Lochkovella deckeri


In the image above, the Order Phacopida (yellow) is of uncertain origin arising in the early Ordovician, and persisting to the end of the Devonian.


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last revised 20 October 2010 by S. M. Gon III

Introduction: large and variable group of related suborders; post-Cambrian, but presumably derived from Cambrian ancestors, perhaps natant Ptychopariida.
Cephalon: typically proparian (Phacopina and Cheirurina) or gonatoparian (Calymenina), preglabellar field often very short or absent, 4 or fewer pairs of glabellar furrows (these sometimes fused); eyes, when present, schizochroal (Phacopina) or holochroal (Cheirurina and Calymenina); with rostral plates (Calymenina and Cheirurina) or without (some Phacopina); hypostome conterminant (all suborders) to impendent (some Phacopina).
Thorax: 8 – 19 segments, sometimes distinctly furrowed, axis sometimes broad (e.g., Homalonotidae).
Pygidium: typically micropygous (most Calymenina and Phacopina), but variable (e.g., subisopygous in Dalmanitoidea and Acastoidea), may be lobed or spiny (e.g., Cheirurina, some Dalmanitoidea, Acastoidea), or smooth-margined, with round or subtriangular outline (e.g., Calymenina, Phacopoidea).
Other: All suborders share similar ontogeny (bearing early protaspides with three pairs of prominent marginal spines, the hindmost pair post-cephalic, example at left) that in particular link the Calymenina to other Phacopida suborders.
Occurrence: Lower Ordovician (Tremadoc) to Upper Devonian (Famennian)
Suborders: Calymenina, Phacopina, Cheirurina.

last edited 08 July 2007 SMGIII


click here for Calymenina pictorial guide

Suborder Calymenina

Cephalon: semicircular to subtriangular, typically with gonatoparian sutures (a few opisthoparian, e.g., Bathycheilidae, primitive Homalonotidae); glabella narrowing forwards; eyes holochroal, often small; hypostome conterminant, rostral plate present.
Thorax: 11 – 13 (typically 13), segments with rounded tips.
Pygidium: semicircular or triangular, without spinose margin.
Superfamilies/Families: Calymenoidea/Bathycheilidae, Bavarillidae, Calymenidae, Homalonotidae, Pharostomatidae.
Bathycheilidae: Bathycheilus (=Parabathycheilus), Calymenia, Eulomina.

Bavarillidae: Bavarilla, Holoubkocheilus.
Calymenidae: Alcymene, Apocalymene, Arcticalymene, Calymene (/Calymena/Calymaena/ Calymmene/Calymmena), Calymenella, Calymenesun, Colpocoryphe (=Thoralocoryphe), Dekalymene, Diacalymene, Flexicalymene, Gravicalymene, Limbocalymene, Linguocalymene, Liocalymene, Metacalymene, Neseuretinus, Neseuretus (=Synhomalonotus), Nipponocalymene, Onnicalymene, Papillicalymene, Paracalymene, Platycalymene (=Sulcocalymene), Pradoella, Protocalymene, Reacalymene, Reedocalymene, Salterocoryphe, Sarrabesia, Spathacalymene, Sthenarocalymene, Tapinocalymene, Thelecalymene, Vietnamia.
Homalonotidae: Arduennella, Brongniartella (=Pamirotellus; =Portaginus), Burmeisterella. Burmeisteria, Digonus, Dipleura, Eohomalonotus (/Brongniartia SALTER), Homalonotus, Huemacaspis, Iberocoryphe, Kerfornella, Leiostegina, Parahomalonotus, Plaesiacomia, Platycoryphe (=Liangshanaspis), Scabrella, Trimerus.

Pharostomatidae: Eopharostoma, Paivinia, Pharostomina (=Colpocoryphoides), Prionocheilus (=Pharostoma), Ptychometopus, Thulincola (=Pharostomaspis), Xuanenia.

last edited 09 NOV 2003 SMGIII


click here for Phacopina pictorial guide
click here for Phacopina pictorial guide 




click here for Phacopina pictorial guide


Suborder Phacopina

Cephalon: proparian sutures (sometimes fused), schizochroal eyes; glabella expands forwards; librigena typically yoked as single piece; hypostome conterminant to impendent, some with no rostral plate; some with genal spines.
Thorax: 10 to (typically) 11 segments, pleurae furrowed, articulating facets distinct, rounded, angular, or spinose tips.
Pygidium: typically smaller than cephalon (but subisopygous in Dalmanitoidea and Acastoidea), smooth or spinose.
Superfamilies: Phacopoidea, Dalmanitoidea, Acastoidea (See below)

Characterizations of the three Phacopine superfamilies:

Superfamily Phacopoidea
Cephalon: generally with strongly divergent axial furrows (glabella greatly expanding anteriorly), anterior glabellar lobes fused into single anterior tri-composite lobe, frontal area generally lacking (obliterated by large glabella), eyes (when present) typically anterior; genal angle typically rounded, without genal spines (exceptions among Pterygometopidae), vincular furrow generally present.
Thorax: variable, but often with rounded tips.
Pygidium: typically micropygous (Phacopidae) to subisopygous (some Pterygometopidae), not spinose.
Families: Phacopidae, Pterygometopidae
Phacopidae: Acernaspis (=Eskaspis; =Otadenus; =Murphycops), Acuticryphops, Adastocephalum, Afrops, Ainasuella, Altaesajania, Ananaspis, Angulophacops, Arduennops, Atopophacops, Babinops, Boeckops, Burtonops, Chotecops (=Cordapeltis), Cryphops (/Gortania/Microphthalmus), Cultrops, Denckmannites (/Denckmannia), Dianops, Dienstina, Drotops, Ductina, Echidnops, Echinophacops, Eldredgeops, Eocryphops, Eophacops (/Pterygometopidella; =Bullicephalus), Geesops, Hypsipariops, Illaenula, Kainops, Liolophops, Lochkovella, Nandanaspis, Nephranomma, Nephranops, Nyterops, Omegops, Orygmatos, Paciphacops, Pedinopariops, Phacopidella (/Glockeria), Phacops, Plagiolaria, Portlockia, Prokops, Rabienops, Reedops, Rhinophacops, Rhinoreedops, Sambremeuaspis, Signatops, Somatrikelon, Spinicryphops, Struveaspis, Struveops, Tangbailaspis, Teichertops, Toxophacops, Trimerocephalus (/Eutrimerocephalus), Viaphacops, Weyerites, Zaplaops, Zhusilengops.
Pterygometopidae: Achatella, Bolbochasmops, Calliops, Calyptaulax (=Ligometopus; =Homalops), Carinopyge, Ceratevenkaspis, Chasmops, Denella, Elasmaspis, Eomonorachus, Estoniops, Evenkaspis, Ingriops, Isalaux, Isalauxina, Keilapyge, Liocnemis, Monorakos, Oculichasmops, Oelandiops, Parevenkaspis, Podowrinella, Pterygometopus, Rollmops, Ruegenometopus, Sceptaspis, Schmidtops, Scopelochasmops, Toxochasmops, Tricopelta, Truncatometopus, Upplandiops, Uralops, Valdariops, Vironiaspis, Volkops, Yanhaoia.

Superfamily Dalmanitoidea
Cephalon: typically bearing genal spines, generally with well-developed preglabellar field, median region of glabella bearing muscle scars; eyes tend to mesial or posterior, true vincular furrows lacking.
Thorax: variable, but often with spinose tips.
Pygidium: typically subisopygous, often spinose (terminal or marginal spines); axial rings of consistent depth along length of pygidial axis, axial furrows with simple and consistent convergence angle.
Families: Dalmanitidae, Diaphanometopidae, Prosopiscidae
Dalmanitidae: Anchiopsis, Andreaspis, Argentopyge, Banilatites, Bessazoon, Blanodalmanites, Chacomurus, Chattiaspis, Coronura, Corycephalus, Crozonaspis, Dalmanites (/Dalmania; =Guaranites; =Hausmannia ETHERIDGE & MITCHELL; =Heliocephalus/Malvernia; =Makaspis; =Ommokris), Dalmanitina, Dalmanitoides, Dalmaniturus, Daytonia, Deloites, Delops, Destombesites, Dreyfussina (=Prephacopidella), Duftonia, Eodalmanitina, Eudolatites, Fenestraspis, Forillonaria, Francovichia, Furacopyge, Gamonedaspis, Glyptambon, Guichenia, Huntoniatonia (/Huntonia), Kasachstania, Lygdozoon, Malladaia, Morgatia, Mucronaspis (=Guaykinites), Mytocephala (=Mirops), Neoprobolium, Odontocephalus, Odontochile (/Hausmannia HALL & CLARK), Ormathops, Pericopyge, Phalangocephalus, Preodontochile, Prodontochile, Prosocephalus, Retamaspis, Reussiana, Roncellia, Schoharia, Songxites, Struveria, Synphoria (/Eocorycephalus; /Neosynphoria), Synphor oides, Thuringaspis, Toletanaspis, Trypaulites, Vokovicia, Zeliszkella, Zlichovaspis (=Devonodontochile; =Spinodontochile).

Diaphanometopidae: Diaphanometopus, Gyrometopus, Prodalmanitina.
Prosopiscidae: Prosopiscus

Superfamily Acastoidea
Cephalon: axial furrows slightly to moderately divergent, anterior glabellar lobes and furrows usually not fused (although furrows may be indistinct), eyes typically distant from posterior border furrows, but not strongly anterior; frontal glabellar lobe auxilliary impression system triangular in outline, maximum width of glabella adjacent to preglabellar furrow, median region of glabella devoid of muscle scars; cephalic margin "shouldered," laterally convex course of genal margin topographically distinct from curvature of axial margin
Thorax: pleural endings blunt, rounded, or angular, sometimes spinose.
Pygidium: micropygous to subisopygous, sometimes spinose (expressed as marginal spines), pygidial axis with deep, apodemal anterior ring furrows, with abrupt transition to shallow posterior ring furrows; coincident decrease in angle of axial furrow convergence.
Other: often similar in general body form to Phacopoidea via convergent evolution, but glabellar and other differences as noted above.
Families: Acastidae, Calmoniidae.
Acastidae: Acastava, Acaste, Acastella, Acastellina, Acastocephala, Acastoides, Acastopyge, Armorigreenops, Asteropyge, Baniaspis, Bellacartwrightia, Bradocryphaeus, Braunops, Breizhops, Centauropyge, Chimaerastella, Coltraneia, Comura, Cryphina, Delocare, Deloops, Destombesina, Dunopyge, Echinopyge, Erbenochile, Ewacaste, Feruminops, Gourdonia, Greenops, Gudralisium, Hallandclarkeops, Harringtonacaste, Heliopyge (=Alcaldops), Hexacosta, Hollardops (=Modellops; =Philipsmithiana), Kayserops, Kennacryphaeus, Kloucekia, Llandovacaste, Metacanthina, Mimocryphaeus, Morocconites, Mrakibina, Neocalmonia, Neometacanthus, Paracryphaeus, Pelitlina, Phacopidina, Philonyx, Pilletina, Protacanthina, Pseudocryphaeus, Psychopyge, Quadratispina, Quadrops, Radiopyge, Rheicops, Rhenops, Saharops, Sanidopyge, Scotiella, Sokhretia, Stummiana, Talus, Tolkienia, Treveropyge, Turcopyge, Walliserops.

Calmoniidae: Anchiopella, Andinacaste, Australocaste, Australops, Awaria, Bainella (=Paradalmanites; =Paranacaste), Belenops, Bouleia (=Dereimsia), Calmonia, Chiarumanipyge, Clarkeaspis, Cryphaeoides, Curuyella, Deltacephalaspis, Eldredgeia, Feistia, Hadrorachus, Jujuyops, Kozlowskiaspis, Malvinella, Malvinocooperella, Metacryphaeus, Oosthuizenella, Palpebrops, Parabouleia, Paracalmonia (/Proboloides), Pennaia, Phacopina, Plesioconvexa, Plesiomalvinella, Prestalia, Probolops, Punillaspis, Renniella, Romanops, Schizostylus, Talacastops, Tarijactinoides (=Bolivianaspis), Tibagya (/Schizopyge), Tormesiscus, Typhloniscus, Vogesina, Wolfartaspis. 

last edited: 09 NOV 2003 SMGIII


click here for Cheirurina pictorial guide





Suborder Cheirurina

Cephalon: proparian sutures (a few opisthoparian), glabella usually expanding forwards or barrel-shaped, up to 4 pairs of furrows; holochroal eyes, often small; gena often with fine pitting; with rostral plate; hypostome conterminant, with anterior wing bearing prominent process.
Thorax: variable numbers of distinctive segments within Phacopid range of 8-19, often spine-tipped.
Pygidium: often highly modified with 2-16 distinct pairs of ribs, and lobed or spinose margin.
Other: often with tuberculate exoskeleton.
Superfamilies/Families: Cheiruroidea/Cheiruridae, Encrinuridae (including Staurocephalidae), Pilekiidae, Pliomeridae.
Cheiruridae: Acanthoparypha, Actinopeltis HAWLE & CORDA, Anasobella, Ancyginaspis, Apollonaspis, Arcticeraurinella, Areia, Areiaspis, Azyptyx, Barrandeopeltis, Borealaspis (=Alreboaspis), Bornholmaspis, Bufoceraurus, Ceraurinella (=Bartoninus), Ceraurinium, Ceraurinus (=Remipyga), Cerauromeros, Cerauropeltis, Ceraurus (=Eoceraurus), Cheirurus, Chiozoon, Contracheirurus, Courtessolium, Crotalocephalides, Crotalocephalina (/Gibbocephalus; =Mezocrotalus), Crotalocephalus (=Cerauroides; =Pilletopeltis/Boeckia PILLET), Cyrtometopella, Cyrtometopus, Deiphon, Didrepanon, Eccoptochile, Eccoptochiloides, Forteyops, Foulonia, Gabriceraurus, Geracephalina, Hadromeros, Hammannopyge, Hapsiceraurus, Heliomera, Heliomeroides, Holia (=Ainoa), Hyrokybe (=Shiqiania), Junggarella, Kawina (=Cydonocephalus), Kolymella, Krattaspis, Ktenoura, Laneites, Lehua, Leviceraurus, Nieszkowskia, Onycopyge, Osekaspis, Pandaspinapyga, Paraceraurus, Parasphaerexochus (=Mayopyge), Parayoungia (=Ichiyamella), Parisoceraurus, Pateraspis, Patomaspis, Placoparina, Pompeckia, Proromma, Protocerauroides, Pseudocheirurus, Pseudosphaerexochus (=Zethus), Radiurus, Ratinkaspis, Reraspis, Skelipyx, Sphaerexochus (=Korolevium; =Onukia; =Parvixochus), Sphaerocoryphe (=Ellipsocoryphe; =Hemisphaerocoryphe), Stubblefieldia, Sycophantia, Turantyx, Valongia, Whittakerites, Xylabion, Xystocrania (=Xialiangshania), Youngia, Zazvorkaspis.

Encrinuridae: Aegrotocatellus, Alwynulus, Atractocybeloides; Atractopyge (=Cybelella), Avalanchurus, Balizoma, Batocara (=Pacificurus/ Australurus), Bevanopsis, Billevittia, Brianurus -(/Briania), Celtencrinurus, Coronaspis, Coronocephalus (=Coronocephalina; =Senticucullus), Cromus (=Encrinuraspis), Curriella, Cybele (=Cybelina), Cybeloides, Cybelurus (=Mitacybele), Dayongia, Deacybele, Dindymene (=Comovica), Distyrax, Dnestrovites, Elsarella, Encrinuroides, Encrinurus (=Saoria), Eodindymene, Erratencrinurus, Fragiscutum, Frammia, Frencrinuroides, Johntempleia, Kailia, Koksorenus, Langgonia, Lasaguaditas, Libertella, Lyrapyge, Mackenziurus, ,Mitchellaspis (/Mitchellia), Nucleurus, Oedicybele (=Dindymenella; =Jemtella), Paracybeloides, Paraencrinurus, Parakailia, Perirehaedulus, Perryus, Physemataspis, Plasiaspis, Prophysemataspis, Prostrix, Rielaspis, Rongxiella, Sinocybele, Staurocephalus, Stiktocybele, Struszia, Tewonia, Walencrinuroides, Wallacia.
Pilekiidae: Anacheiruraspis, Anacheirurus, Chashania, Demeterops, Emsurina, Koraipsis, Landyia, Macrogrammus, Metapilekia, Metapliomerops, Parapilekia, Pilekia, Pliomeroides, Pseudopliomera, Seisonia, Sinoparapilekia, Victorispina.
Pliomeridae: Anapliomera, Benedettia, Canningella, Colobinion, Coplacoparia, Cybelopsis, Ectenonotus, Encrinurella, Evropeites, Gogoella, Guizhoupliomerops, Hawleia, Hintzeia, Humaencrinuroides, Ibexaspis, Josephulus, Kanoshia, Leiostrototropis, Liexiaspis, Ngaricephalus, Obliteraspis, Ovalocephalus (=Hammatocnemis; =Paratzuchiatocnemis), Parahawleia, Parapliomera, Perissopliomera, Placoparia, Pliomera (/Amphion), Pliomerella, Pliomeridius, Pliomerina (/Pliomeraspis), Pliomerops, Protoencrinurella, Protopliomerella, Protopliomerops (=Stototropis), Pseudocybele, Pseudomera, Quinquecosta, Rossaspis, Strotactinus, Tesselacauda, Tienshihfuia, Tzuchiatocnemis.

last revised 23 FEB 2004

Both Cheirurina and Calymenina extend close to the base of the Ordovician, suggesting that there is likely a upper Cambrian sister taxon. Two primitive Calymenines, Pharostomina and Bavarilla, had natant hypostomes, suggesting that the Cambrian sister taxon is likely also natant (the typical Ptychopariine hypostomal pattern). This is consistent with the inclusion of Phacopida as one of the Librostoma (Fortey 1990).
The unity of the suborders Calymenina, Cheirurina and Phacopina via similar ontogeny has been accepted by the vast majority of trilobite workers. The early protaspides of Cheirurina, Phacopina, and Calymenina share three pairs of prominant marginal spines, with the hindmost pair post-cephalic (Fortey 1990, p 565). Since ontogeny patterns define the Phacopida, the search for the sister group will likely require an assessment of the protaspides and meraspides of candidate taxa (such as Calymenidius). Other characters discussed as synapomorphies linking primitive members of the three suborders of Phacopida include: loss of concentric terrace ridges on the cephalic doublure, a hypostomal wing process, granulose surface sculpture, 5+ pygidial segments, and absence of a pygidial border (Fortey 1990, p 566). Some of these characters are secondarily lost in advanced members of the Phacopida clades. The schizochroal-eyed Phacopina are likely derived from a holochroal-eyed cheirurine or calymenine.

Fortey, R. A. 2001. Trilobite systematics: the last 75 years. J. of Paleontology. 75(6):1141-51.
Fortey, R. A. 1990. Ontogeny, hypostome attachment, and trilobite classification. J. of Paleontology. 33:529-76.
Jell, P.A. & J.M. Adrain. 2003  Available generic names for trilobites. Memoirs of the Queensland Museum 48(2):331-553
Rielaspis added to genera in Encrinuridae via:  
Chatterton, B.D.E. and R. Ludvigsen.  2004.  Early Silurian trilobites of Anticosti Island, Québec, Canada. Palaeontographica Canadiana 22, 264 p.
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