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 agree about them being separate because of methods. Actually, the whole philosophical reasoning by logic makes absolute sense to me. If I'm going to engage in a debate. I pretty much follow this line of thinking. But, as for me personally, it seems that we loose something when we try to me so methodical. I'm not referring to philosophy, or science as a profession, but as people, in our daily lives. I guess I just don't agree, from a personal perspective, that faith is irrational. It can be! I think it's wrong to generalize it though. Many people have had "experiences" in life where faith has been the only thing to guide them through a course of action. Sometimes we do illogical things, because of faith, because we believe that it's what's right. Humans are emotional beings. Philosophy doesn't rule out emotion, but nearly. Emotions are only rational if they can be reasoned. If you go along that line of thinking, then love is very often an illegitimate emotion. It hurts us, at times, we will sacrifice far more for it then is reasonable, it clouds our judgment, it's unpredictable, yet we crave it. For most people, it's needed. There is something about us that is elusive when it comes down to mapping the thought process in a logical manner. I dare say that it could be "spirituality". I don't know! We just seem to become very flat, two dimensional, when we try to capture, reason, and understand everything about us. I think there is a great deal about humanity that we do not know.

I have a good story to go along with this, but before I tell it let me add that I do not believe I'm psychic.

My son got a tent for his 11th birthday. We lived, at the time, in a gated subdivision with a neighborhood watch, and a zealous homeowners association. My son was so excited about the tent. He couldn't wait to sleep in it. So, he asked if it would be okay to sleep in the back yard. I told him yes. He happily set it up, and then prepared his little camp site for that evening. As it got closer to bed time, I began to have this almost sick feeling. It was kind of like something pounding in my head and twisting my gut. I just really felt "wrong" about him sleeping outside. I had no reason to! He'd done it before with an older tent. This feeling would not go away. I called him into my room and told him that I preferred he not sleep outside this particular night. He asked why, and all I could say was, "I don't know. For some reason my Mommy Alarm is going off." Pretty silly huh! Mommy alarm, how logical is that? Anyhow, he's a good boy. He giggled at my new term, and then said,"Okay." He didn't fuss with me. Which was a good thing, since I had no logical reason, I probably would have let him. The following morning his tent was gone. It had not been windy. We looked all over. there was no sign of it. I felt quite glad about him sleeping inside that night.
Now this was a mystery. I did believe the tent had been stolen, but I had no clue who would have done it, or if my son would have been in harm's way had he slept in the tent. We have moved since then, but about 4 months ago, my former neighbor told me about some incidents with a 19 year old boy in the house behind our former residence. His family moved into the subdivision about a year before we moved away. It seems this young man had some mental problems. He had been caught stealing stuff from other neighbors yards in the past. This would have been around the same time as my son's tent, I was just unaware of this. Apparently things had escalated with him though. His neighbor's house, which was directly behind my former neighbor's house, had a very nice outbuilding full of all kinds of stuff. One night while the family was asleep in their house, their outbuilding was set ablaze. It burned to the ground, burned a good portion of the house, and also caught the boat on fire. The young man was arrested for arson. It turns out that this was not this young man's first incident with the law. He had, as a stated before, mental issues, and had been in and out of treatment. I believe that some of his prior incidents were attributed to his mental condition. They did involve violence. There are other things that I have heard about him as well, but I know that unsubstantiated rumors tend to fly around in cases like this. I don't know if this young man was the one who took my son's tent, or if he would have harmed him in the process. That same gut feeling says that both of those things would have been so. Either way, I was quite thankful for my Mommy Alarm that night. It would not have been worth finding out whether or not I was wrong.

Having said all this about faith, and intuition, because it is what I personally "feel", I don't know another way to reason through subject matter with others then through philosophy. It's good to be free to depart from time to time in my own life though.

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