9.1, 9.2, & 9.3 Geologic Time

stegosaurus

a dinosaur that is representative of the bird-hipped reptiles abundant during the jurassic

apatosaurus

a dinosaur that is representative of the lizard-hipped reptiles abundant during the jurassic

evolution

a heritable change in the characteristics within a population from one generation to the next; the development of new types of organism from preexisting types or organisms over time.

shield

a large area of exposed Precambrian rock

carboniferous

a period in which forests and swamps covered much of the land; the coal and oil deposits were made during this time. It is divided (in this country) into the Mississippian and Pennsylvanian Periods

triassic

a period in which the first dinosaurs appeared

ordovician

a period in which the first fish appeared and snails, clams, and other mollusks became dominant life-forms

silurian

a period in which the first terrestrial plants and animals (spiders and millipedes) appear.

cambrian

a period of shallow seas and much fluctuation of shorelines dominated by Trilobites and many Brachiopods (shelled animals)

devonian

a period of the first amphibians and ammonites; also, fish were abundant: The Age of the Fishes

Permian

a period when many kids of marine animals became extinct and the land massed to form Pangaea; glaciation occurred at low altitudes; and, this was the end of the Paleozoic Era.

cretaceous

a period when the first flowering plants appear and at the end of which all the dinosaurs became extinct

stromatolite

a reef-like deposit produced by cyanobacteria, (blue-green algae) one of the oldest and simplest of fossils

Crinoid

a relative of the modern sea star which was abundant during the Carboniferous Period.

eurypterid

a scorpion-like sea creature, nearly 2.7 meters in length that lived during the Silurian Period

epoch

a subdivision of a geologic time that is longer than an age, but shorter than a period. a subdivision of a geologic period.

graptolite

a time invertebrate which became a dominant life-form in the Ordovician; an example of an Index Fossil

angiosperm

a true flowering plant such as the magnolia, willow, maple, oak and walnut trees

era

a unit of geologic time that includes two or more periods

period

a unit of geologic time that is longer than an epoch but shorter than an era. a subdivision of a geologic era.

rhipidistian

an air-breathing fish that lived during the Devonian Period

invertebrate

an animal without a backbone

lemuroid

an early primate, small tree-dwelling mammals with thick fur and long flat nails

mass extinction

an episode during which large numbers of species become extinct.

geologic column

an ordered arrangement of rock layers that is based on the relative age of the rocks and in which the oldest rocks are at the bottom

jurassic

dinosaurs became the dominant life forms during this period with three main groups: the saurischians (lizard-hipped reptiles), the orinthischians (bird-hipped reptiles) and, the pterosaurs or pterodactyls (flying reptiles)

archeopteryx

one of the first true birds with feathers that appeared last in the Jurassic period

tyrannosaurus

one of the largest and most spectacular dinosaur which stood nearly 6 meters tall. it was a carnivore with a huge jaw and razor-sharp teeth 15 centimeters long

Cenozoic era

the current geologic age, beginning 65.5 million years ago: The Age of Mammals

Precambrian time

the earliest and longest interval of time in the geologic time scale from the Earth's formation to the beginning of the Paleozoic era, lasting from 4.6 billion to 542 million years ago.

hyracotherium

the earliest known ancestor of the horse

miocene

the fourth epoch of the Cenozoic when there was an abundance of grazing animals and the Calvert Cliffs of Maryland were formed

Paleozoic era

the geologic era that followed Precambrian time, lasting from 542 million to 251 million years ago.

Mesozoic Era

the geologic era that lasted from 251 million to 65.5 million years ago: The Age of Reptiles

baluchitherium

the largest knows land mammal every to have existed, sometimes called Paraceratherium

eon

the largest unit of geologic time

holoscene

the last epoch of the Cenozoic and most recent beginning about 11,000 years ago; modern man appears. Includes the present age and is sometimes referred to as the inter glacial age.

paleoscene

the oldest epoch of the Cenozoic when the first placental mammals and the first primate appear.

eocene

the second epoch of the Cenozoic when many modern types of mammals appear

pleistocene

the sixth epoch of the Cenozoic in which several ice ages occurred and fossils of early hominids appear

pliocene

the sixth epoch of the Cenozoic in which the large carnivores became abundant, (Saber Toothed tiger) and the Bering land bridge appeared

oligocene

the third epoch of the Cenozoic when deer, pigs, horses, camels, and cats and dogs flourished

Ichthyostega

this first true amphibian that probably evolved from air-breathing fish, resembling a salamander, and is thought to be an ancestor of the frogs and toads