There seems to be no better time than now for the discovery and study of early tetrapods, and a new study may further explain how organisms were pre-adapted to leaving the water in favor of more terrestrial habitats. While creationists may see it fit to agonize over limb structure, those who have actually looked at the skeletons of early tetrapods and their earlier relatives know there’s a lot more to the story than the development of the first limbs. Indeed, this LiveScience article explains how new research may show a transition from suction feeding to active biting, an essential change for life on and near dry land.
While behavior may be difficult to discern from bones, this does not mean that the structure of extinct animals give us no clues as to function or behavioral adaptations, and in this case the researchers hypothesized that the skull structure of modern suction-feeding fish could give them clues as to whether early tetrapods and their ancestors sucked in their prey or actively bit prey. The results so far; Acanthostega appears to have been more likely to bite prey than suck it in, suggesting that jaw adaptation began before tetrapods fully left the water. I don’t think this comes as a great surprise to many, but it is important to have the actual observations to back up our assertions, and such a realization does open up a new line of questioning. Why did biting jaws evolve? How were these animals catching their food? Were they occupying the niche now called home by crocodiles, effectively being aquatic ambush predators where trying to suck insects off the banks or out of the air was ineffective, thus providing the right pressure? Hopefully an integrated ecological perspective could provide some clues to these questions, but I have always been amazed by life’s inclination to move out of (and back into) the water.