This worm-like creature is the first ancestor on the human and animal family tree

By Ashley Strickland, CNN

Updated 3:00 PM ET, Mon March 23, 2020

This artist's illustration shows a young Purussaurus attacking a ground sloth in Amazonia 13 million years ago.
Photos: Ancient finds
This artist's illustration shows a young Purussaurus attacking a ground sloth in Amazonia 13 million years ago.
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This bundle of bones is the torso of another marine reptile inside the stomach of a fossilized ichthyosaur from 240 million years ago.
Photos: Ancient finds
This bundle of bones is the torso of another marine reptile inside the stomach of a fossilized ichthyosaur from 240 million years ago.
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Researchers uncovered the fossilized fragments of 200,000-year-old grass bedding in South Africa's Border Cave.
Photos: Ancient finds
Researchers uncovered the fossilized fragments of 200,000-year-old grass bedding in South Africa's Border Cave.
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Meet Sasha, the preserved and reconstructed remains of a baby woolly rhinoceros named that was discovered in Siberia.
Photos: Ancient finds
Meet Sasha, the preserved and reconstructed remains of a baby woolly rhinoceros named that was discovered in Siberia.
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Stone tools made from limestone have helped researchers to suggest that humans arrived in North America as early as 30,000 years ago.
Photos: Ancient finds
Stone tools made from limestone have helped researchers to suggest that humans arrived in North America as early as 30,000 years ago.
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This image shows both sides of the 1.4 million-year-old bone handaxe made from the femur of a hippopotamus. It was most likely crafted by ancient human ancestors like Homo erectus.
Photos: Ancient finds
This image shows both sides of the 1.4 million-year-old bone handaxe made from the femur of a hippopotamus. It was most likely crafted by ancient human ancestors like Homo erectus.
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This illustration shows Kongonaphon kely, a newly described reptile that was an early ancestor of dinosaurs and pterosaurs. The fossil was found in Madagascar. It lived about 237 million years ago.