One group of fishes left the water millions of years ago.
Many thousands of species including salamanders, birds, lizards and mammals were part of these animals. The legacy of the water-to-land transition is shared by human beings and their ancestors.
They might have turned back instead of going onto the shore. What if the animals had left the water and gone back to live in more open waters?
One fish may have done that according to a new fossil. The newly discovered creature had fins that were built for swimming, unlike other animals that used their fins to prop their bodies up on the bottom of the water.
Tom Stewart holds the Qikiqtania fossil. (Stephanie Sang/CC BY-ND)
I was a member of Neil Shubin's lab when I was at the University of Chicago. I was working with another researcher to process a fossil that was collected in 2004.
The jaws and teeth were visible from the surface of the rock. There were patches of scales with different colors. We could see that the fossil was an early one. We wanted to look inside.
We used a technology calledCT scanning, which shoots X-rays through the specimen, to look for anything that could be out of sight.
We scanned a piece of rock that had a few scales on top and found a fin buried inside. Our jaws fell down. The lab and campus were closed a few days later.
This is a very special fin. Scientists can get clues into how early tetrapods evolved and how they lived hundreds of millions of years ago. We can use the shape of certain bones in the skeleton to make predictions about an animal's behavior.
We needed to see the skeleton in high resolution after the initial scans. A professor in the university's department of the geophysics helped us trim the block using a rock saw after we returned to campus.
The block was made more fin, less rock, and allowed for a better look at the fin.
We realized that this animal was a new species when the dust had cleared. The creature with fingers and toes is one of the closest relatives to limbed animals.
It was called Qikiqtania wakei. The traditional name for the region where the fossil was found is Qikiqtaaluk, which means "kick-Kiq-tani-ahh" in the Inuktitut.
Hundreds of millions of years ago, this was a warm place with rivers and streams. David Wake was a scientist and mentor who inspired a lot of us in the field of evolutionary and developmental biology.
There was a critical period in the history of our family. The scales show that it was underwater. The sensory canals would have allowed the animal to smell the water.
According to its jaws, it was a predator, biting and holding onto prey with a series of fangs and drawing food into its mouth.
The pectoral fin is the most surprising. Our upper arm has a bone in it. There is a very peculiar shape.
Tiktaalik has humeri that has a ridge on the underside and a set of bumps. The bumps tell us that early tetrapods lived on the bottom of lakes and streams, using their fins or arms to prop themselves up, first on the ground and then on land.
There is a different humerus. It doesn't have trademark ridges and processes. The rest of the fin is large and paddle-like. The fin was made for swimming.
The other early tetrapods were playing at the water's edge, learning what land had to offer. The humerus is unlike anything else.
I think it shows that Qikiqtania had evolved to live off the ground and in the open water.
The process of evolution isn't simple. It might seem like early tetrapods were destined to live on land, but Qikiqtania shows that's not the case.
Humans were not built a ladder towards evolution. A tree of life is a complex collection of processes. There are new species and they change. The branches can head off in any direction.
(Neil Shubin/CC BY-ND)
Neil Shubin was the person who found the fossil and pointed it to the site where Qikiqtania was found.
There are a lot of reasons why this fossil is special. The fish was preserved in rock for hundreds of millions of years before it was discovered by scientists on the island. It's not just that it's complete, it's also that it's revealed by happenstance at the moment of a global epidemic.
For the first time, it provides a glimpse of the wide range of lifestyles of fishes at the water to land transition. Researchers can see more than a ladder and understand that tree.
Qikiqtania is a part of the community. We were able to conduct this research because of the generosity and support of individuals in the hamlets of Resolute Bay and Grise Fiord.
They were on behalf of our entire research team. I would like to thank you. Our understanding of the history of life on Earth has changed thanks to paleontological expeditions.
Fossils were not allowed to visit field sites across the world due to COVID-19. We want to come back and visit with old friends.
Who knows what other animals are hiding inside blocks of stone?
The assistant professor of biology is Thomas Stewart.
Under a Creative Commons license, this article is re-posted. The original article is worth a read.
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