Some changes in the atmospheric circulation occurred about 6 million years ago in the region now known as South America They increased the expansion of herbivorous mammals and grassland in the area, according to a study published Monday in the journal PNAS.
The team geoscience Arizona State University (USA) have come to the conclusion that these changes in the atmospheric circulation in the Late Miocene led to changes in the weather & # 39; and and vegetation in South America and, consequently, its fauna.
Studies show that between the last 7 years and 6 million cases of the tropical atmospheric circulation known as the Hadley circulation increased.
"As a result, the climate of South America was the land, subtropical steppe expands and the number of species of mammals can eat grass grown," said lead study author Barbara Carrapa.
The author and his colleagues used computer & # 39; a computer model to find out that Hadley circulation has been strengthened at the end of the Miocene, climate change.
Later, they compared the models of past climate predictions with natural rain and files stored on the old vegetation surfaces and saw that model predictions coincide with the natural archives.
"We found a strong correlation between the significant changes in climate and the circulation of the Late Miocene, affecting the environment, plants and animals," said the researcher.
Carrapa argued that this study, a mixture of mammalian paleontology, geochemistry of ancient soils and computer models of global climate, providing new insights into the late Miocene, at a time when most modern ecosystems were created.
Geophysics, Geochemistry, use the old sex, in particular, the form of the elements oxygen and carbon, to be concluded by rainfall and vegetation.
The researchers collected data published on the ratio of different types of oxygen and carbon dioxide, which covers a wide swath of South America, between 15 and 35 degrees south latitude.
Changes in oxygen provide information on past rainfall, while the changes in carbon indicate that the plants are growing at the time.
"The results were surprising: changes in soil geochemistry in the late Miocene changes in the latitudinal strips from north to south, which indicates the underlying cause, which covers a large part of South America, and not only local changes in the height or topography," said Carrapa.