What are some Devonian organisms?
The Devonian period is a geological period that extends from approximately 416 to 359 million years, over the total duration of 57 million years, slightly longer than the average for the geological division. Part of the longer paleozoic era, Devon was preceded by Silurian, followed by carbonus. Its beginning is defined as the appearance of graptolite fossils called monograph uniformis . Graptolites were colonial sea worms related to the worms of modern acorns. The end of the Devoniana is defined as the appearance of Conodont (Eel-similar vertebrates) Siphonodella sulcata .
The Devonian period was characterized by a deep sea inhabited by ever -diversifying species of fish. For this reason, Devonan is often called the "age of fish". During this period, many fish families have evolved, including ancestors of modern bony fish, Osteichthyes class.
The most primitive fish without jaws, Ostracoderms, died out during the early Devonian.The more face -to -face, acanthodians, also called Sharks (although they looked moreAs fish than modern sharks), they appeared in the late Silurian/early Devonian and were one of the most abundant species of freshwater fish for the rest of the paleozoic. These "barbed sharks" were the first known vertebrates and are known for stiff spines ranging from their vertebrae to support numerous fins, sometimes up to eight. Some barbed species of shark even had a small spine throughout the body. This class of fish precedes modern sharks by about 50 million years. Acanthodians and morning sharks had cartilage skeletons.
Another fascinating group of fish that lived during the Devonians were placoderms, fish with severely armored heads and without modern analogs. Placederms were a dominant group of vertebrates during the Devonian period and grew larger than other groups. Placedermy was a relatively short -term (~ 50 million years) group they have ever considered as a "early experiment in the jaw". Unlike allOther jaws of vertebrates were missing Placodermy real teeth. Their "teeth" were instead of a separate extension of their jaws. The largest known Placoderm, dunkleosteus , reached a length of 6 m (20 ft), is considered the first vertebrate superterities.
The colonization of the Earth and the animals appeared throughout Devoniana. Vascular plants first appeared in late Silurian, accompanied by primitive land arthropods and other invertebrates such as molluscs. Vascular plants were allowed by the first real forests and soils, which is a sharp contrast to small moss and "forests" of the liver Silurian. Near the very end of the Devonians, the fish with the lobe began to develop preliminary legs and first used them to navigate the swamps and then traveled on the ground. In just 57 million years, she was supposed to get the ground trap from almost completely infertile to something that is beginning to resemble today's world.