Hoatzin could reshape avian taxonomy

Hoatzins (Opisthocomus hoazin) present an evolutionary enigma — one analysis of their DNA suggests that the birds’ closest relatives are cranes and shorebirds, and another found that they are closely related to a group that includes tiny, hovering birds, such as hummingbirds. The riddle is forcing biologists to consider whether to rethink the shape of the standard ‘tree of life’ for modern birds.