pogoda: Extinction event

Evidence: 100 • authority: 72

An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the background extinction rate and the rate of speciation. Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from disagreement as to what constitutes a "major" extinction event, and the data chosen to measure past diversity.

Evidence: 45 • authority: 72

The Late Devonian mass extinction, also known as the Kellwasser event, was a mass extinction event which occurred around 372.15 million years ago, at the boundary between the Frasnian and Famennian ages of the Late Devonian period. It is placed as one of the "Big Five" most severe mass extinction events in Earth's history, with likely around 40% of marine species going extinct, though the degree of severity is contested. A second mass extinction called the Hangenberg event, also known as the end-Devonian extinction, occurred 13 million years later around 358.86 million years ago, bringing an end to the Famennian and Devonian, as the world transitioned into the Carboniferous Period. The effe…

Evidence: 45 • authority: 72

The Late Ordovician mass extinction (LOME), sometimes referred to as the end-Ordovician mass extinction or the Ordovician–Silurian extinction, is the first of the "big five" major mass extinction events in Earth's history, occurring roughly 445 million years ago (Ma). It is often considered to be the second-largest-known extinction event, behind only the end-Permian mass extinction, in terms of the percentage of genera that became extinct. Extinction was global during this interval, eliminating 49–60% of marine genera and nearly 85% of marine species. Under most tabulations, only the Permian–Triassic mass extinction exceeds the Late Ordovician mass extinction in biodiversity loss. The extin…

Evidence: 45 • authority: 72

Extinction is the termination of a species via the death of its last member. A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover. As 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" (typically in the fossil record) after a period of apparent absence. Over five billion species are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryotes globally, possibly many times more if prokaryotes a…

Evidence: 41 • authority: 80

PHANEROZOIC PALEOTEMPERATURES: THE EARTH’S CHANGING CLIMATE DURING THE LAST 540 MILLION YEARS

Evidence: 38 • authority: 88

Evidence for a Major Meteorite Impact on the Earth 34 Million Years Ago: Implication for Eocene Extinctions. A deep-sea core from the Caribbean contains a layer of sediment highly enriched in meteoritic iridium. This layer underlies a layer of North American microtektites dated at 34.4 million years ago and coincides with the extinction of five major species of Radiolaria. It is suggested that a massive, chemically undifferentiated meteorite collided with the earth, producing the tektites and leading to extinctions 34 million years ago.

Evidence: 30 • authority: 72

The Cretaceous–Paleogene (K–Pg) extinction event, formerly known as the Cretaceous–Tertiary (K–T) extinction event, was a major mass extinction of three-quarters (75%) of the plant and animal species on Earth which occurred around 66 million years ago. The event caused the extinction of all the non-avian dinosaurs and most other tetrapods weighing more than 25 kg (55 lb), excepting some ectothermic species such as sea turtles and crocodilians. It marked the ends of both the Cretaceous period and the Mesozoic era, and logged the beginning of the current geological era, the Cenozoic era. In the geologic record, the K–Pg event is marked by a thin layer of sediment called the K–Pg boundary or K…

Evidence: 30 • authority: 92

Resilience of genetic diversity in forest trees over the Quaternary.. The effect of past environmental changes on the demography and genetic diversity of natural populations remains a contentious issue and has rarely been investigated across multiple, phylogenetically distant species. Here, we perform comparative population genomic analyses and demographic inferences for seven widely distributed and ecologically contrasting European forest tree species based on concerted sampling of 164 populations across their natural ranges. For all seven species, the effective population size, N e , increased or remained stable over many glacial cycles and up to 15 million years in the most extreme cases…

Evidence: 30 • authority: 92

Application of a novel schema for describing fossil fern foliage and investigating taxonomic and morphological change across the Cretaceous-Paleogene boundary in western North America.. Premise The Chicxulub asteroid impact at the Cretaceous-Paleogene (K-Pg) boundary triggered a mass extinction 66 million years ago. Ferns thrived in the aftermath of the extinction, evidenced by the well-documented "fern spore spike." However, fern macrofossil records across the K-Pg boundary are less understood. Methods We analyzed 698 fern macrofossils from 19 Cretaceous and 83 Paleogene localities in the Raton (Colorado and New Mexico), Denver (Colorado), and Williston basins (North Dakota and Montana), g…

Evidence: 22 • authority: 92

The Origin and Early Evolution of Fungi: Challenges, Inferences, and Principles.. Fungi are widespread on our planet and essential for life as we know it, but how did they come about? Their last common ancestor lived hundreds of millions of years ago, but its characteristics, and the contours of early fungal evolution, remain mysterious. This review synthesizes information from fungal and eukaryotic microbial diversity, geology, fossils, and evolutionary genomics to infer the early evolution of fungi, identify challenges and major gaps in our knowledge, dispel misconceptions, and propose general evolutionary principles exemplified by the fungal lineage. Even though fungi likely emerged earl…

Evidence: 22 • authority: 92

Transitions between persistent climate-carbon regimes coincide with elevated Phanerozoic biosphere vulnerability.. Linking abiotic forcing to coherent biotic responses over Phanerozoic time remains difficult to quantify because both environmental drivers and biological dynamics are heterogeneous, irregularly sampled, and affected by proxy and geochronological uncertainty. Here we introduce a regime-based description of the climate-carbon system in which Phanerozoic evolution is organized into a small number of recurring, long-lived mega-climate states separated by relatively sharp transitions. Using recurrence diagnostics on paired carbon and oxygen stable isotope records, together with com…

Evidence: 22 • authority: 80

Ten Million Years of Mammal Extinctions in North America