I have discussed biogeography before. Alfred Russel Wallace used his knowledge of animal ranges to strengthen natural selection as a theory. His work even contributed to the rise of plate tectonics as an accepted theory.
However, before plate tectonics were discovered animal ranges were often as much a hinderance to evolutionary theory as they were a benefit. One particularly annoying example was the disparate distribution of lemurs. Living specimens and fossils could be found in Madagascar and India, but were conspicuously absent in Africa and the Middle East. How could these animals be related to each other when they were thousands of miles apart with no evidence of any intermediate steps? It seemed like they had magically teleported across the Indian Ocean.
An attempt to solve this problem was put forth by a zoologist named Philip Sclater. In an article submitted to The Quarterly Journal of Science, Sclater proposed that there had been, at one point, a landmass between Madagascar and India. This would have provided a land bridge for the animals to walk across. The reason we could not visit the continent, named Lemuria after it’s inhabitants, was that a vast cataclysm had caused it to sink beneath the Indian Ocean, just like the lost continent of Atlantis.
Today, we know that Madagascar and India were in fact linked at one point. However, it was due to the movement of India northward to Asia, not sunken continents, that the two separated. However, the idea of Lemuria persisted, attracting mystic ideas of lost races of man and progenitor races. It has honestly become quite a chore to do any sort of research on this idea. You can’t make two steps before running into seven feet tall egg laying people, aliens, and extraplanar devices. I’m not kidding. And while sunken continents do exist, Lemuria today attracts more fantasy than science.