Arenig

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Contents 1 History 2 In Geochronology 3 Events 4 Brachiopod Fauna 4.1 Acrotretida 4.2 Lingulida 4.3 Orthida 4.4 Paternida 4.5 Pentamerida 4.6 Strophomenida 4.7 Trimerellida 5 Cephalopod Fauna 5.1 Actinocerida 5.1.1 Upper 5.2 Anarcestida 5.3 Barrandeocerida 5.4 Ellesmerocerida 5.5 Endocerida 5.5.1 Lower 5.5.2 Upper 5.6 Intejocerida 5.7 Oncocerida 5.8 Orthocerida 5.9 Tarphycerida 5.9.1 Lower 5.9.2 Upper 6 Trilobite Fauna 6.1 Agnostida 6.2 Asaphida 6.3 Corynexichida 6.4 Lichida 6.5 Odontopleurida 6.6 Phacopids 6.7 Proetida 6.8 Ptychopariida 7 External links 8 References

In geology, the Arenig group is a geological group of rocks deposted during the lowest stage of the Ordovician System.

[edit] History

The term was first used by Adam Sedgwick in 1847 with reference to the "Arenig Ashes and Porphyries" in the neighbourhood of Arenig Fawr, in Merioneth, North Wales. The rock-succession in the Arenig district has been recognized by W. G. Fearnsides (“On the Geology of Arenig Fawr and Moel Llanfnant", Q.J.G.S. vol. lxi., 1905, pp. 608–640, with maps). The above succession is divisible into:

1. A lower series of gritty and calcareous sediments, the “Arenig Series" as it is now understood;
2. A middle series, mainly volcanic, with shale, the "Llandeilo Series"; and
3. The shale and limestones of the Bala or Caradoc Stage.

It was to the middle series (2) that Sedgwick first applied the term "Arenig". In the typical region and in North Wales generally the Arenig series appears to be unconformable upon the Cambrian rocks; this is not the case in South Wales.

The Arenig series is represented in North Wales by the Garth grit and Ty Obry beds, by the Shelve series of the Corndon district, the Skiddaw slates of the Lake District, the Ballantrae group of Ayrshire, and by the Ribband series of slates and shale in Wicklow and Wexford. It may be mentioned here that the "Llanvirn" Series of H. Hicks was equivalent to the bifidus shale and the Lower Llandeilo Series.

[edit] In Geochronology

In the geologic timescale, the Arenig used to refer to an age of the Lower Ordovician epoch, between 478.6 ± 1.7and 471.8 ± 1.6 million years ago. This term is depreciated.^[1]

[edit] Events

The Arenig group was deposited during a worldwide sudden rise in sea level rise in sea level (marine transgression). The early Ordoovician surge in marine diversity also began around this time.^[2].

[edit] Brachiopod Fauna

Incertae Cedis Brachiopods of the Floian
Taxa	Presence	Location	Description	Images
Eurorthisina	Confirmed.[3]			A of a variety of fossil brachiopods.
Tegulella	Confirmed.[3]

[edit] Acrotretida

Acrotretids of the Floian
Taxa	Presence	Location	Description	Images
Acanthambonia	Confirmed.[3]			A of a variety of fossil brachiopods.
Cyrbasiotreta	Confirmed.[3]
Eoconulus	Confirmed.[3]
Issedonia	Confirmed.[3]
Karnotreta	Confirmed.[3]
Lurgiticoma	Confirmed.[3]
Multispinula	Confirmed.[3]
Mylloconotreta	Confirmed.[3]
Numericoma	Confirmed.[3]
Orthisocrania	Confirmed.[3]
Polylasma	Confirmed.[3]
Pomeraniotreta	Confirmed.[3]
Pseudocrania	Confirmed.[3]
Scaphelasma	Confirmed.[3]
Schizotreta	Confirmed.[3]
Torynelasma	Confirmed.[3]

[edit] Lingulida

Placeholders of the Floian
Taxa	Presence	Location	Description	Images
Acanthorthis	Confirmed.[3]			A of a variety of fossil brachiopods.
Aulonotreta	Confirmed.[3]
Dictyobolus	Confirmed.[3]
Ectenoglossa	Confirmed.[3]
Elliptoglossa	Confirmed.[3]
Monobolina	Confirmed.[3]
Paldiskites	Confirmed.[3]
Paterula	Confirmed.[3]
Pseudolingula	Confirmed.[3]
Quasithambonia	Confirmed.[3]
Rafanoglossa	Confirmed.[3]
Volborthia	Confirmed.[3]

[edit] Orthida

Placeholders of the Floian
Taxa	Presence	Location	Description	Images
Acanthorthis	Confirmed.[3]			A of a variety of fossil brachiopods.
Acanthotoechia	Confirmed.[3]
Anchigonites	Confirmed.[3]
Angusticardinia	Confirmed.[3]
Anomalorthis	Confirmed.[3]
Antigonambonites	Confirmed.[3]
Apomatella	Confirmed.[3]
Astraborthis	Confirmed.[3]
Crossiskenidium	Confirmed.[3]
Dalmanella	Confirmed.[3]
Desmorthis	Confirmed.[3]
Diparelasma	Confirmed.[3]
Eodiorthelasma	Confirmed.[3]
Eosotrematorthis	Confirmed.[3]
Estlandia	Confirmed.[3]
Euorthisina	Confirmed.[3]
Famatinorthis	Confirmed.[3]
Fasciculina	Confirmed.[3]
Ferrax	Confirmed.[3]
Ffynnonia	Confirmed.[3]
Fistulogonites	Confirmed.[3]
Glossorthis	Confirmed.[3]
Glypterina	Confirmed.[3]
Hesperonomiella	Confirmed.[3]
Incorthis	Confirmed.[3]
Jaanussonites	Confirmed.[3]
Ladogiella	Confirmed.[3]
Lomatorthis	Confirmed.[3]
Monorthis	Confirmed.[3]
Munhella	Confirmed.[3]
Nereidella	Confirmed.[3]
Neumania	Confirmed.[3]
Nocturneilla	Confirmed.[3]
Notoscaphidia	Confirmed.[3]
Oligorthis	Confirmed.[3]
Orthambonites	Confirmed.[3]
Orthidiella	Confirmed.[3]
Orthidium	Confirmed.[3]
Orthis	Confirmed.[3]
Oslogonites	Confirmed.[3]
Panderina	Confirmed.[3]
Paralenorthis	Confirmed.[3]
Paurorthina	Confirmed.[3]
Paurorthis	Confirmed.[3]
Phragmorthis	Confirmed.[3]
Platystrophia	Confirmed.[3]
Platytoechia	Confirmed.[3]
Polytoechia	Confirmed.[3]
Pomatotrema	Confirmed.[3]
Prantlina	Confirmed.[3]
Productorthis	Confirmed.[3]
Progonambonites	Confirmed.[3]
Protohesperonomia	Confirmed.[3]
Protoskenidiodes	Confirmed.[3]
Pseudomimella	Confirmed.[3]
Raunites	Confirmed.[3]
Rhynchorthis	Confirmed.[3]
Shoshonorthis	Confirmed.[3]
Sinorthis	Confirmed.[3]
Taphrorthis	Confirmed.[3]
Tarfaya	Confirmed.[3]
Treioria	Confirmed.[3]
Trematorthis	Confirmed.[3]
Valcourea	Confirmed.[3]
Virgoria	Confirmed.[3]

[edit] Paternida

Placeholders of the Floian
Taxa	Presence	Location	Description	Images
Dictyonites	Confirmed.[3]			A of a variety of fossil brachiopods.

[edit] Pentamerida

Placeholders of the Floian
Taxa	Presence	Location	Description	Images
Acanthorthis	Confirmed.[3]			A of a variety of fossil brachiopods.
Acanthoglypha	Confirmed.[3]
Boreadocamara	Confirmed.[3]
Camerella	Confirmed.[3]
Doloresella	Confirmed.[3]
Hesperotrophia	Confirmed.[3]
Idiostrophia	Confirmed.[3]
Imbricatia	Confirmed.[3]
Karakulina	Confirmed.[3]
Liricamera	Confirmed.[3]
Lycophoria	Confirmed.[3]
Porambonites	Confirmed.[3]
Rectotrophia	Confirmed.[3]
Rosella	Confirmed.[3]
Rugostrophia	Confirmed.[3]
Stenocamara	Confirmed.[3]
Syntrophia	Confirmed.[3]
Syntrophinella	Confirmed.[3]
Xenelasma	Confirmed.[3]

[edit] Strophomenida

Placeholders of the Floian
Taxa	Presence	Location	Description	Images
Acanthorthis	Confirmed.[3]			A of a variety of fossil brachiopods.
Ahtiella	Confirmed.[3]
Aporthophyla	Confirmed.[3]
Borua	Confirmed.[3]
Calyptolepta	Confirmed.[3]
Christiania	Confirmed.[3]
Ingria	Confirmed.[3]
Leptestia	Confirmed.[3]
Petroria	Confirmed.[3]
Plectambonites	Confirmed.[3]
Reinversella	Confirmed.[3]
Schedophyla	Confirmed.[3]
Taffia	Confirmed.[3]
Tourmakeadia	Confirmed.[3]

[edit] Trimerellida

Placeholders of the Floian
Taxa	Presence	Location	Description	Images
Dinobolus	Confirmed.[3]			A of a variety of fossil brachiopods.

[edit] Cephalopod Fauna

[edit] Actinocerida

• Metactinoceras
• Ordosoceras
• Polydesmia

[edit] Upper

The following is a list of Actinocerid genera whose fossils are geochronologically found first in upper Arenig strata. These genera may survive into later portions of the Arenig stage, or even into later geological stages. This list should not be thought of in terms of the lifespan of the genera included.

• Leurorthoceras
• Nybyoceras
• Actinoceras
• Wutinoceras
• Ormoceras
• Adamsoceras
• Georgina

[edit] Anarcestida

Anarcestids of the Floian
Taxa	Presence	Location	Description	Images
Eobactrites	Confirmed.[4]			An illustration of a variety of fossil nautiloids.

[edit] Barrandeocerida

Barrandeocerids of the Floian
Taxa	Presence	Location	Description	Images
Plectoceras	Confirmed.[4]			An illustration of a variety of fossil nautiloids.

[edit] Ellesmerocerida

Ellesmocerids of the Floian
Taxa	Presence	Location	Description	Images
Amsleroceras	Confirmed.[4]			An illustration of a variety of fossil nautiloids.
Apocrinoceras	Confirmed.[4]
Avoceras	Confirmed.[4]
Bakeroceras	Confirmed.[4]
Baltoceras	Confirmed.[4]
Catoraphinoceras	Confirmed.[4]
Cochlioceras	Confirmed.[4]
Copiceras	Confirmed.[4]
Clelandoceras	Confirmed.[4]
Cumberloceras	Confirmed.[4]
Cyclostomiceras	Confirmed.[4]
Cyrtobaltoceras	Confirmed.[4]
Desioceras	Confirmed.[4]
Diaphoroceras	Confirmed.[4]
Diastoloceras	Confirmed.[4]
Dwightoceras	Confirmed.[4]
Dyscritoceras	Confirmed.[4]
Ectocycloceras	Confirmed.[4]
Endorioceras	Confirmed.[4]
Eocyckistomiceras	Confirmed.[4]
Eothinoceras	Confirmed.[4]
Hemichoanella	Confirmed.[4]
Irianoceras	Confirmed.[4]
Kyminoceras	Confirmed.[4]
Lawrenceoceras	Confirmed.[4]
Meikeloceras	Confirmed.[4]
Microbaltoceras	Confirmed.[4]
Monogonoceras	Confirmed.[4]
Ogygoceras	Confirmed.[4]
Pictetoceras	Confirmed.[4]
Protocycloceras	Confirmed.[4]
Quebecoceras	Confirmed.[4]
Rangeroceras	Confirmed.[4]
Rhabdiferous	Confirmed.[4]
Rioceras	Confirmed.[4]
Rudolfoceras	Confirmed.[4]
Smithvilloceras	Confirmed.[4]
Somalinautilus	Confirmed.[4]
Somalinautilus	Confirmed.[4]
Somalinautilus	Confirmed.[4]
Vassaroceras	Confirmed.[4]
Veneficoceras	Confirmed.[4]
Ventroloboceras	Confirmed.[4]

[edit] Endocerida

• Campendoceras
• Dartonoceras
• Kaipingoceras
• Kugeloceras
• Lobosiphon
• Manitouoceras
• Mcqueenoceras
• Mysticoceras
• Notocycloceras
• Oderoceras
• Parapiloceras
• Phragmosiphon
• Platysiphon
• Pliendoceras
• Retroclitendoceras
• Stenosiphon
• Subpenhsioceras
• Utoceras
• Yorkoceras
• Vaginoceras
• Chisiloceras
• Cyrtovaginoceras
• Tallinnoceras
• Juaboceras
• Penhsioceras
• Ventrolobendoceras

[edit] Lower

The following is a list of Endocerid genera whose fossils are geochronologically found first in lower Arenig strata. These genera may survive into later portions of the Arenig stage, or even into later geological stages. This list should not be thought of in terms of the lifespan of the genera included.

• Allopiloceras
• Choreanoceroides
• Escharendoceras
• Lebetoceras
• Loxochoanella
• Sewardoceras
• Telleroceras
• Clitendoceras
• Coreanoceras
• Cotteroceras
• Piloceras
• Endoceras
• Proterovaginoceras
• Cyrtendoceras
• Anthoceras
• Chaohuceras
• Proterocameroceras
• Thylacoceras

[edit] Upper

The following is a list of Endocerid genera whose fossils are geochronologically found first in upper Arenig strata. These genera may survive into later portions of the Arenig stage, or even into later geological stages. This list should not be thought of in terms of the lifespan of the genera included.

• Allocotoceras
• Cassinoceras
• Chihlioceras
• Cyclocyrtendoceras
• Cyptendoceras
• Kirkoceras
• Lobendoceras
• Najaceras
• Protocyclendoceras
• Yehlioceras
• Nanno
• Dideroceras
• Lobocyclendoceras
• Meniscoceras
• Paracyclendoceras
• Cacheoceras
• Perkinsoceras
• Williamsoceras
• Manchuroceras
• Schmidtoceras

[edit] Intejocerida

Intejocerids of the Floian
Taxa	Presence	Location	Description	Images
Bajkaloceras	Confirmed.[4]			An illustration of a variety of fossil nautiloids.
Evencoceras	Confirmed.[4]
Intejoceras	Confirmed.[4]
Rossoceras	Confirmed.[4]

[edit] Oncocerida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Phthanoncoceras	Confirmed.[4]			An illustration of a variety of fossil nautiloids.
Valhalloceras	Confirmed.[4]

[edit] Orthocerida

Nautiloids of the Bajocian
Taxa	Presence	Location	Description	Images
Buttsoceras	Confirmed.[4]			An illustration of a variety of fossil nautiloids.
Centroonoceras	Confirmed.[4]
Gangshanoceras	Confirmed.[4]
Geisonoceras	Confirmed.[4]
Glenisteroceras	Confirmed.[4]
Michelinoceras	Confirmed.[4]
Orthoceras	Confirmed.[4]
Oxfordoceras	Confirmed.[4]
Rhynchorthoceras	Confirmed.[4]
Stereoplasmoceras	Confirmed.[4]
Tajaroceras	Confirmed.[4]
Wardoceras	Confirmed.[4]

[edit] Tarphycerida

• Deltoceras
• Pseudancistroceras
• Seelyoceras

[edit] Lower

• Alaskoceras
• Moreauoceras
• Pilotoceras
• Shumardoceras
• Pycnoceras
• Campbelloceras
• Aphetoceras

[edit] Upper

• Aethoceras
• Bentoceras
• Centrotarphyceras
• Clytoceras
• Cycloplectoceras
• Eichwaldoceras
• Eurystomites
• Hardmanoceras
• Holmiceras
• Pionoceras
• Trocholitoceras
• Wichitoceras
• Tarphyceras
• Litoceras
• Curtoceras
• Arkoceras
• Estonioceras
• Tragoceras

[edit] Trilobite Fauna

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Canningella	Confirmed.[5]			Drawing of a trilobite fossil.
Gogoella	Confirmed.[5]
Macrogrammus	Confirmed.[5]
Priceaspis	Confirmed.[5]
Thymurus	Confirmed.[5]

[edit] Agnostida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Galbagnostus	Confirmed.[5]			Drawing of a trilobite fossil.
Geragnostella	Confirmed.[5]

[edit] Asaphida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Phthanoncoceras	Confirmed.[5]			Asaphus. Asaphus Asaphus Asaphus Drawing of a trilobite fossil. Nobiliasaphus
Ampyx	Confirmed.[5]
Ampyxoides	Confirmed.[5]
Anebolithus	Confirmed.[5]
Asaphus	Confirmed.[5]
Aspidaeglina	Confirmed.[5]
Australopyge	Confirmed.[5]
Bergamia	Confirmed.[5]
Bohemopyge	Confirmed.[5]
Borogothus	Confirmed.[5]
Bumastides	Confirmed.[5]
Ceratolithus	Confirmed.[5]
Cloacaspis	Confirmed.[5]
Cnemidopyge	Confirmed.[5]
Degamella	Confirmed.[5]
Dionide	Confirmed.[5]
Dionidella	Confirmed.[5]
Ellipsotaphrus	Confirmed.[5]
Falanapis	Confirmed.[5]
Famatinolithus	Confirmed.[5]
Globampyx	Confirmed.[5]
Gog	Confirmed.[5]
Hanchungolithus	Confirmed.[5]
Hoekaspis	Confirmed.[5]
Hungioides	Confirmed.[5]
Hunnebergia	Confirmed.[5]
Isocolus	Confirmed.[5]
Isoteloides	Confirmed.[5]
Lachnostoma	Confirmed.[5]
Lannacus	Confirmed.[5]
Lapidaria	Confirmed.[5]
Liomegalaspides	Confirmed.[5]
Megalaspidella	Confirmed.[5]
Megalaspides	Confirmed.[5]
Mendolaspis	Confirmed.[5]
Merlinia	Confirmed.[5]
Microparia	Confirmed.[5]
Mioptychopyge	Confirmed.[5]
Myttonia	Confirmed.[5]
Ningkianolithus	Confirmed.[5]
Niobides	Confirmed.[5]
Ogmasaphus	Confirmed.[5]
Ogyginus	Confirmed.[5]
Ogygiocaris	Confirmed.[5]
Opipeuter	Confirmed.[5]
Parabasilicus	Confirmed.[5]
Paraptychopyge	Confirmed.[5]
Plesiomegalaspis	Confirmed.[5]
Presbynileus	Confirmed.[5]
Pricyclopyge	Confirmed.[5]
Psilacella	Confirmed.[5]
Psilocara	Confirmed.[5]
Ptychopyge	Confirmed.[5]
Rhombampyx	Confirmed.[5]
Robergiella	Confirmed.[5]
Seleneceme	Confirmed.[5]
Stapeleyella	Confirmed.[5]
Taihungshania	Confirmed.[5]
Thysanopyge	Confirmed.[5]
Trigonocercella	Confirmed.[5]
Tungtzuella	Confirmed.[5]
Zhenganites	Confirmed.[5]
Zuninaspis	Confirmed.[5]

[edit] Corynexichida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Bumastus	Confirmed.[5]			Drawing of a trilobite fossil.
Dysplanus	Confirmed.[5]
Ectillaenus	Confirmed.[5]
Panderia	Confirmed.[5]
Phillipsinella	Confirmed.[5]
Pseudocalymene	Confirmed.[5]
Theamataspis	Confirmed.[5]

[edit] Lichida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Apatolichas	Confirmed.[5]			Drawing of a trilobite fossil.
Autoloxolichas	Confirmed.[5]
Lichakephalina	Confirmed.[5]
Metopolichas	Confirmed.[5]

[edit] Odontopleurida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Phthanoncoceras	Confirmed.[5]			Drawing of a trilobite fossil.
Ceratocephala	Confirmed.[5]
Diacanthaspis	Confirmed.[5]
Selenopeltis	Confirmed.[5]

[edit] Phacopids

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Bathycheilus	Confirmed.[5]
Calymenella	Confirmed.[5]			Drawing of a trilobite fossil. Drawing of a trilobite fossil. Drawing of a trilobite fossil. Drawing of a trilobite fossil.
Ceraurinella	Confirmed.[5]
Colobinion	Confirmed.[5]
Colpocoryphe	Confirmed.[5]
Cybelopsis	Confirmed.[5]
Cybelurus	Confirmed.[5]
Diaphanometopus	Confirmed.[5]
Dindymene	Confirmed.[5]
Eccoptochile	Confirmed.[5]
Ectenonotus	Confirmed.[5]
Encrinurella	Confirmed.[5]
Encrinuroides	Confirmed.[5]
Evropeites	Confirmed.[5]
Gyrometopus	Confirmed.[5]
Heliomeroides	Confirmed.[5]
Kanoshia	Confirmed.[5]
Kawina	Confirmed.[5]
Kolymella	Confirmed.[5]
Lehua	Confirmed.[5]
Lyrapyge	Confirmed.[5]
Neseuretus	Confirmed.[5]
Nieszkowskia	Confirmed.[5]
Ormathops	Confirmed.[5]
Ovalocephalus	Confirmed.[5]
Placoparia	Confirmed.[5]
Platycoryphe	Confirmed.[5]
Pliomeridius	Confirmed.[5]
Pliomerops	Confirmed.[5]
Protoencrinurella	Confirmed.[5]
Protopliomerella	Confirmed.[5]
Pseudocybele	Confirmed.[5]
Pterygometopus	Confirmed.[5]
Strotactinus	Confirmed.[5]
Sycophantia	Confirmed.[5]
Synhomalonotus	Confirmed.[5]
Toletanaspis	Confirmed.[5]
Xystocrania	Confirmed.[5]

[edit] Proetida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Acidiphorus	Confirmed.[5]			Drawing of a trilobite fossil.
Bathyuriscops	Confirmed.[5]
Benthamaspis	Confirmed.[5]
Biolgina	Confirmed.[5]
Bolbocephalus	Confirmed.[5]
Carolinites	Confirmed.[5]
Celmus	Confirmed.[5]
Ceratopeltis	Confirmed.[5]
Decoroproetus	Confirmed.[5]
Dimeropygiella	Confirmed.[5]
Eleutherocentrus	Confirmed.[5]
Goniophrys	Confirmed.[5]
Goniotelina	Confirmed.[5]
Grinnellaspis	Confirmed.[5]
Ischyrophyma	Confirmed.[5]
Ischyrotoma	Confirmed.[5]
Lutesvillia	Confirmed.[5]
Oenonella	Confirmed.[5]
Petigurus	Confirmed.[5]
Rananasus	Confirmed.[5]
Raymondaspis	Confirmed.[5]
Telephina	Confirmed.[5]

[edit] Ptychopariida

Oncocerids of the Floian
Taxa	Presence	Location	Description	Images
Anaximander	Confirmed.[5]			Drawing of a trilobite fossil. Drawing of a trilobite fossil. Drawing of a trilobite fossil. Drawing of a trilobite fossil.
Annamitella	Confirmed.[5]
Balnibarbi	Confirmed.[5]
Bulnibarbi	Confirmed.[5]
Bvalbardites	Confirmed.[5]
Circulocrania	Confirmed.[5]
Endymionia	Confirmed.[5]
Etheridgaspis	Confirmed.[5]
Furcalithus	Confirmed.[5]
Gymnostomix	Confirmed.[5]
Lacorsalina	Confirmed.[5]
Leioshumardia	Confirmed.[5]
Lordshillia	Confirmed.[5]
Nambeetella	Confirmed.[5]
Novakella	Confirmed.[5]
Oopsites	Confirmed.[5]
Peraspis	Confirmed.[5]
Phorocephala	Confirmed.[5]
Porterfieldia	Confirmed.[5]
Prosopiscus	Confirmed.[5]
Pytine	Confirmed.[5]
Sagavia	Confirmed.[5]
Selenoharpes	Confirmed.[5]
Stegnopsis	Confirmed.[5]
Stenorhachis	Confirmed.[5]
Svalbardites	Confirmed.[5]
Tasmanocephalus	Confirmed.[5]
Turgicephalus	Confirmed.[5]
Yinpanolithus	Confirmed.[5]

[edit] External links

• palaeos

[edit] References

1. ^ ICS; see Ordovician
2. ^ http://www.palaeos.com/Paleozoic/Ordovician/Arenig.htm
3. ^ ^{a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de df dg dh di dj dk dl dm dn do dp dq dr ds dt du dv dw dx dy dz} Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (entry on brachiopoda)". Bulletins of American Paleontology 364: p.560. http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=384&rank=phylum. 
4. ^ ^{a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk} Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (entry on cephalopoda)". Bulletins of American Paleontology 364: p.560. http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=231&rank=class. 
5. ^ ^{a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de df dg dh di dj dk dl dm dn do dp dq dr ds dt du dv dw dx dy dz ea eb ec ed ee ef eg eh ei ej ek el em en eo ep eq er es et eu ev ew ex ey ez fa fb fc fd fe ff fg fh fi fj fk fl fm fn fo fp fq fr} Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (entry on trilobita)". Bulletins of American Paleontology 364: p.560. http://strata.geology.wisc.edu/jack/showgenera.php?taxon=307&rank=class. 

This article incorporates text from the Encyclopædia Britannica, Eleventh Edition, a publication now in the public domain.