[Illustration: Georges Cuvier, 1769-1832, was a French anatomist and paleontologist who specialized in the study of animals with backbones, the vertebrates. He had a long and brilliant career as a professor, eventually becoming France’s minister of the interior in 1832. His skill as a comparative anatomist enabled him to understand how vertebrate fossils should be reconstructed to form a complete skeleton, and he was one of the first to use the small muscle scars on fossil bones to reconstruct the extinct animal’s musculature. His classic work _Récherches sur les Ossemens Fossiles de Quadrupèds_ was published in 1812. He is known for his theory of a series of natural catastrophes, each supposedly obliterating all extant life, to account for the great variety of ancient fossils. This theory was later supplanted by the theory of continuous evolution supported by Darwin, Lyell, and others.]
[Illustration: Charles Darwin, 1809-1882, is today a household name that is still invoked in controversy as it was more than a hundred years ago. An extraordinarily patient and insightful biologist, Darwin contributed the idea of natural selection, the “weeding out” of unfit individuals and species, and described it as the guiding principle of the evolution of life on this planet. His book _On the Origin of Species by Means of Natural Selection_, published in 1859, is the most important landmark in evolutionary studies. This was the culmination of decades of work, leading to conclusions startlingly similar to those of his fellow Englishman, Alfred Wallace. Darwin knew nothing of the genetic principle of biological heredity and variation, which has now assumed equal importance with natural selection in the study of the evolution of life. For paleontologists, Darwin’s work meant they must look for transitional forms of life and not content themselves with Cuvier’s assumptions that past life forms had been static and unchanging. During his travels in South America, Darwin contracted a disease, now known as Chagas’ disease, and suffered intense pain and discomfort the rest of his life. He died of a heart attack on April 19, 1882, and was buried in Westminster Abbey in London a few days later.]