Tiktaalik, a lobe-finned fish, is believed to be a transitional form between aquatic and terrestrial vertebrates. Its unique features, such as a flattened, crocodile-like head with sharp teeth and nostrils, bony lobed fins, and a sturdy pectoral girdle, have led some to suggest that it was a fish ready to walk on land. However, others argue that the fossils do not provide sufficient evidence to support the idea that fish evolved into terrestrial vertebrates.
The discovery of Tiktaalik’s pelvis and partial pelvic fin has led some to believe that ancient lobe-finned fish prepared the evolutionary way for terrestrial vertebrates to push off on their strong hind legs. However, others argue that the pelvis and fin of Tiktaalik do not provide evidence of ambulatory evolution, but rather evidence that Tiktaalik was a sturdy and strong fish.