A study has found that a third of all mammal species declared extinct in the past few centuries have turned up alive and well.
As always with a thread started by Denny Crane (never trust a lawyer) we must consider the source.
Talk about rigging a study to achieve the desired result.
Man has had neither the technology, the travel capabilities, nor the desire to actually search out and find the tiny remnants of the hundreds of thousands of species that have gone extinct in the "past few centuries" until quite recently. So it's not surprising some of them have been able to hang on in remote corners of the world unnoticed or at least unrecorded.
This is not to say they won't be extinct in a few more years, which most of them will.
The example used by Denny Crane's laughable source is the Okapi, an animal that was NEVER declared to be extinct, and was present in huge numbers in it's native range when supposedly "discovered" by the west in 1901. They have never been endangered or threatened until recent years. There are 160 of them in American and European zoos, and about 20,000 in the wild. They simply lived where white man did not go. This is probably the case with most of the other species in the study.
from wiki:
The okapi was known to the ancient Egyptians; shortly after its discovery by Europeans, an ancient carved image of the animal was discovered in Egypt.[9] Although the okapi was unknown to the Western world until the 20th century, it was possibly depicted 2,500 years ago on the facade of the Apadana, at Persepolis, as a gift from the Ethiopian procession to the Achaemenid kingdom.[10]
For years, Europeans in Africa had heard of an animal that they came to call the 'African unicorn'. In his travelogue of exploring the Congo, Henry Morton Stanley mentioned a kind of donkey that the natives called the 'Atti', which scholars later identified as the okapi. Explorers may have seen the fleeting view of the striped backside as the animal fled through the bushes, leading to speculation that the okapi was some sort of rainforest zebra.
When the British governor of Uganda, Sir Harry Johnston, discovered some pygmy inhabitants of the Congo being abducted by a German showman for exhibition in Europe, he rescued them and promised to return them to their homes. The grateful pygmies fed Johnston's curiosity about the animal mentioned in Stanley's book. Johnston was puzzled by the okapi tracks the natives showed him; while he had expected to be on the trail of some sort of forest-dwelling horse, the tracks were of some cloven-hoofed beast.
Though Johnston did not see an okapi himself, he did manage to obtain pieces of striped skin and eventually a skull. From this skull, the okapi was correctly classified as a relative of the giraffe; in 1901, the species was formally recognized as Okapia johnstoni.
The okapi is sometimes referred to as an example of a living fossil.
The okapi was adopted as an emblem by the now defunct International Society of Cryptozoology.