© Agence France-Presse/Robert MichaelCoelacanths today use gills to extract oxygen from the water they live in, but millions of years ago, their ancestors probably breathed using a lung
Like all fish, today's coelacanths -- referred to as "living fossils" -- use gills to extract oxygen from the water they live in. But millions of years ago, coelacanth ancestors probably breathed using the lung, the team concluded.
"By the Mesozoic Era, adaptation of some coelacanths to deep marine water, an environment with very low variations of oxygen pressure, may have triggered the total loss of pulmonary respiration," co-author Paulo Brito of the Rio de Janeiro State University told AFP.
This could explain how it survived the extinction event 66 million years ago that wiped all non-avian dinosaurs and most other life from Earth -- and probably those coelacanths inhabiting shallow waters, he said. It would also account for "the marked reduction" of the lung into its shrivelled, present-day form, Brito said by email.
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