An evolutionary missing link that was among the first fish to leave the sea and walk on dry land has been unearthed in the Candadian Arctic, illuminating a chapter in the history of life on Earth that was essential to the ultimate emergence of humans.

Tiktaalik roseae, which lived about 375 million years ago, is a new species with features that blur the distinction between fish and terrestrial limbed creatures, placing it closer to animal life’s transition from water to land than any known fossil.

The fossils, found on Ellesmere Island, just 600 miles (1,000km) from the North Pole, are among the finest examples of evolution in action ever discovered.

They have allowed scientists to freeze-frame a process of adaptation to land that took tens of millions of years, which made possible the development of all the mammals, birds, reptiles and amphibians that have existed since.

Without creatures such as Tiktaalik, there would have been no dinosaurs, no primitive mammals, and none of the hominids such as Australopithecus africanus and Homo erectus that started the human family tree.

"This animal represents the transition from water to land - the part of history that includes ourselves," said Neil Shubin of the University of Chicago, who led the discovery team. "It’s as much a part of our history as, say, Australopithecus africanus."

Tiktaalik rosae was a predator with sharp teeth and a head shaped like a crocodile that grew to between 4ft and 9ft (1.2-1.7m) long. Details of the discovery are published in the journal Nature, and casts of the fossils will be displayed for a month from today at the Science Museum in London.

It was named after consultation with elders from the Inuktikuk people native to the region, who suggested their word for "large shallow-water fish". The second part of the name honours an anonymous benefactor of the research team.

The creature had several remarkable anatomical features that show it was capable not only of wading in shallow water, like slightly earlier fish on the cusp of the move to land, but also of supporting itself outside the water like four-limbed animals or tetrapods.

"Tiktaalik blurs the boundary between fish and land animals," Dr Shubin said. "This animal is both fish and tetrapod; we jokingly call it a fishapod."

Unlike fish, it had a defined neck, and a strong rib cage that would have allowed it to stand outside water. Its pectoral fins also had a wrist joint, which enabled it to crawl along the ground.

Dr Shubin said this wrist is sufficiently similar to that of later animals, including humans, to suggest that Tiktaalik or something very like it was an ancestor of all subsequent land animals.

"Here’s a creature that has a fin that can do push-ups," he said. "When we talk about the fish’s wrist, we’re talking about the origin of parts of our own wrist."

Farish Jenkins of Harvard University said it was clear from Tiktaalik’s skeleton that it could support itself in shallow water or on land. "This represents a critical early phase in the evolution of all limbed animals, including humans - albeit a very ancient step."

The Tiktaalik fossils were found in 2004 after a five-year search of a rock formation in Ellesmere Island, chosen because it was laid down during the late Devonian period, between 380 million and 365 million years ago, when the transition to land is known to have taken place. Though the rocks are now in the Arctic circle, in the late Devonian they lay close to the equator as part of a northern supercontinent.

"The find is a dream come true," said Ted Daeschler of the Academy of Natural Sciences in Philadephia, co-leader of the team. "We knew that the rocks on Ellesmere Island offered a glimpse into the right time period and the right ancient environments to provide the potential for finding fossils documenting this important evolutionary transition. Finding the fossils within this remote, rugged terrain, however, required a lot of time and effort."

The team could work only in the Arctic summer, and were often hampered by bad weather. Dr Shubin said: "And we were always looking over our shoulders for polar bears - we saw a lot of their tracks."

Richard Lane of the US National Science Foundation, which partly funded the research, said: "Human comprehension of the history of life on Earth is taking a major leap forward. These exciting discoveries are providing fossil ‘Rosetta Stones’ for a deeper understanding of this evolutionary milestone - fish to land-roaming tetrapods."

Independent experts said the find was spectacular. Andrew Milner of the Natural History Museum said: "Previous fossils representing this evolutionary event have really been fish with a few land characteristics, or land vertebrates with a few residual fish characteristics. These fossils show an animal that sits bang in the middle between the fish and land animals."

Per Erik Ahlberg of Uppsala University in Sweden and Jennifer Clack of the University of Cambridge said in a Nature commentary that the fossil could be as important as that of the first primitive bird.

"A link between fishes and land vertebrates that might in time become as much of an evolutionary icon as the proto-bird Archaeopteryx."

Explore World News

• World Agenda

• Iraq News

• US & Americas News

• Europe News

• Middle East News

• Asia News

• Africa News

• Ireland News

Times Recommends

• The Japanese Prime Minister is doomed: or is he?
• Brighton company 'involved in cyber attack'
• The art of survival: it’s all in the mind