about 385 million Years ago, during the late Devonian period, a fish came out of the water onto the shore in search of a new home. Its fins were robust enough to move on land. Thus began the history of vertebrates on earth.
Fast-forward to 2004 in the Canadian Arctic archipelago of Nunavut Territory, where researchers found two fossils a kilometer apart. One came from a specimen later known as Tiktaalik rosae (pronounced tick-TA-lick). The other looked like a juvenile. tiktaalik, especially from the look of his jaw. But nearly 20 years after its discovery, paleontologists suspected it was something else entirely.
Researchers from the University of Chicago and Drexel University recently published a study in the journal Nature in which they describe a new species of fish that may have preceded tiktaalik.
What’s new – The researchers now believe that the second fossil comes from a new species of fish they call qikiqtania wakei. Pronounced “kick-kiq-TA-nee-ah”, the specimen’s name comes from the region where the fossil was found in the Qikiqtaaluk region.
“It’s really rare to find an animal like this,” says co-author Tom Stewart. Reverse. “It’s also exciting because some of the anatomy is unexpected.” He points out that some of the bone structure is very similar to that of our bodies. Stewart helped complete this research while she was at the University of Chicago as a postdoctoral researcher and is now a professor of biology at Pennsylvania State University.
According to Stewart, this fossil has large pectorals, or at least a beautifully preserved pectoral and humerus, analogous to our arm. The team X-rayed the fossil with a CT scanner, which allows them to see through the rock containing the fossil. Thus they found the fully preserved fin, pectoral and all.
But it wasn’t until 2020 that the team thought it might be a different species. “We spent many, many hours processing all the skeleton that we could say with such confidence, ‘Yes, this is something different,'” says Stewart.
Why does it matter? qikiqtania adds more nuance to how vertebrates changed and eventually became terrestrial wolves.
“This fossil is exciting because it gives insight into the broader range of fish lifestyles in this part of vertebrate history,” says Stewart. The rarity of these fossils means that any addition fills a gap in scientific knowledge about these fish.
qikiqtania it lacks some other characteristic features of other fishes of this time. For example, it had a large web of fins to help control swimming. fossils like tiktaalik they were more resting on the ground on their flippers, either underwater or right at the water’s edge. “All of that together tells us that this was probably living a different type of lifestyle than something like tiktaalik,” he says.
Delving into the details – qikiqtania did not evolve in Tiktaalik, either.
“It’s totally normal to have two closely related animals that got separated,” says Stewart. Reverse. “That doesn’t mean one came from the other.”
This is where statistical tests called phylogenetic analysis come into play. Stewart says that paleontologists interrogate a lot of fossils, asking what anatomy, scales, or skeletal features they share. By constructing and visualizing how these creatures are related to one another, experts can construct a phylogeny, or the “tree of life,” as Stewart puts it. In this first part of the tree of life, qikiqtania is closely related to tiktaalik as well as another Late Devonian fish fossil called Elpistostege watsoni.
As for why these fish changed habitats, it remains a mystery. Stewart says these creatures could have been searching for more food or escaping predators, for example. The region had been a floodplain, so capable fish could wriggle on land and then lead the floodwaters to dump them into a new pond.
Whats Next – qikiqtania it belongs to a larger context of tetrapods, which Stewart intends to develop further by examining the anatomy.
“I would say this is part of a larger set of studies trying to understand the biology, diversity, development, and biomechanics of early tetrapods,” he says. “We have a new reconstruction of the postcranial skeleton of tiktaalik we’re working on that which we think is really helpful in understanding how he lived and how he would have moved,” he says. This reconstruction could help us understand how the vertebrae and ribs are related to the legs and other appendages.