The natural world has always been full of giants. Long before modern animals evolved into the creatures known today, Earth was home to enormous predators, towering herbivores, and insects so large they would seem unbelievable by modern standards. From giant rats to human-length millipedes and sloths that could tower over people, prehistoric life was terrifying.
But over millions of years, changing climates, shifting ecosystems, food shortages, and competition forced many species to adapt, and often that meant getting a lot smaller.
So, what animals used to be way bigger than they are now? And what happened to them? Click on to find out.