Theory in evolutionary biology
In evolutionary biology, the flying primate hypothesis is that megabats, a subgroup of Chiroptera (also known as flying foxes), form an evolutionary sister group of primates. The hypothesis began with Carl Linnaeus in 1758, and was again advanced by J.D. Smith in 1980. It was proposed in its modern form by Australian neuroscientist Jack...
One of my favourite hypotheses which turned out to be false, not only because it sounds cool, but also because of how certain we are that it is incorrect.