South American Camelids.-
What most people think of as camels—dromedaries and Bactrians—are so firmly associated with the deserts of Africa and Asia that it is hard to believe they have close relatives in South America. Camelids originated in North America 40 to 45 million years ago, then evolved on the continent's grasslands into a diverse array of forms, including the gazelle-like Stenomylus, the giraffe-like Aepycamelus, and the nearly 12-foot-tall Titanotylopus, which resembled today's Old World camels.
William Franklin, professor emeritus at Iowa State University in Ames, says, "At one time, there were probably several dozen genera of camelids in North America. In some areas, they were surely the dominant large herbivores." Then, six to three million years ago, opportunities for leaving their homeland arose when the Earth's climate cooled and sea levels fell, exposing land bridges to the south between Panama and South America, and to the north across the Bering Strait between Alaska and Asia.
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