AB.Base*****Emsian*.1505376344086*405.57
AP.Base*****Emsian*.8172043010753*399.237
Actonian.Base*****Ordovician VI*0.176471*454
Adelaidean.Base*****Ectasian*0.5*1300
Aeronian.Base*439.0*1.8*Graptolite, lowest occurrence of Monograptus austerus sequens.*Trefawr forestry road, north of Cwm-coed-Aeron Farm, Llandovery area, south-central Wales, UK*Aeronian*0*439
Aksayan.Base*****Late Cambrian*0.629921*493
Alaunian.Base*****Norian*0.0387597*216
Albian.Base*112.0*1.0*Calcareous nannofossil, lowest occurrence of Praediscosphaera columnata (= P. cretacea of some earlier studies), is one potential marker.**Albian*0*112
Aldingian.Base*****Priabonian*0.363636*36
Aldingian.Top*****Rupelian*0.163636*33
Alportian.Base*****Serpukhovian*0.228916*324.5
Altonian.Base*****Burdigalian*0.656951*17.5
Animikean.Base*****Rhyacian*0.3*2225
Antipleura bohemica.Base*****Lochkovian*0.0*416
Aptian.Base*125.0*1.0*Magnetic polarity chronozone, base of M0r.**Aptian*0*125
Archean.Base*3800*0.7***Eoarchean*0*3800
Arenig.Base*478.6*1.7*Graptolite, lowest occurrence of Tetragraptus approximatus.*Diabasbrottet quarry, Ødstergøtland, southern Sweden*Arenig*0*478.6
Arikareean.Base*****Rupelian*0.618182*30.5
Arnsbergian.Base*****Serpukhovian*0.0481928*326
Arowhanan.Base*****Cenomanian*0.754098*95
Artinskian.Base*284.4*0.7*Near lowest occurrence of conodont Sweetognathus whitei-Mesogondolella bisselli.**Artinskian*0*284.4
Arundian.Base*****Visean*0.227513*341
Asbian.Base*****Visean*0.412698*337.5
Ashgill.Base*****Ordovician VI*0.666667*449
Atdabanian.Base*****Early Cambrian*0.413793*530
Awamoan.Base*****Burdigalian*0.0964126*20
BZ.Base*****Lochkovian*.7532467532468*412.384
Bairnsdalian.Base*****Langhian*0.418103*15
Baishaean.Base*****Telychian*0.384615*433
Bajocian.Base*171.6*3.0*Ammonite, lowest occurrence of the genus Hyperlioceras (defines base of the Hyperlioceras discites Zone).*Cabo Mondego, western Portugal*Bajocian*0*171.6
Balcombian.Base*****Langhian*0.202586*15.5
Barremian.Base*130.0*1.5*Ammonite, lowest occurrence of Spitidiscus hugii - Spitidiscus vandeckii group.**Barremian*0*130
Barstovian.Base*****Langhian*0.202586*15.5
Bartonian.Base*40.4*0.2*Near extinction of calcareous nannofossil Reticulofenestra reticulata.**Bartonian*0*40.4
Basin Groups.Base*****Hadean*0.543778*4150
Batesfordian.Base*****Burdigalian*0.881166*16.5
Bathonian.Base*167.7*3.5*Ammonite, lowest occurrence of Parkinsonia (G.) convergens (defines base of Zigzagiceras zigzag Zone).**Bathonian*0*167.7
Batyrbayan.Base*****Late Cambrian*0.748031*491.5
Bendigonian.Base*****Arenig*0.529412*475
Bithynian.Base*****Anisian*0.25*243
Blancan.Base*****Zanclean*0.336028*4.75
Bolindian.Base*****Ordovician VI*0.568627*450
Boomerangian.Base*****Middle Cambrian*0.75*504
Bortonian.Base*****Lutetian*0.560976*44
Botomian.Base*****Early Cambrian*0.62069*524
Bridgerian.Base*****Ypresian*0.736111*50.5
Brigantian.Base*****Visean*0.492063*336
Burdigalian.Base*20.43*0.05*Near lowest occurrence of planktonic foraminifer Globigerinoides altiaperturus or top of magnetic polarity chronozone C6An.**Burdigalian*0*20.43
Burrellian.Base*****Ordovician V*0.764706*457
Callovian.Base*164.7*4.0*Ammonite, lowest occurrence of the genus Kepplerites (Kosmoceratidae).  (Defines base of Macrocephalites herveyi Zone in sub-Boreal province of Great Britain to southwest Germany.)**Callovian*0*164.7
Campanian.Base*83.5*0.7*Crinoid, extinction of Marsupites testudinarius.**Campanian*0*83.5
Capitanian.Base*265.8*0.7*Conodont, lowest occurrence of Jinogondolella postserrata.*Pinery Limestone Member, Nipple Hill, SE Guadalupe Mountains, Texas, USA*Capitanian*0*265.8
Carboniferous.Base*359.2*2.5*Conodont, above lowest occurrence of Siphonodella sulcata.*La Serre, Montagne Noir, Cabrieres, southern France*Tournaisian*0*359.2
Cassinian.Base*****Arenig*0.823529*473
Castlemanian.Base*****Ordovician III*0.216216*471
Cautleyan.Base*****Ordovician VI*0.813725*447.5
Cenozoic.Base*65.5*0.3*Iridium Anomaly.  Associated with a major extinction horizon (foraminifers, calcareous nannofossils, dinosaurs, etc.)*Base of boundary clay, El Kef, Tunisia*Danian*0*65.5
Chadronian.Base*****Priabonian*0.0606061*37
Chamovnicheskian.Base*****Kasimovian*0.192308*306
Changhsingian.Base*253.8*0.7*Near lowest occurrence of conodont Clarkina wangi.**Changhsingian*0*253.8
Changlangpuan.Base*****Early Cambrian*0.655172*523
Chatauquan.Base*****Famennian*0.294118*370
Chattian.Base*28.4*0.1*Planktonic foraminifer, extinction of Chiloguembelina (base Zone P21b).**Chattian*0*28.4
Cheltenhamian.Base*****Zanclean*0.191686*5
Cheneyan.Base*****Ordovician VI*0.0784314*455
Cheremshanskian.Base*****Bashkirian*0.5625*314.5
Chesterian.Base*****Visean*0.650794*333
Chewtonian.Base*****Arenig*0.823529*473
Chokerian.Base*****Serpukhovian*0.168675*325
Cincinnatian.Base*****Ordovician VI*0.470588*451
Clarendonian.Base*****Serravallian*0.905975*11.8
Clarkforkian.Base*****Thanetian*0.931034*56
Cliffdenian.Base*****Burdigalian*0.881166*16.5
Comanchean.Base*****Barremian*0.6*127
Coniacian.Base*89.3*1.0*Inoceramid bivalve, lowest occurrence of Cremnoceramus rotundatus.*Salzgitter-Salder Quarry, SW of Hannover, Lower Saxony, northern Germany*Coniacian*0*89.3
Cretaceous.Base*145.5*4.0*Maybe near lowest occurrence of ammonite Berriasella jacobi.**Berriasian*0*145.5
Cryogenian.Base*850*0*Fixed Date**Cryogenian*0*850
Dalanian.Base*****Bashkirian*0.796875*313
Dalejan.Base*****Emsian*0.4301075268817*402.914
Darriwilian.Base*468.1*1.6*Graptolite, lowest occurrence of Undulograptus austrodentatus.*Ningkuo Formation, Huangnitang, Changshan, Zhejiang province, southeast China*Darriwilian*0*468.1
Datangian.Base*****Visean*0.015873*345
Dawanian.Base*****Arenig*0.970588*472
Delamaran.Base*****Middle Cambrian*0.0833333*512
Delmontian.Base*****Tortonian*0.94177*7.5
Desmoinian.Base*****Moscovian*0.711538*308
Devonian.Base*416.0*2.8*Graptolite, lowest occurrence of Monograptus uniformis.*Klonk, Barrandian area, southwest of Prague, Czech Republic*Lochkovian*0*416
Dewuan.Base*****Visean*0.650794*333
Dienerian.Base*****Induan*0.461538*250.4
Dolgellian.Base*****Late Cambrian*0.669291*492.5
Dongganglingian.Base*****Givetian*0.0615385*391.4
Duchesnean.Base*****Bartonian*0.125*40
Duntroonian.Base*****Chattian*0.0744879*28
Dyeran.Base*****Early Cambrian*0.603448*524.5
Eastonian.Base*****Ordovician V*0.960784*456
Ectasian.Base*1400*0*Fixed Date**Ectasian*0*1400
Ediacaran.Base*630*5*Termination of Varanger (or Marinoan) glaciation, and distinctive C-13 change.**Ediacaran*0*630
Eildonian.Base*****Telychian*0.384615*433
Emsian.Base*407.0*2.8*Conodont, lowest occurrence of Polygnathus kitabicus (= Po. dehiscens).*Zinzil'ban Gorge, SE of Samarkand, Uzbekistan*Emsian*0*407
Eocene.Base*55.8*0.2*Base of negative carbon-isotope excursion.*Dababiya Section near Luxor, Egypt*Ypresian*0*55.8
Erqiaoan.Base*****Norian*0.581395*209
Etalian.Base*****Anisian*0.25*243
FD.Base*****Emsian*.4516129032258*402.71
Famennian.Base*374.5*2.6*Just above major extinction horizon (Upper Kellwasser Event), including conodonts Ancyrodella and Ozarkodina and goniatites of Gephuroceratidae and Beloceratidae.*Upper Coumiac quarry, Cessenon, Montagne Noir, southern France*Famennian*0*374.5
Fennian.Base*****Arenig*0.75*473.5
Festiniogian.Base*****Late Cambrian*0.330709*496.8
Florian.Base*****Middle Cambrian*0.416667*508
Fronian.Base*****Aeronian*0.5*437.5
Fujian.Base*****Tortonian*0.11646*11.1
Fupingan.Base*****Mesoarchean*0.25*3100
Fuvelian.Base*****Campanian*0.503876*77
Gelasian.Base*2.588*0.005*Isotopic stage 103, base of magnetic polarity chronozone C2r (Matuyama).  Above are extinction levels of calcareous nannofossil Discoaster pentaradiatus and D. surculus.*Nicola Bed, Monte San Nicola, Gela, Sicily, Italy*Gelasian*0*2.588
Givetian.Base*391.8*2.7*Conodont, lowest occurrence of Polygnathus hemiansatus, near base of goniatite stage "Maenioceras Stufe".*Jebel Mech Irdane ridge, Tafilalt, Morocco*Givetian*0*391.8
Gleedonian.Base*****Homerian*0.242424*425.4
Guandian.Base*****Homerian*0.212121*425.5
Gyliakian.Base*****Cenomanian*0.491803*96.6
Gzhelian.Base*303.9*0.9*Near lowest occurrences of the fusulinids Daixina, Jigulites and Rugosofusulina, or lowest occurrence of Streptognathodus zethu.**Gzhelian*0*303.9
Hadean.Base*4567.17*0.7*Formation of Earth**Hadean*0*4567.17
Haranoyan.Base*****Burdigalian*0.5*18.2
Harnagian.Base*****Ordovician V*0.372549*459
Hauterivian.Base*136.4*2.0*Ammonite, lowest occurrence of genus Acanthodiscus (especially A. radiatus).**Hauterivian*0*136.4
Hemingfordian.Base*****Burdigalian*0.320628*19
Hemphillian.Base*****Tortonian*0.597891*9
Hercynella-Neklania.Base*****Lochkovian*.1315789473684*415.368
Heretaungan.Base*****Ypresian*0.805556*50
Heterian.Base*****Oxfordian*0.945455*156
Hetonian.Base*****Campanian*0.496124*77.1
Hirnantian.Base*445.6*1.5*Potentially at base of the Normalograptus extraordinarius-N. ojsuensis graptolite biozone.**Hirnantian*0*445.6
Holkerian.Base*****Visean*0.333333*339
Holocene.Base*0.01143*0.00013*Excatly 10,000 Carbon-14 years BP.  Near the end of the Younger Dryas cold spell.**Holocene*0*0.01143
Holocene.Top*0*0**1950 A.D.*Now*0*0
Homerian.Base*426.2*2.4*Graptolite, lowest occurrence of Cyrtograptus lundgreni.*Whitwell Coppice, Homer, Shropshire, southwest England, UK*Homerian*0*426.2
Huobachengian.Base*****Carnian*0.782609*219
Hutchinsonian.Base*****Aquitanian*0.780769*21
Ibexian.Base*****Late Cambrian*0.787402*491
Idamean.Base*****Late Cambrian*0.314961*497
Idamean.Top*****Late Cambrian*0.551181*494
Illyrian.Base*****Anisian*0.75*239
Imbrian.Base*****Hadean*0.869651*3900
Isuan.Top*****Paleoarchean*0.25*3500
Janjukian.Base*****Rupelian*0.709091*30
Jeffersonian.Base*****Arenig*0.529412*475
Jinningian.Base*****Statherian*0.25*1750
Joachimia-Cardiolinka-Pygolfia.Base*****Pridoli*.775*416.608
Johannian.Base*****Ypresian*0.527778*52
Jurassic.Base*199.6*0.6*Near lowest occurrence of smooth Psiloceras planorbis ammonite group.**Hettangian*0*199.6
Kaburan.Base*****Serravallian*0.0734574*13.5
Kaihikuan.Base*****Ladinian*0.555556*232
Kalimnan.Base*****Zanclean*0.595843*4.3
Kapitean.Base*****Messinian*0.650993*6
Karatau.Base*****Stenian*0.5*1100
Kashirskian.Base*****Moscovian*0.480769*309.2
Kasimovian.Base*306.5*1.0*Near base of Obsoletes obsoletes and Protriticites pseudomontiparus fusulinid zone, or lowest occurrence of Parashumardites ammonoid.**Kasimovian*0*306.5
Kechienjian.Base*****Gelasian*0.879795*1.9
Kiaitan.Base*****Bartonian*0.125*40
Kimmeridgian.Base*155.7*4.0*Ammonite, near base of Pictonia baylei ammonite zone of Boreal realm.**Kimmeridgian*0*155.7
Korangian.Base*****Aptian*0.461538*119
Kungurian.Base*275.6*0.7*Near lowest occurrence of conodont Neostreptognathus pnevi - N. exculptus.**Kungurian*0*275.6
Ladinian.Base*237.0*2.0*Alternate levels are near base of Reitzi, Secedensis, or Curionii ammonite zone; near first occurrence of the conodont genus Budurovignathus.**Ladinian*0*237
Lancefieldian.Base*****Tremadocian*0.649485*482
Langhian.Base*15.97*0.05*Near first occurrence of planktonic foraminifer Praeorbulina glomerosa and top of magnetic polarity chronozone C5Cn.1n.**Langhian*0*15.97
Late Cambrian.Base*501.0*2.0*Trilobite, lowest occurrence of agnostoid Glyptagnostus reticulatus.  Coincides with base of large positive carbon-isotope excursion.*Huaqiao Formation, Paibi section, Northwest Hunan province, south China*Late Cambrian*0*501
Late Cretaceous.Base*99.6*0.9*Planktonic foraminifer, lowest occurrence of Rotalipora globotruncanoides.*Mont Risou, Rosans, Haute-Alpes, SE France*Cenomanian*0*99.6
Late Devonian.Base*385.3*2.6*Conodont, lowest occurrence of Ancyrodella rotundiloba (defines base of Lower Polygnathus asymmetricus conodont Zone).*Col du Puech de la Suque section, St. Nazaire-de-Ladarez, SE Montagne Noir, southern France*Frasnian*0*385.3
Late Jurassic.Base*161.2*4.0*Ammonite, Brightia thuouxensis Horizon at base of the Cardioceras scarburgense Subzone (Quenstedtoceras mariae Zone).**Oxfordian*0*161.2
Late Ordovician.Base*460.9*1.6*Graptolite, lowest occurrence of Nemagraptus gracilis.*F�gels�ng, Skåne, southern Sweden*Ordovician V*0*460.9
Late Permian.Base*260.4*0.7*Conodont, lowest occurrence of conodont Clarkina postbitteri (Mei & Wardlaw); and termination of a major global sea-level lowstand*Guangxi Province, south China*Wuchiapingian*0*260.4
Late Pleistocene.Base*0.126*0.005*Base of the Eemian interglacial stage (base of marine isotope stage 5e) before final glacial episode of Pleistocene.**Late Pleistocene*0*0.126
Late Silurian.Base*422.9*2.5*Imprecise.  Just below base of local acritarch Leptobrachion longhopense range zone.  May be near base of Neodiversograptus nilssoni graptolite zone.*Pitch Coppice quarry, Ludlow, Shropshire, southwest England, UK*Gorstian*0*422.9
Late Triassic.Base*228.0*2.0*Near first occurrence of the ammonoids Daxatina or Trachyceras, and of the conodont Metapolygnathus polygnathiformis.**Carnian*0*228
Leonardian.Base*****Artinskian*0.5*280
Lillburnian.Base*****Langhian*0.418103*15
Linxiangian.Base*****Ordovician VI*0.127451*454.5
Llandeilo.Base*****Darriwilian*0.569444*464
Longfordian.Base*****Chattian*0.167598*27.5
Longobardian.Base*****Ladinian*0.622222*231.4
Longvillian.Base*****Ordovician V*0.764706*457
Longwangmioan.Base*****Early Cambrian*0.827586*518
Lotharingian.Base*****Sinemurian*0.463768*193.3
Ludfordian.Base*421.3*2.6*Imprecise.  May be near base of Saetograptus leintwardinensis graptolite zone.*Sunnyhill Quarry, Ludlow, Shropshire, southwest England, UK*Ludfordian*0*421.3
Luisian.Base*****Langhian*0.202586*15.5
Luliangian.Base*****Siderian*0.75*2350
Lutetian.Base*48.6*0.2*Planktonic foraminifer, lowest occurrence of Hantkenina.**Lutetian*0*48.6
MN.Base*****Lochkovian*0.0*416
Maastrichtian.Base*70.6*0.6*Mean of 12 biostratigraphic criteria of equal importance.  Closely above is lowest occurrence of ammonite Pachydiscus neubergicus.  Boreal proxy is lowest occurrence of belemnite Belemnella lanceolata.*Grande Carriere quarry, Tercis-les-Bains, Landes province, SW France*Maastrichtian*0*70.6
Malakovian.Base*****Olenekian*0.361702*248
Mangaorapan.Base*****Ypresian*0.527778*52
Mangaotanean.Base*****Turonian*0.119048*93
Mangapanian.Base*****Piacenzian*0.988142*2.6
Mangapirian.Base*****Artinskian*0.727273*278
Mapingian.Base*****Moscovian*0.326923*310
Marjuman.Base*****Middle Cambrian*0.75*504
Marsdenian.Base*****Bashkirian*0.171875*317
Marshbrookian.Base*****Ordovician VI*0.0784314*455
Mayan.Base*****Middle Cambrian*0.916667*502
Melekesskian.Base*****Bashkirian*0.734375*313.4
Meramecian.Base*****Visean*0.280423*340
Mesoarchean.Base*3200*0*Fixed Date**Mesoarchean*0*3200
Mesoproterozoic.Base*1600*0*Fixed Date**Calymmian*0*1600
Mesozoic.Base*251.0*0.4*Conodont, lowest occurrence of Hindeodus parvus; termination of major negative carbon-isotope excursion.  About 1 myr after peak of Late Permian extinctions.*Meishan, Zhejiang, China*Induan*0*251
Messinian.Base*7.246*0.005*Middle of magnetic polarity chronozone C3Br.1r; lowest regular occurrence of the Globorotalia conomiozea planktonic foraminifer group.*Oued Akrech, Rabat, Morocco*Messinian*0*7.246
Miaogoalingian.Base*****Gorstian*0.5625*422
Middle Cambrian.Base*513.0*2.0***Middle Cambrian*0*513
Middle Devonian.Base*397.5*2.7*Conodont, lowest occurrence of Polygnathus costatus partitus; major faunal turnover.*Wetteldorf Richtschnitt, Sch�necken-Wetteldorf, Eifel Hills, western Germany*Eifelian*0*397.5
Middle Jurassic.Base*175.6*2.0*Ammonite, lowest occurrence of Leioceras.*Fuentelsalz, central Spain*Aalenian*0*175.6
Middle Ordovician.Base*471.8*1.6*Conodont, potentially lowest occurrence of Protoprioniodus aranda or of Baltoniodus triangularis.**Ordovician III*0*471.8
Middle Permian.Base*270.6*0.7*Conodont, lowest occurrence of Jinogondolella nanginkensis.*Cutoff Formation, Stratotype Canyon, southern Guadalupe Mountains, Texas, USA*Roadian*0*270.6
Middle Pleistocene.Base*0.781*0.005*Brunhes-Matuyama magnetic reversal.**Middle Pleistocene*0*0.781
Middle Triassic.Base*245.0*1.5*Ammonite, near lowest occurrences of genera Japonites, Paradanubites, and Paracrochordiceras; and of the conodont Chiosella timorensis.**Anisian*0*245
Migneintian.Base*****Tremadocian*0.237113*486
Mitchellian.Base*****Tortonian*0.254012*10.5
Mohawkian.Base*****Darriwilian*0.847222*462
Mohnian.Base*****Serravallian*0.0734574*13.5
Montezuman.Base*****Early Cambrian*0.431034*529.5
Mortesnes.Base*****Cryogenian*0.954545*640
Moscovian.Base*311.7*1.1*Near lowest occurrences of Declinognathodus donetzianus and/or Idiognathoides postsulcatus conodont species, and fusulinid species Aljutovella aljutovica.**Moscovian*0*311.7
Motuan.Base*****Albian*0.645161*104
Myachkovskian.Base*****Moscovian*0.865385*307.2
Nagaolingian.Base*****Lochkovian*0.625*413
Namibian.Base*****Tonian*0.666667*900
Narizian.Base*****Lutetian*0.0731707*48
Nectarian.Base*****Hadean*0.771889*3975
Neoarchean.Base*2800*0*Fixed Date**Neoarchean*0*2800
Neogene.Base*23.03*0.05*Base of magnetic polarity chronozone C6Cn.2n; lowest occurrence of planktonic foraminifer Paragloborotalia kugleri; near extinction of calcareous nannofossil Reticulofenestra bisecta (base Zone NN1).*Lemme-Carrosio section, Carrosio village, north of Genoa, Italy*Aquitanian*0*23.03
Neoproterozoic.Base*1000*0*Fixed Date**Tonian*0*1000
Niagaran.Base*****Aeronian*0.333333*438
Noginskian.Base*****Gzhelian*0.693878*300.5
Norian.Base*216.5*2.0*Base of Klamathites macrolobatus or Stikinoceras kerri ammonoid zones and the Metapolygnathus communisti or M. primitius conodont zones.**Norian*0*216.5
Nukumaruan.Base*****Gelasian*0.803069*1.96
Ohauan.Base*****Kimmeridgian*0.755102*152
Okehuan.Base*****Early Pleistocene*0.68878*1.1
Olenekian.Base*249.7*0.7*Near lowest occurrence of Hedenstroemia or Meekoceras gracilitatis ammonites, and of the conodont Neospathodus waageni.**Olenekian*0*249.7
Oligocene.Base*33.9*0.1*Planktonic foraminifer, extinction of Hantkenina.*Massignano quarry, Ancona, Italy*Rupelian*0*33.9
Onnian.Base*****Ordovician VI*0.27451*453
Opoitian.Base*****Zanclean*0.307159*4.8
Ordian.Base*****Early Cambrian*0.758621*520
Ordovician VI.Base*455.8*1.6*Potentially near first appearance of the graptolite Diplacanthograptus caudatus.**Ordovician VI*0*455.8
Ordovician.Base*488.3*1.7*Conodont, lowest occurrence of Iapetognathus fluctivagus; just above base of Cordylodus lindstromi conodont Zone.  Just below lowest occurrence of planktonic graptolites.*Green Point, western Newfoundland, Canada*Tremadocian*0*488.3
Orellan.Base*****Rupelian*0.0727273*33.5
Oretian.Base*****Carnian*0.26087*225
Orosirian.Base*2050*0*Fixed Date**Orosirian*0*2050
Osagean.Base*****Tournaisian*0.805755*348
Otamitan.Base*****Carnian*0.869565*218
Otapirian.Base*****Rhaetian*0.15*203
Pa.Base*****Pragian*.6923076923077*408.292
Paibian.Top*****Late Cambrian*0.393701*496
Paleoarchean.Base*3600*0*Fixed Date**Paleoarchean*0*3600
Panenka.Base*****Pragian*0.0*411.2
Panenka.Top*****Emsian*0.0*407
Patrocardia-Dualina.Base*****Pridoli*.575*417.147
Payntonian.Base*****Late Cambrian*0.787402*491
Pelsonian.Base*****Anisian*0.5*241
Penglaizhenian.Base*****Tithonian*0.339623*149
Pennsylvanian.Base*318.1*1.3*Conodont, lowest occurrence of Declinognathodus nodiliferus s.l.*Battleship Wash Formation, Arrow Canyon, southern Nevada, USA*Bashkirian*0*318.1
Penutian.Base*****Ypresian*0.388889*53
Permian.Base*299.0*0.8*Conodont, lowest occurrence of Streptognathodus isolatus within the S. "wabaunsensis" conodont chronocline.  6 m higher is lowest fusilinid foraminifer Sphaeroschwagerina.*Aidaralash Creek, Akt�be, southern Ural Mountains, northern Kazakhstan*Asselian*0*299
Phanerozoic.Base*542.0*0.3*Trace fossil, lowest occurrence of Treptichnus (Phycodes) pedum.  Near base of negative carbon-isotope excursion.*Chapel Island Formation, Fortune Head, Burin Peninsula, southeast Newfoundland, Canada*Early Cambrian*0*542
Piacenzian.Base*3.600*0.005*Base of magnetic polarity chronozone C2An (Gauss); extinction levels of planktonic foraminifers Globorotalia margaritae and Pulleniatina primalis.*Punta Piccola, Sicily, Italy*Piacenzian*0*3.6
Pleistocene.Base*1.806*0.005*Just above top of magnetic polarity chronozone C2n (Olduvai) and the extinction level of calcareous nannofossil Discoaster brouweri (base Zone CN13). Above are lowest occurrence of calcareous nannofossil medium Gephyrocapsa spp. and extinction level of planktonic foraminifer Globigerinoides extremus.*Urica, Calabria, Italy*Early Pleistocene*0*1.806
Pliensbachian.Base*189.6*1.5*Ammonite, lowest occurrences of Bifericeras donovani and of genera Apoderoceras and Gleviceras.*Wine Haven section, Robin Hood's Bay, Yorkshire, England, UK*Pliensbachian*0*189.6
Pliocene.Base*5.332***Trubi Formation, Eraclea Minoa, Sicily, Italy*Zanclean*0*5.332
PoW.Base*****Pragian*.2051282051282*410.338
Porangan.Base*****Lutetian*0.195122*47
Portlandian.Base*****Tithonian*0.90566*146
Poundian.Base*****Ediacaran*0.681818*570
Pragian.Base*411.2*2.8*Conodont, lowest occurrence of Eognathodus sulcatus.*Velká Chuchle quarry, southwest part of Prague city, Czech Republic*Pragian*0*411.2
Priabonian.Base*37.2*0.1*Near lowest occurrence of calcareous nannofossil Chiasmolithus oamaruensis (base Zone NP18).**Priabonian*0*37.2
Pridoli.Base*418.7*2.7*Graptolite, lowest occurrence of Monograptus parultimus.*Požáry section near Řeporyje, Barrandian area, Prague, Czech Republic*Pridoli*0*418.7
Proterozoic.Base*2500*0*Fixed Date**Siderian*0*2500
Puaroan.Base*****Tithonian*0.150943*150
Putikian.Base*****Middle Pleistocene*0.459542*0.48
Qianxin.Top*****Paleoarchean*0.5*3400
Quaternary.Base*1.806****Early Pleistocene*0*1.806
Qungzusian.Base*****Early Cambrian*0.344828*532
Rancholabrean.Base*****Middle Pleistocene*0.734351*0.3
Randian.Base*****Mesoarchean*0.5*3000
Rawtheyan.Base*****Ordovician VI*0.911765*446.5
Refugian.Base*****Priabonian*0.666667*35
Relizian.Base*****Burdigalian*0.881166*16.5
Repettian.Base*****Piacenzian*0.6917*2.9
Rhaetian.Base*203.6*1.5*Near lowest occurrence of ammonite Cochlocera, conodonts Misikella spp. and Epigondolella mosheri, and radiolarian Proparvicingula moniliformis.**Rhaetian*0*203.6
Rhyacian.Base*2300*0*Fixed Date**Rhyacian*0*2300
Riphean.Base*1400****Ectasian*0*1400
Rognacian.Base*****Maastrichtian*0.509804*68
Ryzanian.Base*****Berriasian*0.660377*142
Ryzanian.Top*****Valanginian*0.973684*136.5
Sakian.Base*****Late Cambrian*0.511811*494.5
Sakmarian.Base*294.6*0.8*Conodont, near lowest occurrence of conodont Streptognathodus postfusus.**Sakmarian*0*294.6
Santonian.Base*85.8*0.7*Inoceramid bivalve, lowest occurrence of Cladoceramus undulatoplicatus.**Santonian*0*85.8
Saucesian.Base*****Aquitanian*0.396154*22
Selandian.Base*61.7*0.2***Selandian*0*61.7
Senecan.Base*****Givetian*0.584615*388
Serpukhovian.Base*326.4*1.6*Near lowest occurrence of conodont, Lochriea crusiformis.**Serpukhovian*0*326.4
Serravallian.Base*13.65*0.05*Near lowest occurrence of nannofossil Sphenolithus heteromorphus, and within magnetic polarity chronozone C5ABr.**Serravallian*0*13.65
Sevatian.Base*****Norian*0.426357*211
Shaximioan.Base*****Bathonian*0.233333*167
Shinulanian.Base*****Aeronian*0.333333*438
Silurian.Base*443.7*1.5*Graptolites, lowest occurrences of Parakidograptus acuminatus and Akidograptus ascensus.*Birkhill Shale Formation, Dobb's Linn, Moffat, Scotland, UK*Rhuddanian*0*443.7
Sinemurian.Base*196.5*1.0*Ammonite, lowest occurrence of arietitid genera Vermiceras and Metophioceras.*East Quantoxead, Watchet, West Somerset, SW England, UK*Sinemurian*0*196.5
Soudleyan.Base*****Ordovician V*0.568627*458
Spathian.Base*****Olenekian*0.489362*247.4
Statherian.Base*1800*0*Fixed Date**Statherian*0*1800
Stenian.Base*1200*0*Fixed Date**Stenian*0*1200
Stephanian.Base*306.5****Kasimovian*0*306.5
Steptoan.Base*****Late Cambrian*0.511811*494.5
Streffordian.Base*****Ordovician VI*0.372549*452
Sturtian.Base*****Cryogenian*0.227273*800
Su.Base*****Emsian*.9487179487179*397.987
Suchian.Base*****Piacenzian*0.592885*3
Sunwaptan.Base*****Late Cambrian*0.629921*493
Swazian.Base*****Hadean*0.739302*4000
Telfordian.Base*****Sakmarian*0.54902*289
Telychian.Base*436.0*1.9*Brachiopods, just above extinction of Eocoelia intermedia and below lowest succeeding species Eocoelia curtisi.  Near base of  Monograptus turriculatus graptolite zone.*Cefn Cerig road, Llandovery area, south-central Wales, UK*Telychian*0*436
Temaikan.Base*****Bajocian*0.666667*169
Templetonian.Base*****Middle Cambrian*0.25*510
Teratan.Base*****Coniacian*0.657143*87
Thanetian.Base*58.7*0.2*Magnetic polarity chronozone, base of C26n, is a temporary assignment.**Thanetian*0*58.7
Tiffanian.Base*****Selandian*0.4*60.5
Tithonian.Base*150.8*4.0*Near base of Hybonoticeras hybonotum ammonite zone and lowest occurrence of Gravesia genus, and the base of magnetic polarity chronozone M22An.**Tithonian*0*150.8
Toarcian.Base*183.0*1.5*Ammonite, near lowest occurrence of a diversified Eodactylites ammonite fauna; correlates with the NW European Paltus horizon.**Toarcian*0*183
Tommotian.Base*****Early Cambrian*0.275862*534
Tongaporutuan.Base*****Tortonian*0.368638*10
Torrejonian.Base*****Danian*0.789474*62.5
Tortonian.Base*11.608*0.005*Last common occurrences of the calcareous nannofossil Discoaster kugleri and the planktonic foraminifer Globigerinoides subquadratus.  Associated with the short normal-polarity subchron C5r.2n.*Monte dei Corvi beach section, Ancona, Italy*Tortonian*0*11.608
Toyonian.Base*****Early Cambrian*0.810345*518.5
Turonian.Base*93.5*0.8*Ammonite, lowest occurrence of Watinoceras devonense.*Rock Canyon Anticline, east of Pueblo, Colorado, west-central USA*Turonian*0*93.5
Tuvalian.Base*****Carnian*0.26087*225
Tyrrhenian.Base*****Middle Pleistocene*0.79542*0.26
Uintan.Base*****Lutetian*0.390244*45.4
Ulatisian.Base*****Ypresian*0.666667*51
Undillian.Base*****Middle Cambrian*0.583333*506
Uruoan.Base*****Pliensbachian*0.242424*188
Urutawan.Base*****Albian*0.16129*110
Valanginian.Base*140.2*3.0*Calpionellid, lowest occurrence of Calpionellites darderi (base of Calpionellid Zone E); followed by the lowest occurrence of ammonite "Thurmanniceras" pertransiens.**Valanginian*0*140.2
Vendian.Base*****Cryogenian*0.909091*650
Venturian.Base*****Gelasian*0.496164*2.2
Virgilian.Base*****Kasimovian*0.576923*305
Visean.Base*345.3*2.1*Foraminifer, lineage Eoparastaffella simplex morphotype 1/morphotype 2.**Visean*0*345.3
W.Base*****Pragian*.4358974358974*409.369
Waiauan.Base*****Tortonian*0.0247593*11.5
Waipawan.Base*****Thanetian*0.758621*56.5
Waipipian.Base*3.6****Piacenzian*0*3.6
Waitakian.Base*****Chattian*0.260708*27
Warendian.Base*****Tremadocian*0.340206*485
Warepan.Base*****Norian*0.813953*206
Wasatchian.Base*****Ypresian*0.0416667*55.5
Wenlock.Base*428.2*2.3*Imprecise.  Between the base of acritarch biozone 5 and extinction of conodont Pterospathodus amorphognathoides.  May be near base of Cyrtograptus centrifugus graptolite zone.*Hughley Brook, Apedale, Shropshire, southwest England, UK*Sheinwoodian*0*428.2
Werrikooian.Top*****Early Pleistocene*0.786341*1
Westphalian.Base*****Bashkirian*0.484375*315
Wheelerian.Base*****Gelasian*0.879795*1.9
Whitlandian.Base*****Arenig*0.529412*475
Whitneyan.Base*****Rupelian*0.345455*32
Wordian.Base*268.0*0.7*Conodont, lowest occurrence of Jinogondolella aserrata.*Getaway Ledge outcrop, Guadalupe Pass, SE Guadalupe Mountains, Texas, USA*Wordian*0*268
Wutaian.Base*****Neoarchean*0.666667*2600
Xiushanian.Base*****Telychian*0.897436*429
Yanguan.Base*****Tournaisian*0.697842*349.5
Yatalan.Base*****Piacenzian*0.197628*3.4
Yatalan.Top*****Gelasian*0.751918*2
Yeadonian.Base*****Bashkirian*0.40625*315.5
Ynezian.Base*****Selandian*0.0666667*61.5
Ypeenian.Base*****Ordovician III*0.486486*470
Yuian.Base*****Tortonian*0.483265*9.5
Yujianian.Base*****Pragian*0.285714*410
Yurmatian.Base*****Ectasian*0.125*1375
Yuzanjian.Base*****Early Pleistocene*0.298537*1.5
Yuzanjian.Top*****Middle Pleistocene*0.0473282*0.75
Zemorrian.Base*****Rupelian*0.0727273*33.5
Zhungxian.Base*****Middle Cambrian*0.666667*505
Zuzhuangian.Base*****Middle Cambrian*0.333333*509
acuaria.Base*****Pragian*0.0*411.2
agna.Base*****Homerian*.1547619047619*425.689
alata.Base*****Ludfordian*.3*420.52
amorphognathoides.Base*****Telychian*.52*431.944
amsdeni.Base*****Sheinwoodian*.390625*427.419
amsdeni.Top*****Homerian*0.0*426.2
barrandei.Base*****Emsian*.2258064516129*404.855
belophorus.Base*****Sheinwoodian*.3864864864865*427.427
bohemica.Base*****Lochkovian*.4415584415584*413.881
bohemica.Base*****Pridoli*0.0*418.7
bohemicus tenuis.Base*****Ludfordian*.3*420.52
bouceki.Base*****Pridoli*.4075*417.6
cancellata.Base*****Emsian*0.4301075268817*402.914
celloni.Base*****Telychian*.2*434.44
chimaera.Base*****Gorstian*.2115384615385*422.562
colonus.Base*****Gorstian*0.0*422.9
conformis.Base*****Ludfordian*.725*419.415
consaguis.Base*****Gorstian*.5384615384615*422.038
crispa.Base*****Ludfordian*.7763157894737*419.282
crispa.Top*****Pridoli*0.0*418.7
cybele cybele.Base*****Pridoli*.675*416.877
docens.Base*****Ludfordian*0.0*421.3
donigala.Base*****Gorstian*.1923076923077*422.592
dubius.Base*****Sheinwoodian*.1891891891892*427.822
elegans.Base*****Emsian*.3290322580645*403.874
figusi.Base*****Homerian*.2678571428571*425.316
figusi.Top*****Homerian*.4464285714286*424.727
fragmentalis.Base*****Ludfordian*.865*419.051
gibbosa.Base*****Homerian*.8482142857143*423.401
inexpectatus.Base*****Ludfordian*.45*420.13
insolita.Base*****Pridoli*.875*416.337
intermedia.Base*****Lochkovian*.5974025974026*413.132
kozlowskii.Base*****Ludfordian*.5825*419.786
latilobus.Base*****Ludfordian*.725*419.415
linearis.Base*****Ludfordian*0.0*421.3
lochkovensis.Base*****Pridoli*.275*417.957
ludensis.Base*****Homerian*.8408408408408*423.425
lundgreni.Base*****Homerian*0.0*426.2
maureri.Base*****Emsian*.8064516129032*399.339
nassa.Base*****Homerian*.5105105105105*424.515
nivosa.Base*****Sheinwoodian*.5789473684211*427.042
nivosa.Top*****Sheinwoodian*.7105263157895*426.779
parultimus.Base*****Pridoli*0.0*418.7
parvus.Base*****Homerian*.3393393393393*425.08
perneri-ramosus.Base*****Sheinwoodian*.8027027027027*426.595
perneri.Base*****Pridoli*.5625*417.181
ploeckensis.Base*****Gorstian*.1636363636364*422.638
praedeubeli-deubeli.Base*****Homerian*.6756756756757*423.97
pseudopesavis-combinatus.Base*****Rhuddanian*.6341463414634*440.72
pseudopesavis-combinatus.Top*****Aeronian*.1290322580645*438.613
ranuliformis.Base*****Sheinwoodian*.125*427.95
riccartonensis.Base*****Sheinwoodian*0.0*428.2
richteri.Base*****Emsian*.5376344086022*401.892
rigidus.Base*****Sheinwoodian*.5945945945946*427.011
sardiniana.Base*****Pridoli*.125*418.363
sardiniana.Top*****Pridoli*.25*418.025
senex.Base*****Lochkovian*.2987012987013*414.566
signata.Base*****Gorstian*.7307692307692*421.731
siluricus.Base*****Ludfordian*.09473684210526*421.054
siluricus.Top*****Ludfordian*.5526315789474*419.863
staurognathoides.Base*****Aeronian*.3225806451613*438.032
strangulata.Base*****Pragian*.8589743589744*407.592
testis.Base*****Homerian*.1741741741742*425.625
transgrediens.Base*****Pridoli*.7*416.81
ultimus.Base*****Pridoli*.15*418.295
uniformis.Base*****Lochkovian*0.0*416
zlichovensis.Base*****Emsian*.08602150537634*406.183