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
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.