The Universe of Animal Variation (image) University of Bristol Share Print E-Mail Caption This image is based on the presence and absence of anatomical features, like jointed legs and compound eyes, neurons and bony skulls. Considering all of these features, animals that are similar group together, far away from animals that are dissimilar. Most of this 'design space' is unoccupied, in part because of extinction of ancient ancestors that are unrepresented, in part because animals have only been around for half a billion years and that is not enough time to explore all possible designs, but most of the design space is unoccupied because those designs are impossible. Credit University of Bristol Usage Restrictions Single use only to be used with press release. Please do not archive. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.