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The Devonian (/ d ə ˈ v oʊ n i. ən, d ɛ-/ də-VOH-nee-ən, deh-) [9] [10] is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at 419.62 million years ago (), to the beginning of the succeeding Carboniferous period at 358.86 Ma.
The Devonian (/ d ə ˈ v oʊ n i. ən, d ɛ-/ də-VOH-nee-ən, deh-) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at 419.62 million years ago (), to the beginning of the succeeding Carboniferous period at 358.86 Ma.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
Tetrapod-like vertebrates first appeared in the Early Devonian period, and species with limbs and digits were around by the Late Devonian. [63] These early "stem-tetrapods" included animals such as Ichthyostega, [2] with legs and lungs as well as gills, but still primarily aquatic and poorly adapted for life on land.
During the Late Devonian, the continents were arranged differently from today, with a supercontinent, Gondwana, covering much of the Southern Hemisphere.The continent of Siberia occupied the Northern Hemisphere, while an equatorial continent, Laurussia (formed by the collision of Baltica and Laurentia), was drifting towards Gondwana, closing the Rheic Ocean.
The Oligocene was an important transitional period between the tropical world of the Eocene and more modern ecosystems. This period featured a global expansion of grass which led to many new species taking advantage, including the first elephants, felines, canines, marsupials and many other species still prevalent today. Many other species of ...
The largest member of this group, Dunkleosteus, was a true "superpredator" of the latest Devonian period, reaching 3 to as much as 8 metres in length. In contrast, the long-nosed Rolfosteus measured just 15 cm. Fossils of Incisoscutum have been found containing unborn fetuses, indicating that arthrodires gave birth to live young.
The Lochkovian is one of three faunal stages in the Early Devonian Epoch. It lasted from 419.2 ± 3.2 million years ago to 410.8 ± 2.8 million years ago. It marked the beginning of the Devonian Period, and was followed by the Pragian Stage. It is named after the village of Lochkov in the Czech Republic, now part of the city of Prague. [7]