The Pyrenean ibex went extinct after the last surviving member of the species was killed by a falling branch.
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President Richard Nixon signed the US Endangered Species Act into law.
The Soviet Union sent a dog into space aboard the spacecraft Sputnik II.
The UN reported that one million plant and animal species were at risk of extinction.
Researchers identified the earliest known prehistoric ancestor of humans.
The first killer whale calf was born in captivity at Marineland in Los Angeles, California.
