Did the Evolution of Animal Intelligence Begin With Tiktaalik?
Another of the notorious (to the anti-evolution crowd) gap in the fossil record gets filled. As discussed in earlier posts, fossil gaps are not evidence of any alleged failure of evolutionary theory. Gaps are to be expected because fossils only form in special environments. We also haven't found all the fossil beds that do exist. So we should expect to find fossils which fill gaps. In this case we have an important link between land and sea creatures.
Quoting from the Smithsonian Magazine article:
In 2004, when the fossil bones of Tiktaalik roseae were dug from the ground of Ellesmere Island, in the Canadian Arctic, the discovery was hailed as a breakthrough not just for paleontology, but for beleaguered science teachers trying to keep creationism out of their classrooms. A fish (with scales and gills) clearly resembling a tetrapod (with a flat head, a neck and prototypes of terrestrial limb bones in its lobelike fins), it precisely filled one of the gaps in the fossil record that creationists cited as evidence against Darwinian evolution.The article goes on to show how science always learns from new data such as this.
The hip and pelvis were surprisingly robust, suggesting more powerful rear limbs than previously believed. Although almost certainly still encased in fleshy lobes, appendages could have helped support or even propel the animal in shallow water or mud flats. If so, it changes our view of the evolution of tetrapods, whose ancestors were believed to drag themselves by their forefins, only developing useful hind legs once ensconced on land.The article also comments on the underlying assumption of evolution, that new species evolve when there is a new environment to exploit. At the time the ocean had large carnivorous predators a-plenty, such as Taktaalik. But the land had a diverse range of plants and some animals such as mollusks and insects with no predators of any size. Getting out of the ocean also put a creature out of reach of the predators of the sea.
As for what drove this epochal migration, “it’s extremely bloody obvious: There were resources on land, plants and insects, and sooner or later something would evolve to exploit them,” says vertebrate paleontologist Mike Benton of the University of Bristol. It’s also possible, says Shubin, that fear played a part. “If you look at the other fish in the water at the time, they’re big monstrous predators,” he says. Some exceeded 20 feet in length. Even for Tiktaalik, a toothy carnivore itself, this was a “predator-rich, competitive environment.” If you can’t be the biggest fish in the pond, maybe it’s better to get out of the water altogether.