Table of geologic time
Eon
Era
Period[1]
Neogene
Phanerozoic
Series/
Epoch
Major Events
Start,
Million
Years
Ago[2]
0.011430
±
0.00013[4]
Holocene
End of recent glaciation and
rise of modern civilization.
Pleistocene
Flourishing and then
extinction of many large
1.806 ±
mammals (Pleistocene
0.005 *
megafauna). Evolution of
anatomically modern humans.
Pliocene
Intensification of present ice
age; cool and dry climate.
Australopithecines, many of
the existing genera of
mammals, and recent
mollusks appear.
Miocene
Moderate climate; Orogeny in
northern hemisphere. Modern
mammal and bird families
23.03 ±
became recognizable. Horses
0.05 *
and mastodons diverse.
Grasses become ubiquitous.
First apes appear.
Oligocene
Warm climate; Rapid
evolution and diversification
of fauna, especially mammals.
33.9±0.1 *
Major evolution and dispersal
of modern types of flowering
plants
[3]
Cenozoic
Paleogene
5.332 ±
0.005 *
[3]
Eocene
Archaic mammals (e.g.
Creodonts, Condylarths,
Uintatheres, etc) flourish and
55.8±0.2 *
continue to develop during the
epoch. Appearance of several
"modern" mammal families.
Primitive whales diversify.
First grasses. Reglaciation of
Antarctica; current ice age
begins.
Paleocene
Climate tropical. Modern
plants appear; Mammals
diversify into a number of
primitive lineages following
65.5±0.3 *
the extinction of the
dinosaurs. First large
mammals (up to bear or small
hippo size).
Flowering plants proliferate, 99.6±0.9 *
along with new types of
insects. More modern teleost
fish begin to appear.
Ammonites, belemnites,
rudist bivalves, echinoids and
sponges all common. Many
new types of dinosaurs (e.g.
Tyrannosaurs, Titanosaurs,
Cretaceous
duck bills, and horned
145.5 ±
Lower/Early dinosaurs) evolve on land, as
do modern crocodilians; and 4.0
mosasaurs and modern sharks
appear in the sea. Primitive
birds gradually replace
pterosaurs. Monotremes,
marsupials and placental
mammals appear. Break up of
Gondwana.
Upper/Late
Mesozoic
Gymnosperms (especially
conifers, Bennettitales and
cycads) and ferns common.
Many types of dinosaurs, such
Middle
as sauropods, carnosaurs, and
stegosaurs. Mammals
common but small. First birds
and lizards. Ichthyosaurs and
plesiosaurs diverse. Bivalves,
Lower/Early Ammonites and belemnites
abundant. Sea urchins very
common, along with crinoids,
starfish, sponges, and
terebratulid and rhynchonellid
Upper/Late
Jurassic
161.2 ±
4.0
175.6 ±
2.0 *
199.6 ±
0.6
brachiopods. Breakup of
Pangea into Gondwana and
Laurasia.
Archosaurs dominant on land
as dinosaurs, in the oceans as
Ichthyosaurs and nothosaurs,
and in the air as pterosaurs.
Middle
cynodonts become smaller
and more mammal-like, while
first mammals and crocodilia
appear. Dicrodium flora
common on land. Many large
aquatic temnospondyl
Lower/Early amphibians. Ceratitic
ammonoids extremely
common. Modern corals and
teleost fish appear, as do
many modern insect clades.
228.0 ±
2.0
Landmasses unite into
supercontinent Pangea,
creating the Appalachians.
End of Permo-Carboniferous
Guadalupian glaciation. Synapsid reptiles
(pelycosaurs and therapsids)
become plentiful, while
parareptiles and
temnospondyl amphibians
remain common. In the midPermian, coal-age flora are
replaced by cone-bearing
gymnosperms (the first true
seed plants) and by the first
true mosses. Beetles and flies
evolve. Marine life flourishes
Cisuralian
in warm shallow reefs;
productid and spiriferid
brachiopods, bivalves, forams,
and ammonoids all abundant.
Permian-Triassic extinction
event occurs 251 mya: 95
percent of life on Earth
becomes extinct, including all
trilobites, graptolites, and
blastoids.
260.4 ±
0.7 *
Upper/Late
Triassic
Lopingian
Paleozoic
Permian
245.0 ±
1.5
251.0 ±
0.4 *
270.6 ±
0.7 *
299.0 ±
0.8 *
Winged insects radiate
suddenly; some (esp.
Protodonata and
Palaeodictyoptera) are quite
Middle
large. Amphibians common
and diverse. First reptiles and
coal forests (scale trees, ferns,
club trees, giant horsetails,
Cordaites, etc.). Highest-ever
oxygen levels. Goniatites,
Lower/Early brachiopods, bryozoa,
bivalves, and corals plentiful
in the seas. Testate forams
proliferate.
306.5 ±
1.0
Large primitive trees, first
land vertebrates, and
amphibious sea-scorpions live
amid coal-forming coastal
Middle
swamps. Lobe-finned
rhizodonts are big fresh-water
predators. In the oceans, early
sharks are common and quite
diverse; echinoderms (esp.
crinoids and blastoids)
abundant. Corals, bryozoa,
Lower/Early goniatites and brachiopods
(Productida, Spiriferida, etc.)
very common. But trilobites
and nautiloids decline.
Glaciation in East Gondwana.
326.4 ±
1.6
First clubmosses, horsetails
and ferns appear, as do the
first seed-bearing plants
(progymnosperms), first trees
Middle
(the tree-fern Archaeopteris),
and first (wingless) insects.
Strophomenid and atrypid
brachiopods, rugose and
tabulate corals, and crinoids
are all abundant in the oceans.
Lower/Early Goniatite ammonoids are
plentiful, while squid-like
coleoids arise. Trilobites and
armoured agnaths decline,
while jawed fishes
385.3 ±
2.6 *
Upper/Late
Carboniferous[5]/
Pennsylvanian
Upper/Late
Carboniferous[5]/
Mississippian
Upper/Late
Devonian
311.7 ±
1.1
318.1 ±
1.3 *
345.3 ±
2.1
359.2 ±
2.5 *
397.5 ±
2.7 *
416.0 ±
2.8 *
(placoderms, lobe-finned and
ray-finned fish, and early
sharks) rule the seas. First
amphibians still aquatic. "Old
Red Continent" of
Euramerica.
First vascular plants (the
whisk ferns and their
relatives), first millipedes and
Upper/Late arthropleurids on land. First
jawed fishes, as well as many
(Ludlow)
armoured jawless fish,
populate the seas. Seascorpions reach large size.
Wenlock
Tabulate and rugose corals,
brachiopods (Pentamerida,
Rhynchonellida, etc.), and
crinoids all abundant.
Lower/Early
Trilobites and mollusks
(Llandovery)
diverse; graptolites not as
varied.
418.7 ±
2.7 *
Invertebrates diversify into
many new types (e.g., long
straight-shelled cephalopods).
Early corals, articulate
Middle
brachiopods (Orthida,
Strophomenida, etc.),
bivalves, nautiloids, trilobites,
ostracods, bryozoa, many
Ordovician
types of echinoderms
(crinoids, cystoids, starfish,
etc.), branched graptolites,
Lower/Early and other taxa all common.
Conodonts (early planktonic
vertebrates) appear. First
green plants and fungi on
land. Ice age at end of period.
460.9 ±
1.6 *
Pridoli
Silurian
Upper/Late
Upper/Late
(Furongian)
Cambrian
Middle
Major diversification of life in
the Cambrian Explosion.
Many fossils; most modern
animal phyla appear. First
chordates appear, along with a
number of extinct,
422.9 ±
2.5 *
428.2 ±
2.3 *
443.7 ±
1.5 *
471.8 ±
1.6
488.3 ±
1.7 *
501.0 ±
2.0 *
513.0 ±
2.0
problematic phyla. Reefbuilding Archaeocyatha
abundant; then vanish.
Trilobites, priapulid worms,
sponges, inarticulate
brachiopods (unhinged
lampshells), and many other
Lower/Early animals numerous.
Anomalocarids are giant
predators, while many
Edicarian fauna die out.
Prokaryotes, protists (e.g.,
forams), fungi and algae
continue to present day.
Gondwana emerges.
Ediacaran
Neoproterozoic
Good fossils of multi-celled animals.
Ediacaran fauna (or Vendobionta) flourish
worldwide in seas. Trace fossils of wormlike Trichophycus, etc. First sponges and
trilobitomorphs. Enigmatic forms include
oval-shaped Dickinsonia, frond-shaped
Charniodiscus, and many soft-jellied
creatures.
Possible "snowball Earth" period. Fossils
Cryogenian still rare. Rodinia landmass begins to break
up.
Proterozoic
630
+5/-30 *
850 [7]
Tonian
Rodinia supercontinent persists. Trace
fossils of simple multi-celled eukaryotes.
First radiation of dinoflagellate-like
acritarchs.
1000 [7]
Stenian
Narrow highly metamorphic belts due to
orogeny as supercontinent Rodinia is
formed.
1200 [7]
Ectasian
Platform covers continue to expand. Green
algae colonies in the seas.
1400 [7]
[6]
Mesoproterozoic
542.0 ±
0.3 *
Calymmian Platform covers expand.
1600 [7]
Statherian
First complex single-celled life: protists with
nuclei. Columbia is the primoidal
1800 [7]
supercontinent.
Orosirian
The atmosphere became oxygenic. Vredefort
and Sudbury Basin asteroid impacts. Much 2050 [7]
orogeny.
Paleoproterozoic
Archean
[6][8]
Bushveld Formation occurs. Huronian
glaciation.
Siderian
Oxygen Catastrophe: banded iron formations
2500 [7]
result.
2300 [7]
Neoarchean
Stabilization of most modern cratons; possible mantle
overturn event.
2800 [7]
Mesoarchean
First stromatolites, probably colonial cyanobacteria).
Oldest macrofossils.
3200 [7]
Paleoarchean
First known oxygen-producing bacteria. Oldest definitive
3600 [7]
microfossils.
Eoarchean
Simple single-celled life (probably bacteria and perhaps
archaea). Oldest probable microfossils.
[6]
Hadean
Rhyacian
3800
Lower
Imbrian[9]
c.3850
Nectarian[9]
c.3920
Basin
Groups[9]
Oldest known rock (4100 mya).
c.4150
Cryptic[9]
Formation of earth (4570 mya). Oldest known mineral
(4400 mya).
c.4570
http://en.wikipedia.org/wiki/Geologic_timescale
Name _________________________________
Date _____________ Period ______ Page #___
Geology Unit 1 Worksheet 1
Geologic Time:
Complete the following questions using your geologic time scale (or information from
your text book):
1. How long ago did humans populate the earth? What time period was this?
2. Why do movies with both humans and dinosaurs have a serious flaw? Explain!!
3. How long ago did life begin on earth? What time period was this?
4. What happened during the Hadean Eon?
5. What were the Periods of the Paleozoic Era?
6. What were the periods of the Mesozoic Era?
7. What were the periods of the Cenozoic Era?
8. How did each of the above eras differ from each other?
9. The movie “Jurassic Park” had the right era for dinosaurs, but would have been better
named using one of the other periods of the Mesozoic. Why is this statement true?
And, which period would have made a more fitting title?
10. The Cenozoic Era is broken down to two periods. What are these periods and why
are they different from each other?
11. How is the Cenozoic Era further broken down from the two periods? What makes
these divisions possible?
12. How long has human civilization dominated the earth?
13. How long did dinosaurs dominate the earth?
14. How do your answers for the two previous answers compare?
15. What type of living organism held the longest dominance on earth?