 This seeming contradiction between the seasonally dry climate and tropical plant species can be explained by the fact that tropical plants can thrive in a seasonally monsoonal environment today as long as they have access to sufficient amounts of water year-round, and the Haţeg environment seems to have been dominated by braided rivers and lakes.Early rock layers are dominated by volcanic deposits, but these are absent in higher layers, indicating that volcanic activity dropped off during this time.About nine species of dinosaurs, and several species of pterosaur are thought to have been indigenous to the island.