Re: Fossil Fish With "Limbs" Is Missing Link, Study Says

"George" <george@xxxxxxxxxxxxxxxxxxxxx> wrote in message news:ZtWYf.909406$xm3.508689@xxxxxxxxxxxx
http://news.nationalgeographic.com/news/2006/04/0405_060405_fish.html

James Owen
for National Geographic News

April 5, 2006
Fossil hunters may have discovered the fish that made humans possible.

Found in the Canadian Arctic, the new fossil boasts leglike fins, scientists say. The creature is being hailed as a crucial missing link between fish and land animals-including the prehistoric ancestors of humans.

Researchers say the fish shows how fins on freshwater species first began transforming into limbs some 380 million years ago. The change was a huge evolutionary step that opened the way for vertebrates-animals with backbones-to emerge from the water.

"This animal represents the transition from water to land-the part of history that includes ourselves," said paleontologist Neil Shubin of the University of Chicago.

Shubin was co-leader of a team that uncovered three nearly complete fossils measuring up to nine feet (three meters) long on Ellesmere Island in 2004.

The new species, Tiktaalik roseae, had a flattened, crocodile-like head and strong, bony fins.

The large fish probably flexed and extended these fins like legs to help it move through shallow, subtropical waters or even on land, the team says.

The discovery marked the culmination of a five-year, 400-mile (650-kilometer) fossil hunt across the Arctic's frozen tundra. The National Geographic Society partially funded the project, which is to be detailed tomorrow in the journal Nature.

The fish shows other features characteristic of land animals, including ribs, a neck, and nostrils on its snout for breathing air.

The previously unknown creature is the closest known fish ancestor of land vertebrates, Shubin said.

It likely used its fins "to prop its body, much like we do when we do a push-up," he said.

Likewise, the animal's broad ribs would have supported its long, scaly trunk, adds team member Farish Jenkins of Harvard University in Cambridge, Massachusetts.

Land Excursions

Water supports the bodies of submerged fish, making strong ribs largely unecessary, "so this animal must have developed these structures for life in the shallows and making excursions on to land," Jenkins said.

Shubin says the fish's wide head and sharp teeth suggest it hunted much like a crocodile and that it also breathed air.

"Look at the side of the snout. It has a nice big pair of external nostrils," he said.

Tiktaalik could become an icon of evolution in action, write paleontologists Per Ahlberg of Sweden's Uppsala University and Jennifer A. Clack of the University of Cambridge in the United Kingdom in an accompanying commentary.

The paleontologists say the new fish form goes a long way toward filling the evolutionary gap between fish and the earliest amphibians.

"Our remote ancestors were large, flattish, predatory fishes," they write. "Strong limblike pectoral fins enabled them to haul themselves out of the water."

Evolutionary scientists agree that all four-limbed land vertebrates, including dinosaurs and mammals, are descended from lobe-fins, a group of primitive fishes with fins suggesting limbs.

__________________________________

One question: If it had the ability to make excursions on land like a crocodile, possibly to hunt, what was it hunting?

George

Well, that's the strange thing, because according to the fossil record at least, almost all of the early land animals were carnivores. Possibly the smaller carnivores first started leaving the water to feed on insects and/or sun themselves, and the larger carnivores left to prey on the smaller carnivores.

.

Relevant Pages

  • Re: Fossil Fish With "Limbs" Is Missing Link, Study Says
    ... Fossil hunters may have discovered the fish that made humans possible. ... Researchers say the fish shows how fins on freshwater species first ... it move through shallow, subtropical waters or even on land, the team ...
    (sci.geo.geology)
  • Re: Michael Ruses Model
    ... well as lungs to breath and gills to survive under water. ... The swim bladders of teleost fish are modified lungs. ... that walk on their fins. ... This one looks like it could have better locomotion on land then Tiktaalik. ...
    (talk.origins)
  • OT - Gap closed
    ... creationism make is that there are "gaps" in the fossil records. ... sea creatures changing into land creatures. ... Scientists Call Fish Fossil, 375 Million Years Old, 'Missing Link' ...
    (alt.sports.basketball.nba.la-lakers)
  • Re: OT - Gap closed
    ... creationism make is that there are "gaps" in the fossil records. ... demonstrates sea creatures changing into land creatures. ... Scientists Call Fish Fossil, 375 Million Years Old, 'Missing Link' ...
    (alt.sports.basketball.nba.la-lakers)
  • Re: Fossil Fish With "Limbs" Is Missing Link, Study Says
    ... Fossil hunters may have discovered the fish that made humans possible. ... Researchers say the fish shows how fins on freshwater species first began ... it move through shallow, subtropical waters or even on land, the team ...
    (sci.geo.geology)