Known as Lazarus species, these are animals that, at one point or other, have been pronounced extinct, only to be found years later alive and well in their habitats. Some of these animals were considered extinct for longer than others, and some are even extant, meaning very little has changed between the current animals and their fossilized ancestors, making them living fossils.

1. Nelson's Small-Eared Shrew

Pronounced extinct in 1894, it was rediscovered 109 years later by researchers Fernando Cervantes and Lazaro Guevara. They are endemic to Mexico and can be found in ecosystems of the “San Martín” Volcano in the “Los Tuxtlas” Biosphere Reserve. These shrews are so rare that they are considered to be critically endangered.

2. Chacoan Peccary

Originally found in fossil form, these animals were thought to be extinct. They were rediscovered in the "Chaco" region of Argentina, Bolivia, and Paraguay in 1971. Due to an unknown disease and because hunting them is legal, the herds of these animals have been steadily declining. It is believed that they might become endangered or extinct in the near future.

3. Ivory-Billed Woodpecker

Long believed to be extinct, various sightings of these elusive birds have been documented over the decades. The most famous one was captured in film back in 2005 in an Arkansan Swamp Forest, although the reliability of the video is still in question, as no specimen has been found to prove that the birds are still alive. Even so, experts have found breadcrumb trails that are cause for hope in regards of these birds.

4. New-Holland Mouse

Rediscovered in 1967, this rodent had been believed extinct for over 100 years. Endemic to southeastern Australia, these small rodents are classified as a vulnerable species. From fungus and fires to predators and human habitat loss, these mice have been in steady decline in the past years and, without intervention, are estimated to decline by a further 50 percent.

5. Caledonian Crested Gecko

Endemic to the South Province in New Caledonia, these small lizards used to be considered extinct until their rediscovery in 1994. Ever since, the crested geckos have made a very good comeback and some are now even kept as pets. Under proper care they are expected to live between 15 and 20 years in captivity.

6. Pygmy Tarsier

Measuring up to 4 inches, these pocket-sized primates can be found in Sulawesi, Indonesia. Having been considered extinct when no other specimens were found after 1930, the rediscovery of these creatures occurred 80 years later, ironically, during an exploration seeking to confirm their extinction. Being such small nocturnal creatures made it almost impossible to find them, but once the first one was found, another three were located easily. Due to their small size and nocturnal lives, these tarsiers manage to hide themselves fairly easily.

7. Bermuda Petrel

Even though they were protected by one of the first conservation programs established, the Bermuda Petrel was, nonetheless, declared extinct as early as 1620s. Over 300 years later, two specimens were found, but no nests. That was until in 1951 a total of 18 nesting pairs were discovered along with a 15 year old boy who would then become the biggest activist in the species recovery. Today, after years of hard work, the species is considered endangered with a small population of around 300 birds.

8. Terror Skink

Endemic to the Isle of Pines off the coast of New Caledonia, these lizards were considered extinct for over 100 years before their resurrection in 1993. One of the largest reptiles of the area, it can measure up to 20 inches in length. Currently an endangered species, little is known about these lizards as they appear to be quite rare

9. Takahē

A flightless bird native to New Zealand, The Takahē was declared extinct in 1898 and rediscovered 50 years later during a careful expedition aiming to do just that. Ever since their rediscovery, multiple pairs have been taken to reserves and sanctuaries in order to increase the species population. These attempts have all mostly been succesful ad are the cause for a small but steady increase in the birds population. Even so, breeding rates aren't too high and the Takahē still fall under the endangered species category.

10. Laotian Rock Rat

Currently and endangered species, this rat is considered a living fossil. Originally thought to be its own unique breed, these rats actually match some fossils dating back to 11 million years. Rediscovered in 1996, the inhabit the Khammouan region of Laos.

11. Guilbert's Potoro

A critically endangered species, it’s also one of the worlds most endangered mammals. Native to Australia, this marsupial, also known as the rat-kangaroo, was considered extinct for 20 years before its rediscovery in 1994. Attempts at reproduction in captivity haven’t been too successful, but because most females captured in the wild are with young, there’s hope in this species future prospects.

12. Large-Billed Reed Warbler

First discovered in 1867, only a single specimen was captured and kept. After no others were found, the bird was pronounced extinct, until another one was caught. Found in various places of southern and central Asia, this bird is so rare that very few have been caught and little is known about it.