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! Date
! Event
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| align="RIGHT" nowrap | 4600 Ma
| The planet [[Earth]] forms from the [[accretion disc]] revolving around the young [[Sun]].
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| Il pianeta [[Terra]] e il pianeta [[Theia (planet)|Theia]] entrano in collisione, causando la formazione di anelli intorno alla giovane Terra che dureranno per milioni di anni finché non si uniranno a formare la [[Luna]], la cui spinta gravitazionale stabilizza [[asse di rotazione]] fluttuante della Terra, disponendo le condizioni per la formazione della vita.<ref>[http://www.psi.edu/projects/moon/moon.html Planetary Science Institute page] on the Giant Impact Hypothesis. Hartmann and Davis belonged to the PSI. This page also contains several paintings of the impact by Hartmann himself.</ref>
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| align="RIGHT" nowrap | 4100 Ma
| La superficie della Terra si raffredda abbastanza perché la crosta solidifichi. Si formano l'atmosfera e gli oceani della Terra.<ref>"<cite>Comunque, una volta che la Terra si è raffreddata a sufficienza, a circa 700 milioni anni dalla sua nascita, le nuvole cominciano a formarsi nell'atmosfera, e la Terra entra in nuova fase di sviluppo.</cite>" [http://www.oceansonline.com/ocean_form.htm How the Oceans Formed] (URL accessed on [[January 9]], [[2005]])</ref>
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| Appaiono le [[prime forme di vita|Origin of life]], forse derivate da [[RNA world hypothesis|self-reproducing]] molecole di [[RNA]] autoriproducenti. La replicazione di questi organismi richiede risorse quali energia, spazio, e blocchi più piccoli da costruzione, che presto divengono limitati, a causa della competizione. La [[selezione naturale]] favorisce quelle molecole che sono più efficienti nella replicazione. Le molecole di [[DNA]] molecules then take over as the main replicators. They soon develop inside enclosing membranes which provide a stable physical and chemical environment conducive to their replication: [[Cell (biology)#Origins of cells|proto-cells]]. At this time, the atmosphere does not contain any free [[oxygen]].
|- valign="TOP"
| align="RIGHT" nowrap | 3900 Ma
| [[Late Heavy Bombardment]]: peak rate of [[impact event]]s upon the Earth, [[Moon]], [[Mars]] and [[Venus]] by [[asteroid]]s and [[comet]]s ([[planetesimal]]s). This constant [[disturbance]] may encourage life to evolve (see [[panspermia]]). It is thought that these impacts cause the oceans to boil away completely, more than once; yet life persists.<ref>"<cite> Between about 3.8 billion and 4.5 billion years ago, no place in the solar system was safe from the huge arsenal of asteroids and comets left over from the formation of the planets. Sleep and Zahnle calculate that Earth was probably hit repeatedly by objects up to 500 kilometers across</cite>" [http://news-service.stanford.edu/news/1998/december2/marsunder122.html Geophysicist Sleep: Martian underground may have harbored early life] (URL accessed on [[January 9]], [[2005]])</ref>
[[Cell (biology)|Cells]] resembling [[prokaryote]]s appear. These first organisms are [[chemotroph|chemoautotrophs]]: they use [[carbon dioxide]] as a [[carbon]] source and [[redox|oxidize]] inorganic materials to extract energy. Later, prokaryotes evolve [[glycolysis]], a set of chemical reactions that free the energy of organic molecules such as [[glucose]]. Glycolysis generates [[Adenosine triphosphate|ATP]] molecules as short-term energy currency, and ATP continue to be used in almost all organisms, unchanged, to this day.
|- valign="TOP"
| align="RIGHT" nowrap | 3500 Ma
| Lifetime of the [[last universal ancestor]]; the split between the [[bacteria]] and the [[archaea]] occurs.
Bacteria develop primitive forms of [[photosynthesis]] which at first do not produce [[oxygen]]. These organisms generate ATP by exploiting a [[electrochemical gradient|proton gradient]], a mechanism still used in virtually all organisms.
|- valign="TOP"
| align="RIGHT" nowrap | 3000 Ma
| [[Image:Anabaena sperica.jpeg|left|50px]] Photosynthesizing [[cyanobacteria]] evolve; they use water as a [[reducing agent]], thereby producing oxygen as waste product. The oxygen initially oxidizes dissolved iron in the oceans, creating [[iron ore]]. The oxygen concentration in the atmosphere subsequently rises, acting as a poison for many bacteria. The moon is still very close to the earth and causes tides 1000 feet high. The earth is continually wracked by hurricane force winds. These extreme mixing influences are thought to stimulate evolutionary processes.{{citation-needed}}
|- valign="TOP"
| align="RIGHT" nowrap | 2500 Ma
| Some bacteria evolve the ability to utilize oxygen to more efficiently use the energy from organic molecules such as glucose. Virtually all organisms using oxygen employ the same set of reactions, the [[citric acid cycle]] and [[oxidative phosphorylation]].
The "runaway icehouse" effect<ref>Walker, Gabrielle, (2003) "Snowball Earth: The Story of the Great Global Catastrophe that Spawned Life as we know it" Bloomsbury ISBN 0747564337</ref> results in the [[Huronian]] glaciation (2500–2100 Ma).<ref>John, Brian (Ed)(1979) "The Winters of the World: Earth under the Ice Ages" Jacaranda Press ISBN 0-470-26844-1</ref>
|- valign="TOP"
| align="RIGHT" nowrap | 2100 Ma
| More complex cells appear: the [[eukaryote]]s, the closest relatives of whom are probably the [[archaea]]. Eukaryotes contain various [[organelle]]s with diverse functions, probably derived from the [[co-evolution]] of [[symbiosis|symbiotic]] communities of [[prokaryote]]s. The most dramatic examples are [[mitochondrion|mitochondria]], which use oxygen to extract energy from organic molecules and appear similar to today's ''[[Rickettsia]]''. Many eukaryotes also have [[chloroplast]]s, organelles which originated from cyanobacteria and similar organisms, which derive energy from light and synthesize organic molecules.
|- valign="TOP"
| align="RIGHT" nowrap | 1200 Ma
| [[Sexual reproduction#Origin of Reproduction|Sexual reproduction]] evolves, leading to faster evolution.<ref>"'Experiments with sex have been very hard to conduct,' Goddard said. 'In an experiment, one needs to hold all else constant, apart from the aspect of interest. This means that no higher organisms can be used, since they have to have sex to reproduce and therefore provide no asexual control.'<br /> Goddard and colleagues instead turned to a single-celled organism, yeast, to test the idea that sex allows populations to adapt to new conditions more rapidly than asexual populations.<cite></cite>" [http://news.nationalgeographic.com/news/2005/03/0330_050330_sexevolution.html Sex Speeds Up Evolution, Study Finds] (URL accessed on [[January 9]], [[2005]])</ref> While most life still exists in oceans and lakes, some cyanobacteria may already live in moist soil by this time.
|- valign="TOP"
| align="RIGHT" nowrap | 1000 Ma
| [[Multicellular organism]]s appear: initially colonial [[algae]], and later [[seaweed]]s, living in the oceans.<ref>"<cite> What, then, was the selective advantage that led to the evolution of multicellular organisms?</cite>" [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?db=Books&rid=cell.section.61 From Single Cells to Multicellular Organisms] (URL accessed on [[January 9]], [[2005]])</ref>
|- valign="TOP"
| align="RIGHT" nowrap | 900 Ma
| [[Image:Cronoflagelado2.jpg|right|125px|thumb|[[Choanoflagellate]]]] The [[choanoflagellate]]s develop. These [[protist]]s are considered the ancestors of the entire [[animal]] [[kingdom (biology)|kingdom]], and specifically the direct ancestors of the [[sponge]]s: the [[choanocyte]]s ("collar cells") of sponges (and a few other animal groups, such as [[flatworm]]s) have the same basic structure as choanoflagellates, and DNA evidence suggests a close relationship between the two.
The modern species [[proterospongia]], consisting of choanoflagellates that live in colonies and exhibit primitive cell specialization for different tasks, is likely very similar to the ancient ancestor species that would have bridged the gap between choanoflagellates and sponges, and thereby between [[protozoa]] and all metazoa (multicellular animals).
|- valign="TOP"
| align="RIGHT" nowrap | 1000–750 Ma
| The first known [[supercontinent]], [[Rodinia]], forms, and then breaks apart again.
|- valign="TOP"
| align="RIGHT" nowrap | 950–780 Ma
| [[Cryogenian|Sturtian]] [[ice age]], a time of multiple near-global glaciations, with periods oscillating between a [[Snowball Earth]] and a [[greenhouse effect|greenhouse Earth]].
|- valign="TOP"
| align="RIGHT" nowrap | 900 Ma
| There are 481 18-hour days in a year. The [[rotation]] of the Earth has gradually slowed ever since.
|- valign="TOP"
| align="RIGHT" nowrap | 750–580 Ma
| According to the Snowball Earth hypothesis, the [[Precambrian]] [[Cryogenian|Varangian]] ice age is so severe that the Earth's oceans freeze over completely; only in the tropics do oceans remain liquid. This is the last big freeze, and afterwards, evolution begins to accelerate.
|- valign="TOP"
| align="RIGHT" nowrap | 600 Ma
| [[Image:Sponge.jpg|left|thumb|130px|[[Sponge]]]] [[Sponge]]s (Porifera), the earliest multicellular [[animal]]s, develop from cell colonies. Sponges are the simplest and most primitive animals, having partially-differentiated [[biological tissue|tissues]] but no muscles, nerves, internal organs, or capacity for locomotion.
[[Image:Sea nettles.jpg|right|thumb|125px|[[Jellyfish]]]]
Following sponges, [[Cnidaria]] ([[jellyfish]], etc.), [[ctenophore|Ctenophora]], and other multicellular animals appear in the oceans. Cnidaria and Ctenophora are some of the earliest creatures to have [[neuron]]s, in the form of a simple net, with no [[central nervous system]]. They possess [[muscle|muscular]] tissue and [[digestive system]]s with mouths. Unlike sponges, these animals have structured bodies with [[organ (anatomy)|organs]] and [[symmetry (biology)#radial symmetry|radial symmetry]].
[[Image:FlatwormZICA.png|left|thumb|135px|[[Flatworm]]]]
[[Flatworm]]s (Platyhelminthes), the earliest animals to have a rudimentary [[brain]] and the simplest animals with [[symmetry (biology)#bilateral symmetry|bilateral symmetry]], develop. They are also the simplest animals to have organs that form from three [[germ layer]]s ([[triploblasty]]). There are still no organisms with a true [[circulatory system|circulatory]] or [[respiratory system]].
The [[Ozone layer]] forms, allowing for the first major excursions onto the land. The second supercontinent, [[Pannotia]], forms, then breaks up by 540 Ma.
|- valign="TOP"
| align="RIGHT" nowrap | 542–530 Ma
| [[Image:Asaphus.jpg|thumb|115px|[[Trilobite]]]] The [[Cambrian explosion]], a rapid set of evolutionary changes, creates all the major body plans ([[phylum|phyla]]) of modern animals. The cause of this huge expansion in the variety of life forms is still a matter of scientific debate. [[Arthropod]]a, represented by an abundance of [[trilobite]]s, is the dominant [[phylum]]. ''[[Anomalocarid|Anomalocaris]]'' is a predator up to 2 meters in length.<ref>"<cite>The evolutionary foundation for the organization of many animal body plans is segmental—we are made of rings of similar stuff, repeated over and over again along our body length</cite>" [http://pharyngula.org/index/weblog/comments/pycnogonid_tagmosis Pycnogonid tagmosis and echoes of the Cambrian] <br /> "<cite>Pycnogonids are primitive chelicerates related to ticks and mites, and they make their living as predators and scavengers. This one, Haliestes dasos, is the oldest sea spider known.</cite>" [http://pharyngula.org/index/weblog/comments/haliestes_dasos_a_sea_spider/ Haliestes dasos, a sea spider] <br />"<cite>If you were a trilobite or other small Cambrian
animal, you did NOT want to see this coming</cite>" [http://www.trilobites.info/anohome.html The Anomalocaris Homepage (animation)]</ref>
The worm-like organisms develop more highly specialized and advanced structures, such as the [[circulatory system]] of [[acorn worm]]s, which features a [[heart]] that also functions as a [[kidney]]. Acorn worms have a gill-like structure, similar to that of [[prehistoric fish|primitive fish]], used for breathing. Acorn worms are thus sometimes said to be a link between [[vertebrate]]s and [[invertebrate]]s.
[[Image:Pikaia3ZICA.png|left|thumb|163px|[[Pikaia]]]]
''[[Pikaia]]'', a small swimmer and the earliest-known animal with a [[notochord]], is believed to be the ancestor of all [[chordate]]s and [[vertebrate]]s. The [[lancelet]], a species still alive today, retains some of the features of the primitive chordates, and resembles the ''Pikaia'' in many ways. The [[conodont]] is an "eel-shaped animal of 4–20 cm long" with a pair of huge eyes and a complex basket of teeth.
The first known footprints on land date to 530 Ma, indicating that early animal explorations may have predated the development of terrestrial plants.<ref>"<cite>The oldest fossils of footprints ever found on land hint that animals may have beaten plants out of the primordial seas. Lobster-sized, centipede-like animals made the prints wading out of the ocean and scuttling over sand dunes about 530 million years ago. Previous fossils indicated that animals didn't take this step until 40 million years later.</cite>" [http://www.innovations-report.com/print/print_en01.php3?id=9641&ctyp=1 Oldest fossil footprints on land]</ref>
|- valign="TOP"
| align="RIGHT" nowrap | 505 Ma
| [[Image:Agnata.png|thumb|right|205px|[[Agnatha]]]] The first [[vertebrate]]s appear: the [[ostracoderm]]s, jawless fish ([[Agnatha]]) such as ''[[Haikouichthys]]'' and ''[[Myllokunmingia]]''. They have [[cartilage|cartilaginous]] internal skeletons, and lack the paired (pectoral and pelvic) [[fin]]s of more advanced [[prehistoric fish]]. They are precusors of the [[Osteichthyes]] (bony fish), and are related to present-day [[lamprey]]s and [[hagfish]]es.
|- valign="TOP"
| align="RIGHT" nowrap | 488 Ma
| [[Image:PlacodermiZICA.png|thumb|left|200px|[[Placodermi]]]] The first of the seven major [[extinction event]]s over [[Geologic time scale|geological time]] occurs at the [[Cambrian-Ordovician extinction events|Cambrian-Ordovician transition]].
Soon after, the first of the jawed fishes, [[Placodermi]], develop. Their jaws evolve from the first of their gill arches.<ref>[http://www.uhh.hawaii.edu/~ronald/392/Homol-Gill-Jaw.JPG 1]</ref> Their head and thorax are covered by articulated armored plates, while the rest of the body is scaled or naked.
|- valign="TOP"
| align="RIGHT" nowrap | 475 Ma
| The first primitive [[plant]]s move onto land,<ref>"<cite>The oldest fossils reveal evolution of non-vascular plants by the middle to late Ordovician Period (~450-440 m.y.a.) on the basis of fossil spores</cite>" [http://www.clas.ufl.edu/users/pciesiel/gly3150/plant.html Transition of plants to land]</ref> having evolved from green algae living along the edges of lakes.<ref>"<cite>The land plants evolved from the algae, more specifically green algae, as suggested by certain common
biochemical traits</cite>" [http://scitec.uwichill.edu.bb/bcs/bl14apl/conq.htm The first land plants]</ref> They are accompanied by [[fungus|fungi]], and very likely plants and fungi work symbiotically together; [[lichen]]s exemplify such a symbiosis.
|- valign="TOP"
| align="RIGHT" nowrap | 450 Ma
| [[Image:Centipede.jpg|right|125px|[[Centipede]]]] [[Arthropod]]s, with an exoskeleton that provides support and prevents water loss,<ref>"<cite>The waxy cuticle of arachnids and insects prevents water loss and protects against desiccation</cite>" [http://www.nhc.ed.ac.uk/index.php?page=24.25.312.330 Natural history collection: arthropoda]</ref> are the first animals to move onto land.<ref>"<cite>For hundreds of millions of years, animal life resided only in the oceans. And then about 400 million years ago, fossil tracks suggest that an animal called a eurypterid left the water to walk on land. Maybe it was fleeing enemies, maybe it was searching for an easy meal, or maybe it was seeking a safe place to lay its eggs.</cite>" [http://www.pbs.org/kcet/shapeoflife/episodes/conquerors.html The shape of life. The conquerors. PBS]</ref> Among the first are [[Myriapoda]] ([[millipede]]s and [[centipede]]s), later followed by [[spider]]s and [[scorpion]]s.
Over the next ten million years, the two [[Ordovician-Silurian extinction events]] occur. Taken together, these constitute the second mass extinction event.
|- valign="TOP"
| align="RIGHT" nowrap | 400 Ma
| The first [[insect]]s [[insect evolution|evolve]], the wingless [[silverfish]], [[springtail]]s (no longer considered insects), and [[Archaeognatha|bristletails]]. First sharks appear.<ref>"<cite>The ancestry of sharks dates back more than 200 million years before the earliest known dinosaur.</cite> [http://www.elasmo-research.org/education/evolution/evol_s_predator.htm Introduction to shark evolution, geologic time and age determination]</ref> First ''[[Coelacanth]]'' appears; this order of animals had been thought to have no extant members, until living specimens were discovered in 1938. It is often referred to as a [[living fossil]].
|- valign="TOP"
| align="RIGHT" nowrap | 375 Ma
| ''[[Tiktaalik]]'' is a genus of [[sarcopterygii|sarcopterygian]] (lobe-finned) fishes from the late Devonian with many [[tetrapod]]-like features.
|- valign="TOP"
| align="RIGHT" nowrap | 370 Ma
| ''[[Cladoselache]]'', a shark, is a high-speed predator.<ref>"<cite>Cladoselache was something of an oddball among ancient sharks. A four-foot (1.2-metre) long inhabitant of late Devonian seas (about 370 million years ago), it exhibited a strange combination of ancestral and derived characteristics.</cite> [http://www.elasmo-research.org/education/evolution/ancient.htm Ancient sharks]</ref>
|- valign="TOP"
| align="RIGHT" nowrap | 365 Ma
| The [[Late Devonian extinction]] is the third mass extinction.
New insect species evolve on land and in fresh water from the [[myriapoda|myriapods]].
[[Image:PanderichthysZICA.png|thumb|left|200px|[[Panderichthys]]]]
Some lobe-finned [[fish]] ([[Sarcopterygii]]) develop legs and give rise to early four-limbed [[tetrapod]]s: [[Ichthyostega]], [[Acanthostega]] and ''[[Pederpes finneyae]]''. Initially aquatic, dwelling in shallow, [[swamp]]y [[fresh water|freshwater]] [[habitat (ecology)|habitats]], these fishes use their fins as [[paddle]]s to assist in navigating shallow waters choked with plants and [[detritus (biology)|detritus]]—the likely origin of front limbs bending backward at the [[Elbow-joint|elbow]] and hind limbs bending forward at the [[knee]]. Eventually, these tetrapods use their rudimentary legs to move out onto land for brief periods, probably to hunt insects. [[Lung]]s and [[gas bladder|swim bladder]]s evolve.
Primitive tetrapods developed from a fish with a two-lobed [[brain]] in a flattened skull, a wide mouth, and a short snout, whose upward-facing eyes show that it was a bottom-dweller, and which had already developed adaptations of fins with fleshy bases and bones. The "living fossil" [[coelacanth]] is a related lobe-finned fish without these shallow-water adaptations. [[Amphibian]]s today still retain many characteristics of the early tetrapods.
|- valign="TOP"
| align="RIGHT" nowrap | 360 Ma
| Plants evolve [[seed]]s, structures that protect plant embryos and enable plants to spread quickly on land.
Creation of [[Woodleigh crater]] (100 km wide) and [[Siljan (lake)|Siljan Ring]] (40 km wide, [[Dalecarlia]], [[Sweden]]).
|- valign="TOP"
| align="RIGHT" nowrap | 360–286 Ma
| The golden age of sharks<ref>"<cite>Sharks have undergone a lot of evolutionary experimentation since their earliest beginnings. Over hundreds of millions of years, sharks were tested by a mercurial and often violently changeable environment.</cite>" [http://www.elasmo-research.org/education/evolution/golden_age.htm A Golden Age of Sharks]</ref>.
|- valign="TOP"
| align="RIGHT" nowrap | 350-250 Ma
| The [[Karoo Ice Age|Karoo]] [[Ice Age]] begins in the early [[Carboniferous]] and ends in the [[Permian]]. Advancing ice sheets in [[Gondwanaland]] are at first centered in Africa and South America, and later in India and Australia, due to [[true polar wander|polar wandering]].
|- valign="TOP"
| align="RIGHT" nowrap | 300 Ma
| [[Image:Pangaea continents.png|110px|right|thumb|Pangaea before its break-up.]]
The [[supercontinent]] [[Pangaea]] forms and will last for 120 million years; this is the last time all of the earth's continents fuse into one. Evolution of the [[amniotic egg]] gives rise to the [[Amniota]], [[reptile]]s, who can reproduce on land. Insects evolve flight, and include a number of different orders (e.g. [[Palaeodictyoptera]], [[Megasecoptera]], [[Diaphanopterodea]], and [[Protorthoptera]]) Dragonflies ([[Odonata]]) still resemble many of these early insects. Vast [[forest]]s of [[Lycopodiophyta|clubmosses]] ([[lycopods]]), [[Equisetophyta|horsetails]], and [[tree fern]]s cover the land; when these decay they will eventually form [[Coal#Composition and creation|coal]] and [[Petroleum#Biogenic theory|oil]]. [[Gymnosperm]]s begin to diversify widely. [[Cycads]], plants resembling palms, first appear.
|- valign="TOP"
| align="RIGHT" nowrap | 280 Ma
| The [[Protodonata]]n [[dragonfly]] ''[[Meganeura|Meganeura monyi]]'' is among the biggest insects that ever lived, with a wingspan of about 2 feet. Vertebrates include many [[Temnospondyli|Temnospondyl]], [[Anthracosauria|Anthrachosaur]], and [[Lepospondyli|Lepospondyl]] amphibians and early [[Anapsida|anapsid]] and [[Synapsida|synapsid]] (e.g. ''[[Edaphosaurus]]'') [[amniote]]s.
|- valign="TOP"
| align="RIGHT" nowrap | 256 Ma
| ''[[Diictodon]]'', ''[[Cistecephalus]]'', ''[[Dicynodon]]'', ''[[Lycaenops]]'', ''[[Dinogorgon]]'' and ''[[Procynosuchus]]'', are a few of the many [[Therapsida|mammal-like reptiles]] known from South Africa and Russia. [[Pareiasaur]]s were large clumsy herbivores. The first [[Archosauriformes]].
|- valign="TOP"
| align="RIGHT" nowrap | 250 Ma
| [[Image:Lystrosaurus.jpg|105px|right|thumb|''Lystrosaurus''.]]
The [[Permian-Triassic extinction event]] wipes out about 90% of all animal species; this fourth extinction event is the most severe [[Extinction event|mass extinction]] known.
''[[Lystrosaurus]]'' is a common herbivore that survives the extinction event. The [[Archosauria|archosaurs]] split from other reptiles. [[Teleostei|Teleosts]] evolve from among the [[Actinopterygii]] (ray-finned fish), and eventually become the dominant fish group. Atmospheric oxygen, at 10%, is one third of its former level, so animals with air sac breathing systems will do well (present-day [[Bird#Respiration|bird respiration]] exemplifies the air sac system). Some spores of bacteria Bacillus strain 2-9-3 (''Sali bacillus marismortui'') are trapped in salt crystals known as halite in New Mexico. They are re-animated in AD 2000 and have multiplied rapidly. Currently the world oldest living organism. <ref>“<cite>Here we report the isolation and growth of a previously unrecognized spore-forming bacterium (Bacillus species, designated 2-9-3) from a brine inclusion within a 250 million-year-old salt crystal from the Permian Salado Formation. Complete gene sequences of the 16S ribosomal DNA show that the organism is part of the lineage of Bacillus marismortui and Virgibacillus pantothenticus.</cite>” [http://www.nature.com/nature/journal/v407/n6806/abs/407897a0.html Isolation of a 250 million-year-old halotolerant bacterium from a primary salt crystal] (URL accessed on [[April 30]], [[2006]])</ref>
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| align="RIGHT" nowrap | 220 Ma
| [[Image:Eopraptor sketch5.png|115px|right|thumb|''Eoraptor'', an early dinosaur.]]
The [[climate]] is very dry, and dry-adapted organisms are favored: the [[Archosauria|archosaurs]] and the [[Gymnosperm]]s. [[Archosauria|Archosaurs]] diversify into [[crocodilia]]ns, [[dinosaur]]s, and [[pterosaur]]s.
From [[synapsid]]s come the first [[mammal]] precursors, [[therapsid]]s, and more specifically the [[eucynodont]]s. Initially, they stay small and shrew-like. All mammals have milk glands for their young, and they keep a constant body temperature. Also, one of a pair of [[autosome]]s acquires gene [[SRY]] (derived from the SOX3 gene of the [[X chromosome]]) to become the [[Y chromosome]], which has been decreasing in length since.
Gymnosperms (mostly [[conifer]]s) are the dominant land plants. Plant eaters will grow to huge sizes during the dominance of the gymnosperms to have space for large guts to digest the poor food offered by gymnosperms.
|- valign="TOP"
| align="RIGHT" nowrap | 208-144 Ma
| Second major spread of [[shark]]s<ref>"<cite>The second major radiation of sharks occurred during the Jurassic Period, 208 to 144 million years ago. At this time, pterosaurs ruled the skies and the first birds were taking to the air.</cite>" [http://www.elasmo-research.org/education/evolution/origin_modern.htm The Origin of Modern Sharks] (URL accessed on [[January 9]], [[2005]])</ref>.
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| align="RIGHT" nowrap | 200 Ma
| [[Triassic-Jurassic extinction event|Fifth mass extinction event]] occurs at the Triassic-Jurassic transition.
Marine reptiles include [[Ichthyosaur]]s and [[Plesiosaur]]s. [[Ammonite]]s and [[belemnite]]s flourish. Dinosaurs survive the extinction and grow to large size, but the [[thecodont]]s, or "socket-toothed" reptiles, die out. Modern amphibians evolve: the [[Lissamphibia]]; including [[Anura]] (frogs), [[Urodela]] (salamanders), and [[Caecilian|Caecilia]]. [[Geminiviridae]], a diverse group of [[virus]]es, are traceable to this epoch or earlier<ref>"<cite>Viruses of nearly all the major classes of organisms—animals, plants, fungi and bacteria/archaea—probably evolved with their hosts in the seas, given that most of the evolution of life on this planet has occurred there. This means that viruses also probably emerged from the waters with their different hosts, during the successive waves of colonisation of the terrestrial environment.</cite>" [http://www.mcb.uct.ac.za/tutorial/virorig.html Origins of Viruses] (URL accessed on [[January 9]], [[2005]])</ref>.
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| align="RIGHT" nowrap | 180 Ma
| [[Image:Pangea animation 03.gif|150px|thumb|right|Pangaea's break-up.]]
The supercontinent [[Pangaea]] begins to break up into several land masses. The largest is [[Gondwana]], made up of the land masses which are now [[Antarctica]], [[Australia]], [[South America]], [[Africa]], and [[India]]. Antarctica is still a land of forests. [[North America]] and [[Eurasia]] are still joined, forming the Northern supercontinent, [[Laurasia]]. [[Speciation]] occurs due to the water barriers created by the breakup.
The first true mammals appear, from [[mammaliform]] ancestors.
|- valign="TOP"
| align="RIGHT" nowrap | 164 Ma
|The oldest swimming mammal, [[Castorocauda lutrasimilis]], is the immediate predecessor of modern mammals such as the [[platypus]] and [[echidna]].
|- valign="TOP"
| align="RIGHT" nowrap | 160 Ma
| 3 metres long, ''[[Guanlong wucaii]]'' - meaning ''crested dragon from the five colours'', Xinjiang province in northwestern China, is the oldest Tyrannosaur.
|- valign="TOP"
| align="RIGHT" nowrap | 150 Ma
| Giant [[dinosaur]]s are common and diverse - ''[[Brachiosaurus]]'', ''[[Apatosaurus]]'', ''[[Stegosaurus]]'', ''[[Allosaurus]]'', along with smaller forms like ''[[Ornitholestes]]'' and ''[[Othneilia]]''. [[Bird]]s evolve from [[Theropoda|theropod]] dinosaurs. ''[[Archaeopteryx]]'' is an ancestor of birds, with claws, feathers but no beak.
|- valign="TOP"
| align="RIGHT" nowrap | 135 Ma
| New dinosaurs ''[[Iguanodon]]'', ''[[Hylaeosaurus]]'', etc., appear after extinction of Jurassic forms. ''[[Microraptor|Microraptor gui]]'', a 77 cm long dinosaur in Liaoning, Northeast China, has bird-like feathered wings on 4 limbs.
|- valign="TOP"
| align="RIGHT" nowrap | 133 Ma
| ''[[Shenzhouraptor sinensis]]'', a primitive bird found in the Yixian Formation of north-eastern China, eats seeds. The bird has large, strong wings, and also had a long, bony tail, like many dinosaurs.
|- valign="TOP"
| align="RIGHT" nowrap | 130 Ma
| [[Angiosperm]] plants evolve [[flower]]s, structures that attract insects and other animals to spread [[pollen]]. This innovation of the angiosperms causes a major burst of animal evolution and [[co-evolution]].
|- valign="TOP"
| align="RIGHT" nowrap | 128 Ma
| One early [[tyrannosaur]] is ''[[Dilong paradoxus]]'' in Lioning Province of China. Has feathers and a small body of 5 feet (1.5 m) long.
|- valign="TOP"
| align="RIGHT" nowrap | 125 Ma
| ''[[Eomaia scansoria]]'', a [[eutheria]]n mammal, which leads to the formation of modern placental mammals. It looks like a modern dormouse, climbing small shrubs in [[Liaoning]], [[China]]. The parrot-beaked ''[[Psittacosaurus]]'' is the ancestor of the later horned dinosaurs.
|- valign="TOP"
| align="RIGHT" nowrap | 123 Ma
| [[Image:Sinornithosaurus.gif|thumb|150px|[[Sinornithosaurus|Sinornithosaurus millenii]]]]
''[[Sinornithosaurus|Sinornithosaurus millenii]]'' is a dinosaur in Liaoning, China that has primitive feathers not used for flight. Other dinosaurs with feathers are ''[[Sinosauropteryx]]'' (most primitive feathers, simplest tubular structures) and ''[[Changchanornis]]''. Other dinosaurs include ''[[Polacanthus]]'' (armoured herbivore) and ''[[Eotyrannus]]'' (early [[tyrannosaur]]). Evolution of birds has gone underway, with several different lineages existing (e.g. ''[[Confuciusornis]]'' and '[[Yanornis]]'').
|- valign="TOP"
| align="RIGHT" nowrap | 110 Ma
| ''[[Sarcosuchus|Sarcosuchus imperator]]'', eight metric tons, 12 m long, head 2 m long, largest crocodile. Carnivorous dinosaurs included the "[[Dromaeosauridae|raptor]]" ''[[Deinonychus]]'' and sail-backed semi-aquatic [[Spinosauridae|spinosaurs]], herbivores include the tallest known sauropod ''[[Sauroposeidon|Sauroposeidon proteles]]'', as well as the bulbous-nosed iguanodont ''[[Altirhinus]]'' (ancestral to duck-bills) and the [[Nodosauridae|armoured]] ''[[Sauropelta]]''. ''[[Gansus yumenensis]]'', the earliest known essentially modern bird, lives in today's China.
|- valign="TOP"
| align="RIGHT" nowrap | 100 Ma
| The giant theropod dinosaurs ''[[Carcharodontosaurus]]'' and ''[[Giganotosaurus]]'' are even bigger than ''[[Tyrannosaurus]]''.
|- valign="TOP"
| align="RIGHT" nowrap | 88 Ma
| Breakup of [[Indo-Malagasy]] land mass.
|- valign="TOP"
| align="RIGHT" nowrap | 80 Ma
| Many kinds of [[Titanosauridae|sauropod]], [[Hadrosauridae|duck billed]], [[Ceratopsidae|horned]] and [[Theropod|meat-eating]] dinosaurs; half of all known dinosaur species are from the last 30 MY of the [[Mesozoic]], after the rise of the angiosperms. [[India]] starts moving to [[Eurasia]].
|- valign="TOP"
| align="RIGHT" nowrap | 75 Ma
| ''[[Oviraptor]]'' was one of the most bird-like of the non-avian dinosaurs. Last common ancestor of humans and mice <ref>"<cite>A comparison of the two genomes reveals that both have about 30,000 genes, and they share the bulk of them—the human genome shares 99% of its genes with mice. Humans and mice diverged about 75 million years ago, too little time for many evolutionary differences to accumulate.</cite>" [http://www.txtwriter.com/Backgrounders/Compgenomes/compgenomes1.html Comparing genomes] <br /> "<cite> Their conclusion: although the mouse and human genomes are very similar, genome rearrangements occurred more commonly than previously believed, accounting for the evolutionary distance between human and mouse from a common ancestor 75 million years ago.</cite>" [http://www.hindu.com/thehindu/seta/2002/12/19/stories/2002121900070200.htm The Hindu]<br/>"<cite>Mice have many more olfactory genes compared to the human. Smell matters for mice, especially for sex and mating; they also have more genes involved in reproduction (such as [[aphrodisin]], which stimulates mating behaviour in males) and immunity</cite>" [http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2002/12/05/MN153329.DTL&type=science San Francisco Chronicle]</ref>. The [[Hesperornithes]] and [[Ichthyornithes]], extinct birds with teeth, roamed the oceans of the Northern Hemisphere.
|- valign="TOP"
| align="RIGHT" nowrap | 67 Ma
| ''[[Vegavis iaai]]'', the oldest known bird assignable to a group still extant today, lives on the shores of [[Antarctica]]. It is a [[Presbyornithidae|presbyornithid]], a kind of wading goose.
|- valign="TOP"
| align="RIGHT" nowrap | 65 Ma
| [[Image:KT Impact2.jpg|right|thumb|right|120px|An asteroid impact probably wiped out half of all animals species 65 million years ago. Other life forms became extinct as well.]]
The [[Cretaceous-Tertiary extinction event]] (sixth extinction event) wipes out about half of all animal species including all non-avian dinosaurs, probably because of a cooling of the climate precipitated by the giant impact of an asteroid: [[iridium]] powder from the asteroid forms a layer that covers the whole Earth. Creation of the [[Chicxulub Crater]] (170 km across, now half-submerged off the Yucatan peninsula of [[Mexico]]).
Without the presence of the giant and diurnal dinosaurs, [[mammal]]s can increase in diversity and size. Some will later return back to the sea ([[whale]]s, [[sirenia]]ns, [[Seal (mammal)|seal]]s) and others will evolve flight ([[bat]]s). A group of small, nocturnal and arboreal, insect-eating mammals called the [[Archonta]] branches into what will be the [[primate]]s, treeshrews, and bats. Primates have binocular vision and grasping digits, features that help them to jump from one tree branch to another. One example of a proto-primate is ''[[Plesiadapis]]'' which is extinct by 45 million years ago.
Except the [[Neornithes]] lineage which exists today, all birds become extinct in the catastrophe.
|- valign="TOP"
| align="RIGHT" nowrap | 60 Ma
| ''[[Creodont]]'', meat eater, northern hemisphere, extinct by 5.2 million years ago, possible ancestor of [[Miacids]].
|- valign="TOP"
| align="RIGHT" nowrap | 55 Ma
| [[Image:PlesiadapisZICA.png|right|thumb|120px|''[[Carpolestes simpsoni]]'', a primate-like mammal.]]
[[Australia]] breaks away from [[Antarctica]]. Proto-primates first appear in [[North America]], [[Asia]], and [[Europe]]. One example is ''[[Carpolestes simpsoni]]'' at [[Clarks Fork Yellowstone River|Clarks Fork Basin]] of [[Wyoming]]. It has grasping digits but no forward facing eyes. Another (earliest?) euprimate ''[[Teilhardina asiatica]]'' ([[Hunan]], China) is mouse-sized, diurnal, and has small eyes. An ancestor of the [[Shortfin mako shark]] probably gives rise to the lineage of the [[Great White Shark]], but not the [[Megalodon]] <ref>"<cite>I also wish to completely dispel the myth that the modern Great White evolved from the megalodon shark. Is the proper way to do this to write this paper, publish it in a scientific journal, and subject it to peer review—yes? Is that what I am doing—no.......because I think there is no way to "win" with the opinions on this one as set in stone as they seem to be (on both sides)</cite>" [http://www.megalodonteeth.com/articles/article2.html Origin of the Modern Great White Shark] (URL accessed on [[January 9]], [[2005]])<br /> "<cite>'Most scientists would probably say the Great Whites evolved from the megalodon line, which existed from two million to twenty million years ago. They were huge sharks, approximately the length of a Greyhound bus and possessing teeth that were up to six inches [150 mm] long,' explains Ciampaglio. 'However, our research, which is based on analyzing fossils of several hundred shark teeth, shows that the Great White shares more similarities with the mako shark.'</cite>"[http://www.sciencedaily.com/releases/2005/05/050502144430.htm Great White Shark Evolution Debate] (URL accessed on [[January 9]], [[2005]])<br /> "<cite>.. most paleontologists agree [..] that Megalodon is not a direct ancestor of the modern White Shark, more like a great uncle or aunt.</cite>" [http://www.elasmo-research.org/education/evolution/origin_megalodon.htm The Origin of Megalodon] (URL accessed on [[January 9]], [[2005]])</ref>.
|- valign="TOP"
| align="RIGHT" nowrap | 50 Ma
| [[Image:Eohippus.jpg|thumb|150px|''[[Hyracotherium]]'']]
The [[evolution of the horse]] starts with ''[[Hyracotherium]]'': the size of a fox with large nails instead of hoofs. Ancestor of [[whale]]s (which include [[dolphin]]s), ''[[Ambulocetus|Ambulocetus natans]]'' (Pakistan) probably walks on land like the modern sea lion and swims like modern otters. It has webbed feet that give it added power when swimming, and still hears directly from its ears. ''[[Pezosiren portelli]]'', ancestor of modern [[manatee]]s, walks like a hippo and swims like an otter. [[Miacid]]s include ''[[Miacis]]'', a five-clawed ancestor of all dogs, cats, bears, raccoon, fox, hyena, jackal, civet; it is a meat-eating, weasel-like tree climber.
|- valign="TOP"
| align="RIGHT" nowrap | 48.5 Ma
| ''[[Gastornis geiselensis]]'' (Europe, USA), a carnivorous bird 1.75 m tall, is a top predator
|- valign="TOP"
| align="RIGHT" nowrap | 46.5 Ma
| ''[[Rodhocetus]]'', ancestor of whale, successor to ''[[Ambulocetus]]'', no longer needs to drink fresh water.
|- valign="TOP"
| align="RIGHT" nowrap | 43 Ma
| Earliest [[elephant]], ''[[Moeritherium]]'' ([[Egypt]]): 1m tall, size of a large [[pig]], eats soft, juicy plants. It has a long nose, but no [[trunk]] nor [[tusk]]s.
|- valign="TOP"
| align="RIGHT" nowrap | 40 Ma
| Primates (order) diverge into suborders [[Strepsirrhini]] (lemurs and lorises) and [[Haplorrhini]] (tarsiers, monkeys and apes); the latter is diurnal and herbivorous.
|- valign="TOP"
| align="RIGHT" nowrap | 37 Ma
| [[Image:Basilosaurus_illustration.jpg|thumb|150px|[[Basilosaurus]]]]
''[[Basilosaurus]]'', up to 20 m long, snakelike ancestor of [[whale]]s, has reduced but well-developed hind limbs. Hears from sounds transmitted to middle ears through vibrations from lower jaws. In Egypt's '[[Whale Valley]]', what would later be the Wadi Hitan desert is underwater, teeming with ''Basilosaurus isis'' which had no blowhole but had to raise its head above water to breathe. Early ancestors of [[Strepsirrhini|strepsirrhines]] primate appear in the Egyptian desert, ''[[Biretia fayumensis]]'' and ''[[Biretia megalopsis]]''.<ref>"<cite>Researchers have discovered fossilized remains of two previously unknown primate species that lived 37 million years ago in what is now the Egyptian desert.</cite>" "<cite>The discovery, researchers say, is evidence that the common ancestor of living anthropoids arose in Africa and that anthropoids have been evolving on the now separated Africa-Arabia landmass for at least 45 million years.</cite>" [http://news.nationalgeographic.com/news/2005/10/1017_051017_egyptprimates.html New Primate Fossils Support "Out of Africa" Theory] (URL accessed on [[January 9]], [[2005]])</ref>.
|- valign="TOP"
| align="RIGHT" nowrap | 35 Ma
| [[Poaceae|Grasses]] evolve from among the [[angiosperm]]s.
|- valign="TOP"
| align="RIGHT" nowrap | 34 Ma
| [[Cynodictis]], or dawn dog, appears in [[North America]]. [[Canid]]s will eventually colonize the world.
|- valign="TOP"
| align="RIGHT" nowrap | 30 Ma
| [[Haplorrhini]] (suborder) splits into infraorders [[Platyrrhini]] (New World monkeys) and [[Catarrhini]] (Old World primates). New World monkeys have [[prehensile tail]]s and males are color blind. They supposedly migrated to [[South America]] on a raft of vegetation across the Atlantic ocean (circa 4,500km). Catarrhines stay in [[Africa]] as the two continents drift further apart. One ancestor of catarrhines might be ''[[Aegyptopithecus]]''. Haplorrhines: ''[[Bugtipithecus inexpectans]]'', ''[[Phileosimias kamali]]'' and ''[[Phileosimias brahuiorum]]'', similar to today's lemurs, live in rainforests on [[Bugti Hills]] of central Pakistan. Ancestor of all cats, 9 kg ''[[Proailurus]]'', lives in trees in [[Europe]], goes extinct 20 million years ago.
|- valign="TOP"
| align="RIGHT" nowrap | 27.5 Ma
| ''[[Indricothere]]'', rhino relative, 4.5 m tall, tallest mammal on land, lives in [[Mongolia]].
|- valign="TOP"
| align="RIGHT" nowrap | 27 Ma
| The [[Phorusrhacidae]] ("Terror birds"), up to 2.5 m tall, are among the top-level carnivores in the [[Americas]]. They went extinct only 2 million years ago.
|- valign="TOP"
| align="RIGHT" nowrap | 25 Ma
| [[Catarrhini]] males gain color vision but lose the pheromone pathway <ref>"<cite> Once humans could see in color the visual inspection of a potential mate yielded far more useful information and at a greater distance than was the case with scents. As a result of natural selection color-seeing primates came to have neuronal wiring that caused them to place much more importance on appearance in mate choice. In Zhang's view it is therefore not coincidental that around the time human males developed the ability to see color humans also lost the ability to respond to pheromones</cite>" [http://www.futurepundit.com/archives/001412.html Evolution Of Color Eyesight Led To Loss Of Pheromone Response] (URL accessed on [[January 9]], [[2005]])</ref>. Catarrhini splits into 2 superfamilies, Old World monkeys ([[Cercopithecoidea]]) and apes ([[Hominoidea]]). The Old World primates do not have [[prehensile tail]]s (e.g. [[Baboon]]); some do not have tails at all. All hominoids are without tails.
|- valign="TOP"
| align="RIGHT" nowrap | 22 Ma
| [[Image:Himalaya-formation.gif|thumb|right|100px|India colliding with the [[Cimmerian]] coast.]]
India collides with Asia, causing the rise of [[Himalaya]] and the [[Tibetan plateau]]. Cut off from the humidity, [[Central Asia]] becomes a desert. Appearance of ''[[deinotherium]]'', ancient elephant, extinct by 2 million years ago. Evolving from an animal that looks part dog, part bear and part raccoon, the dawn bear (''[[Ursavus elmensis]]'') is the ancestor of all bears living today. It is the size of a fox, hunts in the tree tops, and supplements a diet of meat with plant material and insects. The first group, the ''[[Ailuropodinae]]'', follows a plant-based diet, branches off, and only one member, the giant panda (''[[Ailuropoda melanoleuca]]''), survives today.
|- valign="TOP"
| align="RIGHT" nowrap | 21 Ma
| A [[mongoose]]-like creature floats to Madagascar from Africa on a raft of vegetation. It becomes the ancestor of all carnivorous mammals there.{{fact}}
|- valign="TOP"
| align="RIGHT" nowrap | 20 Ma
| The [[African plate]] collides with [[Asia]]. ''[[Cynodictis]]'', ancestor of dogs, has a shortened fifth claw which foreshadows the [[dewclaw]] (vestigial) of modern dogs. They look like the modern day [[civet]] and have feet and toes suited for running. The two superfamilies of carnivores (canines and felines) are distinct by this time. ''[[Gomphotherium]]'', ancient elephant.
|- valign="TOP"
| align="RIGHT" nowrap | 19 Ma
| ''[[Megatherium|Megatherium americanum]]'' (giant sloth, 6m long, extinct 8000 years ago) and ''[[Argentavis magnificens]]'' (the largest bird ever to fly, wingspan some 7 meters or more) are among the gigantic animals that roam South America.
|- valign="TOP"
| align="RIGHT" nowrap | 16 Ma
| ''[[Squalodon]]'' shows early echolocation of whales. ''[[Megalodon]]'' is a gigantic shark the size of a bus <ref>"<cite>"'At a length of 50 feet (15 metres) and a mass of over 52 tons (47 tonnes), it would take more than a mere morsel to satisfy the megalodon.'"</cite>" [http://www.elasmo-research.org/education/evolution/origin_megalodon.htm The Origin of Megalodon] (URL accessed on [[January 9]], [[2005]])</ref>; it has a long reign and disappears suddenly about 1.6 Ma.
|- valign="TOP"
| align="RIGHT" nowrap | 15 Ma
| Apes from Africa migrate to Eurasia to become [[gibbon]]s ([[lesser ape]]s) and [[orangutan]]s. [[Human]] ancestors speciate from the ancestors of the gibbon. Orangutans, gorillas and chimpanzees are [[great ape]]s. Humans are [[hominin]]s.
|- valign="TOP"
| align="RIGHT" nowrap | 13 Ma
| [[Human]] ancestors speciate from the ancestors of the [[orangutan]]. A relative of orangutans: ''[[Lufengpithecus chiangmuanensis]]'' (Northern Thailand). ''[[Pierolapithecus catalaunicus]]'', Spain, possibly common ancestor of great apes and humans.
|- valign="TOP"
| align="RIGHT" nowrap | 10 Ma
| The [[climate]] begins to dry; [[savanna]]s and [[grassland]]s take over the [[forest]]s. [[Monkey]]s proliferate, and the [[ape]]s go into decline. [[Human]] ancestors speciate from the ancestors of the [[gorilla]]s. This is the heyday of the [[horse]]s as they spread throughout the [[Northern hemisphere]]. After 10 Ma they decline in the face of competition from the [[Artiodactyla|artiodactyls]]. [[Tomarctus]], ancestor of dogs, is an extremely dog like animal.
|- valign="TOP"
| align="RIGHT" nowrap | 7 Ma
| Biggest primate ''[[Gigantopithecus]]'' is 2 m tall and lives in China (''[[Gigantopithecus blacki]]''), Vietnam, and northern India (''[[Gigantopithecus bilaspurensis]]''). Extinct by 300,000 years ago.
|- valign="TOP"
| align="RIGHT" nowrap | 5.6 Ma
| Drying up of the [[Mediterranean Sea]] (the [[Messinian Salinity Crisis|Messinian Event]]).
|- valign="TOP"
| align="RIGHT" nowrap | 5 Ma
| Volcanoes erupt and create the small area of land that joins North and South America. Mammals from North America move South and cause extinction of mammals there.
[[Human]] ancestors speciate from the ancestors of the [[chimpanzee]]s. The latest common ancestor is ''[[Sahelanthropus tchadensis]]'' ([[Chad]], [[Sahara]], west of Rift Valley). The earliest in the human branch is ''[[Orrorin tugenensis]]'' (Millennium Man, Kenya). Chimpanzees and humans share 98% of DNA: biochemical similarities are so great that their hemoglobin molecules differ by only one amino acid. One group of chimps can have more genetic diversity than all of the six [[1000000000 (number)|billion]] humans alive today, due to later [[population bottleneck]]ing on the human lineage. Both chimpanzees and humans have a larynx that repositions during the first two years of life to a spot between the pharynx and the lungs, indicating that the common ancestors have this feature, a precursor of speech.
|- valign="TOP"
| align="RIGHT" nowrap | 4.8 Ma
| [[Chimpanzee]] size [[Hominini|hominin]] genus, ''[[Ardipithecus]]'' walks upright
|- valign="TOP"
| align="RIGHT" nowrap | 3.7 Ma
| Some ''[[Australopithecus afarensis]]'' leave [http://www.ntz.info/gen/b00128.html#03281 footprints] on volcanic ash in Laetoli, Kenya (Northern Tanzania).
|- valign="TOP"
| align="RIGHT" nowrap | 3.5 Ma
| Orangutans diverge into Bornean (''[[Pongo pygmaeus]]'') and Sumatran (''[[Pongo abelii]]'') sub-species. [[Great white shark]]s appear.
|- valign="TOP"
| align="RIGHT" nowrap | 3 Ma
| [[Image:Laetoliafar.jpg.jpg|100px|thumb|[[Australopithecus]]]]
The bipedal [[australopithecines]] (early [[hominin]]s) evolve in the savannas of [[Africa]] being hunted by ''[[Dinofelis]]''. Species include ''[[Australopithecus africanus]]'', ''[[Australopithecus bosei]]''. Other genera include ''[[Kenyanthropus platyops]]''.
[[Gorilla]]s die out on the South bank of the [[Congo River]]. [[North America|North]] and [[South America]] become joined, allowing migration of animals. Modern horses, ''[[Equidae|Equus]]'' first appear. ''[[Deinotherium]]'' (4 m tall), is a gigantic cousin of the elephant, with downward pointing tusks in the lower jaw.
|- valign="TOP";
| align="RIGHT" nowrap | 2.5 Ma
| ''[[Smilodon]]'' ([[Saber-toothed cat]]) appears.
|- valign="TOP"
| align="RIGHT" nowrap | 2.2 Ma
| Gorillas diverge into the Western lowland (''Gorilla gorilla'') and Eastern (''[[mountain gorilla|Gorilla beringei]]'') sub-species.
|- valign="TOP"
| align="RIGHT" nowrap | 2 Ma
| ''[[Homo habilis]]'' (handy man) uses primitive stone tools (choppers) in [[Tanzania]]. Probably lives with ''[[Paranthropus robustus]]''. Emergence of [[Broca's area]] (speech region of modern human brain). ''Homo'' species are meat-eating while ''Paranthropus'' eats plants and termites. Some chimpanzees (''Pan troglodytes'') at the Southern part of the [[Congo River]] branch off to form the [[Bonobo]]s (''Pan paniscus''/pigmy chimps). Bonobos live in female dominated society. Saber Tooth moves from North America to South America.
|- valign="TOP"
| align="RIGHT" nowrap | 1.8 Ma
| ''[[Homo erectus]]'' evolves in [[Africa]] and migrates to other continents, primarily [[Asia#South Asia (or Indian Subcontinent)|South Asia]]. A large-scale extinction of marine life is triggered by some event, possibly a [[supernova]]. Many seabirds, which have dominated the shores and coastal waters for some 20 million years, become extinct; [[marine mammal]]s diversify and take their place.
|- valign="TOP"
| align="RIGHT" nowrap | 1.75 Ma
| Dmanisi man/''[[Homo georgicus]]'' (Georgia, Russia), tiny brain came from Africa, with ''Homo erectus'' and ''Homo habilis'' characteristics. An individual spent the last years of his life with only one tooth by depending on the kindness and compassion of others to obtain sufficient sustenance.
The [[glyptodon]], a giant armadillo the size of a Volkswagen Beetle, lives in southern Peru.
|- valign="TOP"
| align="RIGHT" nowrap | 1.6 Ma
| Biggest marsupials: Appearance of Giant Short-faced Kangaroo (''[[Procoptodon goliah]]'') in Australia, extinct by 40,000 years ago. At 2 m to 3 m tall and weighing 200 kg to 300 kg, it is the largest kangaroo ever known. Wombat-like ''[[Diprotodon optatum]]'', 2,800 kg, 3 m long, Australia, extinct by 45,000 years ago.
|- valign="TOP"
| align="RIGHT" nowrap | 1.5 Ma
| Marsupial lion (''[[Thylacoleo carnifex]]'' or Leo) appears in Australia and goes extinct by 46,000 years ago.
|- valign="TOP"
| align="RIGHT" nowrap | 1 Ma
| Genus ''[[Canis]]'' (coyotes, jackals, wolves, dingoes, domestic dogs) develops as a branch from ''[[Tomarctus]]''. The gray fox, ''[[Urocyon cinereoargenteus]]'' is the most primitive canid still alive today.
|- valign="TOP"
| align="RIGHT" nowrap | 800 ka
| [[Gray Wolf]] (''Canis lupus'') moves to Arctic North America.
|- valign="TOP"
| align="RIGHT" nowrap | 780 ka
| The Earth's last (most recent) [[geomagnetic reversal]].
|- valign="TOP"
| align="RIGHT" nowrap | 700 ka
| Common genetic ancestor of humans and Neanderthals.
|- valign="TOP"
| align="RIGHT" nowrap | 500 ka
| ''Homo erectus'' (Choukoutien, China) uses charcoal to control fire, though they may not know how to create or start it.
|- valign="TOP"
| align="RIGHT" nowrap | 400 ka
| Eastern gorillas (''[[mountain gorilla|Gorilla beringei]]'') diverge into the eastern lowland (''G. beringei graueri'') and mountain (''G. beringei beringei'') sub-species. Giant deer ''[[Megaloceros giganteus]]'', Ireland; the antlers together span about 3.6 m or larger, extinct by 9.5 ka.
|- valign="TOP"
| align="RIGHT" nowrap | 355 ka
| Three 1.5 m tall ''[[Homo heidelbergensis]]'' scramble down [[Roccamonfina]] volcano in Southern Italy, leaving the earliest known ''Homo'' footprints, which were made before the powdery volcanic ash solidified.
|- valign="TOP"
| align="RIGHT" nowrap | 250 ka
| The [[Polar Bear]] evolves from an isolated high latitude population of [[Brown Bear]]s.
|- valign="TOP"
| align="RIGHT" nowrap | 195 ka
| [[Omo Remains|Omo1, Omo2]] (Ethiopia, Omo river) are the earliest known ''[[Homo sapiens]]''.
|- valign="TOP"
| align="RIGHT" nowrap | 160 ka
| ''Homo sapiens'' (''[[Homo sapiens idaltu]]'') in Ethiopia, Awash River, Herto village, practise mortuary rituals and butcher hippos. Their dead bodies are later covered by volcanic rocks.
|- valign="TOP"
| align="RIGHT" nowrap | 150 ka
| "[[Mitochondrial Eve]]" lives in Africa. She is the last female ancestor common to all mitochondrial lineages in humans alive today.
|- valign="TOP"
| align="RIGHT" nowrap | 130 ka
| ''[[Homo neanderthalensis]]'' (Neanderthal man) evolves from ''Homo heidelbergensis'' and lives in [[Europe]] and the [[Middle East]], buries the dead and cares for the sick. Has [[Hyoid|hyoid bone]] (60,000 yrs ago, Kebara cave, Israel), used for speech in modern humans. (Today humans use roughly 6000 spoken languages). Uses spear, probably for stabbing rather than throwing. [[FOXP2]] [[gene]] appears (associated with the development of [[speech]]).
|- valign="TOP"
| align="RIGHT" nowrap | 100 ka
| The first anatomically modern humans (''[[Homo sapiens]]'') appear in [[Africa]] by this time or earlier; they derive from ''Homo heidelbergensis''. ''Homo sapiens'' (humans) live in South Africa (Klasies River Mouth) and Palestine (Qafzeh and [[Es Skhul]]), probably alongside Neanderthals. Modern humans enter Asia via two routes: one North through the Middle East, and another further South from Ethiopia, via the Red Sea and southern Arabia. (See: [[Single-origin hypothesis]]). Mutation causes skin color changes in order to absorb optimal UV light for different geographical latitudes. Modern "race" formation begins. African populations remain more 'diverse' in their genetic makeup than all other humans, since only a subset of their population (and therefore only a subset of their diversity) leaves Africa. For example, [[Mitochondrial DNA|mtDNA]] shows that an individual with English ancestors is more similar genetically to an individual with Japanese ancestors than are two individuals drawn from two African populations.
|- valign="TOP"
| align="RIGHT" nowrap | 82.5 ka
| Humans in Zaire fish using sharp blades spears made from animal bones.
|- valign="TOP"
| align="RIGHT" nowrap | 80 ka
| Humans make bone harpoons in Katanda, Democratic Republic of Congo.
|- valign="TOP"
| align="RIGHT" nowrap | 74 ka
| Supervolcanoic [[Toba catastrophe theory|eruption in Toba]], Sumatra, Indonesia, causes ''Homo sapiens'' population to crash to 2,000. Six years without a summer are followed by a 1,000 year ice-age. Volcanic ash up to 5 m deep covers India and Pakistan.
|- valign="TOP"
| align="RIGHT" nowrap | 70 ka
| The most recent [[ice age]], the [[Wisconsin glaciation]], begins.
Humans in the [[Blombos cave]] in South Africa make tools from bones, show symbolic thinking by creating ochre paintings. They also collect and pierce holes through sea shells to make necklaces.
[[Giant beaver]]s (''Castoroides ohioensis'', Toronto, Canada) largest rodents, length up to 2.5 m, dies out 10,000 years ago.
|- valign="TOP"
| align="RIGHT" nowrap | 60 ka
| "[[Y-chromosomal Adam]]" lives in Africa. He is the last common male ancestor of all humans alive today.
|- valign="TOP"
| align="RIGHT" nowrap | 50 ka
| Modern humans expand from Asia to [[Australia]] (to become today's [[Indigenous Australians]]) and Europe. Expansion along the coasts happens faster than expansion inland. Woolly rhino (''[[Coelodonta antiquus]]'') in Britain.
|- valign="TOP"
| align="RIGHT" nowrap | 40 ka
| [[Cro-Magnon]] Humans paint and hunt [[mammoth]]s in France. They have extraordinary cognitive powers equivalent to modern humans, which enable them to become predators/hunters at the top of the food chain. [[Holocene extinction event|Megafauna extinction]] starts (continuing to current day); most large mammal species disappear, directly or indirectly due to the [[overpopulation|expanding human population]].<ref>Leakey, Richard and Roger Lewin, 1996, The Sixth Extinction : Patterns of Life and the Future of Humankind, Anchor, ISBN 0-385-46809-1</ref>
|- valign="TOP"
| align="RIGHT" nowrap | 32 ka
| First sculpture found in Vogelherd, Germany. First (bird bone) flute found in France. Stone tools in Kota Tampan, Malaysia.
|- valign="TOP"
| align="RIGHT" nowrap | 30 ka
| Modern humans enter North America from [[Siberia]] in numerous waves, some later waves across the Bering land bridge, but early waves probably by island-hopping across the [[Aleutian Islands|Aleutians]]. At least two of the first waves left few or no genetic descendants among Americans by the time Europeans arrive across the [[Atlantic Ocean]]. Humans reach [[Solomon Islands]] and Japan. Bow and arrows used in [[Sahara]] (grassland). Fired ceramic animal models made in Moravia (Czech Republic).
|- valign="TOP"
| align="RIGHT" nowrap | 28 ka
| Oldest known painting: in the Apollo 11 Rock Shelter<ref>"<cite>These stones were found in association with charcoal which has been dated to between 19,000 and 26,000 years old (Wendt 1974, 1976). Border Cave in Kwazulu has yielded engraved bone and wood dated between 35,000 and 37,500 years old (Butzer et al 1979); and a 20,000 year old incised stone was found at Matupi Cave, Zaire (Van Noten 1977).<cite>" [http://www.oubliette.zetnet.co.uk/Six.html Introduction to upper palaeolithic art] (URL accessed on [[January 9]], [[2005]])</ref>., Namibia, Africa. A 20 cm-long, 3 cm-wide object found in Hohle Fels Cave near Ulm in the Swabian Jura in Germany is the earliest sculpted stone penis<ref>"<cite>The 20 cm-long, 3 cm-wide stone object, which is dated to be about 28,000 years old, was buried in the famous Hohle Fels Cave near Ulm in the Swabian Jura. </cite>" [http://news.bbc.co.uk/1/hi/sci/tech/4713323.stm Ancient phallus unearthed in cave] (URL accessed on [[January 9]], [[2005]])</ref>.
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| align="RIGHT" nowrap | 27 ka
| ''Neanderthals'' die out leaving ''Homo sapiens'' and ''Homo floresiensis'' as the only living species of the genus ''[[Homo (genus)|Homo]]''. In today's Czech Republic, humans invent textiles and press weaving patterns into pieces of clay before firing them.
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| align="RIGHT" nowrap | 25 ka
| Throwing sticks for hunting animals made from [[mammoth]] tusk (Poland).
|- valign="TOP"
| align="RIGHT" nowrap | 23 ka
| [[Venus of Willendorf]], a small statuette of a female figure, discovered at a paleolithic site near Willendorf, Austria, dates from this era. First intentional growing of food plants by humans occurs in the Near East, but is not associated with land clearing or [[tillage]].
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| align="RIGHT" nowrap | 20 ka
| Humans leave foot and hand prints in Tibetan plateau. Oil lamps made from animal fats on shells used in caves in Grotte de la Mouthe, France. Bone needles used to sew animal hides. ([[Shandingdong Man]], China). [[Microlith|Microblade]] culture (Northern China). [[Mammoth]] bones used to build houses (Russia).
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| align="RIGHT" nowrap | 18 ka
| ''[[Homo floresiensis]]'' existed in the Liang Bua limestone cave on Flores, remote Indonesian island.
|- valign="TOP"
| align="RIGHT" nowrap | 15 ka
| The [[Wisconsin glaciation|last Ice Age]] ends. Sea levels across the globe rise, flooding many coastal areas, and separating former mainland areas into islands. Japan separates from Asia mainland. Siberia separates from Alaska. Tasmania separates from Australia. Java island forms. Sarawak, Malaysia and Indonesia separate. The [[cave painting]]s of [[Lascaux]] and [[Altamira (cave)|Altamira]] were produced. Sedentary hunter-gather societies develop in the [[Natufian culture]] of the [[Near East]] - an essential precursor to later agricultural societies.
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| align="RIGHT" nowrap | 14 ka
| Megafauna extinction starts in the Americas.
|- valign="TOP"
| align="RIGHT" nowrap | 11.5 ka
| Extinction of the [[saber-toothed cat|Sabertooth]] (''[[Smilodon]]'') and [[Merriam's Teratorn]] (the "thunderbird").
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| align="RIGHT" nowrap | [[9th millennium BC|11 ka]]
| [[World population|Human population]] reaches 5 million. Extinction of ''[[Homo floresiensis]]''.
Extinction of [[mammoth|woolly mammoth]]. [[Canis familiaris#Ancestry and history of domestication|Domestication of dogs]] (first domesticated animal) from [[Gray Wolf]] subspecies (''Canis lupus pallipes''). All modern dogs today (5 main groups, about 400 breeds) belong to a single subspecies ''[[Canis lupus familiaris]]''.
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| align="RIGHT" nowrap | 10 ka
| Humans in the [[Fertile Crescent]] of the [[Middle East]] develop [[agriculture]]. [[Domestication|Plant domestication]] begins with cultivation of [[Neolithic founder crops]]. This process of food production, coupled later with the [[Domestication#History of domestication|domestication]] of animals caused a massive increase in [[World population|human population]] that has continued to the present. [[Jericho]] (modern Israel) settlement with about 19,000 people.
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| align="RIGHT" nowrap | [[8th millennium BC|10 ka]]
| [[Sahara]] is green with rivers, lakes, cattles, crocodiles and [[monsoon]]s. Japan's hunter-gatherer [[Jomon]] culture creates world's earliest pottery. Humans reach [[Tierra del Fuego]] at the tip of [[South America]], the last continental region to be inhabited by humans (excluding [[Antarctica]]).
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| align="RIGHT" nowrap | [[6th millennium BC|8 ka]]
| Common (Bread) wheat ''[[Common wheat|Triticum aestivum]]'' originates in southwest Asia due to hybridisation of [[emmer wheat]] with a goat-grass, ''[[Aegilops|Aegilops tauschii]]''.
|- valign="TOP"
| align="RIGHT" nowrap | 6.5 ka
| Two [[rice]] species are domesticated: Asian rice ''[[Rice|Oryza sativa]]'' and African rice ''[[Rice|Oryza glaberrima]]''.
|- valign="TOP"
| align="RIGHT" nowrap | 3.5 ka
| Humans in Mesoamerica develop the foundations of organized [[religion]], with initiated priests overseeing rituals.
|- valign="TOP"
| align="RIGHT" nowrap | [[1st millennium BC|3 ka]]
| Humans in Eurasia start using [[iron age|iron tools]].
|- valign="TOP"
| align="RIGHT" nowrap | [[1|AD 1]]
| [[World population|Human population]] 150 million.
|- valign="TOP"
| align="RIGHT" nowrap | [[1835|AD 1835]]
| [[World population|Human population]] 1 billion.
|- valign="TOP"
| align="RIGHT" nowrap | [[1969|AD 1969]]
| Humans [[Project Apollo|walk on the moon]].
|- valign="TOP"
| align="RIGHT" nowrap | [[{{CURRENTYEAR}}|AD {{CURRENTYEAR}}]]
| [[World population|Human population]] approaching 6.6 billion.<ref>An [[United States Census Bureau]] estimate of the number of people alive on Earth at any given moment. [http://www.census.gov/cgi-bin/ipc/popclockw United States census bureau]</ref>
[[Holocene extinction event]] continues (''commencing 30-40 ka'') with the observed rate of extinction rising dramatically in the last 50 years. Most biologists believe<ref>The American Museum of Natural History [http://www.amnh.org/museum/press/feature/biofact.html National Survey Reveals Biodiversity Crisis] (URL accessed on [[February 23]], [[2006]])</ref> that we are at this moment at the beginning of a tremendously accelerated anthropogenic mass extinction. Wilson<ref>[[E.O. Wilson]], Harvard University, ''The Future of Life'' (2002)</ref> estimates that at current rates of human destruction of the biosphere, one-half of all species of life will be extinct in 100 years.
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