To be heavy or not - that is the question

Researchers at the University of Bonn study the way of life of extinct amphibians. Metoposaurus (olive green, bottom) led a bottom dwelling lifestyle, - probably to avoid competition from the larger Cyclotosaurus ( blue ) and phytosaur Parasuchus (ochre brown). Illustration: Sudipta Kalita . If you need to lurk at the bottom of a water body waiting for prey, it is wise to stay motionless without resisting against the buoyant forces of water. To do so you need a kind of diving belt that helps to sink. One large amphibian species Metoposaurus krasiejowensis, that lived more than 200 million years ago, compensated for buoyancy with a heavy shoulder girdle. Researchers from the Universities of Bonn and Opole (Poland) examined the bones of the girdle under a microscope.