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17 animals that are living fossils

By: Bryan Nelson on Jan. 29, 2019, 10:47 a.m.
A Hoatzin on a tree branch in Peru

Photo: Bill Bouton/Wikimedia Commons

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Hoatzin

These odd-looking, pheasant-sized birds are arguably the most debated living birds because their evolutionary tree is missing so many branches.

It is the only member of its family (Opisthocomidae), though some taxonomists also place them in their own order. They retain some characteristics that are not found in any other birds. For instance, as chicks they still retain claws on the ends of their wings, which aid them in climbing and clinging to trees.

Regardless of how they fit into the evolutionary picture, they are stunning ancient animals.