Belongs within: Artiopoda.
Contains: Redlichiina, Libristoma, Lichida, Corynexochida, Fallotaspoidea, Olenellus.
Among the best known of all fossil arthropods, trilobites were found from the Cambrian to the Middle Permian, though their greatest diversity was during the Cambrian and Ordovician. Trilobites are the earliest dominant marine arthropod group in the fossil record. Their body plan is characterised by a distinct cephalon and pygidium, separated by a multisegmented thorax. The cephalon is divided between a raised central glabella and lateral genal regions. Compound eyes with calcite lenses are typically present on the genal region though they are lost in some lineages.
The previously recognised early trilobite order Redlichiida (including the Olenellina and Redlichiina) is probably paraphyletic with regard to the remaining trilobite orders. Plesiomorphic characters of ‘redlichiidans’ include a large number of thoracic segments, often terminating in divergent spines, and a relatively small pygidium. The Olenellina are elongate, relatively flat trilobites known from the Lower Cambrian, often bearing prominent terminal spines on the cephalon.
The majority of more derived trilobite groups had a much larger pygidium, and terminal spines on the thoracic segments were much smaller or undeveloped. The Ordovician to Devonian Odontopleurida, however, had extremely long spines on the cephalon, thorax and pygidium, some of which could be longer than the central body. The Ordovician to Devonian Lichida had a particularly large pygidium, often larger than the cephalon and made up of three pairs of expanded, spiny pleurae (Prothero 1998).
Characters (Fortey 2001; Prothero 1998): Calcified exoskeleton with clear division into cephalon, thorax and pygidium. Compound eyes with calcite lenses; facial suture along cheek between eye and central glabella; hypostomal wings connected to anterior pits in the axial furrow. Three (possibly four) pairs of cephalic limbs plus filamentous antennae. Biramous legs with branched exites (probably functioning as gills). Fused pygidium with more than one segment.
Trilobita [Polymera, Redlichiida, Trilobitacea]
|--+--RedlichiinaF01
| `--+--LibristomaF01
| |--LichidaF01
| `--CorynexochidaF90
`--OlenellinaF01
| i. s.: BristoliaP79
|--FallotaspoideaRC93
|--OlenelloideaRC93
| |--OlenellusRC93
| `--HolmiidaeRC93
| |--Holmia kjerulfiP79
| |--Schmidtiellus mickwitzi (Schmidt 1888)RC93
| `--Elliptocephala asaphoides Emmons 1844RC93
`--NevadioideaRC93
|--Nevadella [Nevadiidae]RC93
| |--N. (Nevadella) perfecta (Walcott 1913)RC93
| `--N. (Paranevadella) subgroenlandica (Repina 1965)RC93
`--JudomiidaeRC93
|--Judomia mattajensis Lazarenko 1962RC93
`--Judomiella heba Lazarenko 1962RC93
Trilobita incertae sedis:
LiocalymeneEB01
MegagraulosHLC03
|--M. breviscapus Kobayashi 1962S80
`--M. medius Kobayashi 1962S80
MetagraulosHLC03
Fenghuangella Yang 1978HLC03
Torifera Wolfart 1974HLC03
GoniagnostusA38
|--G. confluens [=Agnostus nathorsti confluens]A38
`--G. nathorsti [=Agnostus nathorsti]A38
XenostegiumGO50
Amorphella Rosova 1963S80
`--A. modesta Rosova 1963S80
ChangshanocephalusS80
LiopariaS80
Erixanium sentumS80, P79
TingocephalusS80
Pseudosolenopleura kotoiS80
Pseudoliostracina monkeiS80
Maduiya Rosova 1963 [incl. Maspakites Lazarenko 1968]S80
Kaninia Walcott & Resser 1924S80
Pedinocephalus Ivshin 1956S80
`--‘Maladioidella’ convexolimbata Endo in Endo & Resser 1937S80
Taenoria expansa Palmer 1960S80
ParabolinaS80
|--P. acanthura (Angelin 1854)S80
|--P. brevispina Westergaard 1922S80
`--P. spinulosaSS84
Simulolenus Palmer 1965S80
`--S. quadrisulcatus Palmer 1965S80
Parabolinites Henningsmoen 1957S80
`--‘Parabolinella’ laticauda Westergaard 1922S80
ProtopelturaS80
|--P. aciculataSS84
|--P. intermedia Westergaard 1922S80
`--P. praecursorP79
Crucicephalus ocellatus Shergold 1972S80
AmzasskiellaS80
|--A. mirabilis Petrunina 1960S80
`--A. obliquaP68
KopturaS80
|--K. biloba Kobayashi 1935S80
`--K. quadrataS80
Temnura granulosa Kobayashi 1935 [=Temnoura granosa (l. c.)]S80
Acanthopyge (Mephiarges)TC71
|--A. (M.) bifidaTC71
|--A. (M.) consanguineaTC71
`--A. (M.) mephistoTC71
Kiskinella cristata Romanenko & Romanenko 1962F05
Bailiaspis inflata Lake 1940F05
Alacephalus Repina 1960PVP85
`--A. latus Romenenko 1978PVP85
Erbiopsis Lermontova 1940PVP85
`--E. coangustus Romanenko 1969PVP85
Kleptothule Budd 1995CB04
‘Plutonia’ Hicks 1871 non Morelet 1864BR17
Paramansuyella puteataDJ71
Neoparabolina frequensVEE04
|--N. f. frequensVEE04
`--N. f. argentinaVEE04
Prouktaspis lutaSB09
Elicicola calva Jell 1990SB09
ConocephalitesT10
|--C. australisT10
`--C. sulzeriR87
Adastocephalum teleotypicum Mitchell 1919F71
Amphion brevispinus Etheridge 1895-1896F71
Bounyongia bowningensis Etheridge & Mitchell 1917F71
BronteusF71
|--B. angusticaudatus Etheridge & Mitchell 1917F71
|--B. bowningensis Etheridge & Mitchell 1917F71
|--B. jenkinsi Etheridge & Mitchell 1890F71
|--B. longispinifex Mitchell 1887F71
|--B. mesembrinus Etheridge & Mitchell 1917F71
|--B. molongensis Etheridge & Mitchell 1917F71
|--B. partschiM87
|--B. platynotus Mitchell 1924F71
`--B. (Goldius) singularis Mitchell 1924F71
Corydocephalus palmata [incl. Lichas sinuata Ratte 1886, C. palmata var. sinuata]F71
CromusF71
|--C. beaumontiM87
`--C. murchisoniF71
CryptonymusF71
|--C. angustus Mitchell 1924F71
|--C. incertus Mitchell 1924F71
|--C. perannulatus Mitchell 1924F71
|--C. platynotus Mitchell 1924F71
`--C. robustus Mitchell 1924F71
Dicranogmus bartonensis Fletcher 1950F71
Lyriaspis alroiensis (Etheridge 1919) [=Ptychoparia alroiensis; incl. P. merrotskii]F71
Leckwyckia Termier & Termier 1951H75
`--*L. enigmatica Termier & Termier 1951H75
Corbinia apopsisJ79
Presbynileus ibexensisJ79
Trigonocerca typicaJ79
Protopliomerella contractaJ79
Hintzeia celsaoraJ79
Comura defensorH79
Acastoides henniH79
|--A. h. henniH79
`--A. h. posthumusH79
Pholonyx philonyxH79
Schizoproetus onyxH79
Longiproetus cultrijugatiH79
Lacunoporaspis norrisN79
Ricticuloharpes reticulatusN79
Platyscutellum brevicaulisN79
Cornuproetus tozeriN79
Astycorphe cimeliaN79
DechenellaN79
|--D. mclareniN79
`--D. tescaN79
Deltadechenella bathurstensisN79
Lepidoderma Reuss 1855B78
Acanthomicmacca walcottiL95
Callavia broeggeriL95
Strenuella strenuaL95
DalmaniaH04
|--D. caudatusT01
|--D. longicaudatusT01
|--D. nexilisT01
`--D. punctataH04
Hydrocephalus saturnoidesH04
Dicellocephalus Owen 1852W77
|--D. coraW77
|--D. flagricaudus White 1874W77
`--D. magnificusW77
Delgadella Walcot 1912M65
`--*D. lusitanica (Delgado 1904) [=Lingulepis lusitanica]M65
Paranorwoodia venustaFO99
Dindymene saronFO99
Colpocoryphe [Colpocoryphinae]FO99
`--C. taylorumFO99
Illaenopsis harrisoniFO99
Bergamia rushtoniFO99
Hemiarges bigenerE84
Bynumina vesculaLM05
Eutychaspis kirkiiLM05
Bayfieldia simataLM05
Apatakephaloides clivosusLM05
Lantugula leonensisLM05
Apoplanius rejectusLM05
Highgatella cordilleriLM05
Hystricurus millardensisLM05
Ogygia buchiR87
Arionellus ceticephalusR87
Tomagnostella Kobayashi 1939TS11
Borealia Maksimova 1977KM17
Kuanyangia pustulosaC12
Nyaya nyaensisP68
Paraceratopyge kousnezkiensisP68
Kitatella avlagriP68
Erdelia sulcataP68
Pliomeroides deferrariisiP68
RaymondinidaeRC93
AvoninidaeRC93
BathynotidaeRC93
|--Bathynotus holopygaRC93
`--Bathynotellus kielcensis (Bednarczyk 1970) [=Jakutus kielcensis]RC93
Bestjubella [Bestjubellidae]RC93
`--B. munificus Ivshin 1983RC93
BurlingiidaeRC93
|--Burlingia laevis Westergård 1936RC93
`--Schmalenseeia amphionura Moberg 1903RC93
Rasettaspis [Rasettaspididae]RC93
`--R. francoi Ivshin 1983RC93
Gog catillusF90
*Giordanella meneghinii [=Illaenus meneghinii]F90
Holasaphus [Andrarinidae]F90
Skjarella [Hapalopleuridae]F90
Kasachstania ulrichiB75
Neoproetus sinensisG31
Kochina Resser 1935EH19
MictosaukiaCT83
|--M. callistoCT83
|--M. orientalisCT83
`--M. perplexaPJK24
HaniwaCT83
|--H. longaCT83
`--H. quadrataCT83
SaukiellaCT83
|--S. paiensisCT83
`--S. serotinaCT83
QuadraticephalusCT83
|--Q. calchasCT83
|--Q. manchuricusCT83
|--Q. pyrusCT83
|--Q. teresCT83
`--Q. walcottiCT83
Pseudokoldinioidia granulosaCT83
DictyellaCT83
|--D. ozawaiCT83
`--D. wuhuensisCT83
DictyitesCT83
|--D. dictysCT83
|--D. dolichocephalaCT83
`--D. trigonalisCT83
Coreanocephalus anhuiensisCT83
Anderssonella jiagouensisCT83
Pseudoglyptagnostus clavatusCT83
Chekiangaspis chekiangensisCT83
WujiajianiaCT83
|--W. expansaCT83
`--W. tachenensisCT83
Coronocephalus rexX97
Megistaspis estonicaPP99
|--M. e. estonicaPP99
`--M. e. rossicaPP99
Microdiscus punctatusC13
Qilianshania Chu 1960BL00
*Type species of generic name indicated
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