During periods of vigorous physical activity, a persons breathing and heart rates increase. this enables the cells of the body to perform more efficiently because it the cells to

Paleontologists have found plant fossils deep within the layers of the north polar region. these leaf fossils have been labeled as to the rock layers they were found in, with the lower numbers being layers close to the earth's surface and higher numbers representing deeper layers. according to the numbers of these four leaf fossils, what might you infer?