A fleshed-out reconstruction of the early tetrapod, Ichthyostega. Image Julia Molnar

25 MAY 2012


New model shows extinct tetrapod Ichthyostega couldn’t walk, so how could it shift to shore in East Greenland millions of years ago?

By greenland today, List of sources at the bottom

Ichthyostega was first discovered in East Greenland in 1932 and is mostly figured as the first four-legged fish. But new work shows that Ichthyostega could not walk using all four limbs because the limbs were not able to rotate in a manner that would allow terrestrial locomotion.
Instead Ichthyostega used the front limbs to haul itself along the surface. So between the transition from swimming to walking was crawling. Perhaps it’s no big surprise, logically, but now it is scientifically proven and animated.
A 3D skeletal reconstruction of Ichthyostega. Image: Stephanie Pierce
3D data from computed tomography (CT) scans is overturning long-held views of how the earliest land animals moved.
Research published in Nature reveals how a famous extinct animal, the early four-legged vertebrate (tetrapod) called Ichthyostega, moved on land 360m years ago.
One major problem in putting together fossil skeletons is actually getting the fossil out of the rock, but now palaeontologists don’t have to. The CT scans allow the virtual preparation of the fossil so delicate bones can be fully isolated and then fitted together so the anatomy can be better understood.

It was this process that has allowed scientists to overturn long held assumptions on how one of the earliest tetrapods moved from the water on to land.
The next step is to achieve what many palaeontologists dream of – to reconstruct the soft anatomy. This study shows how the latest imaging technology combined with a strong knowledge in comparative anatomy can enhance our understanding of how these ancient animals moved.
The origin of tetrapods and the transition from swimming to walking was a pivotal step in the evolution and diversification of terrestrial vertebrates. The new work provides a clearer picture of how our early ancestors made it out of the aquatic environment and on to land.

Earlier Animation from Animal Planet
Kate Trinajstic, Associate Professor, Department of Chemistry at Curtin University, scientists Stephanie E. Pierce and Professor John R. Hutchinson from the UK’s Royal Veterinary College and Professor Jennifer A. Clack from the University of Cambridge, Animal Planet, phys.org, Nature

Shoulder Joint movement

Hip Joint movement