Evidence for the earliest tetrapods takes the form of trace fossils in shallow lagoon environments within a marine carbonate platform/shelf during the Middle Devonian,[47] although these traces have been questioned and an interpretation as fish feeding traces (Piscichnus) has been advanced. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. 443.8 (+/- 1.5) million years ago Silurian/Began This rapid appearance of many plant groups and growth forms has been referred to as the Devonian Explosion or the Silurian-Devonian Terrestrial Revolution.[55]. The period is characterized by major changes in earths geology, climate, and lifeform. Brachiopods reached their widest diversity and greatest abundance during the Devonian. A fossil bryozoan,Sulcoretepora deissil, exhibiting pyrite replacement is prominant in our assemblage. The Devonian Period is sometimes called the Age of Fishes because of the diverse, abundant, and, in some cases, bizarre types of these creatures that swam Devonian seas. The extinction began roughly 380 million years ago, midway through the segment of . During most of the Devonian Period, North America, Greenland, and Europe were united into a single Northern Hemisphere landmass, a minor supercontinent called Laurussia or Euramerica. Both effects resulted from indirect impacts of the new plant ecosystemsswamps and forests tied up carbon dioxide, while runoff into the seas provided carbon to be consumed by aerobic bacteria, depleting the oxygen needed by animals. It had a crocodile-like head, a moveable neck, and nostrils for breathing air. Evidence of cooler average temperatures is provided by annual tree rings in Archaeopteris trunks from New York state that record seasonal growth patterns characteristic of higher latitudes. [50] Fossils of Armoricaphyton chateaupannense, about 400 million years old, represent the oldest known plants with woody tissue. [29] For much of the Devonian, the majority of western Laurussia (North America) was covered by subtropical inland seas which hosted a diverse ecosystem of reefs and marine life. This extinct group of armored fish is represented by fossil skin fromCoccosteussp. The period is named after Devon, a county in southwestern England, where a controversial argument in the 1830s over the age and structure of the rocks found distributed throughout the county was eventually resolved by the definition of the Devonian Period in the geological timescale. Trilobites (ToL: Trilobites

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