o The Frog Blog: Early Tetrapods Didn't Walk But Shuffled

Thursday, 24 May 2012

Early Tetrapods Didn't Walk But Shuffled

Members of the Ichthyostega genus were likely the first four limbed animals, or tetrapods, to venture out of the water and spend some time on land. Understanding that massive behavioural change is important for scientists, principally to get a better understanding of the evolutionary process. These animals, which would have had some fishy traits and some amphibian traits, may have been the ancestors of all land living animals including the dinosaurs and humans! Many believed that members of this group were the first animals to (properly) walk on land but now a new study from researchers from the Royal Veterinary College, London and the University of Cambridge adds some doubt to that idea but sheds new light on how these strange "fishapods" used their limbs.

Using sophisticated 3D modelling tools, the team created of 3D skeleton of Ichthyostega, allowing them to calculate the range of movement in the joints of its limbs for the first time. They found out that the 350 million year old animals would have been very poor walkers and would have shuffled on to land rather than walk. They would have used their front limbs like crutches, pushing its body up and forward onto land while its legs and tail trailed behind, almost like a seal. Ichthyostega would have lived in water predominantly, but would have ventured on to the shore for food.

In a way, this sends scientists back to the drawing board but may intensify the search for the first animal to walk on land. Understanding when and why this took place is important for us to understand the evolutionary pressures to move from water to the land.

For more information on this story, visit Discovery News. The original paper is published in the science journal Nature.