Due to gaps in the fossil record little is known about the change from an aquatic to a terrestrial lifestyle, but a recent study by Peter Bishop at the Queensland Museum in Hendra, Australia has brought new evidence to light.
Peter and his colleagues examined a rare Ossinodus Tetrapod fossil, which at 330 million years old dates from one of those gaps, and discovered that its forearms would have been strong enough to support it on land. The bone has a break which they believe, based on a calculation of the forces involved, could only have occurred on land. The team point out that water would have cushioned the blow, and believe that the Tetrapod fell from a rock or log by as much as 85cm.
Other scientists are less eager to speculate on the exact cause of the break, but there is broad agreement that it must have occurred on land. While we still do not know the exact origin of land animals, this evidence that the Tetrapod spent at least some of it’s time on land pushes back the date when our ancestors emerged from water by around 2 million years, making it a significant contribution to our understanding of the process.