Olenellina

The trilobite Mesonacis vermontanus from the subordination Olenellina

• Worldwide

The Olenellina are a subordination of Trilobitenordnung Redlichiida. The submission consists of two superfamilies, the Olenelloidea ( two families) and the Fallotaspidoidea ( five families). Among the Olenellina to find the first occurring in the fossil record trilobites.

Description

( Morphological terms are explained in more detail below the post trilobites. )

Cephalon: There is a lack facial sutures. The glabella has quite deep side grooves. In some species the frontal Glabellarlobus is almost hemispherical state bulging. The hypostome is konterminant, defines the seated between the rostral Dublüren very broad and non-binding Rostralnähten.

Thorax: Has a large number of just running segments on the spindle occasionally put spikes on.

Pygidium: Narrow, consists of only a few segments.

Calcified protaspide forms of development have not survived. The physique of Olenellina is flattened, their cuticle is thin.

Distribution and occurrence

The Olenellina appear during the Cambrian for the first time and died before the end of the Cambrian again.

The Olenellina are found primarily on Laurentia ( northwest and southwest Canada, southwest and northeast of the United States), to Avalonia ( Shropshire, England), on Baltica (Estonia, Poland, Norway, Sweden), in the western Gondwana (Morocco ), in the northeastern and south-eastern Siberia and western Mongolia.

The family of Olenellidae ( Olenelliden ) is on the Cambrian continent Laurentia - limited (North American faunal province North America and associated territories ). Olenelliden are quite common and likewise define the then expansion Laurentias. Her sudden disappearance defines the boundary between Lower and Middle Cambrian in their area of ​​distribution.

Between the Olenelliden and Redlichiina a clearly developed exclusivity of their occurrence, only in Morocco and Western Mongolia occur both faunas on together.

System

• Superfamily Olenelloidea Olenellidae
• Holmiidae

• Archaeaspidae (or Archaeaspididae )
• Fallotaspidae (or Fallotaspididae )
• Judomiidae
• Neltneriidae
• Nevadiidae

The Daguinaspidae are now Daguinaspinae as a subfamily of Fallotaspidae.