Mass extinction in the context of "Biological diversity"

An impact event is a collision between astronomical objects causing measurable effects. Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, as the impacting body is usually traveling at several kilometres per second (km/s), with a minimum impact speed of 11.2 km/s (25,054 mph; 40,320 km/h) for bodies striking Earth. While planetary atmospheres can mitigate some of these impacts through the effects of atmospheric entry, many large bodies retain sufficient energy to reach the surface and cause substantial damage. This results in the formation of impact craters and structures, shaping the dominant landforms found across various types of solid objects found in the Solar System. Their prevalence and ubiquity present the strongest empirical evidence of the frequency and scale of these events.

Impact events appear to have played a significant role in the evolution of the Solar System since its formation. Major impact events have significantly shaped Earth's history, and have been implicated in the formation of the Earth–Moon system. Interplanetary impacts have also been proposed to explain the retrograde rotation of Uranus and Venus. Impact events also appear to have played a significant role in the evolutionary history of life. Impacts may have helped deliver the building blocks for life (the panspermia theory relies on this premise). Impacts have been suggested as the origin of water on Earth. They have also been implicated in several mass extinctions. The prehistoric Chicxulub impact, 66 million years ago, is believed to be the cause not only of the Cretaceous–Paleogene extinction event but acceleration of the evolution of mammals, leading to their dominance and, in turn, setting in place conditions for the eventual rise of humans.

The Cryogenian (from Ancient Greek: κρύος, romanized: krýos, meaning "cold" and γένεσις, romanized: génesis, meaning "birth") is a geologic period that lasted from 720 to 635 million years ago. It is the second of the three periods of the Neoproterozoic era, preceded by the Tonian and followed by the Ediacaran.

The Cryogenian was a time of drastic climate changes. After the long environmental stability/stagnation during the Boring Billion, the Sturtian glaciation began at the beginning of Cryogenian, freezing the entire planet in a state of severe icehouse climate known as a snowball Earth. After 70 million years it ended, but was quickly followed by another global ice age, the Marinoan glaciation. There is controversy over whether these glaciations indeed covered the entire planet, or whether a band of open sea survived near the equator (i.e. "slushball Earth"), but the extreme climates with massive expanse of ice sheets blocking off sunlight would nevertheless have significantly hindered primary production in the shallow seas and caused major mass extinctions and biosphere turnovers.

The Capitanian mass extinction, also known as the end-Guadalupian, Guadalupian-Lopingian, or pre-Lopingian extinction began around 262 million years ago with its most intense pulse peaking at 259 million years ago, marking the end of the Capitanian stage and Guadalupian (Middle Permian) epoch of the Permian. Historically conflated with the better-known Permian–Triassic extinction, it was only recognised as a distinct event in 1994. Despite this, the mass extinction is believed to be the third-largest of the Phanerozoic in terms of the percentage of genera (33-35%) and species (60-63%) lost after the end-Permian and Late Ordovician mass extinction, while being the fifth worst in terms of ecological severity. The global nature of the Capitanian mass extinction has been called into question by some palaeontologists as a result of some analyses finding it to have affected only low-latitude taxa in the Northern Hemisphere.

The Mesozoic Era is the era of Earth's geological history, lasting from about 252 to 66 million years ago, comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles such as the dinosaurs, and of gymnosperms such as cycads, ginkgoaceae and araucarian conifers; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic.

The Mesozoic is commonly known as the Age of the Dinosaurs because the terrestrial animals that dominated both hemispheres for the majority of it were Dinosaurs. This era began in the wake of the Permian–Triassic extinction event, the largest mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs, pterosaurs, mosasaurs, and plesiosaurs. The Mesozoic was a time of significant tectonic, climatic, and evolutionary activity. The supercontinent Pangaea began to break apart into separate landmasses. The climate of the Mesozoic was varied, alternating between warming and cooling periods. Overall, however, the Earth was hotter than it is today.