TO THE ORDER PROETIDA
last revised 04 July 2007 by S. M. Gon III
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ORDER PROETIDA
Compare the pictorial approach above with the descriptive narrative below:
Compare the pictorial approach above with the descriptive narrative below:
| ORDER PROETIDA
Introduction: typically small trilobites, recently separated from Ptychopariida; protaspid growth stages of the two orders are similar, but protaspides of Proetida show early development of preglabellar field (a meraspid development in Ptychopariida); one of the Libriostomate orders (natant hypostome or derived therefrom); exoskeleton sometimes with pits or small tubercles. The last of the trilobites was of this order (Phillipsiidae). Cephalon: opisthoparian sutures; glabella large, vaulted, well-defined, typically narrowing forwards, typically 4 pairs of glabellar furrows with posterior-most pair longest and deepest, those anterior shorter and fainter; eyes, usually present, holochroal, often large, convex; rostral plate narrow and backward tapering; long hypostome, most species natant, but some secondarily conterminant (e.g., late Proetidae & Bathyuridae); typically with genal spines. Thorax: 8 – 22 (typically 10) segments, tips variable, blunt to long-spined. Pygidium: micropygous to subisopygous, often spineless, and usually with 4 – 10+ distinct pleural furrows. Occurrence: Ordovician (Tremadoc) to Permian (Tartarian) Suborders: None (or nominate Proetina) Superfamilies: Proetoidea, Aulacopleuroidea, Bathyuroidea |
PROETIDA includes three Superfamilies:
(click on the images to view the pictorial guides)
| Proetoidea
|
Aulacopleuroidea
|
Bathyuroidea
|
