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This is a geochronolgy time spiral. Credit: United States Geological Survey.

Geochronology/Paleozoic is the science of applying dates in the past to Paleozoic rocks. In many situations fossils and artifacts may yield dates applicable to the rocks they occur in.

Notations[edit | edit source]


  1. ALMA represent the Asian Land Mammal Age,
  2. b2k represent before AD 2000,
  3. BP represent before present, as the chart is for 2008, this may require an added -8 for b2k,
  4. ELMMZ represent the European Land Mammal Mega Zone,
  5. FAD represent first appearance datum,
  6. FO represent first occurrence,
  7. Ga represent Gegaannum, billion years ago, or -109 b2k,
  8. GICC05 represent Greenland Ice Core Chronology 2005,
  9. GRIP represent Greenland Ice Core Project,
  10. GSSP represent Global Stratotype Section and Point,
  11. HO represent highest occurrence,
  12. ICS represent the International Commission on Stratigraphy,
  13. IUGS represent the International Union of Geological Sciences,
  14. LAD represent last appearance datum,
  15. LO represent lowest occurrence,
  16. Ma represent Megaannum, million years ago, or -106 b2k,
  17. NALMA represent the North American Land Mammal Age,
  18. NGRIP represent North Greenland Ice Core Project, and
  19. SALMA represent South American Land Mammal Age.

"The term b2 k [b2k] refers to the ice-core zero age of AD 2000; note that this is 50 years different from the zero yr for radiocarbon, which is AD 1950 [...]."[1]

Chronostratigraphy[edit | edit source]

This is an International Chronostratigraphic Chart. Credit: K.M. Cohen, S. Finney, and P.L. Gibbard, International Commission on Stratigraphy.

Dates have been assigned to specific geologic stratigraphy frames, columns, or columnar units.

Paleozoic time frames[edit | edit source]

Sortable table
Name (English)[2] base/start (Ma)[3] top/end (Ma)[3] status subdivision of usage named after author, year
Abereiddian 471.8 ± 1.6 464 age Ordovician regional Abereiddy (Wales)
Actonian 454 453 age Ordovician regional Acton Scott (England)
Aeronian 439.0 ± 1.8 436.0 ± 1.9 age Silurian ICS Cwm-coed-aeron (Wales) Cocks et al., 1971
Aksayan 493 491.5 age Cambrian Russia, Kazakhstan
Albertan epoch Cambrian North America
Alportian 324.5 318.1 ± 1.3 age Carboniferous regional Alport (England)
Amgan 513.0 ± 2.0 502 age Cambrian Russia, Kazakhstan
Arenig(-ian) epoch Ordovician Europe Arenig Fawr (Wales) Sedgwick, 1847; Fearnsides 1905
Arnsbergian 326 325 sub-age Carboniferous regional
Artinskian 284.4 ± 0.7 275.6 ± 0.7 age Permian ICS Arti (Russia) Karpinsky, 1874
Arundian 341 339 age Carboniferous regional
Asbian 337.5 333 age Carboniferous regional
Ashbyan age Ordovician North America
Ashgill(-ian) epoch Ordovician Europe Ashgill (Scotland)
Asselian 299.0 ± 0.8 294.6 ± 0.8 age Permian ICS river Assel (Kazakhstan) Ruzhenchev, 1954
Asturian 305 age Carboniferous Europe Asturias
Atdabanian 530 524 age Cambrian Russia, Kazakhstan
Atokan age Carboniferous North America
Aurelucian 460.9 457 age Ordovician Europe
Autunian ~300 ~275 age Carboniferous-Permian Europe Autun (France)
Ayusokkanian 501.0 ± 2.0 494.5 age Cambrian Russia, Kazakhstan
Baishaean 433 429 age Silurian China
Baotan 460.9 454.5 age Ordovician China
Barruelian age Carboniferous Europe
Bashkirian 318.1 ± 1.3 311.7 ± 1.1 age Carboniferous ICS Bashkortostan
Batyrbayan 491.5 488.3 age Cambrian Russia, Kazakhstan
Bendigonian 473.5 471.8 age Ordovician Australia Bendigo, Victoria
Black River(-an) age Ordovician North America
Bolindian 450 443.7 age Ordovician Australia
Bolsovian age Carboniferous Europe Bolsover (England)
Boomerangian 504 501 age Cambrian Australia
Botomian 524 518.5 age Cambrian Russia, Kazakhstan
Brigantian 336 326.4 ± 1.6 age Carboniferous North America, Europe Brigantes (Celtic tribe)
Burrellian 457 455 age Ordovician Europe Glenburrell (England)
Caerfai 542 ± 0.2 513 ± 2 age Cambrian Europe (obsolete) Caerfai Bay (Wales)
Cambrian 542.0 ± 1.0 488.3 ± 1.7 period Paleozoic ICS Cambria (Latin for Wales) Sedgwick, 1835
Canadian epoch Ordovician North America
Cantabrian 305 age Carboniferous Europe
Capitanian 265.8 ± 0.7 260.4 ± 0.7 age Permian ICS Capitan Reef (Texas, US)
Caradocian 460.9 449.5 epoch Ordovician Europe Caradoc (Welsh king) Murchison, 1839
Carboniferous 359.2 ± 2.5 299.0 ± 0.8 period Paleozoic ICS carbon Conybeare & Phillips, 1822
Cassinian 473 471.8 sub-age Ordovician North America
Castlemanian 471 470 age Ordovician Australia Castlemaine
Cautleyan 447.5 446.5 age Ordovician Europe Cautley Spout (England)
Cayugan 421.3 ± 2.6 416.0 ± 2.8 age Silurian North America
Cisuralian 299.0 ± 0.8 270.6 ± 0.7 epoch Permian ICS
Chadian 345.3 ± 2.1 341 age Carboniferous regional
Chamovnicheskian 306 305 age Carboniferous Russia
Champlanian epoch Ordovician North America
Changhsingian 253.8 ±0.7 251.0 ± 0.4 age Permian ICS Changxing (China)
Changlangpuan 523 518 age Cambrian China
Changshanian 496.8 492.5 age Cambrian China
Chatauquan 370 359.2 ± 2.5 age Devonian South America
Chautauquan age Devonian North America
Chazyan age Ordovician North America
Cheneyan 455 452 age Ordovician Europe
Cheremshankian 314.5 313.4 age Carboniferous Russia
Chesterian 333 318.1 age Carboniferous North America
Chewtonian 473 471 age Ordovician Australia
Chokierian 325 324.5 sub-age Carboniferous regional
Cincinnatian 451 443.7 ± 1.5 epoch Ordovician North America Cincinnati
Costonian 460.9 459 age Ordovician regional
Couvinian 397.5 ± 2.7 391.8 ± 2.7 age Devonian Belgium (obsolete) Couvin d'Omalius d'Halloy, 1862
Cressagian 488.3 ± 1.7 486 age Ordovician Europe
Croixan epoch Cambrian North America
Dalanian (Dalaun) 313 310 age Carboniferous China
Dapingian 471.8 ± 1.6 468.1 ± 1.6 age Ordovician ICS Daping (China)
Darriwilian 468.1 ± 1.6 460.9 ± 1.6 age Ordovician ICS Darriwil (Australia) Hall, 1899
Datangian 345 333 age Carboniferous China
Datsonian 488.3 ± 1.7 485 age Ordovician Australia
Dawanian 472 471.8 age Ordovician North America
Deerparkian age Devonian North America
Delamaran 512 504 age Cambrian North America
Demingian 478.6 475 sub-age Ordovician North America
Derryan 311.7 ± 1.1 308 age Carboniferous North America
Desmoinesian age Carboniferous North America
Devonian 416.0 ± 2.8 359.2 ± 2.5 period Paleozoic ICS Devon (England) Murchison & Sedgwick, 1839
Dewuan 333 318.1 ± 1.3 age Carboniferous China
Dinantian 359.2 ± 2.5 326.4 ± 1.6 epoch/sub-period Carboniferous Northern Europe Dinant
Dittonian 418 age Devonian Wales and England (obsolete) Ditton Priors, Shropshire, England
Dolgellian 492.5 488.3 ± 1.7 age Cambrian regional Dolgellau, Wales
Dorogomilovksian 305 303.9 ± 0.9 age Carboniferous regional
Dresbachian 501 496.8 age Cambrian North America
Drumian 506.5 503 age Cambrian ICS Drum Mountains (Utah, US)
Duckmantian age Carboniferous Europe Duckmanton Railway Cutting, England
Dyeran 524.5 512 age Cambrian North America
Eastonian 456 450 age Ordovician Australia
Edenian age Ordovician North America
Eifelian 397.5 ± 2.7 391.8 ± 2.7 age Devonian ICS the Eifel (Germany) Beyrich, 1837
Eildonian 433 428.2 ± 2.3 age Silurian Australia
Elvirian 326 324.5 age Carboniferous regional
Emsian 407.0 ± 2.8 397.5 ± 2.7 age Devonian ICS Bad Ems (Germany) de Dorlodot, 1900
Erian 391.8 ± 2.7 388 age Devonian North America
Famennian 374.5 ± 2.6 359.2 ± 2.5 age Devonian ICS the Famenne (Belgium) Dumont, 1855
Fengshanian 492.5 488.3 ± 1.7 age Cambrian China
Fennian 473 471.8 age Ordovician Europe
Festiniogian 496.8 492.5 age Cambrian regional
Floian 478.6 ± 1.7 471.8 ± 1.6 age Ordovician ICS Flo (Sweden)
Florian 508 504 age Cambrian Australia
Fortunian 542.0 ± 1.0 528 age Cambrian ICS Fortune Head (Canada)
Franconian 496.8 492.5 age Cambrian North America
Frasnian 385.3 ± 2.6 374.5 ± 2.6 age Devonian ICS Frasne (Belgium) d'Omalius d'Halloy, 1862
Furongian 501.0 ± 2.0 488.3 ± 1.7 epoch Cambrian ICS Furong (China)
Gedinian 416.0 ± 2.8 411.2 ± 2.8 age Devonian Belgium (obsolete) Gedinne Dumont, 1848
Gisbornian 460.9 456 age Ordovician Australia
Givetian 391.8 ± 2.7 385.3 ± 2.6 age Devonian ICS Givet (France) d'Omalius d'Halloy, 1839
Gleedonian 425.4 422.9 ± 2.5 age Silurian regional
Gorstian 422.9 ± 2.5 421.3 ± 2.6 age Silurian ICS Gorsty (farm at Ludlow, England) Holland et al., 1980
Guadalupian 270.6 ± 0.7 260.4 ± 0.7 epoch Permian ICS Guadalupe Mountains (Texas, US)
Guandian 425.5 422 age Silurian China
Gushanian 596.8 501 age Cambrian China
Guzhangian 503 499 age Cambrian ICS Guzhang (China)
Gzhelian 303.9 ± 0.9 299.0 ± 0.8 age Carboniferous ICS Gzhel (Russia)
Harnagian 459 458 age Ordovician regional
Hastarian 359.2 ± 2.5 348 age Carboniferous regional
Hirnantian 445.6 ± 1.5 443.7 ± 1.5 age Ordovician ICS Cwm Hirnant (Wales) Bancroft, 1933
Holkerian 339 337.5 age Carboniferous regional
Homerian 426.2 ± 2.4 422.9 ± 2.5 age Silurian ICS Homer (England) Bassett et al., 1975
Honghuayuanian 478.6 472 age Ordovician China
Houldjinian 37.2 33.9 ALMA Asia
Huashibanian 318.1 ± 1.3 313 age Carboniferous China
Ibexian ~505 471.8 age Cambrian-Ordovician North America
Idamean 497 494 age Cambrian Australia
Ivorean 348 345.3 ± 2.1 age Carboniferous regional
Jiusian age Carboniferous China
Jeffersonian 475 473 sub-age Ordovician North America
Karoo Ice Age ~360 ~260 ice age Phanerozoic Karoo (South Africa)
Kashirskian 309.2 308.0 age Carboniferous Russia
Kasimovian 306.5 ± 1.0 303.9 ± 0.9 age Carboniferous ICS Kasimov (Russia)
Katian 455.8 ± 1.6 445.6 ± 1.5 age Ordovician ICS Lake Katy (Oklahoma, US)
Kazanian age Permian Russia
Keiloran 443.7 ± 1.5 433 age Silurian Australia
Kekeamuan 28.4 33.9 ALMA Asia
Kinderhookian 359.2 ± 2.5 348 age Carboniferous North America
Kinderscoutian 318.1 ± 1.3 317 age Carboniferous regional Kinder Scout (England)
Kirkfield 458 457 age Ordovician regional
Klazminskian 303.9 ± 0.9 300.5 age Carboniferous regional
Krevyakinskian 306.5 306 age Carboniferous Russia
Kungurian 275.6 ± 0.7 270.6 ± 0.7 age Permian ICS Kungur (Russia)
Lancefieldian 482 475 age Ordovician Australia
Langsettian 314.5 313.4 age Carboniferous regional Langsett (England)
Leonardian age Permian North America
Linxiangian 454.5 449 age Ordovician China
Livian 335 331 age Carboniferous Belgium (obsolete) Lives
Llandeilo (Llandeilean) epoch/age Ordovician Europe Llandeilo (Wales) Murchison, 1835
Llandovery 443.7 ± 1.5 428.2 ± 2.3 epoch Silurian ICS Llandovery (Wales) Murchison, 1859
Llanvirn(-ian) epoch Ordovician Europe Hicks, 1875
Lochkovian 416.0 ± 2.8 411.2 ± 2.8 age Devonian ICS Lochkov (Czech Republic)
Longmaxian 443.7 ± 1.5 438 age Silurian China
Longvillian 457 455 age Ordovician regional Cheney Longville (England)
Longwangmioan 518 513 age Cambrian China
Lopingian 260.4 ± 0.7 251.0 ± 0.4 epoch Permian ICS Loping (China)
Ludfordian 421.3 ± 2.6 418.7 ± 2.7 age Silurian ICS Ludford (England) Holland et al., 1980
Ludlovian 422.9 ± 2.5 418.7 ± 2.7 epoch Silurian ICS Ludlow (England) Murchison, 1854
Luosuan 318.1 ~314 age Carboniferous China
Maentwrogian 501 496.8 age Cambrian regional Maentwrog (Wales)
Maozhangian 513 509 age Cambrian China
Mapingian 310 299.0 ± 0.8 age Carboniferous China
Marjuman 504 494.5 age Cambrian North America
Marsdenian 317 315.5 age Carboniferous regional Marsden, West Yorkshire, England
Marshbrookian 455 454 age Ordovician regional Marshbrook (England)
Mayan 502 501 ± 2.0 age Cambrian Russia, Kazakhstan
Mayvillian 453 447.5 age Ordovician North America
Medinan age Silurian North America
Meishuchuan 542 532 age Cambrian China
Melbournian 428.2 ± 2.3 416.0 ± 2.8 age Silurian Australia Melbourne
Melekesskian 313.4 311.7 age Carboniferous Russia
Meramecian 340 333 age Carboniferous North America
Merioneth 501 ± 2 488.3 ± 1.7 epoch Cambrian Europe (obsolete) Merioneth (Wales)
Miaogoalingian 422 418.7 age Silurian China
Migneintian 486 478.6 ± 1.7 age Ordovician Europe
Mindyallan 501 497 age Cambrian Australia
Mississippian 359.2 ± 2.5 318.1 ± 1.3 epoch Carboniferous ICS Mississippi River (US)
Missourian age Carboniferous North America
Mohawkian 462 451 epoch Ordovician North America
Montezuman 529.5 524.5 age Cambrian North America
Moridunian 478.6 ± 1.7 475 age Ordovician Europe Moridunum (Wales)
Morrowan age Carboniferous North America
Moscovian 311.7 ± 1.1 306.5 ± 1.0 age Carboniferous ICS Moscow (Russia)
Myachkovskian 307.2 306.5 age Carboniferous Russia
Namurian 326.4 313.0 age Carboniferous Europe Namur (Belgium) Purves, 1883
Nemakit-Daldynian 542 534 age Cambrian Russia, Kazakhstan
Neocomian 145.5 125.0/130.0 epoch obsolete Neocomium, Latin name for Neuchâtel
Niagaran age Silurian North America
Noginskian 300.5 299.0 ± 0.8 age Carboniferous Russia
Ochoan age Permian North America
Okaian 0.5 0.3 sub-age Ordovician North America
Onnian 453 449 age Ordovician regional River Onny (England)
Ordian 520 510 age Cambrian Australia
Ordovician 488.3 ± 1.7 443.7 ± 1.5 period Paleozoic ICS Ordovices, Celtic tribe Lapworth, 1879
Osagean age Carboniferous North America
Paibian 501.0 ± 2.0 496 age Cambrian ICS Paibi (China)
Paleophytic ~450 ~270 era paleobotany old flora
Paleozoic 542.0 ± 1.0 251.0 ± 0.7 era Phanerozoic ICS old life
Payntonian 491 488.3 ± 1.7 age Cambrian Australia
Pendleian 326.4 ± 1.6 326 age Carboniferous regional Pendle Hill (England)
Pennsylvanian 318.1 ± 1.3 299.0 ± 0.8 epoch Carboniferous ICS Pennsylvania (US)
Permian 299.0 ± 0.8 251.0 ± 0.4 period Paleozoic ICS Perm (Russia) Murchison, 1849
Phanerozoic 542.0 ± 1.0 present eon ICS visible life
Podolskian 308 307.2 age Carboniferous Russia
Potsdamian 501 ± 2 488.3 ± 1.7 epoch Cambrian Germany
Poundian 570 542 ± 0.3 age Cambrian Australia
Pragian 411.2 ± 2.8 407.0 ± 2.8 age Devonian ICS Prague (Czech Republic)
Pridoli(an) 418.7 ± 2.7 416.0 ± 2.8 epoch Silurian ICS Přidoli (Czech Republic)
Pusgillian 449 447.5 age Ordovician Europe Pus Gill, Cumbria (England) Dean, 1959
Qungzusian 532 523 age Cambrian China
Rawtheyan 446.5 445.5 age Ordovician Europe River Rawthey (England)
Rhuddanian 443.7 ± 1.5 439.0 ± 1.8 age Silurian ICS Cwm-Rhuddian (Wales)
Richmondian 449 445.6 ± 1.5 age Ordovician North America
Roadian 270.6 ± 0.7 268.0 ± 0.7 age Permian ICS
Rotliegend(-es)[4] 299 270.6 sub-period Permian unofficial German for "Red foot wall". A traditional copper mining term in the Mansfelder Land for the red oreless sandstone below the Kupferschiefer.
Sakian 494.5 493 age Cambrian Russia, Kazakhstan
Sakmarian 294.6 ± 0.8 284.4 ± 0.7 age Permian ICS river Sakmara (Russia) Karpinski, 1874
Sandbian 460.9 ± 1.6 455.8 ± 1.6 age Ordovician ICS Sandby, Sweden
Saxonian ~290 ~258 age Permian Europe (obsolete) Saxony
Senecan 388 370 age Devonian North America
Serpukhovian 326.4 ± 1.6 318.1 ± 1.3 age Carboniferous ICS Serpukhov (Russia)
Shangsian 318.1 age Carboniferous China
Shaodongian 359.2 ± 2.5 349.5 age Carboniferous China
Sheinwoodian 428.2 ± 2.3 426.2 ± 2.4 age Silurian ICS Sheinwood (England) Basset et al., 1975
Shermanian 457 454 age Ordovician regional
Shinulanian 438 433 age Silurian China
Silesian 326.4 299.0 subperiod Carboniferous Europe Silesia
Siegenian age Devonian North America, Europe
Silurian 443.7 ± 1.5 416.0 ± 2.8 period Paleozoic ICS Silures, Celtic tribe Murchison, 1835
Soudleyan 458 457 age Ordovician regional Soudley (England)
Springerian age Carboniferous North America
St. David's 513 ± 2 501 ± 2 epoch Cambrian Europe (obsolete) St Davids (Wales)
Stephanian 303.9 299.0 age Carboniferous Europe Saint-Étienne (France) Mayer-Eymar, 1878
Steptoan 494.5 493 age Cambrian North America
Streffordian 452 449 age Ordovician Europe Strefford (England)
Sunwaptan 493 491 age Cambrian North America
Tangbagouan 359.2 age Carboniferous China
Tatarian age Permian Russia Tatarstan
Telychian 436.0 ± 1.9 428.2 ± 2.3 age Silurian ICS Pen-lan-Telych (Wales) Cocks et al. 1973
Templetonian 510 508 age Cambrian Australia
Terreneuvian 542.0 ± 1.0 521 epoch Cambrian ICS Terre-Neuve, French name for Newfoundland
Thuringian 285 251 age Permian Europe (obsolete) Thuringia (Germany)
Toyonian 518.5 513.0 ± 2.0 age Cambrian Russia, Kazakhstan
Tommotian 534 530 age Cambrian Russia, Kazakhstan
Tournaisian 359.2 ± 2.5 345.3 ± 2.1 age Carboniferous ICS Tournai (Belgium) Dumont, 1832
Tremadoc(-ian) 488.3 ± 1.7 478.6 ± 1.7 epoch Ordovician ICS Tremadoc Bay (Wales) Sedgwick, 1846
Trempealeauan 492.5 488.3 ± 1.7 age Cambrian North America
Trentonian age Carboniferous North America
Ufimian 268 270,6 age Permian obsolete
Ulsterian age Devonian North America
Undillian 506 504 age Cambrian Australia
Vereiskian 311.7 ± 1.1 309.2 age Carboniferous Russia
Virgilian age Carboniferous North America
Visean 345.3 ± 2.1 326.4 ± 1.6 age Carboniferous ICS Visé (Belgium) Dumont, 1832
Warendian 485 478.6 age Ordovician Australia
Waucoban epoch Cambrian North America
Wenlock(-ian) 428.2 ± 2.3 422.9 ± 2.5 epoch Silurian ICS Much Wenlock (England) Murchison, 1833
Westphalian 313.0 303.9 age Carboniferous Europe Westphalia (Germany) de Lapparent & Munier-Chalmas, 1892
Whiterockian 471.8 ± 1.6 462 age Ordovician North America
Whitlandian 475 473.5 age Ordovician Europe Whitland (Wales)
Whitwellian 426.2 ± 2.4 425.4 age Silurian regional Whitwell Coppice (England)
Wolfcampian age Permian North America
Wordian 268.0 ± 0.7 265.8 ± 0.7 age Permian ICS
Wuchiapingian 260.4 ± 0.7 253.8 ± 0.7 age Permian ICS
Xiaodushanian 299 age Carboniferous China
Xiushanian 429 425.5 age Silurian China
Yanguan 349.5 345 age Carboniferous China
Yeadonian 315.5 314.5 age Carboniferous regional Yeadon (England)
Ypeenian 470 468.1 age Ordovician Australia
Zechstein[4] ±270 ±250 sub-period Permian Europe (unofficial)
Zhungxian 505 501 age Cambrian China
Zuzhungian 509 503 age Cambrian China

Permian[edit | edit source]

The Permian lasted from 299.0 ± 0.8 to 251.0 ± 0.4 Mb2k.

Asselian[edit | edit source]

In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian, a subdivision of the Cisuralian Epoch or Series, which lasted between 298.9 and 295 million years ago (Ma), preceded by the Gzhelian (the latest or uppermost subdivision in the Carboniferous) and followed by the Sakmarian.[5]

The Artinskian still encompasses most of the lower Permian – its current definitions are more restricted. The Asselian is named after the Assel River in the southern Ural Mountains of Kazakhstan and Bashkortostan.[6]

The base of the Asselian Stage is at the same time the base of the Cisuralian Series and the Permian System, defined as the place in the stratigraphic record where fossils of the conodont Streptognathodus isolatus first appear, where the global reference profile for the base (the GSSP or golden spike) is located in the valley of the Aidaralash River, near Aqtöbe in the Ural Mountains of Kazakhstan.[7] The top of the Asselian stage (the base of the Sakmarian stage) is at the first appearance of conodont species Streptognathodus postfusus.

The Asselian contains five conodont biozones:

  • zone of Streptognathodus barskovi
  • zone of Streptognathodus postfusus
  • zone of Streptognathodus fusus
  • zone of Streptognathodus constrictus
  • zone of Streptognathodus isolatus

Late Paleozoic icehouse[edit | edit source]

The late Paleozoic icehouse, formerly known as the Karoo ice age, was the climate state 360–260 million years ago (Mya) in which large land-based ice-sheets were present on Earth's surface.[8]

"The late Paleozoic icehouse was the longest-lived ice age of the Phanerozoic, and its demise constitutes the only recorded turnover to a greenhouse state."[8]

Rotliegend[edit | edit source]

The Rotiegend lasted from 302 Ma to 260 Ma.[9]

Late Pennsylvanian[edit | edit source]

The Pennsylvanian also known as Upper Carboniferous or Late Carboniferous is, in the International Commission on Stratigraphy (ICS) geologic timescale, the younger of two subperiods (or upper of two subsystems) of the Carboniferous Period, lasting from roughly 323.2 million years ago to 298.9 million years ago. As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few hundred thousand years. The Pennsylvanian is named after the U.S. state of Pennsylvania, where the coal-productive beds of this age are widespread.[10]

Gzhelian[edit | edit source]

Type locality for the Gzhelian is in Gzhel, Russia. Credit: Vitaliy VK}.{{free media}}

The Gzhelian is an age in the International Commission on Stratigraphy (ICS) geologic timescale or a stage in the stratigraphic column, the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from 303.7 to 298.9 Ma.[11] It follows the Kasimovian age/stage and is followed by the Asselian age/stage, the oldest subdivision of the Permian system.

The Gzhelian is more or less coeval with the Stephanian Stage of the regional stratigraphy of Europe.

The base of the Gzhelian is at the first appearance of the Fusulinida genera Daixina, Jigulites and Rugosofusulina, or at the first appearance of the conodont Streptognathodus zethus. The top of the stage (the base of the Permian system) is at the first appearance of the conodont Streptognathodus isolatus within the Streptognathus "wabaunsensis" chronocline.[12] Six meters higher in the reference profile, the Fusulinida species Sphaeroschwagerina vulgaris aktjubensis appears.

A Global Boundary Stratotype Section and Point (golden spike) for the Gzhelian Stage is yet lacking. A candidate is a section along the Ussolka river (a tributary of the Belaya river) at the edge of the hamlet of Krasnoussolsky, about 120 kilometres south-east of Ufa and 60 kilometres north-east of Sterlitamak (in Bashkortostan).[13]

The Gzhelian Stage is subdivided into five biozones, based on the conodont genus Streptognathodus:

  • Streptognathodus wabaunsensis and Streptognathodus bellus Zone
  • Streptognathodus simplex Zone
  • Streptognathodus virgilicus Zone
  • Streptognathodus vitali Zone
  • Streptognathodus simulator Zone

Kasimovian[edit | edit source]

The Kasimovian is a geochronologic age or chronostratigraphic stage in the International Commission on Stratigraphy (ICS) geologic timescale, the third stage in the Pennsylvanian (late Carboniferous), lasting from 307 to 303.7 Ma.[14] The Kasimovian saw an extinction event which occurred around 305 mya, referred to as the Carboniferous Rainforest Collapse.[15] and corresponds to the Missourian in North American geochronology and the Stephanian in western European geochronology.

Middle Pennsylvanian[edit | edit source]

Moscovian[edit | edit source]

Carboniferous[edit | edit source]

The Carboniferous began 359.2 ± 2.5 Mb2k and ended 299.0 ± 0.8 Mb2k.

Pennsylvanian[edit | edit source]

Fossil of Calamites, an extinct plant, photographed at Museo di Storia Naturale di Verona. Credit: Ghedoghedo{{free media}}

"Specimens of Calamites cistii (Sphenophyta; Pennsylvanian, France) are described showing endophytic cavities, located in the outer cortex of the stem, a tissue that is rarely preserved. This new record shifts the appearance of this behavior back 60 Ma."[16] Two "specimens of the arborescent Calamites cistii (Sphenophyta) [were] collected from the Pennsylvanian basin of Graissessac (Hérault, France)".[16] "The specimens belong to the species Calamites cistii Brongniart, 1828 (Sphenophyta). They are housed in the Collections de Paléobotanique, Service général des Collections, University Montpellier 2 (LPM)."[16]

The Pennsylvanian lasted from 318.1 ± 1.3 to 299.0 ± 0.8 Mb2k.

Mississippian[edit | edit source]

The Mississippian lasted from 359.2 ± 2.5 to 318.1 ± 1.3 Mb2k.

Prolecanites gurleyi is an index fossil of the Mississippian.[17]

Middle Mississippian[edit | edit source]

"This species has been consistently identified with the considerably younger, late Viséan (late Holkerian to Asbian [late Meramecian to early Chesterian]) genus Beyrichoceras Foord, 1903 (type species, Goniatites obtusus Phillips, 1836) (eg, Gordon, 1965, p. 284."[18]

Visean[edit | edit source]

Detail of the Tournaisian/Visean boundary is arrowed in the Pengchong section. Credit: François-Xavier Devuyst, Luc Hance, Hongfei Hou, Xianghe Wu, Shugang Tian, Michel Coen, and George Sevastopulo.

"The first appearance of Eoparastaffella simplex in the lineage Eoparastaffela ovalis - Eoparastaffella simplex (foraminifers) [is] the new biostratigraphic criterion to define the base of the Viséan."[19]

Lower Mississippian[edit | edit source]

Tournaisian[edit | edit source]

"The base of the Carboniferous System, Mississippian Sub-System and Tournaisian Stage is defined at the base of Bed 89 in Trench E' at La Serre, France. It coincides with the first appearance of the conodont Siphonodella sulcata within the evolutionary lineage from Siphonodella praesulcata to Siphonodella sulcata."[20]

Devonian[edit | edit source]

The Devonian spanned 416.0 ± 2.8 to 359.2 ± 2.5 Mb2k.

Upper Devonian[edit | edit source]

Famennian[edit | edit source]

The diagram shows the detailed succession of beds around the GSSP level between beds 31g and 32a. Credit: G Klapper, R Feist, R T Becker and M R House.
Photograph of the succession shows that the GSSP lies between Bed 31g and 32a. Credit: G Klapper, R Feist, R T Becker and M R House.
Fossil is of Platyclymenia intracrostata Credit: Wikipek.
This is another example of Clymenia laevigata. Credit: Hectonichus.

"The boundary for the Frasnian/Famennian Stage Global Stratotype Section and Point (GSSP) [...] is drawn [above] in a section exposed [in the second image above] near the Upper Coumiac Quarry in the southeastern Montagne Noire, France."[21]

A specimen of Clymenia laevigata from the Upper Devonian Famennian of Poland is on the right.

On the left is a fossil of Platyclymenia intracrostata also from the Famennian of Poland.

Frasnian[edit | edit source]

Early Devonian[edit | edit source]

Illustration of Asteroxylon mackiei is from the Rhynie Chert. Credit: Kidston, R., & Lang, W. H.{{free media}}

Asteroxylon ("star-shaped xylem") is an extinct genus of vascular plants of the Division Lycopodiophyta known from anatomically preserved specimens described from the famous Early Devonian Rhynie chert and Windyfield chert in Aberdeenshire, Scotland.[22][23] Asteroxylon is considered the most basal member of the Lycopsida.[24]

This plant consisted of aerial, isotomously and anisotomously branching stems that reached 12 mm in diameter and 40 cm in length.[25] The possibly procumbent aerial stems arose from a leaf-less rhizome which bore smaller-diameter, positively geotropic root-like branches.[25] The rhizomes, which represent an independent origin of roots,[26] reached a depth of up to 20 cm below the surface.[27] The xylem or conducting tissue at the center of the aerial stems is distinctly star-shaped in cross-section and has been considered an early actinostele or an "Asteroxylon-type" protostele.[28] The tracheids are of the primitive annular or helical type (so-called G-type).[29] "Leaves" – not true leaves, but protrusions – were of the form of unbranched strap-shaped enations up to 5 mm long; a single vascular trace branched from the main bundle in the centre of the stem to terminate at the base of each enation.[24][28] Enations and axes bore stomata, indicating that their tissues were capable of photosynthesis.[30]

Asteroxylon differs from other similar Early Devonian lycopsids such as Drepanophycus and Baragwanathia in that the singular vascular leaf trace in these latter plants extends into the leaf.[24] The leaves of Drepanophycus and Baragwanathia are therefore considered to be true microphylls or, alternatively, small leaves.[31]

The type species is Asteroxylon mackiei.

Mimagoniatites is a genus of ammonites from the early Devonian.

"Shell [is] small to large size, evolute, thinly discoidal to discoidal. Whorl cross section of the first two whorls [is] approximately circular, in later whorls subtrapezoidal. Umbilicus [is] narrow to moderately wide, moderately large umbilical window (< 1 mm). Whorl expansion rate increases remarkably from the second whorl on (> 2.5, later up to 3.9). Growth line course [is] biconvex with prominent ventrolateral projection and deep ventral sinus."[32]

The lower boundary of the genus is "LD3C--LD3D: Anetoceras Range Zone top, 405.5 million years" and the upper boundary is "CZB maureri--sulc.antiqua Zone [19,30], 398.5 million years".[32]

Geographic distribution: "Devonian of Algeria (2 collections), Canada (1: Nunavut), China (7), the Czech Republic (5), Germany (3), Morocco (13), the Russian Federation (1), Spain (4), Turkey (3), United States (1: Pennsylvania)".[33]

Silurian[edit | edit source]

The Silurian spanned 443.7 ± 1.5 to 416.0 ± 2.8 Mb2k.

Hexamoceras hertzeri is an index fossil for the Silurian.[17]

Hexamoceras is a genus of the Nautiloidea.[34]

"Rolfe made the important observation that 'Other genera are pre-Devonian and hence cannot be ammonoid aptychi, but Ruedemann's suggestion that aptychi "would naturally also have existed in the Ordovician and Silurian cephalopods" has been largely overlooked'."[35]

Andean-Saharan glaciation[edit | edit source]

"A major glacial episode at c. 440 Ma, is recorded in Late Ordovician strata (predominantly Ashgillian) in West Africa (Tamadjert Formation of the Sahara), in Morocco (Tindouf Basin) and in west-central Saudi Arabia, all areas at polar latitudes at the time. From the Late Ordovician to the Early Silurian the centre of glaciation moved from northern Africa to southwestern South America."[36]

The maximum extent of glaciation developed in Africa and eastern Brazil.[37]

The Andean-Saharan was preceded by the Cryogenian ice ages (720–630 Ma, the Sturtian and Marinoan glaciations), often referred to as Snowball Earth, and followed by the Karoo Ice Age (350–260 Ma).[38]

Telychian[edit | edit source]

Current Telychian GSSP is arrowed parallel to the bedding. Credit: Jeremy R. Davies, Richard A. Waters, Stewart G. Molyneux, Mark Williams, Jan A. Zalasiewicz, Thijs R. A. Vandenbroucke & Jacques Verniers.

On the right is an image of the type locality for the Telychian base GSSP indicated by an arrow which points parallel to the bedding. Older bedding of the Aeronian is to the right. The Telychian GSSP is in the Wormwood Formation, Cefn Cerig quarry.

In the section below for the Aeronian, the lower Telychian is marked with a Ⓣ.

Aeronian[edit | edit source]

Diagram has the Rhuddanian to early Telychian sea level curves where Ⓐ marks the horizon of the Aeronian GSSP. Credit: Jeremy R. Davies, Richard A. Waters, Stewart G. Molyneux, Mark Williams, Jan A. Zalasiewicz, Thijs R. A. Vandenbroucke & Jacques Verniers.
The arrow indicates the Aeronian lower GSSP perpendicular to the bedding. Credit: Jeremy R. Davies, et al.

The diagram above has the GSSP for the base of the Aeronian symbolized by a Ⓐ. The upper GSSP for the end of the Aeronian is symbolized by a Ⓣ.

On the right is the type locality for the base of the Aeronian indicated by the arrow. Actual beds are perpendicular to the arrow. The base of the Aeronian is in the Cefngarreg Sandstone Formation (formerly Trefawr Formation), Trefawr track section, Crychan Forest, Central Wales.

Ordovician[edit | edit source]

The Ordovician lasted from 488.3 ± 1.7 to 443.7 ± 1.5 Mb2k.

Upper Ordovician[edit | edit source]

This is an internal mold of a nautiloid from the Upper Ordovician of northern Kentucky. Credit: Wilson44691.

The image on the right is an over-encrusted, internal mold of a nautiloid from the Upper Ordovician of northern Kentucky.

Actonian[edit | edit source]

Geological map of the Onny Valley section is with the sample localities. Credit: Thijs R. A. Vandenbroucke, Antonio Ancilletta, Richard A. Fortey and Jacques Verniers.

The "Onny Valley [...] is the type locality for the Actonian and Onnian substages, and a [Site of Special Scientific Interest] SSSI."[39]

On the right is a geological map of the Onny Valley section together with a strategraphic column, sample localities and the chrono- and lithostratigraphy of the southern Caradoc area (after Rushton et al. 2000).

Sandbian[edit | edit source]

Nemagraptus gracilis, Sandbian graptolites, are from the Caparo Formation, Venezuelan Andes. Credit: J.C. Gutiérrez-Marco, D. Goldman, J. Reyes-Abril, and J. Gómez.

"The Lower Sandbian Nemagraptus gracilis Zone comprises one of the most widespread, and easily recognizable graptolite faunas in the Ordovician System. The base of the N. gracilis Zone also marks the base of the Upper Ordovician Series, and is internationally defined by the FAD of the eponymous species, with the Global Stratotype Section and Point (GSSP) located at Fågelsång in Scania, southern Sweden (Bergström et al., 2000, 2009)."[40]

Middle Ordovician[edit | edit source]

Darriwilian[edit | edit source]

Abereiddian[edit | edit source]

Ordovician chart illustrates the main regional series, stage and substage divisions. Credit: Hüseyïn Kozlu, M. Cemal Göncüoğu, Graciela N. Sarmiento & M. Alï Gül.

On the right is an Ordovician chart which illustrates the stratigraphic relationships between the Global Series, Stages and key faunal markers, and the main regional series, stage and substage divisions used in different parts of the world (after Webby 1988).

Here, the Abereiddian is the lower portion of the Llanvirn series, which in turn is the upper portion of Darriwilian Stage, of the upper Middle Ordovician.

Lower Ordovician[edit | edit source]

Cambrian[edit | edit source]

The Cambrian lasted from 542.0 ± 1.0 to 488.3 ± 1.7 Mb2k.

Furongian[edit | edit source]

The Furongian Series includes Cambrian Stage 10, Cambrian Stage 9, and the Paibian Stage.[41]

Stage 10[edit | edit source]

The FAD of Lotagnosthus americanus is the primary stratigraphic tool for correlation of the base for Stage 10.[41]

Stage 9[edit | edit source]

The FAD of Agnostotes orientalis is the primary stratigraphic tool for correlation of the base for Stage 10.[41]

Paibian[edit | edit source]

The "FAD of Glyptagnostus reticulatus [is the primary stratigraphic tool for correlation of the base] for the Paibian Stage."[41]

Guzhangian[edit | edit source]

The image shows exposure of the GSSP for the base of the Guzhangian Stage (coinciding with the FAD of Lejopyge laevigata) in the Huaqiao Formation, Luoyixi section, Guzhang County, Hunan Province, China. Credit: Shanchi Peng, Loren E. Babcock, Jingxun Zuo, Huanling Lin, Xuejian Zhu, Xianfeng Yang, Richard A. Robison, Yuping Qi, Gabriella Bagnoli, and Yong’an Chen.
The image shows an exoskeleton of the cosmopolitan agnostoid trilobite Lejopyge laevigata. Credit: Shanchi Peng et al.

"The Global boundary Stratotype Section and Point (GSSP) for the base of the Guzhangian Stage (Cambrian Series 3) is defined at the base of a limestone (calcisiltite) layer 121.3 m above the base of the Huaqiao Formation in the Louyixi section along the Youshui River (Fengtan Reservoir), about 4 km northwest of Luoyixi (4 km southeast of Wangcun), in northwestern Hunan, China."[41]

"The GSSP level contains the lowest occurrence of the cosmopolitan agnostoid trilobite Lejopyge laevigata [in the image on the left] (base of the L. laevigata Zone)."[41]

Drumian[edit | edit source]

Correlation chart of the Cambrian shows the new global chronostratigraphic stage (Drumian; column at left) compared to regional usage in major areas of the world. Credit: Loren E. Babcock, Richard A. Robison, Margaret N. Rees, Shanchi Peng, and Matthew R. Saltzman.

The "FAD of Ptychagnostus atavus [is the primary stratigraphic tool for correlation of the base (GSSP)] for the Drumian Stage".[41]

"The Global boundary Stratotype Section and Point (GSSP) for the base of the Drumian Stage (Cambrian Series 3) is defined at the base of a limestone (calcisiltite) layer 62 m above the base of the Wheeler Formation in the Stratotype Ridge section, Drum Mountains, Utah, USA. The GSSP level contains the lowest occurrence of the cosmopolitan agnostoid trilobite Ptychagnostus atavus (base of the P. atavus Zone)."[42]

Stage 5[edit | edit source]

Observed stratigraphic distribution of trilobites in the lower Wheeler Formation near the base of the Ptychagnostus atavus Zone, Stratotype Ridge section, Drum Mountains, Utah, USA, is modified from Babcock et al., 2004. Credit: Loren E. Babcock, Richard A. Robison, Margaret N. Rees, Shanchi Peng, and Matthew R. Saltzman.
Key agnostoid trilobite species are used for recognition of the base of the Drumian Stage. Credit: Loren E. Babcock, Richard A. Robison, Margaret N. Rees, Shanchi Peng, and Matthew R. Saltzman.

"The polymerid trilobites Ptychoparella (incorporating Elrathina as a junior synonym) and Elrathia have long stratigraphic ranges (Robison, 1964a, 1964b, 1976; Babcock, 1994a) that extend from stage 5 into the lower part of the Drumian Stage (White, 1973) and provide little help in constraining the base of the Drumian."[42]

On the right are images of key agnostoid trilobite species used for recognition of the base of the Drumian Stage.

"A, Ptychagnostus gibbus (Linnarsson), dorsal exoskeleton in shale, x 8.4, from the Wheeler Formation, c. 25 m above base, south side of Swasey Peak, House Range, Utah (R. A. Robison locality 157); KUMIP 153949. B, Ptychagnostus atavus (Tullberg), cephalon in limestone showing scrobiculate genae, x 8.1, from the Wheeler Formation, 27 m above base, House Range, Utah (R. A. Robison locality 196); KUMIP 153830. C, P. atavus (Tullberg), pygidium in limestone, x 7.8, from same locality as specimen in Figure 6B; KUMIP 153933. D, P. atavus (Tullberg), dorsal exoskeleton from shale with cone-in-cone calcite encrusting ventral surface, x 8.1 from the Wheeler Formation, c. 100 below top, “Swasey Spring quarry”, east flank of House Range, Utah (R. A. Robison locality 114); KUMIP 153930."[42]

The "Cambrian lobopodian (panarthropod) worm Hallucigenia sparsa [is] from the Burgess Shale (Cambrian Series 3, Stage 5)."[43]

Stage 4[edit | edit source]

Stage 3[edit | edit source]

The FAD of trilobites is the primary stratigraphic tool for correlation of the base for Stage 3.[41]

Terreneuvian[edit | edit source]

The Terreneuvian Series includes Cambrian Stage 2 and the Fortunian Stage.[41]

Stage 2[edit | edit source]

Hallucigenia sparsa is from the Burgess Shale. Credit: Jean-Bernard Caron, Martin R. Smith, and Thomas H. P. Harvey.

"Hallucigeniids are [...] an important and widespread component of disparate Cambrian communities from late in the Terreneuvian (Cambrian Stage 2) through the ‘middle’ Cambrian (Series 3); their apparent decline in the latest Cambrian may be partly taphonomic. The cone-in-cone construction of hallucigeniid sclerites is shared with the sclerotized cuticular structures (jaws and claws) in modern onychophorans."[43]

In the image on the right "Hallucigenia sparsa [is] from the Burgess Shale: (a,b) Smithsonian Institution, National Museum of Natural History (NMNH) 83935 (holotype), articulated specimen, showing seven pairs of spines, partially decayed towards the rear, presumed head to the right. (a) composite image of part and counterpart; (b) enlargement of the basal part of the spines; (c,d) Royal Ontario Museum (ROM) 61513, complete specimen showing seven pairs of spines and backscatter image of boxed area (d); (e–i) ROM 57776, backscatter images (overview and close-ups of boxed areas) of spine showing four internal cones and lineations; (g) ROM 61513, backscatter image showing lineations and a distal cone; (j–o) ROM 62269, backscatter images of several spines, showing elemental distribution of carbon (l) and phosphorous (m) and details of ornamentation near spines’ mid-length (n) and base (o) (arrows indicate local disturbances in the rhomboid pattern); (p) ROM 61513, backscatter image showing details of ornamentation showing scales in positive relief (top left) and negative relief below the carbon film. Ba, basal region of spines; C, cone; Li, lineations. Scale bars: (a–d) 1000 µm; (e,j–m) 100 µm; (f–i) 50 µm; (n–p) 10 µm."[43]

Fortunian[edit | edit source]

The FAD of Trichophycus pedum is the primary stratigraphic tool for correlation of the base (GSSP) for the Fortunian Stage.[41]

Precambrian[edit | edit source]


  1. "the time and geology dated before the Phanerozoic"[44] or
  2. the "eon (or supereon) and rock formations dated before 541.0±1.0 million years ago, coinciding with the first appearance of the fossils of hard-shelled animals"[44]

is called the precambrian.

Usage notes[44]

  • The International Commission on Stratigraphy, which attempts to standardize the vocabulary of the field, is revising the boundaries between time periods based on physical-science methods rather than the kinds of fossils present.
  • The boundary between the Precambrian and the Phanerozoic has been changed from time to time and will be subject to change.

Hypotheses[edit | edit source]

  1. Each time frame or span of time in geochronology has at least one dating technique.
  2. Late Ordovician and Upper Ordovician are different time frames.

See also[edit | edit source]

References[edit | edit source]

  1. Mike Walker; Sigfus Johnsen; Sune Olander Rasmussen; Trevor Popp; Jørgen-Peder Steffensen; Phil Gibbard; Wim Hoek; John Lowe et al. (2009). "Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records". Journal of Quaternary Science 24 (1): 3-17. doi:10.1002/jqs.1227. Retrieved 2015-01-18. 
  2. Names from local versions of the geologic timescale can often be found in the local language. The English name is usually found by replacing the suffix in the local language for -an or -ian. Examples for "local" suffices are -en (French), -ano (Spanish), -ium (German), -aidd (Welsh) or -aan (Flemish Dutch). The English name "Norian", for example, becomes Noriano in Spanish, Norium in German, Noraidd in Welsh or Norien in French.
  3. 3.0 3.1 Time is given in Megaannum (million years BP, unless other units are given in the table. BP stands for "years before present". For ICS-units the absolute ages are taken from Gradstein et al. (2004).
  4. 4.0 4.1 This name is often still used in a chronostratigraphic or geochronologic sense, although it is now officially a lithostratigraphic unit.
  5. Gradstein, F.M.; Ogg, J.G. & Smith, A.G. (2004). A Geologic Time Scale 2004. Cambridge University Press. 
  6. The Nonmarine Permian: Volume 30 of Bulletin of the New Mexico Museum of Natural History and Science, page 48. Editors Spencer G. Lucas, Kate E. Zeigler, 2005
  7. Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. and Snyder, W.S. (1998). "Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System". Episodes 21 (1): 11–18. 
  8. 8.0 8.1 Montañez, Isabel P.; Poulsen, Christopher J. (2013-05-30). "The Late Paleozoic Ice Age: An Evolving Paradigm". Annual Review of Earth and Planetary Sciences 41 (1): 629–656. doi:10.1146/ ISSN 0084-6597. 
  9. Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press
  10. Gradstein, Felix M.; James G. Ogg; Alan G. Smith (2005). A Geologic Time Scale 2004. Cambridge University Press. p. 288. ISBN 978-0-521-78673-7. 
  11. Gradstein, F.M.; Ogg, J.G. & Smith, A.G. (2004). A Geologic Time Scale 2004. Cambridge University Press. 
  12. Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. & Snyder, W.S. (1998). "Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System". Episodes 21 (1): 11-18. Retrieved 2007-09-28. 
  13. Chernykh, V.V.; Chuvashov, B.I.; Davydov, V.I.; Schmitz, M. & Snyder, W.S. (2006). "Usolka section (southern Urals, Russia): a potential candidate for GSSP to define the base of the Gzhelian Stage in the global chronostratigraphic scale". Geologija 49 (2): 205–217. Retrieved 2007-12-14. 
  14. Gradstein, F.M.; Ogg, J.G. & Smith, A.G. (2004). A Geologic Time Scale 2004. Cambridge University Press. 
  15. Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica". Geology 38 (12): 1079–1082. doi:10.1130/G31182.1. 
  16. 16.0 16.1 16.2 Olivier Béthoux, Jean Galtier, and André Nel (1 August 2004). "Earliest Evidence of Insect Endophytic Oviposition". Palaios 19 (4): 408-413. doi:10.1669/0883-1351(2004)019<0408:EEOIEO>2.0.CO;2. Retrieved 12 October 2021. 
  17. 17.0 17.1 JM Watson (28 July 1997). "Index Fossils". Reston, Virginia USA: US Geological Survey. Retrieved 2015-01-28.
  18. David M. Work; Charles E. Mason (November 2004). "Mississippian (Late Osagean) Ammonoids from the New Providence Shale Member of the Borden Formation, North-Central Kentucky". Journal of Paleontology 78 (6): 1128-37. doi:10.1666/0022-3360(2004)078<1128:MLOAFT>2.0.CO;2). Retrieved 2015-01-30. 
  19. François-Xavier Devuyst; Luc Hance; Hongfei Hou; Xianghe Wu; Shugang Tian; Michel Coen; George Sevastopulo (June 2003). "A proposed Global Stratotype Section and Point for the base of the Viséan Stage (Carboniferous): the Pengchong section, Guangxi, South China". Episodes 26 (2): 105. Retrieved 2015-01-29. 
  20. S. I. Kaiser (2009). "GSSP for Tournaisian Stage". Retrieved 2015-01-29.
  21. G Klapper; R Feist; R T Becker; M R House (December 1993). "Definition of the Frasnian/Famennian Stage Boundary". Episodes 16 (4): 433-41. Retrieved 2015-01-27. 
  22. Kidston, R.; Lang, W. H. (1920). "On Old Red Sandstone Plants showing Structure, from the Rhynie Chert Bed, Aberdeenshire. Part III. Asteroxylon Mackiei, Kidston and Lang". Transactions of the Royal Society of Edinburgh 52 (3): 643–680. doi:10.1017/S0080456800004506. 
  23. Rice, C. M.; Ashcroft, W. A.; Batten, D. J.; Boyce, A. J.; Caulfield, J. B. D.; Fallick, A. E.; Hole, M. J.; Jones, E. et al. (1995). "A Devonian auriferous hot spring system, Rhynie, Scotland". Journal of the Geological Society, London 152 (2): 229–250. doi:10.1144/gsjgs.152.2.0229. 
  24. 24.0 24.1 24.2 Hao, Shougang; Xue, Jinzhuang (2013). The Early Devonian Posongchong Flora of Yunnan - A Contribution to an Understanding of the Evolution and Early Diversification of Vascular Plants. Beijing: Science Press. pp. 244–245. ISBN 978-7-03-036616-0. 
  25. 25.0 25.1 Strullu‐Derrien, Christine; Wawrzyniak, Zuzanna; Goral, Tomasz; Kenrick, Paul (2015). "Fungal colonization of the rooting system of the early land plant Asteroxylon mackiei from the 407‐Myr‐old Rhynie Chert (Scotland, UK)". Botanical Journal of the Linnean Society 179 (1): 201–213. doi:10.1111/boj.12307. 
  26. Hetherington, Alexander J.; Dolan, Liam (2018). "Stepwise and independent origins of roots among land plants". Nature 561 (7722): 235–238. doi:10.1038/s41586-018-0445-z. PMID 30135586. 
  27. Smoot, E.L.; Jansen, R.K.; Taylor, T.N. (1981). "A Phylogenetic Analysis of the Land Plants: A Botanical Commentary". Taxon 30 (1): 65–67. doi:10.2307/1219392. 
  28. 28.0 28.1 Kerp, Hans; Wellman, Charles H.; Krings, Michael; Kearney, Patricia; Hass, Hagen (2013). "Reproductive organs and in situ spores of Asteroxylon mackiei Kidston & Lang, the most complex plant from the lower Devonian Rhynie chert". International Journal of Plant Sciences 174 (3): 293–308. doi:10.1086/668613. 
  29. Kenrick, Paul; Crane, Peter R. (1997). The Origin and Early Diversification of Land Plants: A Cladistic Study. Washington, D.C.: Smithsonian Institution Press. ISBN 978-1-56098-730-7. 
  30. Wilson, Jonathon P.; Fischer, Woodward W. (2011). "Hydraulics of Asteroxylon mackei, an early Devonian vascular plant, and the early evolution of water transport tissue in terrestrial plants". Geobiology 9 (2): 121–130. doi:10.1111/j.1472-4669.2010.00269.x. PMID 21244621. 
  31. Tomescu, Alexandru M.F. (2009). "Megaphylls, microphylls and the evolution of leaf development". Trends in Plant Science 14 (1): 5–12. doi:10.1016/j.tplants.2008.10.008. PMID 19070531. 
  32. 32.0 32.1 Eichenberg (1930). "Genus Mimagoniatites". GONIAT Online. Retrieved 2015-01-28.
  33. John Alroy (2014). "†Mimagoniatites Eichenberg 1930 (ammonite)". Australia: Macquarie University. Retrieved 2015-01-28.
  34. IONHexamoceras (15 April 2015). "Name - Hexamoceras". Thomson Reuters. Retrieved 2015-04-15.
  35. C. H. Holland (October 1987). "Aptychopsid Plates (Nautiloid Opercula) from the Irish Silurian". The Irish Naturalists' Journal 22 (8): 347-51. Retrieved 2015-04-15. 
  36. Eyles, Nicholas; Young, Grant (1994). Deynoux, M.; Miller, J.M.G.; Domack, E.W. et al.. eds. Geodynamic controls on glaciation in Earth history, in Earth's Glacial Record. Cambridge: Cambridge University Press. pp. 5–10. ISBN 0521548039. 
  37. Aber, James S. (2008). "ES 331/767 Lab III". Emporia State University. Retrieved 7 November 2015.
  38. Högele, M. A. (2011). Metastability of the Chafee-Infante equation with small heavy-tailed Lévy Noise. Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II. Retrieved 7 November 2015. 
  39. Thijs R. A. Vandenbroucke; Antonio Ancilletta; Richard A. Fortey; Jacques Verniers (2009). "A modern assessment of Ordovician chitinozoans from the Shelve and Caradoc areas, Shropshire, and their significance for correlation". Geology Magazine 146 (2): 216-36. doi:10.1017/S0016756808005815. Retrieved 2015-01-15. 
  40. J.C. Gutiérrez-Marco; D. Goldman; J. Reyes-Abril; J. Gómez (2011). J.C. Gutiérrez-Marco, I. Rábano and D. García-Bellido. ed. A Preliminary Study of Some Sandbian (Upper Ordovician) Graptolites from Venezuela, In: Ordovician of the World. Madrid: Instituto Geológico y Minero de España. pp. 199-206. ISBN 978-84-7840-857-3. Retrieved 2015-01-15. 
  41. 41.0 41.1 41.2 41.3 41.4 41.5 41.6 41.7 41.8 41.9 Shanchi Peng; Loren E. Babcock; Jingxun Zuo; Huanling Lin; Xuejian Zhu; Xianfeng Yang; Richard A. Robison; Yuping Qi et al. (March 2009). "The Global Boundary Stratotype Section and Point (GSSP) of the Guzhangian Stage (Cambrian) in the Wuling Mountains, Northwestern Hunan, China". Episodes 32 (1): 41-55. Retrieved 2015-01-21. 
  42. 42.0 42.1 42.2 Loren E. Babcock; Richard A. Robison; Margaret N. Rees; Shanchi Peng; Matthew R. Saltzman (June 2007). "The Global boundary Stratotype Section and Point (GSSP) of the Drumian Stage (Cambrian) in the Drum Mountains, Utah, USA". Episodes 30 (2): 84-94. Retrieved 2016-10-26. 
  43. 43.0 43.1 43.2 Jean-Bernard Caron; Martin R. Smith; Thomas H. P. Harvey (31 July 2013). "Beyond the Burgess Shale: Cambrian microfossils track the rise and fall of hallucigeniid lobopodians". Proceedings of the Royal Society B 280 (1767): 1613. doi:10.1098/rspb.2013.1613. Retrieved 2016-10-26. 
  44. 44.0 44.1 44.2 "Precambrian, In: Wiktionary". San Francisco, California: Wikimedia Foundation, Inc. 4 November 2014. Retrieved 2015-02-12.

External links[edit | edit source]

{{Archaeology resources}}