The Late Devonian World
Events of the Devonian Period -420 — – -415 — – -410 — – -405 — – -400 — – -395 — – -390 — – -385 — – -380 — – -375 — – -370 — – -365 — – -360 — – -355 — Silurian Lochkovian Pragian Emsian Eifelian Givetian Frasnian Famennian Carbon-iferous ← Rhynie chert ← Hangenberg event ← Kellwasser event(s) ← Widespread
shrubs & trees ← S. America
glaciation begins ← Hunsrück fauna
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Key events of the Devonian Period.
Axis scale: millions of years ago.
During the Late Devonian, the continents were arranged differently, 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. The Caledonian mountains were also growing across what is now the Scottish highlands and Scandinavia, while the Appalachians rose over America; these mountain belts were the equivalent of the Himalaya today.
The biota was also very different. Plants, which had been on land in forms similar to mosses, liverworts, and lichens since the Ordovician, had just developed roots, seeds, and water transport systems that allowed them to survive away from places that were constantly wet—and consequently built huge forests on the highlands. Several different clades had developed a shrubby or tree-like habit by the Late Givetian, including the cladoxylalean ferns, lepidosigillarioid lycopsids, and aneurophyte and archaeopterid progymnosperms. Fish were also undergoing a huge radiation, and the first tetrapods were beginning to evolve leg-like structures.
Read more about this topic: Late Devonian Extinction
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