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+{-# OPTIONS_GHC -Wall #-}
+{-# language NoImplicitPrelude #-}
+{-# language OverloadedStrings #-}
+{-# language QuasiQuotes #-}
+
+module CosmicCalendarEvents where
+
+import Rebase.Prelude
+import NeatInterpolation
+
+import CosmicCalendar
+
+theYear, yearsBeforeCommonEra :: Integer -> NominalDiffTime
+theYear = yearsAgo . toRational . (currentYear -)
+yearsBeforeCommonEra = yearsAgo . toRational . ((+) (currentYear - 1))
+
+theCalendar :: Map NominalDiffTime CalendarEntry
+theCalendar = buildCalendar $
+  [
+    CalendarEntry 0
+    Nothing
+    "The Big Bang"
+    "The universe begins"
+    ""
+    "",
+
+    CalendarEntry (370 & thousandYears & afterBigBang)
+    Nothing
+    "Recombination"
+    "The universe becomes transparent"
+    [text|
+    At about 370,000 years,[3][4][5][6] neutral hydrogen atoms finish forming
+    ("recombination"), and as a result the universe also became transparent for
+    the first time. The newly formed atoms—mainly hydrogen and helium with
+    traces of lithium—quickly reach their lowest energy state (ground state) by
+    releasing photons ("photon decoupling"), and these photons can still be
+    detected today as the cosmic microwave background (CMB). This is the oldest
+    direct observation we currently have of the universe.
+    |]
+    [text|
+    https://en.wikipedia.org/wiki/Chronology_of_the_universe#The_very_early_universe
+
+    3. Tanabashi, M. 2018, p. 358, chpt. 21.4.1: "Big-Bang Cosmology" (Revised
+    September 2017) by Keith A. Olive and John A. Peacock.
+
+    4. Notes: Edward L. Wright's Javascript Cosmology Calculator (last modified
+    23 July 2018). With a default H 0 {\displaystyle H_{0}} H_{0} = 69.6 (based
+    on WMAP9+SPT+ACT+6dFGS+BOSS/DR11+H0/Riess) parameters, the calculated age of
+    the universe with a redshift of z = 1100 is in agreement with Olive and
+    Peacock (about 370,000 years).
+
+    5. Hinshaw, Weiland & Hill 2009. See PDF: page 45, Table 7, Age at
+    decoupling, last column. Based on WMAP+BAO+SN parameters, the age of
+    decoupling occurred 376971+3162−3167 years after the Big Bang.
+
+    6. Ryden 2006, pp. 194–195. "Without going into the details of the
+    non-equilibrium physics, let's content ourselves by saying, in round
+    numbers, zdec ≈ 1100, corresponding to a temperature Tdec ≈ 3000 K, when the
+    age of the universe was tdec ≈ 350,000 yr in the Benchmark Model. (...) The
+    relevant times of various events around the time of recombination are shown
+    in Table 9.1. (...) Note that all these times are approximate, and are
+    dependent on the cosmological model you choose. (I have chosen the Benchmark
+    Model in calculating these numbers.)"
+
+    https://en.wikipedia.org/wiki/Recombination_(cosmology)#cite_note-2
+    |],
+
+    CalendarEntry (13.4 & billionYearsAgo) Nothing
+    "The first observed star"
+    ""
+    "First Light Viewed Through the Rich Cluster Abell 2218"
+    "https://sites.astro.caltech.edu/~rse/firstlight/",
+
+    CalendarEntry (4.6 & billionYearsAgo) Nothing
+    "Formation of the Sun"
+    "The formation of the solar system begins"
+    [text|
+    The formation of the Solar System began about 4.6 billion years ago with the
+    gravitational collapse of a small part of a giant molecular cloud.[1] Most
+    of the collapsing mass collected in the center, forming the Sun, while the
+    rest flattened into a protoplanetary disk out of which the planets, moons,
+    asteroids, and other small Solar System bodies formed.
+    |]
+    "https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System",
+
+    CalendarEntry (4.54 & billionYearsAgo) Nothing
+    "Formation of Earth"
+    ""
+    [text|
+    The standard model for the formation of the Solar System (including the
+    Earth) is the solar nebula hypothesis.[23] In this model, the Solar System
+    formed from a large, rotating cloud of interstellar dust and gas called the
+    solar nebula. It was composed of hydrogen and helium created shortly after
+    the Big Bang 13.8 Ga (billion years ago) and heavier elements ejected by
+    supernovae. About 4.5 Ga, the nebula began a contraction that may have been
+    triggered by the shock wave from a nearby supernova.[24] A shock wave would
+    have also made the nebula rotate. As the cloud began to accelerate, its
+    angular momentum, gravity, and inertia flattened it into a protoplanetary
+    disk perpendicular to its axis of rotation. Small perturbations due to
+    collisions and the angular momentum of other large debris created the means
+    by which kilometer-sized protoplanets began to form, orbiting the nebular
+    center.[25]
+
+    The center of the nebula, not having much angular momentum, collapsed
+    rapidly, the compression heating it until nuclear fusion of hydrogen into
+    helium began. After more contraction, a T Tauri star ignited and evolved
+    into the Sun. Meanwhile, in the outer part of the nebula gravity caused
+    matter to condense around density perturbations and dust particles, and the
+    rest of the protoplanetary disk began separating into rings. In a process
+    known as runaway accretion, successively larger fragments of dust and debris
+    clumped together to form planets.[25] Earth formed in this manner about 4.54
+    billion years ago (with an uncertainty of 1%)[26][27][4] and was largely
+    completed within 10–20 million years.[28] The solar wind of the newly formed
+    T Tauri star cleared out most of the material in the disk that had not
+    already condensed into larger bodies. The same process is expected to
+    produce accretion disks around virtually all newly forming stars in the
+    universe, some of which yield planets.[29]
+    |]
+    "https://en.wikipedia.org/wiki/History_of_Earth#Solar_System_formation",
+
+    CalendarEntry (8.8 & billionYearsAgo) Nothing
+    "Thin disk of the Milky Way Galaxy"
+    "Our galaxy begins to form"
+    [text|
+    The age of stars in the galactic thin disk has also been estimated using
+    nucleocosmochronology. Measurements of thin disk stars yield an estimate
+    that the thin disk formed 8.8 ± 1.7 billion years ago. These measurements
+    suggest there was a hiatus of almost 5 billion years between the formation
+    of the galactic halo and the thin disk.[253] Recent analysis of the chemical
+    signatures of thousands of stars suggests that stellar formation might have
+    dropped by an order of magnitude at the time of disk formation, 10 to 8
+    billion years ago, when interstellar gas was too hot to form new stars at
+    the same rate as before.[254]
+    |]
+    "",
+
+    CalendarEntry (4.4 & billionYearsAgo) Nothing
+    "Formation of the moon"
+    "A collision of the planet Theia with Earth creates the moon"
+    [text|
+    Astronomers think the collision between Earth and Theia happened at about
+    4.4 to 4.45 bya; about 0.1 billion years after the Solar System began to
+    form.[15][16] In astronomical terms, the impact would have been of moderate
+    velocity. Theia is thought to have struck Earth at an oblique angle when
+    Earth was nearly fully formed. Computer simulations of this "late-impact"
+    scenario suggest an initial impactor velocity at infinity below 4 kilometres
+    per second (2.5 mi/s), increasing as it fell to over 9.3 km/s (5.8 mi/s) at
+    impact, and an impact angle of about 45°.[17] However, oxygen isotope
+    abundance in lunar rock suggests "vigorous mixing" of Theia and Earth,
+    indicating a steep impact angle.[3][18] Theia's iron core would have sunk
+    into the young Earth's core, and most of Theia's mantle accreted onto
+    Earth's mantle. However, a significant portion of the mantle material from
+    both Theia and Earth would have been ejected into orbit around Earth (if
+    ejected with velocities between orbital velocity and escape velocity) or
+    into individual orbits around the Sun (if ejected at higher velocities).
+    Modelling[19] has hypothesised that material in orbit around Earth may have
+    accreted to form the Moon in three consecutive phases; accreting first from
+    the bodies initially present outside Earth's Roche limit, which acted to
+    confine the inner disk material within the Roche limit. The inner disk
+    slowly and viscously spread back out to Earth's Roche limit, pushing along
+    outer bodies via resonant interactions. After several tens of years, the
+    disk spread beyond the Roche limit, and started producing new objects that
+    continued the growth of the Moon, until the inner disk was depleted in mass
+    after several hundreds of years.
+    |]
+    [text|
+    https://en.wikipedia.org/wiki/Giant-impact_hypothesis#Basic_model
+    https://www.psi.edu/epo/moon/moon.html
+    |],
+
+    CalendarEntry (3.77 & billionYearsAgo) Nothing
+    "Life on Earth"
+    ""
+    [text|
+    The earliest time for the origin of life on Earth is at least 3.77 billion
+    years ago, possibly as early as 4.28 billion years,[2] or even 4.41 billion
+    years[4][5]—not long after the oceans formed 4.5 billion years ago, and
+    after the formation of the Earth 4.54 billion years ago.[2][3][6][7]
+    |]
+    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
+
+    CalendarEntry (3.42 & billionYearsAgo) Nothing
+    "Earliest known life on Earth"
+    "The fossil record begins"
+    [text|
+    The earliest known life forms on Earth are putative fossilized
+    microorganisms found in hydrothermal vent precipitates, considered to be
+    about 3.42 billion years old.[1][2] The earliest time for the origin of life
+    on Earth is at least 3.77 billion years ago, possibly as early as 4.28
+    billion years,[2] or even 4.41 billion years[4][5]—not long after the oceans
+    formed 4.5 billion years ago, and after the formation of the Earth 4.54
+    billion years ago.[2][3][6][7] The earliest direct evidence of life on Earth
+    is from microfossils of microorganisms permineralized in
+    3.465-billion-year-old Australian Apex chert rocks.[8][9]
+    |]
+    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
+
+    CalendarEntry (3.4 & billionYearsAgo) Nothing
+    "First photosynthetic bacteria"
+    "(Still no Oxygen)"
+    [text|
+    They absorbed near-infrared rather than visible light and produced sulfur or
+    sulfate compounds rather than oxygen. Their pigments (possibly
+    bacteriochlorophylls) were predecessors to chlorophyll.
+    |]
+    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
+
+    CalendarEntry (2.7 & billionYearsAgo) Nothing
+    "Oxygen from photosynthesis"
+    [text|
+    Cyanobacteria (blue-green algae) initiates "rusting of the Earth"
+    The resulting Ozone layer will make life possible on land
+    |]
+    [text|
+    These ubiquitous bacteria were the first oxygen producers. They absorb
+    visible light using a mix of pigments: phycobilins, carotenoids and several
+    forms of chlorophyll.
+
+    The Great Oxidation Event (GOE), also called the Great Oxygenation Event,
+    the Oxygen Catastrophe, the Oxygen Revolution, and the Oxygen Crisis, was a
+    time interval when the Earth's atmosphere and the shallow ocean first
+    experienced a rise in the amount of oxygen. This occurred approximately
+    2.4–2.0 Ga (billion years) ago, during the Paleoproterozoic era.[2]
+    Geological, isotopic, and chemical evidence suggests that
+    biologically-produced molecular oxygen (dioxygen, O2) started to accumulate
+    in Earth's atmosphere and changed it from a weakly reducing atmosphere
+    practically free of oxygen into an oxidizing atmosphere containing abundant
+    oxygen.[3]
+
+    The sudden injection of toxic oxygen into an anaerobic biosphere caused the
+    extinction of many existing anaerobic species on Earth.[4] Although the event is
+    inferred to have constituted a mass extinction,[5] due in part to the great
+    difficulty in surveying microscopic species' abundances, and in part to the
+    extreme age of fossil remains from that time, the Oxygen Catastrophe is
+    typically not counted among conventional lists of "great extinctions", which are
+    implicitly limited to the Phanerozoic eon.
+
+    The event is inferred to have been caused by cyanobacteria producing the
+    oxygen, which may have enabled the subsequent development of multicellular
+    life-forms.[6]
+
+    The current scientific understanding of when and how the Earth's atmosphere
+    changed from a weakly reducing to a strongly oxidizing atmosphere largely
+    began with the work of the American geologist Preston Cloud in the 1970s.[9]
+    Cloud observed that detrital sediments older than about 2 billion years ago
+    contained grains of pyrite, uraninite,[9] and siderite,[12] all minerals
+    containing reduced forms of iron or uranium that are not found in younger
+    sediments because they are rapidly oxidized in an oxidizing atmosphere. He
+    further observed that continental redbeds, which get their color from the
+    oxidized (ferric) mineral hematite, began to appear in the geological record
+    at about this time. Banded iron formation largely disappears from the
+    geological record at 1.85 billion years ago, after peaking at about 2.5
+    billion years ago.[14] Banded iron formation can form only when abundant
+    dissolved ferrous iron is transported into depositional basins, and an
+    oxygenated ocean blocks such transport by oxidizing the iron to form
+    insoluble ferric iron compounds.[15] The end of the deposition of banded
+    iron formation at 1.85 billion years ago is therefore interpreted as marking
+    the oxygenation of the deep ocean.[9] Heinrich Holland further elaborated
+    these ideas through the 1980s, placing the main time interval of oxygenation
+    between 2.2 and 1.9 billion years ago, and they continue to shape the
+    current scientific understanding.[10]
+    |]
+    [text|
+    https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/
+    https://en.wikipedia.org/wiki/Great_Oxidation_Event
+    |],
+
+    CalendarEntry (2.05 & billionYearsAgo) Nothing
+    "Eukaryotic cells"
+    "Cells with nucleus (inner membrane holding DNA)"
+    [text|
+    Eukaryotes (/juːˈkærioʊts, -əts/) are organisms whose cells have a nucleus
+    enclosed within a nuclear envelope.[1][2][3] They belong to the group of
+    organisms Eukaryota or Eukarya; their name comes from the Greek εὖ (eu,
+    "well" or "good") and κάρυον (karyon, "nut" or "kernel").[4] The domain
+    Eukaryota makes up one of the three domains of life; bacteria and archaea
+    (both prokaryotes) make up the other two domains.[5][6] The eukaryotes are
+    usually now regarded as having emerged in the Archaea or as a sister of the
+    Asgard archaea.[7][8] This implies that there are only two domains of life,
+    Bacteria and Archaea, with eukaryotes incorporated among archaea.[9][10]
+    Eukaryotes represent a small minority of the number of organisms;[11]
+    however, due to their generally much larger size, their collective global
+    biomass is estimated to be about equal to that of prokaryotes.[11]
+    Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the
+    Proterozoic eon, likely as flagellated phagotrophs.[12][13]
+    |]
+    "https://en.wikipedia.org/wiki/Eukaryote",
+
+    CalendarEntry (1.2 & billionYearsAgo) Nothing
+    "Red and brown algae"
+    ""
+    [text|
+    These organisms have more complex cellular structures than bacteria do. Like
+    cyanobacteria, they contain phycobilin pigments as well as various forms of
+    chlorophyll.
+    |]
+    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
+
+    CalendarEntry (0.75 & billionYearsAgo) Nothing
+    "Green algae"
+    ""
+    [text|
+    Green algae do better than red and brown algae in the strong light of
+    shallow water. They make do without phycobilins.
+    |]
+    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
+
+    CalendarEntry (0.475 & billionYearsAgo) Nothing
+    "First land plants"
+    ""
+    [text|
+    Mosses and liverworts descended from green algae. Lacking vascular structure
+    (stems and roots) to pull water from the soil, they are unable to grow
+    tall.
+    |]
+    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
+
+    CalendarEntry (0.423 & billionYearsAgo) Nothing
+    "Vascular plants"
+    ""
+    [text|
+    These are literally garden-variety plants, such as ferns, grasses, trees and
+    cacti. They are able to grow tall canopies to capture more light.
+    |]
+    "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
+
+    CalendarEntry (750 & millionYearsAgo) Nothing
+    "Bones and shells"
+    ""
+    [text|
+    A series of spectacularly preserved, 750-million-year-old fossils represent
+    the microscopic origins of biomineralization, or the ability to convert
+    minerals into hard, physical structures. This process is what makes bones,
+    shells, teeth and hair possible, literally shaping the animal kingdom and
+    even Earth itself.
+
+    The fossils were pried from ancient rock formations in Canada's Yukon by
+    earth scientists Francis Macdonald and Phoebe Cohen of Harvard University.
+    In a June Geology paper, they describe their findings as providing "a unique
+    window into the diversity of early eukaryotes."
+
+    Using molecular clocks and genetic trees to reverse-engineer evolutionary
+    histories, previous research placed the beginning of biomineralization at
+    about 750 million years ago. Around that time, the fossil record gets
+    suggestive, turning up vase-shaped amoebas with something like scales in
+    their cell walls, algae with cell walls possibly made from calcium carbonate
+    and sponge-like creatures with seemingly mineralized bodies.
+    |]
+    "https://www.wired.com/2011/06/first-shells/",
+
+    CalendarEntry (440 & millionYearsAgo) Nothing
+    "Fish with jaws"
+    ""
+    [text|
+    Prehistoric armoured fishes called placoderms were the first fishes to have
+    jaws. They arose some time in the Silurian Period, about 440 million years
+    ago, to become the most abundant and diverse fishes of their day.
+
+    Placoderms dominated the oceans, rivers and lakes for some 80 million years,
+    before their sudden extinction around 359 million years ago. This is possibly
+    due to the depletion of trace elements in our oceans.
+    |]
+    "",
+
+    CalendarEntry (518 & millionYearsAgo) Nothing
+    "Vertebrates"
+    "Animals with backbones"
+    [text|
+    Vertebrates (/ˈvɜːrtəbrɪts, -ˌbreɪts/)[3] comprise all animal taxa within
+    the subphylum Vertebrata (/ˌvɜːrtəˈbreɪtə/)[4] (chordates with backbones),
+    including all mammals, birds, reptiles, amphibians, and fish. Vertebrates
+    represent the overwhelming majority of the phylum Chordata, with currently
+    about 69,963 species described.[5]
+    |]
+    "",
+
+    CalendarEntry (385 & millionYearsAgo) Nothing
+    "Insects"
+    ""
+    [text|
+    Comprising up to 10 million living species, insects today can be found on
+    all seven continents and inhabit every terrestrial niche imaginable. But
+    according to the fossil record, they were scarce before about 325 million
+    years ago, outnumbered by their arthropod cousins the arachnids (spiders,
+    scorpions and mites) and myriapods (centipedes and millipedes).
+
+    The oldest confirmed insect fossil is that of a wingless, silverfish-like
+    creature that lived about 385 million years ago. It’s not until about 60
+    million years later, during a period of the Earth’s history known as the
+    Pennsylvanian, that insect fossils become abundant.
+    |]
+    "https://earth.stanford.edu/news/insects-took-when-they-evolved-wings",
+
+    CalendarEntry (368 & millionYearsAgo) Nothing
+    "Amphibians"
+    ""
+    [text|
+    The earliest well-known amphibian, Ichthyostega, was found in Late Devonian
+    deposits in Greenland, dating back about 363 million years. The earliest
+    amphibian discovered to date is Elginerpeton, found in Late Devonian rocks
+    of Scotland dating to approximately 368 million years ago. The later
+    Paleozoic saw a great diversity of amphibians, ranging from small legless
+    swimming forms (Aistopoda) to bizarre "horned" forms (Nectridea). Other
+    Paleozoic amphibians more or less resembled salamanders outwardly but
+    differed in details of skeletal structure. Exactly how to classify these
+    fossils, and how they might be related to living amphibians, is still
+    debated by paleontologists. Shown at the right is Phlegethontia, an aistopod
+    from the Pennsylvanian.
+
+    The familiar frogs, toads, and salamanders have been present since at least
+    the Jurassic Period. (The fossil frog pictured to the left is much younger,
+    coming from the Eocene, only 45 to 55 million years ago). Fossil caecilians
+    are very rare; until recently the oldest known caecilians were Cenozoic in
+    age (that is, less than 65 million years old), but recent finds have pushed
+    back the ancestry of the legless caecilians to Jurassic ancestors that had
+    short legs. The rarity of fossil caecilians is probably due to their
+    burrowing habitat and reduced skeleton, both of which lessen the chances of
+    preservation.
+    |]
+    "https://ucmp.berkeley.edu/vertebrates/tetrapods/amphibfr.html",
+
+    CalendarEntry (320 & millionYearsAgo) Nothing
+    "Reptiles"
+    ""
+    [text|
+    Reptiles, in the traditional sense of the term, are defined as animals that
+    have scales or scutes, lay land-based hard-shelled eggs, and possess
+    ectothermic metabolisms.
+
+    Though few reptiles today are apex predators, many examples of apex reptiles
+    have existed in the past. Reptiles have an extremely diverse evolutionary
+    history that has led to biological successes, such as dinosaurs, pterosaurs,
+    plesiosaurs, mosasaurs, and ichthyosaurs.
+    |]
+    [text|
+    https://en.wikipedia.org/wiki/Evolution_of_reptiles
+    https://www.thoughtco.com/the-first-reptiles-1093767
+    |],
+
+    CalendarEntry (335 & millionYearsAgo) Nothing
+    "Pangea forms"
+    ""
+    [text|
+    Pangaea or Pangea (/pænˈdʒiː.ə/)[1] was a supercontinent that existed during
+    the late Paleozoic and early Mesozoic eras.[2] It assembled from the earlier
+    continental units of Gondwana, Euramerica and Siberia during the
+    Carboniferous approximately 335 million years ago, and began to break apart
+    about 200 million years ago, at the end of the Triassic and beginning of the
+    Jurassic.[3] In contrast to the present Earth and its distribution of
+    continental mass, Pangaea was centred on the Equator and surrounded by the
+    superocean Panthalassa and the Paleo-Tethys and subsequent Tethys Oceans.
+    Pangaea is the most recent supercontinent to have existed and the first to
+    be reconstructed by geologists.
+    |]
+    "https://en.wikipedia.org/wiki/Pangaea",
+
+    CalendarEntry (243 & millionYearsAgo) Nothing
+    "Dinosaurs"
+    ""
+    [text|
+    For the past twenty years, Eoraptor has represented the beginning of the Age
+    of Dinosaurs. This controversial little creature–found in the roughly
+    231-million-year-old rock of Argentina–has often been cited as the earliest
+    known dinosaur. But Eoraptor has either just been stripped of that title, or
+    soon will be. A newly-described fossil found decades ago in Tanzania extends
+    the dawn of the dinosaurs more than 10 million years further back in time.
+
+    Named Nyasasaurus parringtoni, the roughly 243-million-year-old fossils
+    represent either the oldest known dinosaur or the closest known relative to
+    the earliest dinosaurs. The find was announced by University of Washington
+    paleontologist Sterling Nesbitt and colleagues in Biology Letters, and I
+    wrote a short news item about the discovery for Nature News. The paper
+    presents a significant find that is also a tribute to the work of Alan
+    Charig–who studied and named the animal, but never formally published a
+    description–but it isn’t just that. The recognition of Nyasasaurus right
+    near the base of the dinosaur family tree adds to a growing body of evidence
+    that the ancestors of dinosaurs proliferated in the wake of a catastrophic
+    mass extinction.
+    |]
+    [text|
+    https://www.smithsonianmag.com/science-nature/scientists-discover-oldest-known-dinosaur-152807497/
+    |],
+
+    CalendarEntry (210 & millionYearsAgo) Nothing
+    "Mammals"
+    ""
+    [text|
+    The earliest known mammals were the morganucodontids, tiny shrew-size
+    creatures that lived in the shadows of the dinosaurs 210 million years ago.
+    They were one of several different mammal lineages that emerged around that
+    time. All living mammals today, including us, descend from the one line that
+    survived.
+    |]
+    "https://www.nationalgeographic.com/science/article/rise-mammals",
+
+    CalendarEntry (150 & millionYearsAgo) Nothing
+    "Birds"
+    ""
+    [text|
+    The first birds had sharp teeth, long bony tails and claws on their hands.
+    The clear distinction we see between living birds and other animals did not
+    exist with early birds. The first birds were in fact more like small
+    dinosaurs than they were like any bird today.
+
+    The earliest known (from fossils) bird is the 150-million-year-old
+    Archaeopteryx, but birds had evolved before then. A range of birds with more
+    advanced features appeared soon after Archaeopteryx. One group gave rise to
+    modern birds in the Late Cretaceous.
+    |]
+    "https://australian.museum/learn/dinosaurs/the-first-birds/",
+
+    CalendarEntry (130 & millionYearsAgo) Nothing
+    "Flowers"
+    ""
+    [text|
+    Today, plants with flowers--called angiosperms--dominate the landscape.
+    Around 80 percent of green plants alive today, from oak trees to grass, are
+    flowering plants. In all of these plants, flowers are part of the
+    reproductive system. But 130 million years ago, flowering plants were rare.
+    Most plants reproduced with spores, found today on ferns, or with seeds and
+    cones, found today on pine trees. The plant fossils found in Liaoning,
+    China, show evidence of plants with spores or seeds--and perhaps one of the
+    first flowering plants.
+
+    Researchers have found an ancient plant in Liaoning, Archaefructus, that has
+    very small, simple flowers and could be one of the first flowering plants.
+    Archaefructus lived around 130 million years ago and probably grew in or
+    near the water.
+    |]
+    "https://www.amnh.org/exhibitions/dinosaurs-ancient-fossils/liaoning-diorama/when-flowers-first-bloomed",
+
+    CalendarEntry (85 & millionYearsAgo) Nothing
+    "Tyranosaurids"
+    "The Tyrant Lizards"
+    [text|
+    The name says it all. This group of huge carnivores must have tyrannically
+    ruled the land during the last part of the Cretaceous, 85 to 65 million
+    years ago. Short but deep jaws with banana-sized sharp teeth, long hind
+    limbs, small beady eyes, and tiny forelimbs (arms) typify a tyrannosaur. The
+    Tyrannosauridae included such similar animals (in rough order of increasing
+    size) as Albertosaurus, Gorgosaurus, Daspletosaurus, Tarbosaurus, and of
+    course Tyrannosaurus rex.
+
+    T. rex was one of the largest terrestrial carnivores of all time. It stood
+    approximately 15 feet high and was about 40 feet in length, roughly six tons
+    in weight. In its large mouth were six-inch long, sharp, serrated teeth.
+
+    Just about two dozen good specimens of these animals have been found and
+    these finds are from highly restricted areas in western North America. Henry
+    Fairfield Osborn, of the American Museum of Natural History in New York
+    City, first described Tyrannosaurus rex in 1905. This first specimen of
+    Tyrannosaurus is now on display at the Carnegie Museum of Natural History in
+    Pittsburgh, Pennsylvania.
+    |]
+    "",
+
+    CalendarEntry (445 & millionYearsAgo) Nothing
+    "The first mass extinction"
+    "Fluctuating sea levels cause mass die-off of marine invertebrates"
+    [text|
+    The earliest known mass extinction, the Ordovician Extinction, took place at
+    a time when most of the life on Earth lived in its seas. Its major
+    casualties were marine invertebrates including brachiopods, trilobites,
+    bivalves and corals; many species from each of these groups went extinct
+    during this time. The cause of this extinction? It’s thought that the main
+    catalyst was the movement of the supercontinent Gondwana into Earth’s
+    southern hemisphere, which caused sea levels to rise and fall repeatedly
+    over a period of millions of years, eliminating habitats and species. The
+    onset of a late Ordovician ice age and changes in water chemistry may also
+    have been factors in this extinction.
+    |]
+    "https://www.amnh.org/shelf-life/six-extinctions",
+
+    CalendarEntry (370 & millionYearsAgo) Nothing
+    "Late Devonian Extinction"
+    "The Kellwasser Event and the Hangenberg Event combine to cause an enormous loss in biodiversity"
+    [text|
+    Given that it took place over a huge span of time—estimates range from
+    500,000 to 25 million years—it isn’t possible to point to a single cause for
+    the Devonian extinction, though some suggest that the amazing spread of
+    plant life on land during this time may have changed the environment in ways
+    that made life harder, and eventually impossible, for the species that died
+    out.
+
+    The brunt of this extinction was borne by marine invertebrates. As in the
+    Ordovician Extinction, many species of corals, trilobites, and brachiopods
+    vanished. Corals in particular were so hard hit that they were nearly wiped
+    out, and didn’t recover until the Mesozoic Era, nearly 120 million years
+    later. Not all vertebrate species were spared, however; the early bony
+    fishes known as placoderms met their end in this extinction.
+    |]
+    "https://www.amnh.org/shelf-life/six-extinctions",
+
+    CalendarEntry (252 & millionYearsAgo) Nothing
+    "The Great Dying"
+    "Mass extinction kills more than 95 percent of marine species and 70 percent of land-dwelling vertebrates"
+    [text|
+    So many species were wiped out by this mass extinction it took more than 10
+    million years to recover from the huge blow to global biodiversity. This
+    extinction is thought to be the result of a gradual change in climate,
+    followed by a sudden catastrophe. Causes including volcanic eruptions,
+    asteroid impacts, and a sudden release of greenhouse gasses from the
+    seafloor have been proposed, but the mechanism behind the Great Dying
+    remains a mystery.
+    |]
+    "https://www.amnh.org/shelf-life/six-extinctions",
+
+    CalendarEntry (201 & millionYearsAgo) Nothing
+    "Triassic-Jurassic Extinction"
+    "Death of more than a third of marine species and of most large amphibians"
+    [text|
+    This extinction occurred just a few millennia before the breakup of the
+    supercontinent of Pangaea. While its causes are not definitively
+    understood—researchers have suggested climate change, an asteroid impact, or
+    a spate of enormous volcanic eruptions as possible culprits—its effects are
+    indisputable.
+
+    More than a third of marine species vanished, as did most large amphibians
+    of the time, as well as many species related to crocodiles and dinosaurs.
+    |]
+    "https://www.amnh.org/shelf-life/six-extinctions",
+
+    CalendarEntry (66 & millionYearsAgo) Nothing
+    "Dinosaurs extinct"
+    "Mammals take over land & sea"
+    [text|
+    An asteroid more than 6 miles across strikes the Yucatan Peninsula,
+    triggering the fifth mass extinction in the world’s history.
+
+    Some of the debris thrown into the atmosphere returned to Earth, the
+    friction turning the air into an oven and sparking forest fires as it landed
+    all over the world. The intensity of the heat pulse gave way to a prolonged
+    impact winter, the sky blotted out by soot and ash as temperatures fell.
+
+    More than 75 percent of species known from the end of the Cretaceous period,
+    66 million years ago, didn’t make it to the following Paleogene period. The
+    geologic break between the two is called the K-Pg boundary, and beaked birds
+    were the only dinosaurs to survive the disaster.|]
+    [text|
+    https://www.smithsonianmag.com/science-nature/why-birds-survived-and-dinosaurs-went-extinct-after-asteroid-hit-earth-180975801/,
+    https://www.amnh.org/shelf-life/six-extinctions
+    |],
+
+    CalendarEntry (27.5 & millionYearsAgo) Nothing
+    "Apes and monkeys split"
+    ""
+    [text|
+    Studies of clock-like mutations in primate DNA have indicated that the split
+    between apes and Old World monkeys occurred between 30 million and 25
+    million years ago.
+    |]
+    "https://www.nsf.gov/news/news_summ.jsp?cntn_id=127930",
+
+    CalendarEntry (12.1 & millionYearsAgo) Nothing
+    "Humans and chimpanzees split"
+    ""
+    [text|
+    A 2016 study analyzed transitions at CpG sites in genome sequences, which
+    exhibit a more clocklike behavior than other substitutions, arriving at an
+    estimate for human and chimpanzee divergence time of 12.1 million years.[20]
+    |]
+    [text|
+    https://en.wikipedia.org/wiki/Chimpanzee%E2%80%93human_last_common_ancestor
+    |],
+
+    CalendarEntry (4.4 & millionYearsAgo) Nothing
+    "Humans first walk upright"
+    ""
+    [text|
+    The earliest hominid with the most extensive evidence for bipedalism is the 4.4-million-year-old Ardipithecus ramidus.
+    |]
+    [text|
+    https://www.smithsonianmag.com/science-nature/becoming-human-the-evolution-of-walking-upright-13837658/
+    |],
+
+    CalendarEntry (300 & thousandYearsAgo) Nothing
+    "Modern humans evolve"
+    ""
+    [text|
+    Among the oldest known remains of Homo sapiens are those found at the
+    Omo-Kibish I archaeological site in south-western Ethiopia, dating to about
+    233,000[2] to 196,000 years ago,[3] the Florisbad site in South Africa,
+    dating to about 259,000 years ago, and the Jebel Irhoud site in Morocco,
+    dated about 300,000 years ago.
+    |]
+    [text|
+    https://en.wikipedia.org/wiki/Early_modern_human
+    |],
+
+    CalendarEntry (100 & thousandYearsAgo) Nothing
+    "Human migration out of Africa"
+    ""
+    [text|
+    Between 70,000 and 100,000 years ago, Homo sapiens began migrating from the
+    African continent and populating parts of Europe and Asia. They reached the
+    Australian continent in canoes sometime between 35,000 and 65,000 years ago.
+
+    Map of the world showing the spread of Homo sapiens throughout the Earth
+    over time.
+    |]
+    [text|
+    https://www.khanacademy.org/humanities/world-history/world-history-beginnings/origin-humans-early-societies/a/where-did-humans-come-from
+    |],
+
+    CalendarEntry (600 & millionYearsAgo) Nothing
+    "Multicellular life"
+    ""
+    [text|
+    |]
+    "",
+
+    CalendarEntry (2.6 & millionYearsAgo) Nothing
+    "First Stone Tools"
+    [text|
+    Mode I: The Oldowan Industry
+    Stone flakes with sharp edges for cutting
+    |]
+    [text|
+    The earliest known Oldowan tools yet found date from 2.6 million years ago,
+    during the Lower Palaeolithic period, and have been uncovered at Gona in
+    Ethiopia.[16] After this date, the Oldowan Industry subsequently spread
+    throughout much of Africa, although archaeologists are currently unsure
+    which Hominan species first developed them, with some speculating that it
+    was Australopithecus garhi, and others believing that it was in fact Homo
+    habilis.[17]
+
+    Homo habilis was the hominin who used the tools for most of the Oldowan in
+    Africa, but at about 1.9-1.8 million years ago Homo erectus inherited them.
+    The Industry flourished in southern and eastern Africa between 2.6 and 1.7
+    million years ago, but was also spread out of Africa and into Eurasia by
+    travelling bands of H. erectus, who took it as far east as Java by 1.8
+    million years ago and Northern China by 1.6 million years ago.
+    |]
+    "",
+
+    CalendarEntry (1.8 & millionYearsAgo) Nothing
+    "First major transition in stone tool technology"
+    [text|
+    Mode II: The Acheulean Industry
+    Stone hand-axes shaped symmetrically from two sides
+    |]
+    [text|
+    From the Konso Formation of Ethiopia, Acheulean hand-axes are dated to about
+    1.5 million years ago using radiometric dating of deposits containing
+    volcanic ashes.[6] Acheulean tools in South Asia have also been found to be
+    dated as far as 1.5 million years ago.[7] However, the earliest accepted
+    examples of the Acheulean currently known come from the West Turkana region
+    of Kenya and were first described by a French-led archaeology team.[8] These
+    particular Acheulean tools were recently dated through the method of
+    magnetostratigraphy to about 1.76 million years ago, making them the oldest
+    not only in Africa but the world.[9] The earliest user of Acheulean tools
+    was Homo ergaster, who first appeared about 1.8 million years ago. Not all
+    researchers use this formal name, and instead prefer to call these users
+    early Homo erectus.[3]
+    |]
+    "",
+
+    CalendarEntry (160 & thousandYearsAgo) Nothing
+    "Second major transition in stone tool technology"
+    [text|
+    Mode III: The Levallois technique; The Mousterian Industry
+    Stone scrapers, knives, and projectile points
+    |]
+    [text|
+    Levallois is a "prepared-core" technique: one face of a stone core is fully
+    shaped by knapping in perparation. Then a large sharp flake is created by
+    cracking off the entire prepared face in one final stroke.
+
+    The technique is first found in the Lower Palaeolithic but is most commonly
+    associated with the Neanderthal Mousterian industries of the Middle
+    Palaeolithic. In the Levant, the Levallois technique was also used by
+    anatomically modern humans during the Middle Stone Age. In North Africa, the
+    Levallois technique was used in the Middle Stone Age, most notably in the
+    Aterian industry to produce very small projectile points. While Levallois
+    cores do display some variability in their platforms, their flake production
+    surfaces show remarkable uniformity. As the Levallois technique is
+    counterintuitive, teaching the process is necessary and thus language is a
+    prerequisite for such technology.[2]
+
+    The Mousterian (or Mode III) is a techno-complex (archaeological industry)
+    of stone tools, associated primarily with the Neanderthals in Europe, and to
+    a lesser extent the earliest anatomically modern humans in North Africa and
+    West Asia. The Mousterian largely defines the latter part of the Middle
+    Paleolithic, the middle of the West Eurasian Old Stone Age. It lasted
+    roughly from 160,000 to 40,000 BP. If its predecessor, known as Levallois or
+    Levallois-Mousterian, is included, the range is extended to as early as c.
+    300,000–200,000 BP.[2] The main following period is the Aurignacian (c.
+    43,000–28,000 BP) of Homo sapiens.
+    |]
+    "",
+
+    CalendarEntry (115 & thousandYearsAgo) (Just $ 11.7 & thousandYearsAgo)
+    "The Ice Age begins"
+    "Glaciers cover most land on Earth, joining Asia to North America"
+    [text|
+    The Last Glacial Period (LGP), also known colloquially as the last ice age
+    or simply ice age,[1] occurred from the end of the Eemian to the end of the
+    Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago. The
+    LGP is part of a larger sequence of glacial and interglacial periods known
+    as the Quaternary glaciation which started around 2,588,000 years ago and is
+    ongoing.[2] The definition of the Quaternary as beginning 2.58 million years
+    ago (Mya) is based on the formation of the Arctic ice cap. The Antarctic ice
+    sheet began to form earlier, at about 34 Mya, in the mid-Cenozoic
+    (Eocene–Oligocene extinction event). The term Late Cenozoic Ice Age is used
+    to include this early phase.[3]
+    |]
+    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
+
+    CalendarEntry (50 & thousandYearsAgo) Nothing
+    "Third major transition in stone tool technology"
+    [text|
+    Mode IV: The Aurignacian Industry
+    Long stone blades
+    |]
+    [text|
+    The widespread use of long blades (rather than flakes) of the Upper
+    Palaeolithic Mode 4 industries appeared during the Upper Palaeolithic
+    between 50,000 and 10,000 years ago, although blades were produced in small
+    quantities much earlier by Neanderthals.[20] The Aurignacian culture seems
+    to have been the first to rely largely on blades.[21] The use of blades
+    exponentially increases the efficiency of core usage compared to the
+    Levallois flake technique, which had a similar advantage over Acheulean
+    technology which was worked from cores.
+    |]
+    "https://en.wikipedia.org/wiki/Stone_tool#Mode_IV:_The_Aurignacian_Industry",
+
+    CalendarEntry (35 & thousandYearsAgo) Nothing
+    "Last major transition in stone tool technology"
+    [text|
+    Mode V: The Microlithic Industries
+    Stone blades fastened to wood or bone handles
+    |]
+    [text|
+    Mode 5 stone tools involve the production of microliths, which were
+    used in composite tools, mainly fastened to a shaft.[22] Examples include
+    the Magdalenian culture. Such a technology makes much more efficient use of
+    available materials like flint, although required greater skill in
+    manufacturing the small flakes. Mounting sharp flint edges in a wood or bone
+    handle is the key innovation in microliths, essentially because the handle
+    gives the user protection against the flint and also improves leverage of
+    the device.
+    |]
+    "https://en.wikipedia.org/wiki/Stone_tool#Mode_V:_The_Microlithic_Industries"
+    ,
+
+    CalendarEntry (12 & thousandYearsAgo) Nothing
+    "Agriculture leads to permanent settlements"
+    "Neolithic age (\"new stone age\")"
+    [text|
+    Wild grains were collected and eaten from at least 105,000 years ago.[2]
+    However, domestication did not occur until much later. The earliest evidence
+    of small-scale cultivation of edible grasses is from around 21,000 BC with
+    the Ohalo II people on the shores of the Sea of Galilee.[3] By around 9500
+    BC, the eight Neolithic founder crops – emmer wheat, einkorn wheat, hulled
+    barley, peas, lentils, bitter vetch, chickpeas, and flax – were cultivated
+    in the Levant.[4] Rye may have been cultivated earlier, but this claim
+    remains controversial.[5] Rice was domesticated in China by 6200 BC[6] with
+    earliest known cultivation from 5700 BC, followed by mung, soy and azuki
+    beans. Rice was also independently domesticated in West Africa and
+    cultivated by 1000 BC.[7][8] Pigs were domesticated in Mesopotamia around
+    11,000 years ago, followed by sheep. Cattle were domesticated from the wild
+    aurochs in the areas of modern Turkey and India around 8500 BC. Camels were
+    domesticated late, perhaps around 3000 BC.
+    |]
+    "https://en.wikipedia.org/wiki/History_of_agriculture",
+
+    CalendarEntry (6.5 & thousandYearsAgo) Nothing
+    "First copper tools"
+    ""
+    ""
+    "",
+
+    CalendarEntry (5.3 & thousandYearsAgo) Nothing
+    "First bronze tools, first written language"
+    "The Bronze Age"
+    ""
+    "",
+
+    CalendarEntry (3000 & yearsBeforeCommonEra) (Just $ 2350 & yearsBeforeCommonEra)
+    "Corded Ware culture"
+    "Indo-European languages spread across Europe and Asia"
+    [text|
+    The Corded Ware culture comprises a broad archaeological horizon of Europe
+    between ca. 3000 BCE – 2350 BCE, thus from the late Neolithic, through the
+    Copper Age, and ending in the early Bronze Age.[2] Corded Ware culture
+    encompassed a vast area, from the contact zone between the Yamnaya culture
+    and the Corded Ware culture in south Central Europe, to the Rhine on the
+    west and the Volga in the east, occupying parts of Northern Europe, Central
+    Europe and Eastern Europe.[2][3] The Corded Ware culture is thought to have
+    originated from the westward migration of Yamnaya-related people from the
+    steppe-forest zone into the territory of late Neolithic European cultures
+    such as the Globular Amphora and Funnelbeaker cultures,[4][5][6] and is
+    considered to be a likely vector for the spread of many of the Indo-European
+    languages in Europe and Asia.[1][7][8][9]
+
+    Corded Ware encompassed most of continental northern Europe from the Rhine
+    on the west to the Volga in the east, including most of modern-day Germany,
+    the Netherlands, Denmark, Poland, Lithuania, Latvia, Estonia, Belarus, Czech
+    Republic, Austria, Hungary, Slovakia, Switzerland, northwestern Romania,
+    northern Ukraine, and the European part of Russia, as well as coastal Norway
+    and the southern portions of Sweden and Finland.[2] In the Late
+    Eneolithic/Early Bronze Age, it encompassed the territory of nearly the
+    entire Balkan Peninsula, where Corded Ware mixed with other steppe
+    elements.[11]
+
+    Archaeologists note that Corded Ware was not a "unified culture," as Corded
+    Ware groups inhabiting a vast geographical area from the Rhine to Volga seem
+    to have regionally specific subsistence strategies and economies.[2]: 226 
+    There are differences in the material culture and in settlements and
+    society.[2] At the same time, they had several shared elements that are
+    characteristic of all Corded Ware groups, such as their burial practices,
+    pottery with "cord" decoration and unique stone-axes.[2]
+    |]
+    "",
+
+    CalendarEntry (2800 & yearsBeforeCommonEra) (Just $ 1800 & yearsBeforeCommonEra)
+    "Bell Beaker culture"
+    [text|
+    copper daggers, v-perforated buttons, stone wrist-guards
+    copper, bronze, and gold working
+    long-distance exchange networks, archery
+    social stratification and the emergence of regional elites
+    |]
+    [text|
+    The Bell Beaker culture (also described as the Bell Beaker complex or Bell
+    Beaker phenomenon) is an archaeological culture named after the
+    inverted-bell beaker drinking vessel used at the very beginning of the
+    European Bronze Age. Arising from around 2800 BC, it lasted in Britain until
+    as late as 1800 BC[1][2] but in continental Europe only until 2300 BC, when
+    it was succeeded by the Unetice culture. The culture was widely dispersed
+    throughout Western Europe, being present in many regions of Iberia and
+    stretching eastward to the Danubian plains, and northward to the islands of
+    Great Britain and Ireland, and was also present in the islands of Sicily and
+    Sardinia and some small coastal areas in north-western Africa. The Bell
+    Beaker phenomenon shows substantial regional variation, and a study[3] from
+    2018 found that it was associated with genetically diverse populations.
+
+    In its mature phase, the Bell Beaker culture is understood as not only a
+    collection of characteristic artefact types, but a complex cultural
+    phenomenon involving metalwork in copper and gold, long-distance exchange
+    networks, archery, specific types of ornamentation, and (presumably) shared
+    ideological, cultural and religious ideas, as well as social stratification
+    and the emergence of regional elites.[6][7] A wide range of regional
+    diversity persists within the widespread late Beaker culture, particularly
+    in local burial styles (including incidences of cremation rather than
+    burial), housing styles, economic profile, and local ceramic wares
+    (Begleitkeramik). Nonetheless, according to Lemercier (2018) the mature
+    phase of the Beaker culture represents "the appearance of a kind of Bell
+    Beaker civilization of continental scale."[8]
+
+    Bell Beaker people took advantage of transport by sea and rivers, creating a
+    cultural spread extending from Ireland to the Carpathian Basin and south
+    along the Atlantic coast and along the Rhône valley to Portugal, North
+    Africa, and Sicily, even penetrating northern and central Italy.[50] Its
+    remains have been found in what is now Portugal, Spain, France (excluding
+    the central massif), Ireland and Great Britain, the Low Countries and
+    Germany between the Elbe and Rhine, with an extension along the upper Danube
+    into the Vienna Basin (Austria), Hungary and the Czech Republic, with
+    Mediterranean outposts on Sardinia and Sicily; there is less certain
+    evidence for direct penetration in the east.
+    |]
+    "https://en.wikipedia.org/wiki/Bell_Beaker_culture",
+
+    CalendarEntry (11.7 & thousandYearsAgo) Nothing
+    "Ice Age ends"
+    ""
+    ""
+    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
+
+    CalendarEntry (1600 & yearsBeforeCommonEra) Nothing
+    "Dynastic China"
+    "History begins"
+    [text|
+    The earliest known written records of the history of China date from as
+    early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the king
+    Wu Ding's reign
+
+    The state-sponsored Xia–Shang–Zhou Chronology Project dated them from c.
+    1600 to 1046 BC based on the carbon 14 dates of the Erligang site.
+    |]
+    "",
+
+    CalendarEntry (480 & yearsBeforeCommonEra) Nothing
+    "Old Testament, Buddha"
+    ""
+    ""
+    "",
+
+    CalendarEntry (6 & yearsBeforeCommonEra) Nothing
+    "Christ born"
+    ""
+    ""
+    "",
+
+    -- CalendarEntry (300 & yearsBeforeCommonEra) Nothing
+    -- "Eratosthenes calculates the circumference of Earth"
+    -- ""
+    -- ""
+    -- "",
+
+    CalendarEntry (theYear 570) Nothing
+    "Muhammad born"
+    ""
+    ""
+    "",
+
+    CalendarEntry (theYear 1492) Nothing
+    "Columbus arrives in America"
+    ""
+    ""
+    ""
+  ]