|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Trilobita - Redlichiida - Nevadiidae
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.
|C. D. Walcott 1910||
Dorsal shield broad, ovate. Cephalon large, semicircular in out-
line, about one-third the length of the dorsal shield genal angles ;
extended into spines ; facial sutures rudimentary or in a condition of symphysis ; eyes crescentic, with ridges uniting them with the anterior lobe oi the glabella ; glabella elongate, with a relatively small anterior lobe and three posterior transverse lobes ; strong occipital ring.
Thorax with twent}'-eight segments ; body of pleurcie nearly straight ; pleural furrow broad and parallel to the transverse axis of the jilcune ; pleura; terminating in long, curved spines that are much shorter on the posterior eleven segments in the type species which are without a distinct, furrowed pleural lobe.
Pygidium small, without pleural lobes and transverse furrows.
Surface minutely granular and with irregular network of fine, irregular, anastomosing ridges.
|A. R. Palmer and L. N. Repina 1993||Nevadiidae with width of interocular area less than one-fourth width of extraoctihu- area. Preglabellar- field present. Thorax of 27 segments. Pleural spines long. Transverse length of pleurae at least twice width of axis. Transition to opistluoliorax between segments 15 and 18. Pygidium small, subquadrate.|