Mollusc missing link discovered
12 Nov 2012 by Evoluted New Media
A rare fossil called Kulindroplax, the missing link between two mollusc groups, has been discovered. The findings, which were revealed in a 3D computer model of the fossil, are published in Nature. The scientists found the Kulindroplax fossil, which is the only one of its kind, in the Welsh borderland. The caterpillar-sized fossil provides the evolutionary missing link between two groups of molluscs and sheds more light on their early origins.
Kulindroplax lived in the sea during the Silurian Period approximately 425 million years ago, when most life was aquatic and the first plants were beginning to grow on land.
Dr Sutton from Imperial College London, who led the study said: “Most people don’t realise that molluscs, which have been around for hundreds of millions of years, are an extremely rich and diverse branch of life on Earth. Just as tracing a long lost uncle is important for developing a more complete family tree, unearthing this extremely rare and ancient Kulindroplax fossil is helping us to understand the relationship between two mollusc groups, which is also helping us to understand how molluscs have evolved on Earth.”
The researchers analysed the 3D model of kullindroplax and discovered that it had a worm-like body and was partly shelled, representing a missing link between two groups of molluscs – aplacophorans and chitons. To develop their 3D animation, the team cut the Kulindroplax into 1300 slices and took digital images of each one. This method provides unprecedented detail from the fossils, enabling researchers to analyse previously unseen features.
The evolutionary relationship between aplacophorans and chitons has been hotly debated for over 20 years. Both groups still live in the our oceans today; Aplacophorans are carnivorous, worm-like, sea-living creatures and chitons are molluscs that have shell plates for armour and live in the sea or on the seashore.
The scientists believe that their 3D fossil provides fresh inside into the mollusc evolutionary tree by demonstrating that the worm-like aplacophorans evolved from citon-like ancestors by losing their shells.
