Ptychopariida Trilobites


Ptychopariida Trilobites Geological Time RangeOrders Ptychopariida and Corynexochida trilobites both have related taxa that could be placed in Redlichiida, making both orders paraphyletic (Lieberman, 2010). In fact, Ptychopariida Superfamily Ellipsocephaloidea was once placed within Order Redlichiida, but is now accepted as an evolutionary step from the Redlichiids to the Ptychopariids. Fortey (2001) considered the highly diverse Family Olenidae to likely be monophyletic. The first Ptychopariid trilobites appeared toward the end of the Lower Cambrian, and the entire order met extinction in the Ordovician to Silurian extinction event some 440 to 450 mllion years ago.

A primary trait of the Ptychopariida is a hypostome that is conterminant
in the protaspid stage, but becomes natant early in development and remains natant in the holaspid stage.

Subclass Librostoma*
Trilobite Order Ptychopariida

  • Suborder Olenina
    • Superfamily Olenoidea
  • Suborder Ptychopariina
    • Superfamily Ellipsocephaloidea
    • Superfamily Ptychoparioidea

* Subclass Librostoma contains Proetida, Harpetida, Ptychopariida, Asaphida


Ptychopariid Trilobite Fossils