An illustration by Zina Deretsky, National Science Foundation, depicting Tiktaalik roseae, the extinct limbed fish that flopped its way onto land one day 375 million years ago.
It may not be the worst of times, but it is certainly not the best of times. The pandemic has no end in sight. The world is warming, the seas are rising and polar bears are barreling toward extinction Also: taxes, the 9-to-5 workweek, the renewed threat of nuclear war.
As people looked for someone to blame besides themselves and all of humanity, a culprit emerged in the form of a fish, specifically the 375-million-year-old Tiktaalik (pronounced tic-TAH-lick). Our modern woes would never have existed if our ancestors had never left the water, the reasoning went. Tiktaalik’s four whispers of feet made the fish an easy target
Scientists may never know exactly why fish like Tiktaalik and early tetrapods — vertebrates with four limbs — moved onto land, said Alice Clement, an evolutionary biologist and paleontologist at Flinders University in South Australia. “Was it to seek out more food, escape predators in the water, find a safe haven for their developing young?” Clement asked.
Regardless, their legacy is enormous. The group of fish that moved onto land gave rise to almost half of all vertebrates today, including all amphibians, reptiles, birds, mammals and us. And although we probably cannot trace our family tree directly back to Tiktaalik, “an animal very much like Tiktaalik was a direct ancestor of humans,” said Julia Molnar, an evolutionary biomechanist at the New York Institute of Technology.
If Tiktaalik is our ancestor, then perhaps our holding it accountable for the chaos it sowed is an expression of love.
Other scans revealed the delicate bones of its pectoral fin. Unlike the symmetrical rays of fish fins, Tiktaalik’s fin bones were noticeably asymmetrical, which allowed the joints to bend in one direction. “We think that was because these animals were interacting with the ground,” said Thomas Stewart, an incoming evolutionary and developmental biologist at Penn State University.
