Fossil Record and Evolution

Prior to the nineteenth century, uncovered fossilized skeletal remains appeared to differ rather abruptly and dramatically in form and without apparent intermediate transitions. This was widely interpreted as support of creationism and the view that no animal species had ever become extinct. When Cuvier studied fossilized mammalian skeletons in 1796, he rejected the concept of evolution. By contrast, analogous fossilized skeletons were one of the major linchpins Darwin used when formulating his theory of evolution.

Georges Cuvier, the great French naturalist-zoologist, combined his knowledge of paleontology with his expertise in comparative anatomy when comparing the fossilized remains of mammals with their living counterparts. In 1796, Cuvier presented two papers; one comparing living elephants with extinct mammoths and, in the other, the giant sloth and the extinct Megatherium found in Paraguay. His findings and many of the geological features of the earth, he believed, could best be explained by several catastrophic events, causing the extinction of many animal species and followed by successive creations. He was a major proponent of catastrophism and highly critical of evolution.

The first discoveries of fossil remains of extinct mammals in the 1790s challenged support for the concept that living organisms were unchanged since the time of creation. This image is of an ammonite, an extinct marine invertebrate classified as a mollusk, whose name was inspired by tightly coiled rams’ horns

Charles Darwin’s voyage on the Beagle in the early 1830s took him to Patagonia, where he found the fossilized remains of mastodons, Megatheria, horses, and the large armadillo-like Glyptodons. Upon returning to England in 1836, Darwin took the fossils and his detailed notes to anatomist Richard Owen. Owen determined that these remains were more closely related to living mammals in South America than anywhere else. (He later rejected Darwin’s theory of natural selection.) In his Origin of Species (1859), Darwin noted the importance of these fossils and acknowledged that while “missing links” or transitional forms between the fossilized and living forms might never be found, and represented the greatest objection to his conclusions, nevertheless, the evidence strongly supported his theory of evolution. In 2012, a collection of 314 fossil slides collected by Darwin and his peers were rediscovered in a corner of the British Geological Survey, after being lost for more than 150 years.