Page 9 - DINOSOUR ATLAS

time chart

. Pleistocene: A period of ice ages, when large areas are covered by ice
sheets. These are interspersed with subtropical interglacials. A warmer
phase of the current ice age sees the rise of humans, and a mass mYa
extinction of large mammals such as the camel-like Macrauchenia. . 2 Macrauchenia
. Pliocene: North and South America become linked, allowing
animals to migrate between the two. The first bipedal
hominids evolve in Africa, and eventually give rise to early
humans such as Homo habilis. . 5 hoMo habilis

. miocene: The Antarctic icecap forms, lowering sea levels.
The climate becomes cooler, encouraging the expansion of
grasslands and the evolution of specialized grazing mammals. . 23 GoMphotheriuM

. Oligocene: Mammals similar to modern forms appear.
Some are giant “megaherbivores” like Paraceratherium, a
type of rhinoceros that stood 20 ft (6 m) high at the shoulders
and browsed tree foliage. . 34 paraceratheriuM
. eocene: Plant-eating and hunting mammals become established
as the dominant animals on land. Many are still quite small,
like the dog-sized Phenacodus, an early hoofed mammal. . 55 phenacodus

cenozoic 65-0 mya . Paleocene: The first epoch of the Tertiary Period sees the rise of . 5 icaronycteris
giant, predatory land birds. Surviving reptiles flourish in the warm
climate, and mammals begin to diversify. The first bat appears.

. cretaceous: Dinosaurs flourish on land until the last of them are
wiped out by a mass extinction at the end of the period. The first
flowering plants evolve, and small mammals become widespread. . 145 deinonychus

. Jurassic: Dinosaurs, flying pterosaurs, and marine reptiles diversify
into many forms, including giant plant-eating sauropods like
Camarasaurus and bipedal, carnivorous theropods. . 200
caMarasaurus
mesozoic 251-65 mya . triassic: The first period of the Mesozoic Era is marked by warm, . 251 coelophysis
wet climates that gradually become hotter and drier. The first
dinosaurs such as Coelophysis appear, and the first mammals.

. Permian: The last period of the Paleozoic sees the formation of
the giant supercontinent Pangaea, the development of vast deserts,
and a mass extinction of animals at the end of the period. . 299 scutosaurus

. carboniferous: Tropical conditions almost worldwide lead to
the growth of lush fern forests that become fossilized as coal.
The first reptiles evolve and spread rapidly over the land. . 359 hylonoMus

. Devonian: Green plants spread over the land, and trees
and insects appear. Many forms of fish evolve, and the earliest
four-legged amphibians such as Acanthostega colonize the land. . 41 acanthosteGa

. Silurian: The first jawed fish, such as Climatius, appear in the
oceans. True land plants appear, and primitive invertebrate land
animals such as centipedes develop toward the end of the period. . 444 cliMatius

. Ordovician: Strange relatives of starfish such as Cothurnocystis
evolve in the oceans, and the earliest jawless fish appear.
The first primitive green plants start to grow on land. . 488 cothurnocystis

paleozoic 542-251 mya . cambrian: The first period of the Palaeozoic Era sees an . 542 trilobite
“explosion” of multicellular life in the oceans, including the
appearance of the trilobites, which resemble modern sea slaters.

precambrian 4,567-542 . Precambrian: Over most of Precambrian time—80 percent of
Earth’s history—the only life forms are bacteria, which appear
about 3,500 million years ago. Multicelled marine animals like
mya
spriGGina
Spriggina appear at the end of the era.
. 4,5