With its focus on the ancient past, archaeology somewhat resembles paleontologythe study of fossils of long-extinct animals, such as dinosaurs.
Archaeology plays a major role in the study of early civilizations, such as those of the Sumerians of Mesopotamia, who built the city of Ur, and the ancient Egyptians, who are famous for the pyramids near the city of Giza and the royal sepulchers (tombs) of the Valley of the Kings at Thebes.
Other sites that represent great human achievement are as varied as the cliff dwellings of the ancient Anasazi (a group of early Native Americans) at Mesa Verde, Colorado (see Mesa Verde National Park); the Inca city of Machu Picchu high in the Andes Mountains of Peru; and the mysterious, massive stone portrait heads of remote Easter Island in the Pacific.
For the most part, the only things that survive are durable items such as potsherds (small fragments of pottery), tools or buildings of stone, bones, and teeth (which survive because they are covered with hard enamel).
Because many items disintegrate over time, archaeologists get an incomplete view of the past that they must fill in with other kinds of information and educated reasoning.
On rare occasions, however, delicate objects have been preserved.
For example, fabrics and flowers were found in the celebrated tomb of Tutankhamun, an Egyptian pharaoh who was buried in 1323 BC.These remains include the fossils (preserved bones) of humans, food remains, the ruins of buildings, and human artifactsitems such as tools, pottery, and jewelry.From their studies, archaeologists attempt to reconstruct past ways of life.Many of the objects left behind by past human societies are not present in the archaeological record because they have disintegrated over time.The material remains that still exist after hundreds, thousands, or millions of years have survived because of favorable preservation conditions in the soil or atmosphere.Laetoli even reveals footprints of humans from 3.6 million years ago.