Fossil Friday, let’s meet Dunkleosteus terrelli. It lived some 360 million years ago during the Devonian. Scientists think it was one of the first large jawed vertebrates in the ocean and an aggressive predator. The razor-sharp edges of bones in its jaws served as cutters, and as they rubbed against each other, the opposing jaw blades acted like self-sharpening shears. These bones continued to grow as they were worn down by use.

This specimen, on display in the Museum’s Hall of Vertebrate Origins, was found in Ohio. Spot Dunkleosteus and other prehistoric animals at the Museum! Plan your visit.

Photo: Image no. ptc-5861 © AMNH Library

Welcome back to Trilobite Tuesday! Every trilobite fossil tells a story, including this large 6.7-in- (17-cm-) long Ectinaspis. Notice the coral branch on the upper-left corner? Such specimens provide insight into the marine environments in which trilobites, like this one, inhabited during the Paleozoic Era.

Ammonites were some of the most diverse organisms in the ancient ocean. The Museum holds one of the world’s largest collections of ammonites, containing nearly two million specimens that represent 300 million years of Earth’s history!