Paleontology is the study of fossils, particularly fossils of life forms prior to the Holocene Epoch. Like archaeology, paleontology often involves excavation—digging in the dirt in remote places—using scientific methods as a guide. However, paleontology differs from archaeology in that it excludes the study of humans. While paleontology, as a science, is concerned with processes such as evolution, the general public usually associates it with dinosaurs.
For a number of years I taught archaeology at a small, rural community college. Many of the students came into the class expecting to learn something about dinosaurs. In addition, non-students would approach me with dinosaur questions or show me old fossils. I have to explain that my interests are focused on humans and human ancestors and so this means that I am primarily interested in only the past six million years or so. By this time, dinosaurs had been long extinct—in spite of what some creationists may want to believe, humans and dinosaurs never coexisted.
Paleontology deals with the study of fossils: traces or impressions of organisms of past geologic times that have been preserved in the earth’s crust. Fossils typically show the hard parts of dinosaurs: bones, teeth, shells, and horns. The process of fossilization involves the replacement of these hard parts with mineral deposits. Sometimes, however, there may be impressions showing things like feathers.
Before talking about dinosaurs, let’s put things into a time line. First of all, at the present time the evidence suggests that life on this planet began about 3-4 billion years ago. The first animals appear about 580 million years ago. The first evidence of dinosaurs is found during the Triassic period about 231 million years ago and they became the dominant terrestrial vertebrates during the Jurassic (201 million years ago). About 66 million years ago the Cretaceous-Paleogene extinction event resulted in the extinction of most plant and animal species on the planet, including all non-avian dinosaurs. This event was probably triggered by a massive comet or asteroid impact which resulted in a lingering impact winter.
Shown below are photographs of some museum displays about dinosaurs from a special exhibit at the Oregon Museum of Science and Industry (OMSI) in Portland.
Shown above is a display of what a dinosaur dig site looks like. Understanding dinosaurs begins by uncovering fossils, such as the ones shown above from the Zigong dig site in China. This site has provided a great quantity and diversity of well-preserved fossils. More than 100 individual dinosaurs have been uncovered here. The fossils are in a sandy layer of the Meso-Jurassic period which dates from about 160 million years ago.
Shown above is a Hadrosaur skull from the Late Cetaceous (98 to 65 million years ago). The beak-shaped snout did not have teeth. Hadrosaurs were quadrupedal plant-eaters whose fossils have been found in Europe, Asia, and North America. This dinosaur is sometimes called the Duck-billed dinosaur.
Shown above is an Allosaurus skull which dates to the Late Jurassic (150 million years ago). This is a commonly found dinosaur with remains in North America (Montana, North Dakota, South Dakota, Kansas, Nebraska, Wyoming, and Colorado) and in Europe (Portugal). This was a fierce carnivore. The typical Allosaurus was about 30 feet long, weighed 3 tons, and ate other dinosaurs.
Shown above is a Yangchaunosaurus skull from the Late Jurassic (160 million years ago) in China. This was the largest Late Jurassic theropod in China, standing 10 meters (34 feet) high and weighing about 2,300 kilograms (5,000 pounds). Yangchaunosaurus is considered to be a close relative of Allosaurus.
Shown above is a Tuojiangosaurus skeleton from the Late Jurassic (155 to 145 million years ago) in China. It is 7 meters (23 feet) in length, stands 2.2 meters (7.2 feet tall), and had an estimated weight of 4,000 kilograms (8,800 pounds). It grazed along the banks of rivers and streams and does not appear to have been able to rear up on its hind legs.
Shown above are Placoolithus eggs from the Late Cretaceous Period (98 to 65 million years ago). Note: fossil eggs are named for their shape or structure, not for the dinosaur that laid them.
Shown above is a reconstruction of a young adult Corthorasaurus created using CT scanning.
Shown above are Shunosaurus phalanges. Phalanges are part of the finger and toe bones. In sauropods, the number of phalanges in the foot is greater than those of the hand. Typically, only one digit in the hand (manus) bears a claw attached to the phalange. According to the display:
“As large as Shunosaurus was, at first glance it may appear to have been walking gingerly rather than heavily stomping as it searched for food. The back feet were in many ways similar to an elephant’s foot with a large fleshy ‘cushion’ forming a sort of heel. Just as elephants appear to walk delicately for their large size, so might have Shunosaurus.”