It s hard for us to imagine a world without grass, yet as major plant groups go, it's the new kid on the block. Visualize the landscape inhabited by dinosaurs, but leave out grasses. The last dinosaur died about 65 million years ago, and our earliest fossil grass evidence seems to date about 3 million years later.
It's difficult to overestimate the importance of grasses to humans and to wildlife in general. Estimates are that somewhere around two-thirds of human calorie intake is from grasses—such as wheat, barley, and corn.
Over 20 million years ago, forested areas began to be replaced by open
grasslands—to the point that today, grasslands are estimated to cover some 25% of the
earth's land surface. Numerous North American mammals responded evolutionarily to
the new environmental pressures by specializing for outrunning predators in the open
landscape and by developing dentition fit for a grass diet. The next time you see one
of our desert Pronghorns or Bighorn Sheep, marvel at what a simple plant has
wrought.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Feather Grass in the Grass Garden of the Chihuahuan Desert Gardens. Photograph by A.H. Harris, 29 Jun 2001.