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|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Trilobita - Redlichiida - Biceratopsidae
It was assigned to Olenellinae by Harrington (1956); to Bristoliinae by Palmer and Repina (1993) and Lieberman (1999); to Olenellida by Sepkoski (2002); and to Olenellidae by Whittington et al. (1997) and Jell and Adrain (2003).
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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.
|H. J. Harrington 1956||Olenellinae with well advanced genal spines. Metagenal spines absent in adult. Metagenal angle narrowly obtuse to acute. Glabella with three pairs of lateral glabellar lobes, strongly constricted at the level of the preoccipital furrow. Second (3p) furrow transglabellar, gently curved backward, not reaching the axial furrows. Preoccipital (2p) furrow curved, chevron shaped, disconnected at middle. Frontal glabellar lobe pyriform, expanded in front and encroaching over anterior border of cephalon. Occipital ring broad (sag.) and as wide (tr.) as frontal glabellar lobe. Eye lobes short, submedian (slightly anterior), reaching level of preoccipital furrow. Cephalic border raised, narrowing anteriorly.|
|A. R. Palmer and L. N. Repina 1993||Bristollinae with cephalon subpentagonal to subquadrate in outline. Genal spine originating opposite or anterior to L2. Intergenal spine absent. Preglabellar field absent. Posterior tips of ocular lobes opposite or anterior to Ll. Fifteenth thoracic segment with long axial spine. Opisthothorax of at least 17 segments.
|B. S. Lieberman 1999||Anterior cephalic border between L4 and genal spine angle relatively short, length (exsag.) less than or equal to length (sag.) of L1; anterior cephalic border developed as elevated, flattened ridge, prominently separated from extraocular area; frontal lobe con- tacts anterior border furrow; anterolateral margins of frontal lobe deflected posteriorly at roughly 10 degree angle relative to transverse line; frontal lobe moderately long (sag.), length equal to length of L0 and L1 medially; glabellar furrows prominently incised; S3 same depth laterally as medially; lateral margins of L2 when proceeding anteriorly bulging laterally relative to L0; lateral margins of glabella between posterior margin of L0 and L1 constrict; distal tips of S0 straight; extraocular region flattened; intergenal ridge visible as faint trace; intergenal spine absent in adult; genal spine length (exsag.) of approximately first eight thoracic segments; thorax divided into pro- and opisthothorax; nodes present on medial part of thoracic axial rings; T3 macropleural, spine length (exsag.) greater than length of thoracopygidium; anterior margin of T3 deflects anteriorly before flexing poste- riorly; anterior margin of pleural furrow on T3 parallels transverse line before flexing pos- teriorly; anterior margin of thoracic pleural furrow separated from body of segment by prominent ridge; thoracic pleural spines, behind T4, developed as short sweeping projec- tions extending two to three thoracic segments back, lying in roughly same dorso-ventral plane as pleural segments; prominent spine on axial ring of T15 (see Harrington 1956 and Lieberman 1998 for additional characters).|