Researchers have discovered that an evolutionary change from 65 million years ago may have set the pace for the rapid growth rate of present-day flowering plants.
Taylor Feild, associate professor of ecology and evolutionary biology at the University of Tennessee, Knoxville, in collaboration with a group of other researchers from around the world, have determined the precise dates that angiosperms, or flowering plants, experienced two surges in growth during the Cretaceous period.
Their findings are published in the current edition of the Proceedings of the National Academy of Sciences .
The researchers measured the vein densities, or number and length of veins in a given area, in the fossils of more than 300 angiosperm leaves and then compared them to the fossils of nonangiosperms that lived at the same time.
"Because leaf veins supply the water necessary for how plants 'eat' the air to obtain carbon dioxide that is necessary for growth and reproduction, the discovery of shift toward densely veined leaves during the latest Cretaceous strongly suggests that modern functioning vegetation first appeared during that time," Feild said.
The results also provide additional evidence that modern tropical rainforests appear to be no older than the latest Cretaceous.
The international research team included scientists from the University of Tasmania, Brown University, Universidad Nacional de La Plata in Argentina, the Smithsonian Tropical Research Institute in Panama, Texas State University, the Natural History Museum of Berlin, the University of Lyon, and the Czech Republic National Museum.
Proceedings of the National Academy of Sciences