The only known specimen of the Liberian Greenbul.
The only known specimen of the Liberian Greenbul. Courtesy University of Aberdeen

The Liberian Greenbul is one of the world’s rarest songbirds—so rare, in fact, that experts are beginning to wonder whether it ever existed in the first place. This little bird, with its butter-yellow chest, was allegedly first spotted in a West African forest about 25 years ago. Just one specimen exists, with a spattering of distinctive white spots across its plumage that differentiate it from its common cousin, the Icterine Greenbul. Unless, of course, they don’t. New DNA analysis and research from the University of Aberdeen suggest that this handsome little fellow is, in fact, just an Icterine Greenbul, and that those spots are just an “unusual plumage variant.” The Liberian Greenbul is so hard to find because, well, there is no Liberian Greenbul.

The latest is that brontosaurus was a real species, but it's taken an awful long time to get here.
The latest is that brontosaurus was a real species, but it’s taken an awful long time to get here. Biodiversity Heritage Library/CC BY 2.0

Beyond the obviously mythological (unicorns and the like), species like the Liberian Greenbul, that were once thought to exist but no longer are, are few and far between. They crop up most often in paleontology, and have lumped some beloved dinosaurs together with others. Triceratops, for instance, may have been juvenile versions of the “rarer” torosaurus, scientists said in 2010, though other scientists disagreed a few years later. Paleontologists also haven’t always been able to make up their minds about brontosaurus—the field has gone back and forth on whether they’ve just been apatosauruses all along. It’s estimated that as much as a third of all known dinosaurs may have never existed as separate species.

In more recent times, the sweet little Hunter Island penguin was thought to have lived around Tasmania, Australia, and gone extinct. Like the Liberian Greenbul, there were few specimens available. DNA testing earlier this year, however, showed that the bones from which the species was identified were actually a smorgasbord of other penguins: the Fiordland crested, the Snares crested, and the little fairy. Just like that, the Hunter Island penguin was gone. The eastern cougar, native to Canada’s New Brunswick, is almost certainly just a regular cougar, say local zoologists. The kouprey, an endangered Cambodian ox with huge, curving horns, was in 2006 revealed to be a feral hybrid of ordinary wild oxen. And the panther? It is to a leopard what a black Labrador retriever is to a golden retriever. Same species, different look.