Mass extinction in two pulses across 1 million years, eliminating more than three-quarters of all species ( Late Ordovician), linked to volcanic activityД®arliest woody stems of vascular plants ( Early Devonian) в†’ evolution driven by hydraulic constraints, pre-adapting plants for taller morphologiesД®arliest tetrapods amongst the vertebrates ( Devonian Period): limbs replacing paired fins still fully aquaticД®arliest forests ( Devonian Period, Cairo, New York, North America) в†’ three-dimensional terrestrial habitat rising atmospheric Oв‚‚ and diminishing COв‚‚

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 EarthвЂ™s rotational speed slows, improving conditions for complex lifeД®xplosion in animal diversification (earliest Cambrian Period), including Deuterostomia appearing amongst the metazoans: tiny bag-like body with multiple openingsД®arliest chordates amongst the deuterostomes ( Early Cambrian Period): notochord and pharyngeal gill slitsДЇirst 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 lifeД®arliest multicellular life, with cell-to-cell signalling and coordinated responses ( Proterozoic Eon) в†’ 37 trillion mutually-dependent cells in an adult human bodyД®arliest Eukaryotes amongst the Prokaryotes, arising from the merger of an archaeon with a bacterium: sexual reproduction with meiosis and recombination ( Proterozoic Eon)Д®arliest Metazoa вЂ“ animals вЂ“ 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)Д®arliest atmospheric oxygen, present at low levels ( Archean Eon)

Ignition of hydrogen stars, bathing the Universe in first light of cosmic dawn в†’ earliest galaxies of stars forming 400 million years after the Big Bang helium in stars fusing into carbon, leading to stellar nucleosynthesis of all elementsД®arliest water: an interstellar vapour, and repository for oxygenДЇormation of the Milky Way galaxy, a warped disc of 100 billion stars, now one of 2 trillion galaxies in the observable UniverseДЇormation of the Sun and Solar System within the Milky Way, orbiting a supermassive black hole at its Galactic Centre every 240 million yearsДЇormation of the Moon from a giant impact with proto-EarthДЇormation of planet Earth with 510 million kmВІ of surface area, orbiting the Sun on a yearly cycle, rotating eastward on a daily cycle around a tilted axis that perpetuates opposing polar seasonsДЇormation of EarthвЂ™s oceans and moist atmosphere, protected from solar wind and cosmic rays by EarthвЂ™s magnetosphere generated by its iron coreД®arliest subduction of EarthвЂ™s crust в†’ continental plate tectonics by 3 billion years ago, unique to Earth in the Solar SystemД®arliest 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 в‡“)Д«ig Bang singularity, creation of all particles of matter and counterpart antimatter, and the laws of physics governing their interactions expansion and cooling of space в†’ formation of the observable Universe, its galaxies, solar systems, stars, planets, moons, asteroids and comets

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