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CNN) -- While the cloning technology used by Oregon scientists to create the monkey Tetra is new, she is not the first monkey to be cloned. In fact, several mammals have been cloned in the last four years.

Remember Dolly? Dr. Ian Wilmut introduced the world's first cloned mammal, a sheep, in February 1997.

Tetra differs from Dolly. Tetra has both a mother and a father and is a clone of neither. Rather, the offspring of those parents are clones of each other.

Dolly had only one parent, of whom she was a genetic copy. Dolly was developed from an adult animal cell using a technique called somatic cell nuclear transfer.

Wilmut's 1997 achievement spurred fear, debate and new legislation around the world.

President Bill Clinton issued a moratorium banning the use of federal dollars for any project relating to human cloning and asked the National Bioethics Advisory Commission to explore the legal and ethical issues surrounding cloning.

Later in 1997, a bull was cloned. Named Gene, this bull started life as a collection of very basic fetal cells. The cells were grown until they were ready to be put inside a specially prepared cow's egg.

The egg, which had completely new genetic content, was implanted into a cow and months later Gene was born.

Dolly and Gene were joined by calves George and Charlie and cloned sheep Molly and Polly, as well as cloned multiple generations of mice.

"Tetra is the world's first monkey cloned by embryo splitting," says Gerald Shatten of the Oregon Regional Primate Research Center.