Ik heb expres goed naar de datum gekeken, maar er staat 6 april boven, niet 1 april.
Toch was die tiktaalik al eerder bekend, maar kennelijk niet met pootjes.
In elk geval hierbij even een artikel. Mijn bedoeling is wel om het later te vertalen, maar daar heb ik vanmiddag geen zin meer in.
Fossil discovery fills a piece of evolutionary puzzle
In a fish, scientists see link to humans
By Gareth Cook, Globe Staff | April 6, 2006
Scientists working in the Canadian Arctic have discovered fossils of a fish that had fins like limbs, capturing in stone the crucial period in evolution when creatures climbed from water onto land.
The new species, named Tiktaalik roseae, lived about 375 million years ago, and was a sharp-toothed predator that resembled a crocodile and grew to at least 9 feet in length. Like its fish ancestors, Tiktaalik had scales, but also a number of innovations, including fins with an elbow joint that could lift the animal from the ground.
''It is like a fish that can do a push-up," said Neil H. Shubin, a paleontologist at the University of Chicago and one of the principal scientists. The team, which also included a Harvard University scientist, describes the find in the journal Nature today.
Scientists hailed the long-sought discovery of the transition from sea to land. In the story of life on earth, these fish fossils mark what is considered one of the major transitions, along with such milestones as the first multicellular organism or the first warm-blooded animal. The find, scientists said, provides the clearest picture yet of this moment, as well as clues to how such major shifts in evolution happen. The fossils are especially interesting, they said, because they show the beginning of the basic human body plan: Over the course of eons, Tiktaalik's front fins became the human arm and hand.
''It is an extraordinary discovery," said Philippe Janvier, a leading paleontologist at the National Museum of Natural History in Paris who was not involved in the find. ''It fits perfectly in the tree of life."
For the public, the fossils will probably become an icon of evolution and the transition to land because of the animals' mix of features, but also because the fossils are unusually well preserved, researchers said. The rust-red cache of fossils features a number of skeletons, including three skulls. Often, paleontologists find bones scattered by the elements or fossils that have become deformed by their long residence in rock. But these fish have largely held their shape. Even the fine lines of individual scales are visible.
''It is so incredible that we got it," said Farish A. Jenkins Jr., a Harvard zoology professor who was the senior member of the team. As it became clear what they had found, Jenkins recalled, he had meetings with the two other lead scientists in which all of them ended up screaming, as each insight provoked several new ones.
The discovery is a product of extreme paleontology. The team traveled to the uppermost reaches of the North American continent, because there is fossil-bearing rock there of the age when the transition from water to land was known to have occurred. They were ferried by helicopter to a spot just 887 miles short of the North Pole, a rocky place called Ellesmere Island, where the weather is so bad that July is the only month when excavating is possible. One storm kept the scientists hunkered down in their tents for 10 straight days, said Shubin. He and the others carried 12-gauge shotguns to fend off polar bears.
Page 2 of 2 --Scientists have long known from other fossils that humans and all other vertebrate land animals descended from fish. Other finds have narrowed the time of the transition to a stretch of 10 or 20 million years, said Shubin. One day in 1998, Shubin was in his office talking with a former graduate student about where to search for the elusive animal. In an undergraduate textbook, the two saw a map showing a large block of rock of just the right age, in the Canadian Arctic. Shubin said he knew that was the place to go.
The former student, Ted Daeschler, is now the curator of paleontology at the Academy of Natural Sciences of Philadelphia and was the third principal member of the team.
Over four years, the team mounted three expeditions to Ellesmere Island, with only modest finds. Shubin said he had decided that July 2004, their fourth try, would be their last. In the first few days of the expedition, the team started uncovering the trove of fossils.
The animal had several elements that separated it from the fish that came before, Jenkins said. The shape of the skull had shifted toward a model used by the tetrapods, the family of four-limbed animals that went on to populate all the continents. It had a longer snout and less bone behind the eyes. The head was flatter, like a crocodile, and the eyes had moved from the side of the head to the top.
The neck was also new. Unlike more primitive forms, Tiktaalik's head was not anchored to its shoulder with bone, allowing it to move its head without also moving its body -- and making it easier to operate out of water.
GLOBE GRAPHIC: Missing link
But most of the attention will probably focus on the changes seen in the fins, scientists said. The fins have a highly flexible elbow joint and the beginnings of a wrist. These fins would have allowed the animal to lift itself out of shallow water, with a portion of the end of the fin pushing against the bottom, the way a seal does.
Evolution predicts the existence of such transitional forms, as one species evolves into another. Finding such a clear example gives scientists confidence that they understand how different organisms are related.
The fish lived in a warm, lush environment near the equator. (Nearly 400 million years of continental drift carried the rocks to their present location.) At the time, the place probably was similar to the Mississippi Delta region, according to the pair of papers in Nature. The animal moved through shallow, muddy waters fed by emptying streams during the Late Devonian, the geological name for that period in history.
The limb-like fins would have given Tiktaalik access to areas that other big predatory fish could not reach, places where the water was very shallow and tangled with fallen trees and branches.
Researchers do not, however, know precisely why the fins would have given the animal an advantage. Some argue that the animal would have had greater access to food, others that it could have better escaped large predators. Robert Carroll, a paleontologist at McGill University in Montréal, said the limb-like fins would have allowed the animal to bask in the sun, like a crocodile. After its cold-blooded metabolism was warmed by the sun, it would have had faster reflexes.
The name of the newly discovered animal, Tiktaalik roseae, is inspired by people who made the research possible. The team does its research with the permission of the government of Nunavut Territory, which administers the traditional territory of the Inuit people. The scientists consulted with a group of Inuit elders, who chose the name Tiktaalik (pronounced Tick-TAH-lick), which is an Inuit name for ''large shallow-water fish." The species is named after Rose, the first name of an anonymous donor who helped pay for the expedition.
The work was also financed by the Academy of Natural Sciences, the Putnam Expeditionary Fund at Harvard, the University of Chicago, the National Science Foundation, and the National Geographic Society.
This week, the team received permission from the Nunavut authorities to mount another expedition this July. They hope to find fossils that preserve the rear portion of the animal, including the hind fin, which they have not seen. They will also be looking for closely related animals, perhaps representatives of species that came just before or just after Tiktaalik.
''When you discover a missing link," said John G. Maisey, a paleontologist at the American Museum of Natural History in New York, ''you create two new missing links."
Gareth Cook can be reached at cook@globe.com.
© Copyright 2006 Globe Newspaper Company.
Maar hij heeft dus vinnen die een beetje zijn opgebouwd als ledematen, zodat hij door ondiep water kon bewegen. Hij kon natuurlijk niet op het land, want het was een vis.
