Fossilised moa poo paints a picture of the past

Knowledge of the diets of New Zealand's extinct moa (Aves: Dinornithiformes) comes from careful analysis of moa coprolites (fossilized poop) and gizzard contents. Moa coprolites and gizzard contents can be dissected and analyzed ...

Mammals in the time of dinosaurs held each other back

A new study led by researchers from the Oxford University Museum of Natural History, University of Oxford and the University of Birmingham for Current Biology has used new methods to analyze the variability of mammal fossils, ...

Ankle and foot evolution gave mammals a leg up

The evolution of ankle and foot bones into different shapes and sizes helped mammals adapt and thrive after the extinction of the dinosaurs, a study suggests.

Southern African dinosaur had irregular growth

Anyone who's raised a child or a pet will know just how fast and how steady their growth seems to be. You leave for a few days on a work trip and when you come home the child seems to have grown an inch! That's all well and ...

Time for a mass extinction metrics makeover

Researchers at Yale and Princeton say the scientific community sorely needs a new way to compare the cascading effects of ecosystem loss due to human-induced environmental change to major crises of the past.

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Extinction

In biology and ecology, extinction is the end of a species or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that 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 "re-appears" (typically in the fossil record) after a period of apparent absence.

Through evolution, new species arise through the process of speciation—where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche—and species become extinct when they are no longer able to survive in changing conditions or against superior competition. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Extinction, though, is usually a natural phenomenon; it is estimated that 99.9% of all species that have ever lived are now extinct.

Prior to the dispersion of humans across the earth, extinction generally occurred at a continuous low rate, mass extinctions being relatively rare events. Starting approximately 100,000 years ago, and coinciding with an increase in the numbers and range of humans, species extinctions have increased to a rate unprecedented since the Cretaceous–Tertiary extinction event. This is known as the Holocene extinction event and is at least the sixth such extinction event. Some experts have estimated that up to half of presently existing species may become extinct by 2100.

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