General Information

The Ordovician Period is the second period of the Paleozoic Era. This period saw the origin and rapid evolution of many new types of invertebrate animals which replaced their Cambrian predecessors.

Primitive vascular plants appeared the land, until then almost totally barren.

The supercontinent of Gondwana drifted over the south pole, initiating a great Ice Age that gripped the earth at this time. The end of the period is marked by a major extinction event.

Arbuscular mycorrhiza

An arbuscular mycorrhiza (plural mycorrhizae or mycorrhizas, aka AM Fungi) is a type of mycorrhiza in which the fungus penetrates the cortical cells of the roots of a vascular plant.

B r y o p h y t eNon-vascular plants. It's a

collective term for mosses, hornworts, and liverworts, which appeared around that period.

Green algaeThe green algae (singular: green alga)

are the large group of algae from which the embryophytes (higher plants) emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic (and often just known as kingdom Plantae).

T r il o b it e s

They are a well-known fossil group of extinct marine arthropods that form the class Trilobita.

The trilobites were among the most successful of all early animals, roaming the oceans for over 270 million years.

Gr a p t o l it h in iaGraptolites are fossil colonial

animals known chiefly from the Upper Cambrian through the Lower Carboniferous (Mississippian). A possible early graptolite, Chaunograptus, is known from the Middle Cambrian.

Nautiloid

Nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals, and developed an extraordinary diversity of shell shapes and forms.

Ag n a t h aAgnatha (Greek, "no jaws") is a

superclass of jawless fish in the phylum Chordata, subphylum Vertebrata. The group excludes all vertebrates with jaws, known as gnathostomes.

Bi val v i a Taxonomic class of marine and

freshwater molluscs that have a shell in two hinged parts. This class includes clams, oysters, mussels, scallops, and many other families.

Os t r a c o d e r mAny of several groups of extinct,

primitive, jawless fishes that were covered in an armor of bony plates. They belong to the taxon Ostracodermi, and their fossils are found in the Ordovician and Devonian Period strata of North America and Europe.

A r c h a e o c y a t h aWere sessile, reef-building

marine organisms of warm tropical and subtropical waters.