Ermine C. Case, a prominent American geologist and palaeontologist, was awarded the degrees Bachelor of Arts (BA) and Master of Arts (MA) at Kansas University in 1893, Master of Science (MSc) at Cornell University in 1895, and Doctor of Philosophy (PhD) at the University of Chicago in 1896. He was assistant professor of the history of geology and physical geography at the Wisconsin State Normal School, Milwaukee, from 1897 to 1907. In the latter year he was appointed assistant professor in the history of geology and palaeontology at the University of Michigan, where he subsequently became curator of palaeontological collections in 1911, professor in 1912, director of the Museum of Geology (from 1928 the Museum of Palaeontology), and chairman of the Department of Geology from 1934 to 1941. He wrote a book on the geology and physical geography of Wisconsin (1907). Among others he made a study of the Permian and Carboniferous vertebrates of the so-called red beds of Texas, New Mexico and Oklahoma. His numerous research papers on the vertebrate palaeontology of the United States also dealt with reconstructions of the environment in which extinct vertebrates lived.
Case travelled all over the world in connection with his work. During the early nineteen-twenties he visited South Africa and is reported to have taken fossils back with him to the United States for study. Tragically his wife, who had accompanied him, died during this visit. He published many papers on the fossil reptiles of the Karoo, particularly the Pelycosauria and Therapsida, between 1897 and 1934, and his work was influential in establishing the ancestry of mammals. Thus in an important paper which he co-authored with G. Baur, "On the morphology of the skull of the Pelycosauria and the origin of mammals" in Anatomischer Anzeiger (1897, Vol. 13, pp. 109-120) the authors state, "We are fully convinced that among these South African forms [the Therapsida] ... we have those reptiles which might be considered as ancestral to mammals or at least closely related to their ancestors". He co-authored a second paper with Baur two years later, on "The history of the Pelycosauria, with a description of the genus Dimetridon, Cape" in the Transactions of the American Philosophical Society. From this time onwards Case published almost entirely on his own. Between 1902 and 1918 he produced some 22 papers dealing with the anatomy of fossil reptiles, many of them on the osteology of the Pelycosaurian genus Dimetrodon. Most of these were published in the Journal of Geology, Science, Ameriacan Naturalist, Transactions of the American Philosophical Society, Publications of the Carnegie Institution of Washington, and Bulletin of the American Museum of Natural History. In 1926 he prepared a monograph, Environment of tetrapod life in the late palaeozoic regions other than North America, which includes a description of the Permian deposits of Africa (pp. 141-168). One of his later papers on a South African species, "Description of a skull of Kannemyeria erithrea Haughton, E.C. Chase", appeared in Contributions from the Museum of Geology, University of Michigan in 1934.
Case was president of the Palaeontological Society of America in 1929 and was involved in many other societies. He received many awards and honours.