Part 5- Geologic Time

Precambrian

90% of Earth's History, unicellular organisms, soft-bodied multicellular organisms. trilobites

Paleozoic

'Era of Ancient Life" Age of Invertebrates, Age of Fishes, The Appalachian Mountains, Age of Amphibians, Reptiles, Formation of Pangaea, 2 Mass Extinctions

Mesozoic

"Era of Middle Life" Age of Vertebrates, Dinosaurs, Break-up of Pangaea, small mammals, Rocky Mountains, Mass Extinction

Cenozoic

Era of Recent life", Large mammals, humans, Himalayan Mountains, Cascades and Sierra Nevada Mountains, Alps

When did members of the genus Homo appear?

Appeared about 2.5 million years ago.

Australopithecus afarensis

earliest human ancestor best known for 3.2-million-year-old fossil called 'Lucy" found in Ethiopia.

homo habilis

made stone tools- called "Handy Man" and had the planet to themselves for 1 million years. Large skull

Homo floresiensis

known as "Flores Man or "The Hobbit" because of its small size

Homo neanderthals

became extinct 40, 000 years ago. Heavy boned frame, large brain, made musical instruments, buried their dead and performed ritual sacrifices. They hunted large animals and used needles to sew animal hides. Died without leaving any ancestors.

homo erectus

called "upright man" was the first to bear a passing resemblance to the modern human. Larger brain than its predecessors, made hand axes and mastered the use of fire.

Homo Floresiensis

Lived on the Island of Indonesia, Known as the "Flores Man" or the "Hobbit" due to its small size.

Homo Heidelbergenisis

second species after Homo Erectus to migrate out of Africa. Inhabited Europe. He was a skilled hunter, made spears to hunt large game and the first to build simple shelters.

Homo Sapiens

called 'Wise man" started using language about 70,000 years ago. Built shelters and boats, painted in caves, bow and arrows, oil lamps, religion, used abstract thought and had large brains.

Potassium-Argon dating

is used to date ancient rocks millions of years old.

Has a half life of 1.3 billion years.

Dates rocks as young as 50,000 years

Carbon-14 dating

is used to date bones, wood and charcoal up to 70,000 years old.

It has a half life of 5, 730 years.

Uranium Lead dating

has a half-life of 4.5 billion years.

Dates the oldest rocks of Earth's crust.

Not reliable on rocks younger than 10 million years old.

Rubidium-Strontium Dating

has a half-life of 47 billion years.

Can date most igneous rock.