Related Research Articles
An extinction event is a widespread and rapid decrease in the biodiversity 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. The number of major mass extinctions in the last 440 million years are estimated from as few as five to more than twenty. These differences stem from disagreement as to what constitutes an extinction event as "major", and the data chosen to measure past diversity.
The Mesozoic Era, also called the Age of Reptiles and the Age of Conifers, is the second-to-last era of Earth's geological history, lasting from about 252 to 66 million years ago and comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles, like the dinosaurs; an abundance of conifers and ferns; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of three eras since complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic.
The PaleozoicEra is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from 541 to 251.902 million years ago, and is subdivided into six geologic periods : the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era.
The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 541 million years to the present, and it began with the Cambrian Period when animals first developed hard shells preserved in the fossil record. The time before the Phanerozoic, called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons.
The Permian–Triassicextinction event, also known as the End-Permian Extinction and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras, approximately 251.9 million years ago. It is the Earth's most severe known extinction event, with the extinction of 57% of biological families, 83% of genera, 81% of marine species and 70% of terrestrial vertebrate species. It was the largest known mass extinction of insects.
The Triassic is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic.
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" after a period of apparent absence.
The Siberian Traps is a large region of volcanic rock, known as a large igneous province, in Siberia, Russia. The massive eruptive event that formed the traps is one of the largest known volcanic events in the last 500 million years.
The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and date between 272.3 ± 0.5 – 259.8 ± 0.4 Mya. The series saw the rise of the therapsids, a minor extinction event called Olson’s Extinction and a significant mass extinction called the end-Capitanian extinction event.
Oceanic anoxic events or anoxic events (anoxia conditions) describe periods wherein large expanses of Earth's oceans were depleted of dissolved oxygen (O2), creating toxic, euxinic (anoxic and sulfidic) waters. Although anoxic events have not happened for millions of years, the geological record shows that they happened many times in the past. Anoxic events coincided with several mass extinctions and may have contributed to them. These mass extinctions include some that geobiologists use as time markers in biostratigraphic dating. On the other hand, there are widespread, various black-shale beds from the mid-Cretaceous which indicate anoxic events but are not associated with mass extinctions. Many geologists believe oceanic anoxic events are strongly linked to the slowing of ocean circulation, climatic warming, and elevated levels of greenhouse gases. Researchers have proposed enhanced volcanism (the release of CO2) as the "central external trigger for euxinia."
The clathrate gun hypothesis is a proposed explanation for the periods of rapid warming during the Quaternary. The idea is that changes in fluxes in upper intermediate waters in the ocean caused temperature fluctuations that alternately accumulated and occasionally released methane clathrate on upper continental slopes, these events would have caused the Bond Cycles and individual interstadial events, such as the Dansgaard–Oeschger interstadials.
Methanosarcina is a genus of euryarchaeote archaea that produce methane. These single-celled organisms are known as anaerobic methanogens that produce methane using all three metabolic pathways for methanogenesis. They live in diverse environments where they can remain safe from the effects of oxygen, whether on the earth's surface, in groundwater, in deep sea vents, and in animal digestive tracts. Methanosarcina grow in colonies.
The geological history of Earth follows the major events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.
A marine regression is a geological process occurring when areas of submerged seafloor are exposed above the sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously-exposed land.
Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic. While it is a long-term natural process, methane release is exacerbated by global warming. This results in a positive feedback cycle, as methane is itself a powerful greenhouse gas.
The Medea hypothesis is a term coined by paleontologist Peter Ward for a hypothesis that contests the Gaian hypothesis and proposes that multicellular life, understood as a superorganism, may be self-destructive or suicidal. In this view, microbial-triggered mass extinctions result in returns to the microbial-dominated state it has been for most of its history. The metaphor refers to the mythological Medea, who kills her own children.
A paleocontinent or palaeocontinent is a distinct area of continental crust that existed as a major landmass in the geological past. There have been many different landmasses throughout Earth's time. They range in sizes, some are just a collection of small microcontinents while others are large conglomerates of crust. As time progresses and sea levels rise and fall more crust can be exposed making way for larger landmasses. The continents of the past shaped the evolution of organisms on Earth and contributed to the climate of the globe as well. As landmasses break apart, species are separated and those that were once the same now have evolved to their new climate. The constant movement of these landmasses greatly determines the distribution of organisms on Earth's surface. This is evident with how similar fossils are found on completely separate continents. Also, as continents move, mountain building events (orogenies) occur, causing a shift in the global climate as new rock is exposed and then there is more exposed rock at higher elevations. This causes glacial ice expansion and an overall cooler global climate. Which effects the overall global climate trend of Earth. The movement of the continents greatly affects the overall dispersal of organisms throughout the world and the trend in climate throughout Earth's history. Examples include Laurentia, Baltica and Avalonia, which collided together during the Caledonian orogeny to form the Old Red Sandstone paleocontinent of Laurussia. Another example includes a collision that occurred during the late Pennsylvanian and early Permian time when there was a collision between the two continents of Tarimsky and Kirghiz-Kazakh. This collision was caused because of their askew convergence when the paleoceanic basin closed.
Olson's Extinction was a mass extinction that occurred 273 million years ago in the early Guadalupian of the Permian period and which predated the Permian–Triassic extinction event. It is named after Everett C. Olson. There was a hiatus and a sudden change in between the early Permian and middle/late Permian faunas. Since then this event has been realized across many groups, including plants, marine invertebrates, and tetrapods.
"The Lost Worlds of Planet Earth" is the ninth episode of the American documentary television series Cosmos: A Spacetime Odyssey. It premiered on May 4, 2014 on Fox, and aired on May 5, 2014 on National Geographic Channel. The episode was directed by Brannon Braga, written by Ann Druyan and Steven Soter, and featured the voice of Amanda Seyfried as geologist Marie Tharp. The episode explores the history of the Earth starting with the period of the Late Heavy Bombardment, approximately "3.8 to 4.1 Billion years ago during which the Moon, Mercury, Venus, and the Earth were battered by space debris." Host Neil deGrasse Tyson then delves into the biography of the Earth, expressed "in its continents, oceans and life living on and in them, saying 'the past is another planet,'" alluding to how plate tectonics have shaped the Earth over millions of years.
Michael R. Rampino is a Geologist and Professor of Biology and Environmental Studies at New York University, known for his scientific contributions on causes of mass extinctions of life. Along with colleagues, he's developed theories about periodic mass extinctions being strongly related to the earth’s position in relation to the galaxy. "The solar system and its planets experience cataclysms every time they pass "up" or "down" through the plane of the disk-shaped galaxy." These ~30 million year cyclical breaks are an important factor in evolutionary theory, along with other longer 60-million- and 140-million-year cycles potentially caused by mantle plumes within the planet, opining "The Earth seems to have a pulse," He is also a research consultant at NASA’s Goddard Institute for Space Studies (GISS) in New York City.
References
- ↑ Hoffmann J.H. (2000), "When life nearly came to an end", National Geographic 198(3): p. 100-113.
- ↑ The Day The Earth Nearly Died, www.bbc.co.uk.
