Page 11 - The Dinosaur Book and Other Wonders of the Prehistoric World (DK-Smithsonian)

Geological periods 23–2 MYA 2 MYA to present
Earth’s history stretches back
4.6 billion years. This vast span Neogene Quaternary
of time is divided into long sections Mammals and Our ancestors
called eras, which are divided in birds evolved evolved larger
into recognizably
brains in this period
turn into shorter sections called modern forms in and invented ever
periods. The Jurassic Period, for the Neogene. Our more ingenious
instance, is when many of the ape ancestors left tools to hunt, make
dinosaurs lived. The periods are the trees and adapted Dryopithecus fire, build homes,
to life in grasslands by
sew clothes, and
named after different bands of walking on two legs. farm the land.
sedimentary rock, each of which
has a distinctive collection of fossils. Homo habilis
66–23 MYA
Paleogene
The death of the giant dinosaurs
Uintatherium allowed mammals to take their
place. They evolved from small
nocturnal creatures into a great
Chalicotherium diversity of land and sea animals,
including giant herbivores such as
Chalicotherium, which used its
long arms to reach the highest
branches of trees.

145–66 MYA

Cretaceous
Dinosaurs of the
Cretaceous included Ichthyornis
Tyrannosaurus and the
plant-eating ceratopsians,
which had distinctive horned
faces, neck frills, and beaks. All
dinosaurs except for a few birds
perished in a mass extinction at the Magnolia
end of the period, along with many Triceratops
other prehistoric animals.

358–299 MYA 416–358 MYA
Sigillaria Carboniferous Devonian
This period gets its name from Fish ruled the ocean in the Devonian, which is
the carbon deposits found in sometimes called the age of fish. The largest
Meganeura its rock as coal. Coal is the of them were placoderms—jawed fish with
fossilized remains of lush armor-plated bodies to protect them
rainforests that covered the from their enemies’ jaws.
land. These were home to
giant millipedes, giant
dragonflylike insects, and
early amphibians, which had
evolved from Devonian fish. Rolfosteus

488–444 MYA 444–416 MYA

Ordovician Silurian
Warm waters covered much of Coral reefs flourished in the
Earth in the Ordovician, submerging Silurian, providing habitats for the
the continent that would later form first fish with bones and the first
North America. The oceans fish with powerful, biting jaws
teemed with trilobites—large, rather than sucking mouths. Land
pillbug-shaped creatures plants remained small, but they
that scuttled across the seabed began to acquire the tough,
or swam shrimplike through the water-carrying veins that
water. The first fish and starfish would later form wood and
appeared, and simple plants trigger the rise of trees.
probably began to colonize
the land.
Trilobite fossils Baragwanathia 9

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