Famennian

The Famennian is the latter of two faunal stages in the Late Devonian epoch. It lasted from 372.2 ± 1.6 million years ago to 358.9 ± 0.4 million years ago. It was preceded by the Frasnian stage and followed by the Tournaisian stage.

It was during this age that tetrapods first appeared. In the seas, a novel major group of ammonoid cephalopods called clymeniids appeared, underwent tremendous diversification and spread worldwide, then just as suddenly went extinct.

The beginning of the Famennian is marked by a major extinction event, the Kellwasser Event, and the end with a smaller but still quite severe extinction event, the Hangenberg Event.

North American subdivisions of the Famennian include the Chautauquan, Canadaway, Conneaut, Conneautan, Conewango and Conewangan.

Name and definition

The Famennian stage was proposed in 1855 by Belgian geologist André Hubert Dumont and was accepted for the upper stage of the Upper Devonian by the Subcommission on Devonian Stratigraphy in 1981. It is named after Famenne, a natural region in southern Belgium.

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 419.2 Mya (million years ago), to the beginning of the Carboniferous Period, about 358.9. It is named after Devon, England, where rocks from this period were first studied. The Devonian period experienced the first significant adaptive radiation of terrestrial life. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the "Age of Fish". The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating almost every known aquatic environment.

The ancestors of all tetrapods began adapting to walking on land, their strong pectoral and pelvic fins gradually evolving into legs. In the oceans, primitive sharks became more numerous than in the Silurian and the late Ordovician. The first ammonite mollusks appeared. Trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction which started about 375 million years ago severely affected marine life, killing off all placoderms, and all trilobites, save for a few species of the order Proetida.

2014

2014 (MMXIV) was a common year starting on Wednesday (dominical letter E) of the Gregorian calendar, the 2014th year of the Common Era (CE) and Anno Domini (AD) designations, the 14th year of the 3rd millennium, the 14th year of the 21st century, and the 5th year of the 2010s decade.

2014 was designated as:

Events

January

February

Extinction event

An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the amount of life on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the rate of speciation. Because the majority of diversity and biomass on Earth is microbial, and thus difficult to measure, recorded extinction events affect the easily observed, biologically complex component of the biosphere rather than the total diversity and abundance of life.

Extinction occurs at an uneven rate. Based on the fossil record, the background rate of extinctions on Earth is about two to five taxonomic families of marine animals every million years. Marine fossils are mostly used to measure extinction rates because of their superior fossil record and stratigraphic range compared to land organisms.

The Great Oxygenation Event was probably the first major extinction event. Since the Cambrian explosion five further major mass extinctions have significantly exceeded the background extinction rate. The most recent and debatably best-known, the Cretaceous–Paleogene extinction event, which occurred approximately 66 million years ago (Ma), was a large-scale mass extinction of animal and plant species in a geologically short period of time. In addition to the five major mass extinctions, there are numerous minor ones as well and the ongoing mass-extinction caused by human activity is sometimes called the sixth extinction. Mass extinctions seem to be a mainly Phanerozoic phenomenon, with extinction rates low before large complex organisms arose.