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(THE CONVERSATION) Paleontologists like us are used to working with fossils that would seem bizarre to many biologists accustomed to living creatures. And as we go farther back in Earth’s history, the fossils start to look even weirder. They lack tails, legs, skeletons, eyes…any characteristics that would help us understand where these organisms fit in the tree of life. Under these circumstances, the science of paleontology becomes significantly harder.

Nowhere is this issue more a...