Newly found species fills evolutionary gap between fish and land animals

Paleontologists have discovered fossils of a species that provides the missing evolutionary link between fish and the first animals that walked out of water onto land about 375 million years ago. The newly found species, Tiktaalik roseae, has a skull, a neck, ribs and parts of the limbs that are similar to four-legged animals known as tetrapods, as well as fish-like features such as a primitive jaw, fins and scales.

These fossils, found on Ellesmere Island in Arctic Canada, are the most compelling examples yet of an animal that was at the cusp of the fish-tetrapod transition. The new find is described in two related research articles highlighted on the cover of the April 6, 2006, issue of Nature.

"Tiktaalik blurs the boundary between fish and land-living animal both in terms of its anatomy and its way of life," said Neil Shubin, professor and chairman of organismal biology at the University of Chicago and co-leader of the project.

Tiktaalik was a predator with sharp teeth, a crocodile-like head and a flattened body. The well-preserved skeletal material from several specimens, ranging from 4 to 9 feet long, enabled the researchers to study the mosaic pattern of evolutionary change in different parts of the skeleton as fish evolved into land animals.

The high quality of the fossils also allowed the team to examine the joint surfaces on many of the fin bones, concluding that the shoulder, elbow and wrist joints were capable of supporting the body-like limbed animals.

"Human comprehension of the history of life on Earth is taking a major leap forward," said H. Richard Lane, director of sedimentary geology and paleobiology at the National Science Foundation. "These exciting discoveries are providing fossil 'Rosetta Stones' for a deeper understanding of this evolutionary milestone--fish to land-roaming tetrapods."

One of the most important aspects of this discovery is the illumination of the fin-to-limb transition. In a second paper in the journal, the scientists describe in depth how the pectoral fin of the fish serves as the origin of the tetrapod limb.

Embedded in the fin of Tiktaalik are bones that compare to the upper arm, forearm and primitive parts of the hand of land-living animals.

"Most of the major joints of the fin are functional in this fish," Shubin said. "The shoulder, elbow and even parts of the wrist are already there and working in ways similar to the earliest land-living animals."

At the time that Tiktaalik lived, what is now the Canadian Arctic region was part of a landmass that straddled the equator. It had a subtropical climate, much like the Amazon basin today. The species lived in the small streams of this delta system. According to Shubin, the ecological setting in which these animals evolved provided an environment conducive to the transition to life on land.

"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," said Ted Daeschler of the Academy of Natural Sciences in Philadelphia, a co-leader of the project. "Finding the fossils within this remote, rugged terrain, however, required a lot of time and effort."

The nature of the deposits where the fossils were found and the skeletal structure of Tiktaalik suggests the animal lived in shallow water and perhaps even out of the water for short periods.

"The skeleton of Tiktaalik indicates that it could support its body under the force of gravity whether in very shallow water or on land," said Farish Jenkins, professor of organismic and evolutionary biology at Harvard University and co-author of the papers. "This represents a critical early phase in the evolution of all limbed animals, including humans--albeit a very ancient step."

The new fossils were collected during four summers of exploration in Canada's Nunavut Territory, 600 miles from the North Pole, by paleontologists from the Academy of Natural Sciences in Philadelphia, the University of Chicago and Harvard University. Although the team has amassed a diverse assemblage of fossil fish, Shubin said, the discovery of these transitional fossils in 2004 was a vindication of their persistence.

The scientists asked the Nunavut people to propose a formal scientific name for the new species. The Elders Council of Nunavut, the Inuit Qaujimajatuqangit, suggested "Tiktaalik" (tic-TAH-lick)--the word in the Inuktikuk language for "a large, shallow water fish."

The scientists worked through the Department of Culture, Language, Elders and Youth in Nunavut to collaborate with the local Inuit communities. All fossils are the property of the people of Nunavut and will be returned to Canada after they are studied.

The team depended on the maps of the Geological Survey of Canada. The researchers received permits from the Department of Culture, Language, Elders and Youth of the Government of Nunavut, and logistical support in the form of helicopters and bush planes from Polar Continental Shelf Project of Natural Resources Canada. The National Science Foundation and the National Geographic Society, along with an anonymous donor, also helped fund the project.

I wanted to add earlier, but didn't, that this is another case of SLOPPY WRITING. If the spot was on the Equator, then it was TROPICAL, not SUBTROPICAL. And, no, Brazil does not have a SUBTROPICAL climate.

If no one has posted a comment to you, here goes. Location on the equator does not mean tropical. For instance, if you lived on the equator in the Andes the climate would vary betweeen alpine and tundra/glacial.

Conversely, there are places on the earth above/below the tropic lines of demarcation that are tropical. Weather patterns and ocean currents play a significant role in such examples. For instance, palm trees grow in southeast Ireland because of the Gulf Stream current.

As for Brazil, it does have subtropical climate in the south, near Uraguay. I'll cite World Atlas:

" Brazil's weather varies widely from north to south; the inland plateaus, including cities such as Belo Horizonte and Brasilia enjoy a rather mild climate, while the coastal cities of the east and southeast, like Salvador and Rio de Janeiro, are much warmer.

The northeastern area is the hottest region in the country, where summer temperatures exceeding 100°F are somewhat common. In the far south, conditions are subtropical, with frequent frosts in fall and winter..."

What a joke. What is there, 2 supposed transitionals now? Boy, anything passes as science now.

There's a couple of problems with this "missing link" like the Archaeopteryx before it, the famous fossil that bridged the gap between reptiles and birds." Here's the problem with these fossils labeled as "transitionals":

It has long been predicted that fossils should reveal many organisms “in transition” between different types. What the record does reveal is a history of mass extinctions and sudden appearances of new complex types. After each extinction (brought about by various mechanisms such as impact events), hundreds and sometimes thousands of life forms appear in their final form without transitions.

Millions of year’s worth of fossil layers should produce consistent and numerous transitional fossils if evolutionary theory is correct. The fossils do not produce such evidences. The most popular transitional debate is over the possible link between birds and dinosaurs. Dinosaur fossils that are similar to birds, or birds that seem similar to dinosaurs, are held up as transitionals. There are a couple problems with this debate that are usually glossed over.

First, defining these, or any, fossils as transitionals is based largely upon appearance. Determining the relation of various life forms used to be chiefly based on these appearances, also known as homology. However, we can find similar features between many very different animal types. Exactly what is the duck-billed platypus a transition from or to? In fact, many types of animals originally thought to be related or descended from the same ancestor — such as two types of river dolphins which look virtually identical — have been shown through genetics to have developed independently. Genetics is revealing that homology is often a poor indicator of relation.

Another point of contention over dinosaur-to-bird fossils is that in spite of similarities between certain types of birds and dinosaurs, their differences represent an impassable gulf. This gulf is known as biochemical complexity or irreducible complexity. The biochemical systems of any organism are extremely complex and interdependent. Remove or damage one system, many others are affected and the organism will die or have a greatly reduced life span. The origin of new, complex biochemical systems, such as those needed to create the avian lung or flight itself, cannot be created piecemeal without endangering the organism or killing it.

This is why evolution’s idea of cumulative steps producing new traits, which in turn are supposed to produce entirely new life forms, is problematic. Creating such a new form of life requires a complete and simultaneous change of major and minor biochemical systems. Small, singular changes are more apt to be ignored and larger ones seen as defects by the organism. What kind of mechanism could produce the structural changes in a dinosaur to gradually or suddenly allow it to become bird-like? Evolutionists do not know.

Also realize that whether or not these transitionals are indeed transitions is often based on who is defining the fossil. Is this fossil simply a bird-like dinosaur or a dinosaur-like bird? Or is it really a transition? If we were to assume for a moment that these fossils are transitional forms, we still have the serious problem known as the temporal paradox. These supposed transitional forms are in the fossil record after the first known, fully formed, undisputed bird fossils. Also consider that because the “transitionals” are fully formed in all their components, they are not in transition by definition. No partial developments indicating a future transformation. The logical conclusion is that we cannot consider these fossils transitions to anything.

In the end, the problems with changing from one complex system to another is the simplest reason of why the fossil record is devoid of undisputed transitions. Consider one last example, the giraffe. We do not find many fossils attesting to the “evolution” or “transition” of the giraffe from earlier ancestors. This does not stop evolutionists from trying to explain its origin. Its long neck and legs were supposedly formed to overcome a need to feed off trees with each generation having slightly longer necks and legs. This height introduces the problem of making it difficult for the giraffe to drink by creating pressure changes in the circulatory system when it bends its neck to reach the ground.

Without an exceedingly complex system to control pressure changes, the brain would hemorrhage and the giraffe would die when it bent over to drink water. This system had to develop simultaneously with the gradual expansion of the neck from generation to generation. Assuming for a moment that each giraffe could indeed pass on its stretched neck (produced by trying to reach higher branches) to the next generation, exactly how would this produce the advanced pressure control system to keep the giraffe alive? Evolution cannot explain the development of this necessary survival feature in the giraffe. The astute observer may also conclude that if giraffes so badly needed to reach trees to survive, they would have died long before they grew long necks.

So this new "transitional" story is just like previous ones in that it doesn't explain the appearance of complex, fully-formed animals. Indeed, how can a fully-formed, complex animal be a transitional? It's simply wishful thinking on the part of Darwinian Fundamentalists.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.