The common trilobite Selenopeltis lived in cool waters along the coast of Gondwana, a mighty prehistoric continent that later broke apart to form South America, Africa, and Australia. It had long, sweeping spines that give its fossils a graceful appearance, making them a favorite among fossil collectors.
■ When: 471–445 million years ago (Early to Late Ordovician)
■ Fossil location: British Isles, France, Iberia, Morocco, Czech Republic, Turkey
■ Habitat: Ocean waters
■ Length: Up to 4.1/2in (12 cm)
Selenopeltis had a wide skeleton and a distinctive squarish head. Spines extended backward from its cheeks and the sides of each body segment. Unlike most other trilobites, it had small eyes.