Mass extinction in a series of pulses across 20 million years, eliminating more than two-thirds of all species ( Late Devonian), linked to climatic coolingĮarliest land vertebrates ( Carboniferous Period): semi-aquatic amphibian tetrapodsĮarliest fully terrestrial tetrapod vertebrates, laying amniote eggs ( Early Carboniferous Period)Įarth’s largest mass extinction, eliminating nine tenths of all species during 61 thousand years ( Permian- Triassic transition), caused by hot and acidifying volcanic CO₂ emissions from the Siberian Trapsĭawn of the modern world: major biological turnover linked to volcanism ( Late Triassic) → rapid diversifications and originations of conifers, insects, dinosaurs, reptiles and stem mammals Mass extinction in two pulses across 1 million years, eliminating more than three-quarters of all species ( Late Ordovician), linked to volcanic activityĮarliest woody stems of vascular plants ( Early Devonian) → evolution driven by hydraulic constraints, pre-adapting plants for taller morphologiesĮarliest tetrapods amongst the vertebrates ( Devonian Period): limbs replacing paired fins still fully aquaticĮarliest forests ( Devonian Period, Cairo, New York, North America) → three-dimensional terrestrial habitat rising atmospheric O₂ and diminishing CO₂ Radiation of vertebrates amongst the chordates ( Ordovician Period): aquatic with a mineralised skeleton, armour and scales Neoproterozoic Oxygenation Event: 100 million years of rising photosynthesis with lengthening days as Earth’s rotational speed slows, improving conditions for complex lifeĮxplosion in animal diversification (earliest Cambrian Period), including Deuterostomia appearing amongst the metazoans: tiny bag-like body with multiple openingsĮarliest chordates amongst the deuterostomes ( Early Cambrian Period): notochord and pharyngeal gill slitsįirst colonisation of land, by algal plants of the Middle Cambrian, probably facilitated by fungi The Great Oxygenation Event: 1-10 million years of rapidly accumulating atmospheric oxygen ( Proterozoic Eon): product of photosynthesis, energy source for complex lifeĮarliest multicellular life, with cell-to-cell signalling and coordinated responses ( Proterozoic Eon) → 37 trillion mutually-dependent cells in an adult human bodyĮarliest Eukaryotes amongst the Prokaryotes, arising from the merger of an archaeon with a bacterium: sexual reproduction with meiosis and recombination ( Proterozoic Eon)Įarliest Metazoa – animals – amongst the Eukaryotes: sponges, then worms and jellyfish ( Proterozoic Eon), prior to Snowball Earth episodes of worldwide glaciation Photosynthesising bacteria amongst the Archaea ( Archean Eon)Įarliest atmospheric oxygen, present at low levels ( Archean Eon)Įmergence of Earth’s first continents from the ocean ( Archean Eon, 3.2 to 3.3 billion years ago) Ignition of hydrogen stars, bathing the Universe in first light of cosmic dawn → earliest galaxies of stars forming 400 million years after the Big Bang helium in stars fusing into carbon, leading to stellar nucleosynthesis of all elementsĮarliest water: an interstellar vapour, and repository for oxygenįormation of the Milky Way galaxy: a warped disc of 100 billion stars, now one of 2 trillion galaxies in the observable Universeįormation of the Sun and Solar System within the Milky Way, orbiting a supermassive black hole at its Galactic Centre every 240 million yearsįormation of the Moon from a giant impact with proto-Earthįormation of planet Earth with 510 million km² of surface area, orbiting the Sun on a yearly cycle, rotating eastward on a daily cycle around a tilted axis that perpetuates opposing polar seasonsįormation of Earth’s oceans and moist atmosphere, protected from solar wind and cosmic rays by Earth’s magnetosphere generated by its iron coreĮarliest subduction of Earth’s crust → continental plate tectonics by 3 billion years ago, unique to Earth in the Solar SystemĮarliest life on Earth: single-celled prokaryotic Archaea ( Hadean Eon, 3.8-4.2 billion years ago) Discs fill with colour as time passes towards the present (further explanation below ⇓)īig Bang singularity, creation of all particles of matter and counterpart antimatter, and the laws of physics governing their interactions expansion and cooling of space → formation of the observable Universe, its galaxies, solar systems, stars, planets, moons, asteroids and comets
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