Editing Template:Period start

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<!-- Some other notable dates -->

|burgess shale|middle middle cambrian<!--Middle middle is approximate; cf. Burgess Shale-->=508
|chengjiang=518
|sirius passet=518
|doushantou=570

<!-- Data from ICS chart

| Supereon
|   Eon
|     Era
|       Period
|         Epoch/Series
|           Age/Stage
|             other division (other sources - not in ICS chart)
The names from the ICS chart are always first on the line.
-->
| precambrian
|   hadean              = 4567
|   archean
|     eoarchean | isuan = 4031
|     paleoarchean      = 3600
|     mesoarchean       = 3200
|     neoarchean        = 2800
|   proterozoic
|     paleoproterozoic
|       siderian        = 2500
|       rhyacian        = 2300
|       orosirian       = 2050
|       statherian      = 1800
|     mesoproterozoic
|       calymmian       = 1600
|       ectasian | riphean
                        = 1400
|       stenian         = 1200
|             mayanian  = 1100
|             sinian | sturtian
                        = 1050
|     neoproterozoic
|       tonian          = 1000
|             baikalian = 850 
|       cryogenian      = 720
|       ediacaran | vendian
                        = 635
  <!-- end of precambrian -->
|   phanerozoic
|     paleozoic
|       cambrian
|        lower cambrian <!-- group of two epochs, not in ICS chart -->
|         terreneuvian | lowest cambrian | earliest cambrian
|           fortunian
|             manykaian | nemakit daldynian
                         = 538.8
|             caerfai | tommotian
                         = 530
|           cambrian stage 2
                         = 529
|         cambrian series 2
|           cambrian stage 3 | middle lower cambrian
|             atdabanian = 521
|             botomian   = 522
|             toyonian | upper lower cambrian
                         = 516
|           cambrian stage 4
                         = 514.5
         <!-- end of lower cambrian -->
|         cambrian series 3 | middle cambrian | miaolingian
|           cambrian stage 5 | lower middle cambrian | st davids | wuliuan
                         = 506.5
|           drumian      = 504.5
|           guzhangian | nganasanian | mindyallan
                         = 500.5
|         furongian | upper cambrian | merioneth
|           paibian | franconian<!--unofficial and approximate!-->
                         = 497
|           jiangshanian = 494.2
|             upper upper cambrian | mansian
                         = 489.5
|           cambrian stage 10     = 491.0
|       ordovician
|         lower ordovician
|           tremadocian  = 486.85
|             upper lower ordovician
                         = 479
|           floian | arenig
                         = 477.1
|         middle ordovician
|           dapingian | ordovician iii | lower middle ordovician
                         = 471.3
|           darriwilian  = 469.4
|         upper ordovician
|           sandbian | ordovician v | lower upper ordovician
                         = 458.2
|             middle upper ordovician
                         = 455
|           katian | ordovician vi
                         = 452.8
|           hirnantian   = 445.2
|       silurian
|         llandovery | lower silurian
|           rhuddanian   = 443.1
|           aeronian     = 440.5
|           telychian    = 438.6
|         wenlock
|           sheinwoodian = 432.9
|           homerian     = 430.6
|         ludlow | upper silurian
|           gorstian     = 426.7
|           ludfordian   = 425
|         pridoli
|           unnamed pridoli stage
                         = 422.7
|       devonian
|         lower devonian
|           lochkovian | downtonian<!--approx-->
                         = 419.62
|           pragian | praghian
                         = 413.02
|           emsian       = 410.62
|         middle devonian
|           eifelian     = 393.47
|           givetian     = 387.95
|         upper devonian
|           frasnian     = 382.31
|           famennian    = 372.15
|       carboniferous
|        mississippian | lower carboniferous <!-- Subperiod from ICS chart -->
|         lower mississippian
|           tournaisian  = 358.86
|         middle mississippian
|           visean       = 346.7
|         upper mississippian
|           serpukhovian = 330.3
|             namurian   = 326
|        pennsylvanian | upper carboniferous <!-- Subperiod from ICS chart -->
|         lower pennsylvanian
|           bashkirian   = 323.4
|             westphalian= 313
|         middle pennsylvanian
|           moscovian    = 315.2
|         upper pennsylvanian
|           kasimovian   = 307.0
|             stephanian = 304
|           gzhelian     = 303.7
|       permian
|         cisuralian | lower permian
|           asselian     = 298.9
|           sakmarian    = 293.52
|           artinskian   = 290.1
|           kungurian    = 283.3
|         guadalupian | middle permian
|           roadian | ufimian
                         = 274.4
|           wordian      = 266.9
|           capitanian   = 264.28
|         lopingian | upper permian
|           wuchiapingian | longtanian
                         = 259.51
|           changhsingian= 254.14
|     mesozoic
|       triassic
|         lower triassic
|           induan       = 251.902
|           olenekian | spathian
                         = 249.9
|         middle triassic 
|           anisian      = 246.7
|           ladinian     = 241.464
|         upper triassic
|           carnian      = 237
|           norian       = 227.3
|           rhaetian     = 205.7
|       jurassic
|         lower jurassic
|           hettangian   = 201.4
|           sinemurian   = 199.5
|           pliensbachian= 192.9
|           toarcian     = 184.2
|         middle jurassic
|           aalenian     = 174.7
|           bajocian     = 170.9
|           bathonian    = 168.2
|           callovian    = 165.3
|         upper jurassic
|           oxfordian    = 161.5
|           kimmeridgian = 154.8
|           tithonian    = 149.2
|       cretaceous
|         lower cretaceous
|           berriasian | neocomian
                         = 143.1
|           valanginian  = 137.05
|           hauterivian  = 132.6
|           barremian | gallic
                         = 125.77
|           aptian       = 121.4
|           albian       = 113.2
|         upper cretaceous
|           cenomanian   = 100.5
|           turonian     = 93.9
|           coniacian | senonian
                         = 89.8
|           santonian    = 85.7
|           campanian    = 83.6
|           maastrichtian= 72.2
|     cenozoic
|      tertiary <!-- Group of 2 periods, former term -->
|       paleogene
|         paleocene
|           danian | lower paleocene
                         = 66.0
|             puercan    = 65
|             torrejonian= 63.3
|           selandian | middle paleocene
                         = 61.66
|             tiffanian  = 60.2
|           thanetian | upper paleocene
                         = 59.24
|             clarkforkian
                         = 56.8
|         eocene
|           ypresian | lower eocene | mp 10
                         = 56.00
|             wasatchian = 55.4
|             bridgerian = 50.3
|          middle eocene <!-- Group of two stages, not in ICS chart -->
|           lutetian | mp 11
                         = 48.07
|             uintan     = 46.2
|             duchesnean = 42
|           bartonian    = 41.03
|             chadronian = 38
           <!-- end of middle eocene -->
|           priabonian | upper eocene
                         = 37.71
|         oligocene
|           rupelian | lower oligocene
|             orellan    = 33.90
|             whitneyan  = 33.3
|             arikeean   = 30.6
|           chattian | upper oligocene
                         = 27.30
|       neogene
|         miocene
|          lower miocene
|           aquitanian   = 23.04
|             hemingfordian
                         = 20.6
|           burdigalian  = 20.45
|             barstovian = 16.3
|          middle miocene
|           langhian     = 15.98
|           serravallian = 13.82
|             clarendonian
                         = 13.6
|          upper miocene
|           tortonian    = 11.63
|             hemphillian= 10.3
|           messinian    = 7.246
|         pliocene
|           zanclean | lower pliocene
                         = 5.333
|             blancan    = 4.75
|           piacenzian | upper pliocene
                         = 3.600
       <!-- end of tertiary -->
|       quaternary
|         pleistocene
|          lower pleistocene
|           gelasian     = 2.58
|           calabrian    = 1.80
|             irvingtonian
                         = 1.8
           <!-- end of lower pleistocene -->
|           middle pleistocene | ionian | chibanian<!--the name "Chibanian" was formally adopted for this stage by the ICS in January 2020. The term "Ionian" was a proposed term for this same span of time.-->
                         = 0.774<!--this date has been redefined by the ICS.-->
|             rancholabrean
                         = 0.24
|           upper pleistocene | tarantian<!--proposed name for this as-yet formally undefined stage-->
                         = 0.129<!--this date has been redefined by the ICS.-->
|         holocene
|           greenlandian | lower holocene   
                         = 0.0117
|           northgrippian | middle holocene
                         =0.0082
|           meghalayan | upper holocene
                         =0.0042
|           
| now | recent | present | current
                         = 0

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