|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Trilobita - Redlichiida - Biceratopsidae
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.
|A. R. Palmer and L. N. Repina 1993||Bristoliinae with posterior margin of cephalon nearly straight or deflected anterolaterally distal to intergenal spine or intergenal angle. Genal spine origi- nates opposite or posterior to Ll. In tergenal spine present on some species. L4 prominent, subglobular, may overlap border in dorsal view. Preglabellar field absent. Posterior tips of ocular lobes approximately opposite occipital furrow.|
|B. S. Lieberman 1999||Anterior cephalic border prominently separated from extraocular area by fur- row, developed as raised, rounded ridge; plectrum absent; L4 contacts anterior border furrow; anterior margins of L4 at each side of midline deflected posteriorly at roughly 40 degree angle relative to transverse line; length (sag.) of L4 equal to 1.5 times length of L0 and L1 (sag.); L4 expands prominently dorsally; lateral margins of L4 distal to lateral margins of L0; region of anterior part of ocular lobe between visual surfaces and L4 nar- row (tr.); ocular lobe with ocular furrow; line from posterior tip of ocular lobe to junc- tion of posterior margin of lobe with glabella forms roughly 10 degree angle relative to sagittal line; transverse profile of ocular lobes convex dorsally; interocular area arched; posterior tips of ocular lobes developed opposite S0 or medial part of distal margin of L1; width (tr.) of interocular area roughly equal to width of ocular lobe; S3 jaggedly convex, conjoined medially; entire margin of S3 arched furthest anteriorly at point three-quarters of way between midline of glabella and axial furrows; L1, L2, and L3 of strong transverse convexity; L2 and L3 do not merge; S2 conjoined medially; distal margins of L2 when proceeding anteriorly subparallel; S1 conjoined medially; distal sector of S0 straight, con- joined medially, proximal end well posterior of distal end; axial part of L0 with axial node; posterior margin of L0 convex posteriorly; lateral lobes on L0 absent; posterior cephalic border between L0 and intergenal angle deflected posterolaterally; prominent anasto- mosing ridges present on extraocular area; width (tr.) of extraocular region opposite L1 equal to roughly 75% of width of glabella at L1; genal spine near cephalic border directed posterolaterally at angle greater than or equal to 25 degrees relative to sagittal line; genal spine length (exsag.) greater than or equal to length of first 4 to 5 thoracic segments; intergenal angle developed two-thirds of way between distal tips of ocular lobes and genal spine angle, or directly behind genal spine angle.|