The First Zoological Society in the US was formed in Philadelphia.
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Researchers identified the earliest known prehistoric ancestor of humans.
Delegates started to gather in Philadelphia to draw up the US constitution.
The Pyrenean ibex went extinct after the last surviving member of the species was killed by a falling branch.
The Soviet Union sent a dog into space aboard the spacecraft Sputnik II.
Sputnik 2 soviet spacecraft burned up, returning through Earth's atmosphere.
