What are Some Devonian Organisms?
The Devonian period is a geologic period that extends from approximately 416 to 359 million years ago, for a total duration of 57 million years, slightly longer than average for a geologic division. Part of the longer Paleozoic era, the Devonian was preceded by the Silurian and followed by the Carboniferous. Its start is defined as the appearance of graptolite fossils called Monograptus uniformis. Graptolites were colonial marine worms related to modern-day acorn worms. The end of the Devonian is defined as the appearance of the conodont (eel-like vertebrate) Siphonodella sulcata. The Devonian period was characterized by deep seas inhabited by increasingly diversifying fish species. For this reason, the Devonian is often called “The Age of Fishes.” Many fish families evolved during this period, including the ancestors of modern bony fish, class Osteichthyes. The most primitive jawless fishes, the ostracoderms, had died out during the early Devonian. The earliest jawed fish, the acantho
