Glossary of Organisms
Pelycosaurs
Finback reptiles, such as Dimetrodon, which were the dominant reptile group in the Permian
Geologic Range: Pennsylvanian to Late Permian
Placoderms
A group of heavily armored jawed fish that ranged from the Late Silurian to Late Permian
Geologic Range: Late Silurian to Late Permian
Sauropods
A group of saurischian dinosaurs which includes large, quadrapedal forms such as Apatosaurus(Brontosaurus), Brachiosaurus, and Diplodocus
Geologic Range: Early to Late Jurassic
Stegosaurs
A group of ornithischian dinosaurs characterized by their bony armor and large spikes on the tail
Stromatolites
Structures produced by cyanobacteria by entrapment of sediment grains on the sticky surfaces of the bacteria
Geologic Range: Archean to Recent
Stromatoporoids
Primitive sponges that secreted layered calcareous skeletons and were prominent reef-builders
Geologic Range: Middle Ordovician to Recent
Trilobites
Marine arthropods with a chitinous or calcareous exoskeleton
Geologic Range: Cambrian to Permian
Click here to view Mass Extinctions of the Phanerozoic Menu
Click here to view the Main Menu