Page 32 - DINOSOUR ATLAS

Dinosaur Monument 5 4 ! ( # / , / 2 ! $ / north america
30

Dinosaur national monument is in a remote part of Colorado and Utah, in the
western United States. It is a protected area of more than 200,000 acres, where %JBNPOE 1MBUFBV
(SFFO 3JWFS
hundreds of Late Jurassic dinosaurs have been found, including the meat-eaters $INOSAUR
Allosaurus and Ceratosaurus, the plant-eaters Diplodocus and Stegosaurus, together 1UARRY :BNQB 3JWFS
with about 15 other species. They lived 150 million years ago, on low-lying $INOSAUR .ATIONAL
ground over which a great river periodically flooded. As it spilled across its *ENSEN -ONUMENT
floodplain, it washed the carcasses of dead dinosaurs onto a sandbank,
where they were slowly fossilized.

. StegoSaUrUS Skeleton
cope and marsh More than 300 tons of dinosaur u Site location

In the 1870s, two American fossil hunters, fossils were recovered from Excavations began in 1909, centered on a site known as
Edward Drinker Cope (1840–97) and Othniel the bone bed, including the Dinosaur Quarry. In 1915 the Dinosaur National Monument
was created in recognition of the importance of the
Charles Marsh (1831–99), began searching skeleton of Stegosaurus, a surrounding landscape.
for dinosaur fossils within the rocks of the plant-eating dinosaur with
Morrison Formation. They competed to see bony plates on its back.
who could find the best specimens, and who ridge of hard
could name the most new species. Their bonelike plates
bitter rivalry lasted for many years, and ran along its back
is now known as the “Bone Wars.”

ceratoSaUrUS .
A big predator, Ceratosaurus
crossed the low-lying floodplain
on the hunt for prey. Its bones
have been found at the site,
u DiPloDocUS SkUll
mixed among the fossils of tail helped
Several almost complete Diplodocus skeletons herbivores. A short horn grew to balance the
were excavated. This giant sauropod (a from its head, between its weight of the head
plant-eating dinosaur), whose small head eyes. This may have been used
was just 1½ ft (0.5 m) long, stripped leaves in a headbutting contest
edward drinker cope othniel charles marsh
from trees with its peglike teeth. with a rival Ceratosaurus.
nearly 2,000
dinosaur bones can
toDay’S lanDScaPe . be seen locked in rock
at Dinosaur Quarry
Visitors to the Dinosaur National
Monument see an area of
high sandstone cliffs, and the
valleys of the Green and Yampa
Rivers. The cliffs are part of
the Morrison Formation—an
extensive deposit created in the
Late Jurassic from sediments
spread by rivers across
their floodplains.

, JUraSSic PreDator
Several Allosaurus have been
collected at the Dinosaur
National Monument. The largest
carnivore of the Jurassic Period,
an adult reached lengths of 39 ft
(12 m). Its long teeth sliced into
flesh then, as it tossed its head
from side to side, its powerful
jaws tore a chunk from the
huge openings in the skull, Jaw muscles were powerful, eyes were on the side of body of its prey.
which was 1 m (3 ft) long, allowing Allosaurus to swallow the head, giving Allosaurus
made it lighter huge mouthfuls of flesh a wide field of vision