Ordovician Arthropod Fossils

The arthropods are a thriving group of animals that have existed since at least the Cambrian Period, 543 - 490 million years ago. During the Cambrian Period, the arthropods underwent rapid evolution. Soft bodied relatives of the arthropods appeared even earlier during the Vendian Period, 650 to 543 million years ago. The arthropods include groups such as spiders, crabs, and insects. During the Ordovician, the trilobites fluorished.

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Subphylum:Schizoramia
Superclass:Arachnomorpha
Class:Trilobita
Order:Phacopida
Suborder:Calymenina
Family:Calymenidae

Genus/species:	Flexicalymene meeki
Images
Notes:	Enrolled specimen, 3.2 cm wide from cheek to cheek. Approx 4.6 cm from tail to front of cephalon. HERE to view a QuicktimeVR movie of this fossil.

Genus/species:	Flexicalymene meeki
Images
Notes:	Enrolled specimen, 2.33 cm wide from cheek to cheek. Approx 4.57 cm from tail to front of cephalon.

Genus/species:	Flexicalymene meeki
Images
Notes:	First picture is of a tail fragment still partially encased in its surrounding matrix. 1.3 cm wide. Three middle pictures are nearly complete thorax approx 2.1 cm in length. Last picture is a free tail fragment. Approx 1 cm wide.

Genus/species:	Flexicalymene retrorsa/meeki?
Images
Notes:	First two pictures are a nearly complete thorax 2.24 cm in length. Last specimen is a complete pygidium 1.12 cm long and 1.51 cm wide. It is difficult to determine the species of these specimens without the cephalon or any indication of genal spines. Close examination shows small bumps on both specimens.

Subphylum:Schizoramia
Superclass:Arachnomorpha
Class:Trilobita
Order:Asaphida
Superfamily:Asaphoidea
Family:Asaphidae
Subfamily:Isotelinae

Genus/species:	Isotelus sp.
Images
Notes:	Genal spine of an Isotelus specimen 1.43 cm long.

Subphylum:Schizoramia
Superclass:Arachnomorpha
Class:Trilobita
Order:Asaphida
Superfamily:Asaphoidea
Family:Asaphidae
Subfamily:Isotelinae

Genus/species:	Isotelus sp.
Images
Notes:	Very large Isotelus (maximus?) cephalon/pygidium fragment partially encased in matrix.