Devonian : Overview

Leaf and wood of Archaeopteris.
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Placoderm
Ammonite
Shark
Brachiopods
Trilobites
Centipede
Lobe-finned fish
Amphibian skull

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OVERVIEW

Devonian 416 - 359 mya

Defining Characteristics:

• “Age of Fishes”
• diverse land invertebrates and first land vertebrates
• diversification of vascular plants
• Map of the Devonian World

Secondary Characteristics:

• Late Devonian extinction
• first true trees

The recognition of the Devonian Period was the result of great debate on the part of many nineteenth-century European geologists. The debate centered on whether the “Old Red Sandstone”—the rock layers above the Silurian (and therefore younger)—actually represented a distinct system or merely a later stage of the Silurian. In 1839, Roderick Murchison and Adam Sedgwick collaborated to name the Devonian, which they based on rock exposures in Devonshire, England. Devonian-age rocks are also common in Scotland, central Pennsylvania, western New York, and Greenland, but they have been found on all continents.

During the Devonian, most of Earth’s landmasses formed two neighboring supercontinents, Gondwana and Euramerica. The rest of the Earth’s surface was covered by a vast ocean. The Devonian world was populated by now-extinct, very primitive plants and animals, so it looked much different from our world today. In the marine realm, many members of the Paleozoic Fauna continued to diversify. On land, vascular plants and arthropods formed diverse terrestrial ecosystems, while the earliest tetrapods appeared in shallow waters nearby.

Overview | Life in the Devonian Seas | Terrestrial Habitats Conquered
The Devonian Extinction | Climate and Tectonics during the Devonian

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Devonian Period

The fourth of six periods constituting the Paleozoic Era, from about 418 to 362 million years ago.

Silurian

The third of six periods constituting the Paleozoic Era, from about 438 to 418 million years ago.

Gondwana

An ancient supercontinent made up of the modern Southern Hemisphere land masses Africa, South America, Australia, India, and Madagascar.

Euramerica

An ancient supercontinent consisting of large parts of the modern continents of North America, Europe, and Greenland. Euramerica formed as the supercontinents Laurentia and Baltica collided in the Late Silurian/Devonian. Euramerica collided with Gondwana during the Carboniferous, helping to form the supercontinent Pangaea.

fauna

Animals or animal life from a specific geologic time or geographic locality.

vascular plant

Any member of the land plant group Tracheophyta, which have specialized tissues (xylem and phloem) for conducting fluid through the stem. Among living land plants only mosses, liverworts, and hornworts lack these conducting tissues. Vascular plants are first known from the Late Silurian or Early Devonian.

arthropod

Any member of the phylum Arthropoda, which are characterized by jointed appendages, an exoskeleton, and segmented body parts. Arthropods are the most diverse group of animals on Earth and include insects, crustaceans, arachnids, myriapods, and onychophorans as well as extinct forms like trilobites.