the Colorado Plateau region, has yielded some of the largest dinosaur fossils.
Many of the best specimens are displayed at Dinosaur National Monument
near Vernal, Utah (Fig. 148).
More than 500 dinosaur genera have been discovered over the last two
centuries. Among the largest dinosaur species were the sauropods. These gar-
gantuan creatures fully deserve the title “thunder lizard.”They had long, slen-
der tails and necks, and the front legs were generally longer than the hind legs.
Their fossils are found in Colorado and Utah, southwestern Europe, and East
Africa,with some species probably having traveled to Africa by way of Europe.
Dinosaurs are often portrayed as lumbering, unintelligent brutes.Yet the
fossil record suggests that many species,such as velociraptor, were swift and
intelligent.All dinosaurs were not giants, and many species were no larger than
most mammals today. The Protoceratops—a parrot-beaked, shield-headed
dinosaur—and the ankylosaur, whose name means “stiff lizard”—an elephant-
sized dinosaur heavily covered with protective bone and swinging a club-
shaped tail—were very common and ranged throughout the world.
Some large bipedaled dinosaurs later reverted to a four-footed stance as
their weight increased. They eventually evolved into gigantic, long-tailed,
long-necked sauropods such as the apathosaurs (Fig. 149), which belong to the
Figure 148Restoration
of dinosaur bones at
Dinosaur National
Monument,Utah.
(Courtesy National Park
Service)JURASSIC BIRDS