|
Phanerozoic
EON
(541 mya to present)
"The
age of visible life"
|
ERA
|
Periods
|
Epoch
|
Evolutionary
Milestones
|
|
Cenozoic
Era
(65
mya to today)
|
Quaternary
(1.8
mya to today)
|
Holocene
(11 kya
to today)
|
Modern
man radiates, "science" appears and eventually computers
and the Internet and Iphones become ubiquitous
Plants and
animals domesticated at ~ 13 kya. |
Pleistocene
(1.8
mya to 11K)
|
Neandertals
appear and disappear; Homo erectus and Homo sapiens appear; Homo sapien
speech attained at ~ 75kya. Stone age commences with a human extinction
near miss do to continuing ice age. |
Neogene
(23
to 1.8 mya
|
|
Ape-like
ancestors of modern humans (Hominids), the australopithecines, as well
as Homo habilis appear. Land and marine animals including mammals generally
modern. Cooler & drier climate reduces tropical plants as deciduous
& coniferous
forests as well as grasslands & savannas expand. |
|
|
Expansive
grasslands formed giving rise to new mammal forms, especially grazing
horses, rhinoceros, camels, & antelopes, & of course their predators. Many
primates & 1st bipedal apes. Mastodons (megafauna) appear late
in epoch.
Some 95% of epoch plants are extant today; almost all extant bird families
present by epoch end, as well as about half of modern invertebrates.
Marine vertebrates diversify; whales reaching their maximum.
In the seas, vast proliferating kelp and algae fosters new vertebrate
and higher mammal (seals) marine life species and associated apex predators
like megalodon sharks.
|
|
|
|
Evolution
of more modern animals continued, particularly among mammals (1st
seals) and among angiosperms. Most modern bird forms present.
Grazers adapt to apex predators like the saber-toothed cat with
longer legs and speed. Oreodonts herebivores abundant.
|
|
|
Eocene
ends with extinction event.
First grasses appear, a resource for herbovores;
trees thrive.
Most extant placental mammals appear: modern camels, cats, dogs,
horses & rodents & 1st true primates; 1st whales and sea cows.
Earth covered with forests, with rain forests in North America turning
to deciduous trees over epoch.
Snakes and turtles abundant and many new avian orders arise.
Insects abundant and appear modern.
Cartilaginous and ray-finned fish thrive worldwide. |
|
|
Flowering
plants (angiosperms begin radiation extending through the Eocene, fostered
by co-evolution and appearance of bees. Small mammals radiate |
|
|
Cretaceous
(146
to 65 mya
|
Upper
|
Ends
with Cretaceous - Tertiary
(K–T) extinction event. Major
extinctions include non avian dinosaurs and ammonites.
Mosasaurs appear
late.
|
Lower
| Flowering
plants (angiosperms diversify.); lizards; placental animals (early
mammals); Also appearing: snakes; social marsupial
and primitive placental animals.
New insect forms appear and radiate; pterosaurs common, then decline; Archosaur
reptiles
and dinosaurs small to huge apex predators common on land, and Chondrichthyes
and
Actinopterygii
fishes in the seas. |
|
| Upper
| Earliest
flowering plants (angiosperms) appear at ~ 160 mya or earlier. Appearances
include birds; crabs; frogs and salamanders.
Dinosaurs
radiate to dominate the land. |
Middle
|
Lower
|
|
| Upper
| Breakup
of Pangaea begins
Major extinction event: tabulate corals and conodonts disappear
- ammonoids, reptiles and amphibians decimated
Appearances include: dinosaurs; crocodiles; marine reptiles; turtles;
Pterosauria and
mammals
Major groups of seed plants appear.
|
Middle
|
Lower
|
|
Paleozoic
Era
(541
to 252 mya)
|
|
Lopingian
|
Permian-Triassic
(P-T) extinction event at 251 mya eradicates 95% of all life including
graptolites,
blastoids & remaining Proetid trilobites; all
but articulate crinoids dissapear.
|
Guadalupian
| Seed
plants are producing large trees. |
Cisuralian
| ~
10 miilion years for life to recover from P-T extinction. |
|
|
Pennsylvanian
(323 to 299 mya)
| 1st
Conifers near end of epoch.
Diverse and common amphibians give rise to 1st reptiles
(possibly amniotic) at ~ 315 mya - reptiles become dominant tetrapods
by end
of epoch.
Dense coal forests form, comprising scale trees, ferns, club trees,
tree ferns, giant horsetails, cordaites.
Major
radiation of
winged insects.
Hexapod arthropods large, diverse, and the primary forest herbivores.
|
Mississippian
(359
to 323 mya)
| High
diversity of marine
life across brachiopods, bryozoans, echinoderms
fishes, mollusks,
and .
Land plants divide with seed plants to drier areas and lycopods to
wetter areas.
Amniotic
eggs appear.
Trilobites become
scarce.
|
|
|
Upper
| Mass
extinction (F-F)
Land colonized by plants and animals. Appearances include: insects; sharks;
amphibians (tetrapods); lung fishes and the earliest seed plants. Extensive
radiation of fishes.
Rhizodont predatory lobe-finned
fishes appear at ~ 377 mya dominate fresh water well into Pennsylvanian. |
Middle
|
Lower
|
|
|
Pridoli
| Jawed
fish, cartilaginous fish and vascular plants appear. Primitive terrestrial
predators: Arachnids. |
Ludlow
|
Wenlock
|
|
Llandovery
|
|
|
Upper
| Mass
extinction.
First land plants; bryozoans appear. Trilobites begin to specialize.
Stromatolites become
rare & mostly replaced by complex reef systems. |
|
Middle
| |
|
Lower
| Commences
with the great Ordovician radiation (Ordovician explosion), as life
recovers
from the Cambrian – Ordovician
extinction event (488 mya). |
|
|
Furongian
| Cambrian – Ordovician
event ended the Cambrian Period, where many brachiopods
and conodonts perished, and trilobites were severely reduced. |
Series
3
| Appearances
include: vertebrates; jawless fish; small shelly animals mostly extinct
by end of early Cambrian (End-Botomian mass extinction); conodonts; trilobites radiate
repeatedly and reach their peak diversity. |
Series
2
| |
Terreneuvian
| Cambrian
Explosion, the 1st major radiation of animals when most
phyla appear. Appearance
of hard parts and vision - macroscopic fossils become common. |
|
Proterozoic
EON
(2500
to 541 mya)
|
Neoproterozoic
(1000
to 541 mya)
- Late
|
Ediacaran or
Vendian
(635
to 541 mya)
|
Extinction
at end of Ediacaran.
Appearance of Tommotian mineralized
Fauna (small shelly animals) at ~ 550 mya: they radiate
worldwide.
Macroscopic, soft-bodied organisms radiating, the oldest metazoan (multicellular
animals) - fossils known as the Ediacaran
Biota, including trilobitamorphs, poriferans and other enigmatic
forms.
|
|
Stromatolites diminishing
further, possibly providing food for herbivorous eukaryotes.
|
Cryogenian
(850 to 635 mya)
|
|
|
Chloroblasts
arise from cyanobacteria through endosymbiosis at
~ 1000 mya.
Acritarchs radiate, becoming widespread & some
perhaps eukaryotic and photosynthetic dinoflagellates or eukaryotic
protists. |
Mesoproterozoic
(1600
to 1000 mya)
- Middle
|
Stenian
(1200
to 1000 mya)
|
|
Ectasian
(1400
to 1200 mya)
|
|
Calymmian
(1600
to 1400 mya)
|
Free
atmospheric
oxygen build-up continues desimating some prokaryotic bacteria, but
enabling replacement by newly evolved eukaryotic forms,
including photosynthetic multicellular algae. |
Paleoproterozoic
(2500
to 1600 mya)
- Early
|
Statherian
(1800
to 1600 mya)
|
More
complex single-celled life with aerobic metabolism begin diversification.
Eukaryotic
mitochondria evolve.
Approximate peak of stromatolites with
cyanobacteria oxygenating the atmosphere.
Fossilized filamentous algae (eukaryote)
at ~ 1700 mya.
|
Orosirian
(2050
to 1800 mya)
|
Banded
iron formation diminishes allowing atmosphere to oxygenate rapidly,
reaching ~ 15% at ~ 1800 mya. |
Rhyacian
(2300
to 2050 mya)
|
The
oldest known potential multicellular eukaryote is Grypania spiralis,
appearing as a coiled algae in 2100 mya banded iron formations in Michigan.
Earliest known single-celled eukaryote fossils are acritarchs, which
become widespread at ~ 2100 mya. acritarchs
are most common fossils of late Proterozoic. |
Siderian
(2500
to 2300 mya)
|
Banded
iron formation accelerates at ~ 2400 mya, continuing at high rate until
diminishing at ~ 1800 mya -- the rusting of the seas. |
Archaean
EON
(4000 to
2500 mya) |
Neoarchean
(2800 to 2500 mya)
|
Molecular
fossils from
Australia
suggest eukaryotes appeared at ~ 2700 mya, but this is not a widely
accepted view, with other estimates at ~ 3500 mya.
Atmospheric oxygen only ~ 1%.
|
Mesoarchean
(3200 to 2800 mya)
|
Prokaryotes
dominate (Eubacteria
and Archaea); simple cell forms generate extensive stromatolite reef
systems. First acritarch microscopic fossils.
1st substantial free oxygen from photosynthetic archaea and bacteria
at ~ 3000 to 2300 mya, after which free oxygen produced by these prokaryotes
combined with dissolved iron in the oceans to form banded
iron formations until ~ 2000 to 1300 mya -- the
so-called rusting of the Earth. |
Paleoarchean
(3600 to 3200 mya)
|
Primitive Eukaryotes as
early as ~ 3500 mya after endosymbiosis.
Oxygenic photosynthetic cyanobacteria appear ~ 3500 mya.
Oldest
fossils - Apex Chert at ~ 3550 mya & Strelly Pool
at ~ 3430 mya in Pilbara, Western Australia
|
Eoarchaean
(4000 to 3600 mya)
|
First
banded iron formation at ~ 3700 mya.
Oxygenic
photosynthetic prokaryotic bacteria appear at ~ 3500 mya.
First life appears, at ~
3800 mya & is Archaea
or Bacteria, chemotrophic, anerobic, asexual, prokaryotes,
fairly soon after end of earth bombardment.
Oldest sedimentary rocks ~ 3800 mya.
Earth's crust cooled by ~ 4000 mya, but atmosphere comprised volcanic
gases and minimal oxygen.
The 1st oceans were formed.
|
Hadean
EON
(4567 to
4000 mya) |
Lower
Imbrian
(4100 to 4000 mya)
|
Self
replicating RNA molecules may might have appeared at ~ 4000 mya.
Late heavy bombardment from space ends at ~ 4000 mya ends, setting stage
for life to appear.
Earth's oldest surviving rock from Canada dated at ~ 4030 mya. |
Nectarian
(4300 to 4100 mya)
|
Nectarian
begins with so-called Late Heavy Bombardment of Earth from space. |
Basin
Groups
(4500 to 4300 mya)
|
Name
derived from groupings of major impact crators. |
Cryptic
(4567 to 4500 mya)
|
Earth's
environment exceedingly hostile to life as we know it.
Meager geological evidence survives from this time, having been destroyed
by bombardment of earth from space projectiles, including the one that
putatively formed the moon.
Earth forms at ~ 4567 mya. |
