Keith Campbell, a British cell biologist who helped usher into being one of the most famous animals in creation, Dolly the cloned sheep, died last Friday at his home in the Derbyshire region of England. He was 58.

His death was announced by the University of Nottingham, where he had taught since 1999. The cause was not made public.

In February 1997, Dr. Campbell and his colleague Ian Wilmut, both then on the staff of the Roslin Institute, a research center near Edinburgh, disclosed that Dolly, the first mammal to be cloned from an adult animal, had been born in Scotland the summer before.

The announcement, which seized the attention of the world news media, was divisive. On the one hand, the experiment engendered great excitement for defying conventional scientific belief: cloning a living being from an adult cell had long been deemed impossible.