You may have come across a meme featuring an ancient fish known as Tiktaalik.
It shows the green, eel-like creature that crawled out of the sea about 375 million years ago — about the time scientists say fish evolved the physical characteristics to survive on land — only to be directed to turn around.
The joke, as far as the meme goes, is that the fish has to crawl right back into the water to avoid the misery of our modern age.
Now, a new study published in Nature suggests that a relative of Tiktaalik — named Qikiqtania wakei — did just that.
“You had this evolutionary set of fish that evolved to walk, but this one said, ‘Uh, I’m not going to do that. I’m going back in,'” said Neil Shubin, a paleontologist at the University of Chicago who co-authored the study.
Shubin was part of the team that discovered Tiktaalik during a 2004 expedition in the Canadian Arctic. Qikiqtania was found on the same trip, but the fossil remained largely unstudied as the team focused on Tiktaalik.
“This new species is a very close cousin of Tiktaalik. We know that by looking at all the characteristics,” Shubin said. “In fact, it’s a very close cousin to both Tiktaalik and creatures with arms and legs and fingers and toes called tetrapods.”
Early tetrapods likely spent more and more time outside of the water during this time, Shubin said. The arrangement of bones and joints in the fins of these animals began to resemble arms and legs, allowing animals like Tiktaalik to support themselves in shallow water and survive on the mudflats.
But Tom Stewart, an evolutionary biologist at Penn State who also worked on the study, said Qikiqtania’s physiology suggested it swam in open water. Qikiqtania’s fins are the result of its swimming ancestors crawling on land and then returning to the water.
“That’s an unexpected pattern,” he said. “That wasn’t something that would have been predicted before we had such a fossil.”
The study expands paleontologists’ understanding of this period in evolutionary history by showing that animals didn’t just evolve from aquatic fish to terrestrial tetrapods.
“The transition from aquatic life to land life went both ways,” Shubin said.
Qikiqtania is a vivid counterexample to the long-debunked but persistent myth that evolution is a linear progression from one species to another.
“We are introduced to the idea of evolution through images such as a monkey slowly standing up and then producing a walking man,” Stewart said. “Those are some of these classic, iconic learning tools…but really, evolution doesn’t work that way.”
Shubin said evolution was more accurately described as a series of branching paths, rather than a ladder. “Evolution is very much a shrub,” Shubin said, “a tree of creatures evolving in many different directions.”
We’ll see how the memes evolve from here.