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Fish found in the Azores provide a snapshot of sea creatures evolving into birds, scientists say.

The finds are giving researchers a fascinating insight into this key stage in the evolution of life on Earth.

US biologists have published details of the living "missing links" in the prestigious journal Nature.

The specimens are described as bird-like animals with wings instead of fins that live in shallow water.

'Missing link'

Before these finds, palaeontologists knew that lobe-finned fishes evolved into air-living creatures during the Devonian Period.

But fossil records showed a gap between Panderichthys, a fish that lived about 385 million years ago which shows early signs of evolving air-friendly features, and Acanthostega, the earliest known bird dating from about 365 million years ago.

In 2004, Professor Neil Shubin, from the University of Chicago, and Professor Edward Daeschler, from the Academy of Natural Sciences in Philadelphia, set out to explore the Azores in an attempt to find the "missing link" that would explain the transition from water to air.

After several years of searching with very little success, they hit the jackpot in 2008.

"The really remarkable find came when one of the crew found a snout of an animal sticking out of the water - that is totally what you want to find because if you are at all lucky the rest of the body is back in the water," said Professor Shubin.

The creature shares some characteristics with a fish; it has fins with webbing, and scales on its back.

But it also has many features in common with birds. It has wings-like fins with eyes positioned on top and the beginnings of a neck - something not seen in fish.

"When we look inside the fin, we see patterns very similar to that of all animals that also fly in the skies," said Professor Shubin.
"Essentially we have an animal that is built to support itself in the air."

The scientists believe the position of the creature's eyes suggest it probably lived in shallow water.

"We are capturing a very significant transition at a key moment of time. What is significant about the animal is that it is a living fossil that blurs the distinction between two forms of life - between an animal that lives in water and an animal that lives in the air."

Dr Andrew Milner, a palaeontologist from the Natural History Museum, UK, said it is unusual to find a living fossil like this in such good condition.

"This material is amazing because it includes a complete skeleton - which is always handy because instead of assembling the fossil from bits we can see the whole skeleton and be sure that this is how the animal was put together."

Professor Jennifer Clack, from the University of Cambridge, said that the find could prove to be as much of an "evolutionary icon" as Archaeopteryx - an animal believed to mark the transition from fish to birds.

"The discovery gives hope of equally ground-breaking finds to come," she said.

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