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Time Period: Late Cambrian to Recent Characteristics: Marine cephalopods with straight or coiled shells

Time Period: Ordovician to Silurian Characteristics: A type of coral known for its honeycomb-like structures

Time Period: Middle Devonian to Recent Characteristics: Lobe-finned fish, often considered a 'living fossil'

Time Period: Ordovician to Triassic Characteristics: Straight-shelled nautiloid

Time Period: Late Carboniferous Characteristics: One of the earliest known diapsid reptiles

Time Period: Late Permian Characteristics: Large, herbivorous reptile with heavy body armor

Time Period: Appears in the early Cambrian and still exists today Characteristics: Has a hard 'valve' (shell) on the top and bottom

Time Period: Late Carboniferous to Permian Characteristics: A large plant resembling a tree with vertical ribbed and fluted trunk

Time Period: Carboniferous to Permian Characteristics: Commonly referred to as 'scale trees', they are giant lycophytes

Time Period: Ordovician to Permian Characteristics: Known as 'sea scorpions', includes some of the largest arthropods to have ever lived

Time Period: Appears in the Late Cambrian and still exists today Characteristics: Snails and similar organisms with a single, spirally coiled shell

Time Period: Late Carboniferous Characteristics: A very large dragonfly-like insect

Time Period: Cambrian to Carboniferous Characteristics: Colonial organisms known for their distinctive 'fence-like' structure

Time Period: Late Devonian Characteristics: Thought to be one of the first true trees

Time Period: Early Devonian Characteristics: A jawless fish with a shield-shaped head

Time Period: Late Devonian Characteristics: Giant armored fish, part of the placoderm group

Time Period: Early Devonian to Permian Characteristics: A type of trilobite with a semi-circular head

Time Period: Early Permian Characteristics: Possessed a large sail on its back, carnivorous

Time Period: Cambrian to Permian Characteristics: Distinct three-lobed, three-segmented body form