For decades, geologists were baffled by massive underground tunnels in Brazil — but the mystery has finally been solved. Scientists have confirmed these enormous structures, known as “paleotunnels,” were carved by giant prehistoric sloths living between 8 million and 10,000 years ago.

What do these tunnels reveal about Earth’s past megafauna? Could there be more undiscovered beneath our feet? Dive deep into this groundbreaking discovery and learn why these extinct creatures were nature’s original diggers.

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