Geologic Time Line 4.7 bya to present

I. Precambrian 3 parts: 1. Hadean Eon 2. Archeozoic Eon 3. Proterozoic Eon

1. Hadean Eon 4.6 to 3.9 bya Earth's continental and oceanic crusts solidify

2. Archean Eon 3.9 to 2.5 bya 1 st life forms evolve - one celled organisms Blue-green algae, and bacteria appear in the sea These begin to put oxygen into the atmosphere

3. Proterozoic Eon 2.5 bya to 540 mya multi-celled animals appear, including sponges, colonial algae, & jellyfish mass extinction occurred continents merge into a single supercontinent called Rodinia

II. Phanerozoic Eon 540 mya through today 3 eras: A. Paleozoic Era B. Mesozoic Era C. Cenozoic Era

A. Paleozoic Era 540 to 248 mya Organisms with skeletons or hard shells This era is broken into 7 periods (a-g)

a. Cambrian Period 540 to 500 mya “The Age of Trilobites”

The Cambrian Explosion of life occurs; all existent phyla develop. Many marine invertebrates 1 st vertebrates Earliest fish Mild climate

Rodinia starts breaking apart mass extinction of trilobites and nautiloids at end of Cambrian 50% of all animal families went extinct, probably due to glaciers.

b. Ordovician Period 500 to 438 mya 1 st plants on land 1 st corals seaweed Gastropods, bivalves, and echinoids High sea levels at first, glaciation, and much volcanism North America under shallow seas Ends in huge extinction, due to glaciation

coral

c. Silurian Period 438 to 408 mya 1 st jawed fish, centipedes and millipedes appear 1 st vascular plants (plants with water-conducting tissue) appear on land High seas worldwide Brachiopods, crinoids, coral

crinoids

d. Devonian Period 408 to 360 mya

“The Age of Fish” amphibians, sharks, & bony fish Many coral reefs, brachiopods, crinoids Springtails (insects) appeared

brachiopods

Mass extinction (345 mya) wiped out 30% of all animal families) due to glaciation or meteorite impact

e. Mississippian Period 360 to 325 mya First winged insects

The first known dragonfly fossil had a wingspan of about 29 inches.

320-million-year fossil dragonfly

f. Pennsylvanian Period 325 to 280 mya 1 st reptiles Many ferns mayflies and cockroaches appear

Pennsylvanian-aged lagoon in central Kansas

g. Permian Period 280 to 248 mya "The Age of Amphibians"

Amphibians and reptiles dominant Gymnosperms dominant plant life the continents merge into a single super-continent, Pangaea oxygen the Earth's atmosphere to close to modern levels first stoneflies, true bugs, & beetles

ULTRA-RARE GIANT SCLEROCEPHALUS - PERMIAN AMPHIBIAN Pfalz, Germany

The Permian ended with largest mass extinction Trilobites go extinct, as do 50% of all animal families, 95% of all marine species, and many trees, perhaps caused by glaciation or volcanism

B. Mesozoic Era 248 to 65 mya "The Age of Reptiles" 3 periods: ai.Triassic aii.Jurassic aiii. Cretaceous

ai. Triassic Period 248 to 208 mya Coelophysis

first dinosaurs & mammals appear Mollusks are the dominant invertebrate Many reptiles, turtles, ichthyosaurs True flies appear Triassic period ends with a minor extinction 213 mya (35% of all animal families die out and all marine reptiles except ichthyosaurs). This allowed the dinosaurs to expand into many niches.

ichthyosaurs

aii. Jurassic Period 208 to 146 mya Brachiosaurus

Plesiosaurus

A 33-foot-long (10-meter-long) marine reptile dubbed the Monster (pliosaurs) leaps from the water to snare a smaller reptile known as a plesiosaur in this artist's interpretation.

Many dinosaurs, including the giant Sauropods The first birds appear (Archaeopteryx) The first flowering plants evolve Many ferns, cycads, gingkos, rushes, conifers, ammonites, and pterosaurs Minor extinctions at 190 and 160 mya

Archaeopteryx The Berlin Archaeopteryx fossil

Index Fossils Ammonite fossils are found in great quantities and are used as an index fossil. Index fossils are commonly found fossils that are limited in a particular time span. They help in dating other fossils. Ammonites only existed during the Mesozoic Era, but went extinct at the end of the Cretaceous period.

The heyday of the dinosaurs The first crocodilians The earliest-known butterflies appear (about 130 million years ago) as well as the earliest-known snakes, ants, and bees Minor extinctions at 144 and 120 mya Apatosaurus

pterosaurs

aiii. Cretaceous Period 146 to 65 mya

Tyrannosaurus

T-Rex

High tectonic and volcanic activity Primitive marsupials develop Continents have a modern-day look Minor extinction 82 mya Ended with large extinction (the K-T extinction) of dinosaurs, pterosaurs, ammonites, about 50 percent of marine invertebrate species, etc., probably caused by asteroid impact or volcanism

C. Cenozoic Era 65 Million Years to the Present “Age of Mammals” two main sub-divisions: bi. Tertiary Period bii. Quaternary Period

bi. Tertiary Period 65 to 1.8 mya First hominids (australopithecines) Modern forms of whales Megalodon swam the seas australopithecines

The 3.3 million-year- old skull of a female Australopith- ecus afarensis

Megalodon: a 50 foot long shark

Comparing sizes of 'Megalodon' (length about 13 m) and Great White Shark (length about 6.5 m). © L. Andres

Fossilised tooth of Carcharocles megalodon. Height: 13 cm. Middle to Late Miocene, Florida/USA. © Photo L. Andres

bii. Quaternary Period 1.8 mya to today "The Age of Man" broken into 2 sections: ci.Pleistocene cii.Holocene

ci. Pleistocene 1.8 million to ~10,000 years ago Mammoths, longhorned bison, saber- toothed cats, giant ground sloths Great teratorn birds with 25-foot wingspans stalked prey Around the end of the Pleistocene, all these creatures went extinct

teratorn bird

evolution of early man and by the close of the Pleistocene, early humans had spread through most of the world human hunting caused the extinction of many of the Pleistocene large mammals

Woolly Mammoth La Brea Tar Pits Sabre-Toothed Cat

cii. Holocene 11,000 years ago to today Modern Human civilization The Last Ice Age ended 10,000 years ago

BC Originally the Latin was "a.C.n.", an abbreviation of "Ante Christum Natum", which is Latin for "before the birth of Christ". However, this changed at some point to BC or B.C. Now people say CE for common era.

AD Anno Domini (abbreviated as AD or A.D.) Latin for The Year Of Our Lord - used in the Gregorian Calendar to refer to the current era. A date such as 1945 A.D. literally means 'the 1945th year of our lord', the lord in question being Jesus Christ.

There is no year zero in this calendar, so the year AD 1 immediately follows the year 1 BC.