Plants set stage for evolutionary drama
Oxygen increase triggered by vascular plants enabled the development of complex animals.
by Joseph Milton
Plants made the evolution of large, complex animals such as predatory fish possible, a study of ocean sediments suggests. The findings, published in this week’s Proceedings of the National Academy of Sciences1, are the first empirical evidence to support a theory that there was a dramatic rise in oxygen levels in the Devonian period, 400 million years ago, and the first to indicate that the rise and spread of higher plants probably drove the increase.
“The evolution of vascular plants completely changed history, allowing a high concentration of oxygen in the atmosphere to be sustained. Eventually, that process led to higher animals such as ourselves,” says Tais Dahl, an earth scientist at the University of Southern Denmark in Odense, who led the study.
Dahl’s team looked at the concentration of molybdenum and the ratios of its isotopes — atoms of the same element with different numbers of neutrons and different masses — in oceanic rocks for clues to the concentration of oxygen in the seas over time…
(read more: Nature)
(image: Dunkleosteus, a predatory prehistoric fish of the late Devonian, was able to evolve because of the rise of higher plants. - JAIME CHIRINOS / SCIENCE PHOTO LIBRARY)
reference: Dahl, T. W. et al. Proc. Natl Acad. Sci. USA. doi:10.1073/pnas.1011287107 (2010).