Glossary of Organisms

Echinoderms

A diverse group of organisms(including the crinoids and the blastoids) whose members characteristically exhibit five-fold symmetry (a modern-day example of an echinoderm is the sea urchin)
Geologic Range: Cambrian to Recent

Eurypterids

A group of extinct arthropods which were highly successful Paleozoic predators
Geologic Range: Silurian to Permian

Fusulinid Foraminifera

Large protozoan fossils with a spindle-shaped shell
Geologic Range: Mississippian to Late Cretaceous

Graptolites

Colonial hemi-chordates commonly preserved as flat carbonized streaks on black shales
Geologic Range: Late Cambrian to Pennsylvanian

Mammal-like Reptiles

Members of the group Synapsida who were the predecessors of mammals
Geologic Range: Early Permian to Late Triassic

Marine Reptiles

Successful Paleozoic and Mesozoic marine vertebrate groups including the icthyosaurs, plesiosaurs, and mosasaurs
Geologic Range: Triassic to Late Cretaceous

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