Impala Grazing (IMAGE) University of the Witwatersrand Caption The arrival of medium and large antelope in Africa coincides directly with the evolution of thorn trees in the African savanna. Credit Gareth Hempson Usage Restrictions None 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.