User:Mateuszica/timelinetemp

Source: Wikipedia, the free encyclopedia.
Date Event
4600 Ma The planet Earth forms from the accretion disk revolving around the young Sun.
4100 Ma The surface of the Earth cools enough for the crust to solidify. The atmosphere and the oceans form[1].
4000 Ma Life appears, possibly derived from self-reproducing RNA molecules. These molecules copying/reproducing/replicating requires resources like energy, space and smaller building blocks, which soon become limited, resulting in competition. Natural selection favors those molecules which are more efficient at replication. DNA molecules then took over as the main replicators. They soon develop inside an enclosing membrane which provide a stable physical and chemical environment conducive to their replication - the birth of proto-cells. The atmosphere does not contain any free oxygen.
3900 Ma Late Heavy Bombardment: peak rate of impact events upon the Earth, Moon, Mars and Venus by asteroids and comets (planetesimals); this constant disturbance may encourage life to evolve (See: Panspermia). It is thought these impacts cause the oceans to boil away completely, more than once; yet life persists[2].

Cells resembling prokaryotes appear. These first organisms are chemoautotrophs: they use carbon dioxide as a carbon source and 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 ATP molecules as short term energy currency and is used in almost all organisms unchanged to this day. Lifetime of the last universal ancestor; the split between the bacteria and the archaea occurs.

3500 Ma Bacteria develop primitive forms of photosynthesis which at first do not produce oxygen. These organisms generate ATP by exploiting a proton gradient, a mechanism still used in virtually all organisms.
3000 Ma Photosynthesizing cyanobacteria evolve; they use water as reductant, thereby producing oxygen as waste product. The oxygen initially oxidizes dissolved iron in the oceans, creating iron ore. Then the oxygen concentration in the atmosphere rises, acting as a poison for many bacteria.
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[3] results in the Huronian glaciation (2,500-2,100 Ma)[4].
2100 Ma More complex cells appear: the eukaryotes, which contain various organelles. The closest relatives of these are probably the Archaea. Most have organelles which are probably derived from symbiotic bacteria: mitochondria, which use oxygen to extract energy from organic molecules and appear similar to today's Rickettsia, and often chloroplasts, which derive energy from light and synthesize organic molecules and originated from cyanobacteria and similar forms. This is an example of co-evolution.
1200 Ma Sexual reproduction evolves and leads to faster evolution [5]. While most life occurs in oceans and lakes, some cyanobacteria may already live in moist soil by this time.
1000 Ma Multicellular organisms appear: initially colonial algae and later, seaweeds, living in the oceans.[6]
1000-750 Ma The first known supercontinent, Rodinia, forms and then breaks apart again.
950-780 Ma Sturtian Ice Age. This is a time of multiple near-global glaciation with periods oscillating between a Snowball Earth and a greenhouse Earth.
900 Ma There are 481 18-hour days in a year. The rotation of the Earth has gradually slowed ever since.
750-580 Ma According to the Snowball Earth hypothesis, the Precambrian Varangian ice age is so severe that the Earth's oceans freeze over completely; only in the tropics do oceans remain liquid.
600 Ma Sponges (Porifera), Jellyfish (Cnidaria), flat worms (Platyhelminthes) and other multicellular animals appear in the oceans. Cnidaria and Ctenophora are some of the earliest creatures to have neurons; these are in the form a simple net, with no brain or central nervous system. The Ozone layer forms, allowing for the first invasions of the land.
600-540 Ma The second supercontinent, Pannotia, forms and breaks up.
565-525 Ma The Cambrian explosion, a rapid set of evolutionary changes, creates all the major body plans (phyla) of modern animals. The cause of this huge expansion in the variety of life forms is still a matter of scientific debate. Arthropoda, represented by an abundance of trilobites, is the dominant phylum. Pikaia, a small swimmer of the phylum chordata, is possibly the ancestor of humans. Anomalocaris is a predator up to 2 meters in length whose living descendant today may well be the Pycnogonid, or Sea Spider[7].
530 Ma First footprints on land [8]
505 Ma The first vertebrates appear: the ostracoderms, jawless fish related to present-day lampreys and hagfishes. Haikouichthys and Myllokunmingia are examples of these jawless fish, or Agnatha. (See also prehistoric fish).
488 Ma The first of the seven major extinction events over geological time occurs at the Cambrian-Ordovician transition.
475 Ma The first primitive plants move onto land[9], having evolved from green algae[10] living along the edges of lakes. They are accompanied by fungi, and very likely plants and fungi work symbiotically together; lichens exemplify such a symbiosis.
450 Ma Arthropods, with an exoskeleton that provides support and prevents water loss[11], are the first animals to move onto land[12]. Among the first are Myriapoda (millipedes and centipedes), later followed by spiders and scorpions.
450-440 Ma The two Ordovician-Silurian extinction events occur. Taken together these constitute the second mass extinction event.
400 Ma First insects are without wings: silverfish, springtails, bristletails. First sharks appear[13]. 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.
375 Ma Tiktaalik is a genus of sarcopterygian (lobe-finned) fishes from the late Devonian with many tetrapod-like features.
370 Ma Cladoselache, a shark, is a high speed predator[14].
365 Ma The Late Devonian extinction is the third mass extinction.

Insects evolve on land and in fresh water from the myriapods. Some fresh water lobe-finned fish (Sarcopterygii) develop legs and give rise to the Tetrapoda. This happens in the water; tetrapods (Ichthyostega , Acanthostega and Pederpes finneyae) then use their legs to move out onto land, probably to hunt insects. Lungs and swim bladders evolve. Amphibians today still retain many characteristics of the early tetrapods.

360 Ma Plants evolve seeds, structures that protect plant embryos and enable plants to spread quickly on land. Creation of Woodleigh crater (100 km wide) and Siljan Ring (40 km wide, Dalecarlia, Sweden).
360-286 Ma The golden age of sharks[15].
350-250 Ma Karoo Ice Age, beginning with early Carboniferous and ending with late Permian. Two particular periods in which much of Gondwanaland is glaciated from an early centre in Africa and South America, and a later centre in India and Australia, caused by polar wandering
300 Ma The supercontinent Pangea 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, reptiles, 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 forests of clubmosses (lycopods), horsetails, and tree ferns cover the land; when these decay they will eventually form coal and oil. Gymnosperms begin to diversify widely. Cycads, plants resembling palms, first appear.
280 Ma The Protodonatan dragonfly Meganeura monyi is among the biggest insects that ever lived, with a wingspan of about 2 feet. Vertebrates include many Temnospondyl, Anthrachosaur, and Lepospondyl amphibians and early anapsid and synapsid (e.g. Edaphosaurus) reptiles.
256 Ma Diictodon, Cistecephalus, Dicynodon, Lycaenops, Dinogorgon and Procynosuchus, are a few of the many mammal-like reptiles known from South Africa and Russia. Pareiasaurs were large clumsy herbivores. The first Archosauriformes.
250 Ma The Permian-Triassic extinction event wipes out about 90% of all animal species; this fourth extinction event is the most severe mass extinction known.

Lystrosaurus is a common herbivore that survives the extinction event. The archosaurs split from other reptiles. 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 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. [16]

220 Ma The climate is very dry, and dry-adapted organisms are favored: the archosaurs and the Gymnosperms. Archosaurs diversify into crocodilians, dinosaurs, and pterosaurs.

From synapsids come the first mammal precursors, therapsids, and more specifically the eucynodonts. 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 autosomes 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 conifers) 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.

208-144 Ma Second major spread of sharks[17].
200 Ma Fifth mass extinction event occurs at the Triassic-Jurassic transition.

Marine reptiles include Ichthyosaurs and Plesiosaurs. Ammonites and belemnites flourish. Dinosaurs survive the extinction and grow to large size, but the thecodonts, or "socket-toothed" reptiles, die out. Modern amphibians evolve: the Lissamphibia; including Anura (frogs), Urodela (salamanders), and Caecilia. Geminiviridae, a diverse group of viruses, are traceable to this epoch or earlier<ref>"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 wa

  1. ^ "However, once the Earth cooled sufficiently, sometime in the first 700 million years of its existence, clouds began to form in the atmosphere, and the Earth entered a new phase of development." How the Oceans Formed (URL accessed on January 9, 2005)
  2. ^ " 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" Geophysicist Sleep: Martian underground may have harbored early life (URL accessed on January 9, 2005)
  3. ^ Walker, Gabrielle, (2003) "Snowball Earth: The Story of the Great Global Catastrophe that Spawned Life as we know it" Bloomsbury ISBN 0747654337
  4. ^ John, Brian (Ed)(1979) "The Winters of the World: Earth under the Ice Ages" Jacaranda Press ISBN 047026844-1
  5. ^ "'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.'
    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." Sex Speeds Up Evolution, Study Finds (URL accessed on January 9, 2005)
  6. ^ " What, then, was the selective advantage that led to the evolution of multicellular organisms?" From Single Cells to Multicellular Organisms (URL accessed on January 9, 2005)
  7. ^ "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" Pycnogonid tagmosis and echoes of the Cambrian
    "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." Haliestes dasos, a sea spider
    "If you were a trilobite or other small Cambrian animal, you did NOT want to see this coming" The Anomalocaris Homepage (animation)
  8. ^ "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." Oldest fossil footprints on land
  9. ^ "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" Transition of plants to land
  10. ^ "The land plants evolved from the algae, more specifically green algae, as suggested by certain common biochemical traits" The first land plants
  11. ^ "The waxy cuticle of arachnids and insects prevents water loss and protects against desiccation" Natural history collection: arthropoda
  12. ^ "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." The shape of life. The conquerors. PBS
  13. ^ "The ancestry of sharks dates back more than 200 million years before the earliest known dinosaur. Introduction to shark evolution, geologic time and age determination
  14. ^ "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. Ancient sharks
  15. ^ "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." A Golden Age of Sharks
  16. ^ “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.” Isolation of a 250 million-year-old halotolerant bacterium from a primary salt crystal (URL accessed on April 30, 2006)
  17. ^ "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." The Origin of Modern Sharks (URL accessed on January 9, 2005)
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