|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Trilobita - Proetida
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|R. A. Fortey 1990||Libristoma having fusiform glabella in the protaspis stage, and natant hypostomal condition attained early in ontogeny. Larval hypostome margin lacking spines. Most species natant also in adult; some secondarily conterminant or impendent. Median occipital tubercle usually present.|