text: 20th and 21st century Moving on to the 20th century, Alfred Wegener introduced the Theory of Continental Drift in 1912, though it was not widely accepted until the 1960s. This theory was revolutionary because it changed the way that everyone thought about species and their distribution around the globe. The theory explained how continents were formerly joined in one large landmass, Pangea, and slowly drifted apart due to the movement of the plates below Earth's surface. The evidence for this theory is in the geological similarities between varying locations around the globe, the geographic distribution of some fossils (including the mesosaurs) on various continents, and the jigsaw puzzle shape of the landmasses on Earth. Though Wegener did not know the mechanism of this concept of Continental Drift, this contribution to the study of biogeography was significant in the way that it shed light on the importance of environmental and geographic similarities or differences as a result of climate and other pressures on the planet. Importantly, late in his career Wegener recognised that testing his theory required measurement of continental movement rather than inference from fossils species distributions.
  In 1958 paleontologist Paul S. Martin published A Biogeography of Reptiles and Amphibians in the Gómez Farias Region, Tamaulipas, Mexico, which has been described as "ground-breaking" and "a classic treatise in historical biogeography". Martin applied several disciplines including ecology, botany, climatology, geology, and Pleistocene dispersal routes to examine the herpetofauna of a relatively small and largely undisturbed area, but ecologically complex, situated on the threshold of temperate – tropical (nearctic and neotropical) regions, including semiarid lowlands at 70 meters elevation and the northernmost cloud forest in the western hemisphere at over 2200 meters.