Lystrosaurus (IMAGE) California Academy of Sciences Caption After the mass extinction, the ecosystem was unusual, with hugely common examples of the dicynodont Lystrosaurus, sometimes comprising 90% of the assemblage. Credit © Xiaochong Guo Usage Restrictions Photos for editorial use only. Credits mandatory. License Licensed content 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.