Trilobite Order Asaphida

Trilobites

 

Asaphid Trilobites

Page within: Class Trilobita - Trilobite Classification

See also: Russian Asaphid Trilobites

 

The most conspicuous morphological feature of the Asaphid trilobites is the smooth and isopygous (similar in size) cephalon
Trilobite Taxonomy
Trilobite Phylogeny
Phylum Arthropoda
Subphylum Chelicerata
or Subphylum Schizoramia *
Superclass Arachnomorpha *
Class Trilobita

    Order Agnostida
    Order Redlichiida
    Order Corynexochida
    Order Phacopida
    Order Lichida
    Order Proetida
    Order Harpetida
    Order Ptychopariida
    Order Asaphida
    Order Odontopleurida
    Order Nectaspida
Trilobite Relatives
o Arthropoda
`--o Trilobita
   |?-Agnostida
   |?-Eodiscina
   `--+--o Redlichiida
      |  |--Olenellina
      |  `--Redlichiina
      |--Corynexochida
      |--Phacopida
      |--Lichida
      |--Odontopleurida
      `--o Librostoma
         |--Proetida
         |--Harpetida
         |--Ptychopariida
         `--Asaphida
* Different taxonomies are found, most recently with trilobites contained in Superclass Arachnomorpha in Subphylum Schizoramia.
and pygidium, an evolutionary adaptation called effacement believed to have helped trilobites more easily burrow into sediment to achieve stealth. Another theory is that the smoothing of the exoskeleton streamlined the trilobite for locamotion. Effacement is also evident among the Agnostids, and Suborder Illaenina of Order Corynexochida. The Asaphids appeared in the Middle Cambrian and persisted to the Lower Silurian. Order Asaphida comprises six Superfamilies: Anomocaroidea; Asaphoidea; Cyclopygoidea; Trinucleioidea; Dikelokephaloidea; and Remopleuridoidea listed at the bottom of this page. The order contains a very large morphological diversity and number of species; in fact, some 20% of known species.

The major extinction event concluding the Ordovician Period markedly reduced trilobite diversity across all the orders. Among the Asaphids, only some members of superfamily Trinucleioidea survived, and they too met extinction near the end of the Silurian.

Phylum Arthropoda
Subphylum Chelicerata Class Trilobita Order Asaphida Suborder Asaphina Superfamily Anomocaroidea Family Andrarinidae Family Anomocarellidae Family Anomocaridae Family Aphelaspididae Family Parabolinoididae Family Pterocephalidae Superfamily Asaphoidea Family Asaphidae Family Ceratopygidae Superfamily Cyclopygoidea Family Cyclopygidae Family Nileidae Family Taishunghaniidae Superfamily Dikelokephaloidea Family Dikelokephalidae Family Eurekiidae Family Loganellidae Family Ptychaspididae Family Saukiidae Superfamily Remopleuridioidea Family Auritamiidae Family Bohemillidae Family Hungaiidae Family Idahoiidae Family Remopleurididae Superfamily Trinucleioidea Family Alsataspididae Family Dionididae Family Liostracinidae Family Raphiophoridae Family Trinucleidae Also see: Asaphida families and genera

Superfamily Anomocaroidea

Housia sp.
Superfamily Anomocaroidea Family Pterocephaliidae
Upper Cambrian
Radium, British Columbia

Pterocephalia norfordi
Superfamily Anomocaroidea Family Pterocephaliidae
Upper Cambrian
Cranbrook, British Columbia
 
Glyphaspis capella
Superfamily Anomocaroidea Family Anomocarellidae
Middle Cambrian
Wolsey Formation, Montana
 
 

Superfamily Asaphoidea

Isoteloides flexus (rare)
Superfamily Asaphoidea Family Asaphidae
Ordovician
Fillmore Formation, Millard County, Utah
Megistaspis triangularis
Superfamily Asaphoidea Family Asaphidae
Lower Ordovician
Wolchow river, Russia
Homotelus florencevillensis
Superfamily Asaphoidea
Family Asaphidae
Subfamily Isotelinae
Upper Ordovician
Clayton County, Iowa
Ptyocephalus yersini
Superfamily Asaphoidea
Family Asaphidae
Subfamily Ptyocephalinae
Ordovician
Fillmore Formation
Millard County, Utah
Pseudoasaphus tecticaudatus
Niobe schmidti
Superfamily Asaphoidea
Family Asaphidae
Middle Ordovician
Wolchow River, Russia
Pseudoasaphus tecticaudatus
Superfamily Asaphoidea
Family Asaphidae
Middle Ordovician
Wolchow River, Russia
Isotelus gigas
Superfamily Asaphoidea
Family Asaphidae
Ordovician
Lindsay Formation, Ontario, Canada
Lachnostoma latucelsum
Superfamily Asaphoidea
Family Asaphidae
Middle Cambrian
Ninemile Formation, Nevada
Asaphus cornutus
Superfamily Asaphoidea
Family Asaphidae
Middle Ordovician
Wolchow River, Russia
Asaphus expansus
Superfamily Asaphoidea
Family Asaphidae

Lower Ordovician
Wolchow River, Russia
Asaphus punctatus
Superfamily Asaphoidea
Family Asaphidae

Middle Ordovician
Wolchow River, Russia
Asaphus kowalewskii
Superfamily Asaphoidea Family Asaphidae
Middle Ordovician
Wolchow River, Russia
Pseudogygites
Cyclopyge
 

Asaphus cornutus
Superfamily Asaphoidea Family Asaphidae
Middle Ordovician
Wolchov River, Russia

Pseudogygites latimarginatus
Family Asaphidae
Upper Ordovician
Lower Whitby Formation, Ontario, Canada
Cyclopyge bohemica
Superfamily Asaphoidea Ceratopygidae
Middle Ordovician
Czech Republic
 

Superfamily Trinucleioidea

Nankinolithis sp.
Superfamily Trinucleoidea Family Trinucleidae
Ordovician
El Kaid Errami, Morocco
Paratrinucleus acervulosus
Family Trinucleidae
Upper Ordovician
Blacksburg, Virginia
Onnia superba
Death Assemblage
Superfamily Trinucleoidea
Family Trinucleidae
Middle Devonian
Blekos, Morocco
Salterolithus caractaci
Superfamily Trinucleoidea Family Trinucleidae
Upper Ordovician
Caradoc Series, Harnage (Shales) Formation, Welshpool, England
Raphiophorus
Cnemidopyge bisecta
Raphiophorus parvulus
Family Raphiophoridae
Upper Silurian
Shropshire, United Kingdom
Cnemidopyge bisecta
Family Raphiophoridae
Upper Ordovician
Wales, United Kingdom
Lochodomas volborthi
Superfamily Trinucleoidea Family Trinucleidae
Ordovician
Wolchow River, Russia
Deanaspis goldfussi
Superfamily Trinucleoidea Family Trinucleidae
Ordovician
Bohemia Czech Republic

(Asah-phee-da)