Scottish naturalist and paleontologist who became known as an authority on lamp shells, a phylum of bottom-dwelling marine invertebrates (Brachiopoda) whose fossils are among the oldest found.

Davidson studied at the University of Edinburgh (1835–36) and on the Continent, where he participated in several geologic tours. Soon afterward, he began a study of brachiopods that was to occupy his entire life. An accomplished painter, Davidson prepared 250 excellent plates for his classic Monograph of the British Fossil Brachiopoda, 6 vol. (1851–86). He is also known for his exhaustive memoir Recent Brachiopoda.