Patagonia - Walking On Eggs - page 3

peaks that make up the jagged backbone of the Andes mountain
range and south of the Rio Colorado. The Argentine portion of
Patagonia is subdivided into five provinces: Neuquen and Rio Negro
in the north, Chubut and Santa Cruz to the south, and the island of
Tierra del Fuego at the southern tip.
Little rain makes it over the Andes to fall on the hills and plains to
the east. Thus, east of the magnificent forests and lakes that adorn the
ice-capped peaks of the Andes, Patagonia is mostly a barren and
dusty desert, whipped by strong gusts of wind. The sun cracks the sur-
face of the earth during the blazing heat of summertime, but the win-
ter brings bitterly cold temperatures to some parts of the region. In this
desolate and inhospitable land live the puma, the condor, and the
ostrichlike rhea. Beneath it are the abundant remains of past organ-
isms, such as the dinosaur eggs that we found, because Patagonia is
covered by layer upon layer of rocks that entomb fossils of mammals
and dinosaurs that lived millions of years ago.
In fact, Argentina and other regions of South America played an
important role in the development of Charles Darwin's theory of evo-
lution by natural selection. Between 1833 and 1836, the HMS Beagle
anchored off the southern shore of Argentina. There, at Bahia Blanca,
Darwin wandered along the beach and collected fossils of Ice Age
mammals. He was amazed at the contrast between the modern fauna
and the fauna of Ice Age Argentina. In a two-hundred-square-yard area
of reddish mud and gravel bluffs along the beach, Darwin and his col-
leagues discovered fossils of huge mammals. The ancient fauna
included several species of giant ground sloths and a glyptodont—an
armadillo-like animal with a nearly complete covering of bony armor
arranged in small polygonal plates across the body. Some glyptodonts
grew to lengths of five or six feet, resembling small tanks. The giant
sloths, of which Darwin collected a nearly complete skeleton, were also
enormous, reaching heights of over ten feet.
Darwin and other members of the Beagle's crew sailed farther
south to Puerto San Julian, where Darwin found beds of rock con-
taining fossil oysters up to one foot in diameter, as well as shells of
other marine creatures. Later research has shown that these animals
lived more than 20 million years ago, when much of Patagonia was
submerged under a shallow sea. In other rock layers above the oyster-
bearing beds, Darwin found a skull-less skeleton of a terrestrial fossil