Wooded Grassland Savanna (IMAGE) University of Utah Caption Giraffes roam in a wooded grassland savanna in Kenya's Nakuru National Park. The savanna grades into the woodland in the background. University of Utah researchers developed a new way to use fossil soils to determine the amount of tree cover in prehistoric landscapes. They conclude savannas predominated East Africa's landscape during some 6 million years of evolution of apes, human ancestors and humans. Credit Naomi Levin, Johns Hopkins University. 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.