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Desert Diary
Biology/Land Bridge


Focusing on our own little world may have advantages in day to day survival, but events in far away places have the nasty habit of intruding. This is true not only today, but throughout the history of the universe.

One example that helped change the nature of our Chihuahuan Desert is an event that happened far south of us, in Central America, some 3 to 4 million years ago. What happened? The previously separate continents of North and South America became joined by a land bridge, both separating the Pacific Ocean from the Caribbean and allowing a dry-land passage between the continents for land animals. Thus began what often is known as the Great American Interchange.

Our Chihuahuan Desert fossil faunas show the result, among which are the dramatically large ground sloths and the huge, armored glyptodont. Even today, the porcupine wanders through our desert landscape, a descendent of a South American rodent that crossed the Panama Land Bridge, every much a pioneer as humans who entered North America over the Bering Land Bridge millions of years later.
pen and ink


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.

Extinct North American camel

Sketch by Florence Schwein of the North American extinct camel, Camelops hesternus. rule


Stehli, F. G., and S. D. Webb, eds. 1985. The Great American Biotic Interchange, Plenum Press. 536 pp.

Web Resources

Land Bridge. Somewhat technical. SAM=South American mammals; NAM=North American mammals.