A British biologist who was a key part of the team which created Dolly the sheep, a breakthrough in animal cloning, has died, it was confirmed Thursday. Professor Keith Campbell, who was 58, passed away last Friday, a spokesman from the University of Nottingham said. Campbell oversaw the scientific research that helped create Dolly, the first mammal to be cloned from an adult cell, in 1996 at the University of Edinburgh\'s Roslin Institute. Ian Wilmut, who led the Dolly team, was reported as saying Campbell deserved two-thirds of the credit for the lamb\'s creation. \"I am very saddened and upset to have heard of the death of my former colleague Keith Campbell,\" Wilmut said in a statement. \"I want to send sympathy and best wishes to his family in this difficult time.\" Dolly created a sensation when she was revealed to the public one year after she was born. Animal cloning research has progressed rapidly since, with cattle, sheep, pigs, goats, horses, dogs and cats all cloned, as well as laboratory animals like mice and rats. Campbell worked with the Roslin Institute from 1991 to 1999 before becoming a professor of animal development at the University of Nottingham.