A species becomes extinct when the last existing member of that species dies. Extinction therefore becomes a certainty when there are no surviving individuals that are able to reproduce and create a new generation. A species may become functionally extinct when only a handful of individuals survive, which are unable to reproduce due to poor health, age, sparse distribution over a large range, a lack of individuals of both sexes (in sexually reproducing species), or other reasons. Pinpointing the extinction (or pseudo extinction) of a species requires a clear definition of that species. If it is to be declared extinct, the species in question must be uniquely identifiable from any ancestor or daughter species, or from other closely related species. Extinction of a species (or replacement by a daughter species) plays a key role in the punctuated equilibrium hypothesis of Stephen Jay Gould and Niles Eldredge. In ecology, extinction is often used informally to refer to local extinction, in which a species ceases to exist in the chosen area of study, but still exists elsewhere. This phenomenon is also known as extirpation. Local extinctions may be followed by a replacement of the species taken from other locations; wolf reintroduction is an example of this. Species which are not extinct are termed extant. Those that are extant but threatened by extinction are referred to as threatened or endangered species.
An important aspect of extinction at the present time are human attempts to preserve critically endangered species, which is reflected by the creation of the conservation status "Extinct in the Wild" (EW). Species listed under this status by the World Conservation Union (IUCN) are not known to have any living specimens in the wild, and are maintained only in zoos or other artificial environments. Some of these species are functionally extinct, as they are no longer part of their natural habitat and it is unlikely the species will ever be restored to the wild. When possible, modern zoological institutions attempt to maintain a viable population for species preservation and possible future reintroduction to the wild through use of carefully planned breeding programs. The extinction of one species' wild population can have knock-on effects, causing further extinctions. These are also called "chains of extinction".
The earliest settlers in the New World were amazed by the passenger pigeon, a bird with flocks so huge that it would take days for them to travel overhead, blackening the sky as they passed. Any farmer who had the misfortune of hosting passenger pigeons for a meal would quickly find his entire crop decimated within the blink of an eye. Then, virtually overnight, the most abundant bird in North America suddenly disappeared from the planet. The extinction of the passenger pigeon is an example of nature coming into direct conflict with man. Its population numbered an astounding 3 to 5 billion when the first Europeans arrived in America. However, there was not room enough in the New World for both species. Passenger pigeons were soon wiped out due to merciless hunting, deforestation and other factors related to humankind's ever-expanding range. The extinction was only becoming apparent at the start of the 20th century; by 1914, the last known bird was dead.
An important aspect of extinction at the present time are human attempts to preserve critically endangered species, which is reflected by the creation of the conservation status "Extinct in the Wild" (EW). Species listed under this status by the World Conservation Union (IUCN) are not known to have any living specimens in the wild, and are maintained only in zoos or other artificial environments. Some of these species are functionally extinct, as they are no longer part of their natural habitat and it is unlikely the species will ever be restored to the wild. When possible, modern zoological institutions attempt to maintain a viable population for species preservation and possible future reintroduction to the wild through use of carefully planned breeding programs. The extinction of one species' wild population can have knock-on effects, causing further extinctions. These are also called "chains of extinction".
Passenger Pigeon
Quagga
The quagga is a mammal closely related to modern horses and zebras. In fact, it looks like a cross between a horse and a zebra, with stripes only on its head and neck that disappear as they approach the brownish hindquarters of the animal. The quagga was native to desert areas of South Africa until it was hunted to extinction in the 1870s. The last captive animals died in Europe in the 1880s. As an extinct species, the quagga has a couple claims to fame. For starters, it was the first animal to have its DNA analyzed, which led to the discovery that the quagga was not a distinct species but a subspecies of the plains zebra. Also, the quagga is the subject of an ambitious breeding effort by the aptly named Quagga Project, the result of which was a foal born in 2005. Based on appearances, the "re-created" quagga closely resembles the ancient quagga, but DNA evidence has yet to determine whether this animal is authentic.
The quagga is a mammal closely related to modern horses and zebras. In fact, it looks like a cross between a horse and a zebra, with stripes only on its head and neck that disappear as they approach the brownish hindquarters of the animal. The quagga was native to desert areas of South Africa until it was hunted to extinction in the 1870s. The last captive animals died in Europe in the 1880s. As an extinct species, the quagga has a couple claims to fame. For starters, it was the first animal to have its DNA analyzed, which led to the discovery that the quagga was not a distinct species but a subspecies of the plains zebra. Also, the quagga is the subject of an ambitious breeding effort by the aptly named Quagga Project, the result of which was a foal born in 2005. Based on appearances, the "re-created" quagga closely resembles the ancient quagga, but DNA evidence has yet to determine whether this animal is authentic.
Archaeopteryx
Holding the No.8 spot in our countdown is an ancient creature named Archaeopteryx, whose discovery in the mid-1800s turned the world of paleontology upside down. It looked like some sort of feathered dinosaur, but it also had a number of bird characteristics. Was it a bird, a dinosaur or some other beast entirely? Clues would come in time, but only after decades of contentious debate and close examination. In order to fully understand the natural history of Archaeopteryx, one needs first to take a look at some of its unusual characteristics. Its dinosaur features include a full set of teeth, a flat breastbone, a bone tail and claws on the end of its wing. On the other hand, its feathers and wings also made it quite birdlike. However, details of Archaeopteryx anatomy indicated that it was not ideally built for flight and probably spent as much time running, leaping, climbing and gliding as it did flying.
Saber-Toothed Cat
Of all the cute, cuddly animals found in the fossil record, the saber-toothed cat (also called the saber-toothed tiger) is one of the last you would want to meet in a dark alley. With their daggerlike canine teeth and powerful bodies, this animal was one of the most ferocious predators of the Cenozoic Period. It lived in North America and Europe and went extinct about 10,000 years ago. There have been several thousand saber-toothed cat specimens found at the famous La Brea Tar Pits in Los Angeles, Calif. – so many that it was named the state fossil of California.
So, what were these big beasts like in the wild? Evidence suggests that the saber-toothed cat had a social structure much like modern lions, living together and cooperating in order to bring down prey.
Interestingly, researchers also believe that a certain amount of nurturing went on in a saber-toothed cat pack. Many individual fossils show signs of extensive regeneration and healing after disease and injury, suggesting an environment in which individuals could be cared for by other members of the group. Despite their terrifying appearance, it seems these animals had a soft side.
The Dodo Bird
Contrary to popular belief, the dodo was not a stupid or lazy bird. After all, it lived in a predator-free environment where food was plentiful on the ground. Why bother flying when you can simply stroll about at a leisurely pace? But what was by all accounts the sweet life for the dodo came to an abrupt end in the1600s, when European explorers landed on Mauritius, the island in the Indian Ocean where the dodo made its home. After their arrival, it would be only a few short years before the animal was hunted to extinction, primarily because it was a much-needed source of meat for weary sailors. In addition, the pigs, dogs and rats that inevitably accompanied sailing ships made short work of dodo eggs, which were all too accessible from their nests on the ground. The dodo never stood a chance.
Mammoth
If there is one animal most associated with the Ice Age, it has to be the woolly mammoth, that giant shaggy beast with long ivory tusks curling up from its massive trunk-like nose. The woolly mammoth was one of several species of mammoth, the earliest of which were probably small and amphibious creatures living in North Africa until about three million years ago. Their descendants eventually dispersed throughout Eurasia and the woolly mammoth, one of the smaller mammoth species, migrated to North America across the Bering Land Bridge sometime during late Pleistocene. Alas, this enigmatic creature did not survive long in the New World. The last of the woolly mammoths died out at the end of the last ice age, about ten thousand years ago.
Thylacine-Tasmanian Tiger
The Thylacine the largest known carnivorous marsupial of modern times. Native to continental Australia, Tasmania and New Guinea, it is thought to have become extinct in the 20th century. It is commonly known as the Tasmanian Tiger (because of its striped back), the Tasmanian Wolf, and colloquially the Tassie (or Tazzy) Tiger or simply the Tiger. It was the last extant member of its genus, Thylacinus, although several related species have been found in the fossil record dating back to the early Miocene.
The Thylacine became extinct on the Australian mainland thousands of years before European settlement of the continent, but it survived on the island of Tasmania along with several other endemic species, including the Tasmanian Devil. Intensive hunting encouraged by bounties is generally blamed for its extinction, but other contributory factors may have been disease, the introduction of dogs, and human encroachment into its habitat. Despite its official classification as extinct, sightings are still reported.
Like the tigers and wolves of the Northern Hemisphere, from which it obtained two of its common names, the Thylacine was an apex predator. As a marsupial, it was not related to these placental mammals, but because of convergent evolution it displayed the same general form and adaptations. Its closest living relative is thought to be either the Tasmanian Devil or Numbat.
Contrary to popular belief, the dodo was not a stupid or lazy bird. After all, it lived in a predator-free environment where food was plentiful on the ground. Why bother flying when you can simply stroll about at a leisurely pace? But what was by all accounts the sweet life for the dodo came to an abrupt end in the1600s, when European explorers landed on Mauritius, the island in the Indian Ocean where the dodo made its home. After their arrival, it would be only a few short years before the animal was hunted to extinction, primarily because it was a much-needed source of meat for weary sailors. In addition, the pigs, dogs and rats that inevitably accompanied sailing ships made short work of dodo eggs, which were all too accessible from their nests on the ground. The dodo never stood a chance.
Mammoth
If there is one animal most associated with the Ice Age, it has to be the woolly mammoth, that giant shaggy beast with long ivory tusks curling up from its massive trunk-like nose. The woolly mammoth was one of several species of mammoth, the earliest of which were probably small and amphibious creatures living in North Africa until about three million years ago. Their descendants eventually dispersed throughout Eurasia and the woolly mammoth, one of the smaller mammoth species, migrated to North America across the Bering Land Bridge sometime during late Pleistocene. Alas, this enigmatic creature did not survive long in the New World. The last of the woolly mammoths died out at the end of the last ice age, about ten thousand years ago.
Thylacine-Tasmanian Tiger
The Thylacine the largest known carnivorous marsupial of modern times. Native to continental Australia, Tasmania and New Guinea, it is thought to have become extinct in the 20th century. It is commonly known as the Tasmanian Tiger (because of its striped back), the Tasmanian Wolf, and colloquially the Tassie (or Tazzy) Tiger or simply the Tiger. It was the last extant member of its genus, Thylacinus, although several related species have been found in the fossil record dating back to the early Miocene.
The Thylacine became extinct on the Australian mainland thousands of years before European settlement of the continent, but it survived on the island of Tasmania along with several other endemic species, including the Tasmanian Devil. Intensive hunting encouraged by bounties is generally blamed for its extinction, but other contributory factors may have been disease, the introduction of dogs, and human encroachment into its habitat. Despite its official classification as extinct, sightings are still reported.
Like the tigers and wolves of the Northern Hemisphere, from which it obtained two of its common names, the Thylacine was an apex predator. As a marsupial, it was not related to these placental mammals, but because of convergent evolution it displayed the same general form and adaptations. Its closest living relative is thought to be either the Tasmanian Devil or Numbat.
