Everybody wants to win the sweepstakes and get set up for life. Of course, usually you have to venture something in order to have a chance of winning, and there aren't very many winners. With this in mind, a famous paleontologist called a risky process "sweepstakes dispersal". Suitable habitats for organisms often are separated by long stretches of unsuitable habitats: barriers. Large bodies of water, such as oceans, are good examples for most terrestrial animals. The odds of making it across such a barrier are bad, and most attempts are doomed to failure by drowning, thirst, or starvation.
Nevertheless, on rare occasion some animal wins the sweepstakes, such
as the ancestral South American monkeys making it across the Atlantic from Africa. On a
more local level, one line of giant ground sloths managed to make it from South America
into our region before Central America joined the northern and southern continents.
Perhaps this is doubly amazing when we consider the reputation of sloths:
excruciatingly slow and just somewhat on the lazy side.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
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.