WEDNESDAY, JANUARY 19TH, 2011

Learning TargetsDefine the Geologic Time ScaleDistinguish between Eons, Eras, Periods,

and Epochs Homework

Ch. 21.1 L.T.s due on ThursdaySyllabus due FridayReview for Quiz Friday

Q.O.D. In your own words, define what the geologic

time scale is

CHAPTER 21Fossils and the Rock

Record

ORGANIZING TIME Geologic Time Scale

Fossils are found in rocksThese rocks help scientists interpret, or

learn, about Earth’s historyFossils and their records are used to divide

time into unitsAll time units put together make up the GTS

ORGANIZING TIME When was the

GTS developed?GTS was

established over 300 years ago

It has been changed a little, but mainly remains the same

The GTS and its units are based on FOSSILS and their PRESENCE IN ROCKS

VISUALIZING THE GTS EONS

Largest of all time unitsPrecambrian- consists of Hadean, Archean,

and Proterzoic Precambrian makes up 90% of all geologic time Earth was formed during this time Earth could support simple life Many fossils were simple, soft bodied animals

PRECAMBRIAN 4.6 billion years ago - about 550 million

years ago (formation of Earth) No life on land Fossil bacteria and algae Crust becomes solid Oxygen in atmosphere

VISUALIZING THE GTS ERAS

Second Largest Unit of TimeDetermined by LIFE/FOSSILSNamed for the time period

(Paleo)zoic= old life(Meso)zoic= middle life(Ceno)zoic= recent life-zoic mean life

VISUALIZING GTS Periods

Shorter than eras and eonsGenerally named for the region where the

rocks where first observed

EpochsSmallest divisions of timeRocks from the Cenozoic era are the best

PRESERVED due to being the newest Fossils are less subjective to weathering

and erosion

SUCCESSION OF LIFE-FORMS Early life was

very SIMPLE

As time passed, life became more COMPLEX

PHANEROZOIC EON Fossils from this eon are ABUNDANT

Phanerozoic means “visible life”

PALEOZOIC ERA About 550 mya - 250 mya Age of invertebrates Oceans full of different organisms Trilobites: first hard shelled life-forms Land plants appeared later, followed by

animals Mass extinction- end of Paleozoic Era

Largest extinction where 90% of marine organisms became extinct

Broken down into 6 Periods

CAMBRIAN PERIOD 550 mya - 490 mya Cambrian explosion First great

expansion of sea life Burgess Shale

ORDOVICIAN PERIOD 490 mya- 440

mya Jawless fish First land plants Ends in mass

extinction

Hagfish

SILURIAN PERIOD

440 mya - 408 mya First jawed fish Insects like millipedes and centipedes

First vascular plants on land

DEVONIAN PERIOD 408 mya - 360 mya Age of Fish --> Fish

and land plants become very diverse

First sharks appear Non-winged insects

move to land Tetrapods move to

land near end Late Mass extinction

Dunkleosteus

CARBONIFEROUS PERIOD 360 mya - 280 mya Can be split into

Mississippian and Pennsylvanian periods

First insects with wings First reptiles Cockroaches first

appear Wide spread Coal

Swamps

PERMIAN PERIOD

280 mya - 248 mya

Age of Amphibians

Continents merge into Pangea

Largest ever extinction ends the Permian

http://palaeo.gly.bris.ac.uk/Palaeofiles/Permian/PALIntro.html

MESOZOIC ERA 250 mya - 65 mya “Age of Dinosaurs” All different species thrived during this

time, reptiles ruled ocean, large insects evolved

Water dwelling amphibians adapted to land

Mammals evolved and began to diversify

Flowering plants and trees emerged 3 Time periods --> Triassic, Jurassic,

Cretaceous

TRIASSIC PERIOD 250 mya - 208 mya First dinosaurs,

mammals, and crocodyloforms

Ends with a mass extinction

Extinction allows dinosaurs to fill niches and diversify

JURASSIC PERIOD

208 mya - 146 mya Lots of dinosaurs including sauropods

First flowering plants

CRETACEOUS PERIOD 146 mya - 65 mya Dinosaurs rule the

earth First crocodiles,

ants, bees, snakes Feathered dinosaurs

appear K/T mass extinction

-- no more dinosaurs

CENOZOIC ERA 65 mya - ?????? “Age of the Mammals” Increased numbers and diversity Human ancestors appeared

First primates emerged in Paleocene EpochModern humans emerged in the Pleistocene

Epoch 2 time periods --> Tertiary and

Quaternary

TERTIARY PERIOD 65 mya - 1.8 mya Mammals abound Primitive primates Horses, whales, pigs,

deer Grasses common Megalodon

QUATERNARY PERIOD 1.8 mya - ???? Ice Ages Large mammals like

mammoths, mastadons, sabertooths, giant sloths

First Homo sapiens