This Amazonian bird digests leaves like a cow, and hatches with claws on its wings
The hoatzin is the only bird known to rely on foregut fermentation, using bacteria in an enlarged crop to break down leaves, the same strategy cows use, which gives the bird a strong manure-like smell and the nickname 'stinkbird.' Its chicks also hatch with two functional claws on their wings, used to clamber through branches, an echo of the wing claws seen in the fossil bird Archaeopteryx.