The nature of life is such that animal species tend to enjoy a good multi-million-year run on the planet, get pushed out by evolution and changing environments, and then go extinct. They’re then lost forever, chalked up by scientists as unfit or unlucky and confined to the dusty realm of paleontology. Except getting an accurate headcount of a species is tough.
As much as it might seem some animal is completely gone, there could be some of its kind still alive, living just out of sight. This happens more than you’d think. Some animals thoughtfully eradicated by man or predated to extinction turn out to still be alive, sometimes even as part of a large, healthy population totally unawares of its so-called extinction. These are what biologists call Lazarus taxon- species thought dead and then ‘brought back to life’ by a new discovery.