Conrad Gesner (March 26, 1516 - December 13, 1565) was a Swiss naturalist and bibliographer. His five-volume Historiae animalium (1551-1558) is considered the beginning of modern zoology, and the flowering plant genus Gesneria (Gesneriaceae) is named after him. He is denoted by the author abbreviation Gesner when citing a botanical name. To his contemporaries he was best known as a botanist, but in 1551 he was the first to describe brown adipose tissue; and in 1565 the first to document the pencil. He died of the plague, in 1565 at the age of 49, the year after his ennoblement.