After Whittington, Chang, Dean, Fortey, Jell, Laurie, Palmer, Repina, Rushton & Shergold, 1997 and Lieberman, 2001

<==o †Olenellidae [taxonomic history]
   |--o †Olenellinae Walcott, 1890b [taxonomic history]
   |  |--o †Fremontella Harrington, 1956
   |  |  `-- †F. halli (Walcott, 1910) [Wanneria halli Walcott, 1910]
   |  |--o †Mummaspis Frotz, 1992
   |  |  `-- †M. occidens (Walcott, 1913b) [Wanneria occidens Walcott, 1913b]
   |  `--o †Olenellus Hall, 1861 [Fermontia Raw, 1936]
   |     |-- †O. fowleri Palmer, 1998
   |     |--o †(Olenellus) Hall, 1861
   |     |  `-- †O. (O.) thompsoni (Hall, 1859)
   |     |--o †(Angustolenellus) Palmer & Repina, 1993
   |     |  `-- †O. (A.) hamoculus Cowie & McNamara, 1978
   |     |--o †(Mesolenellus) Palmer & Repina, 1993
   |     |  `-- †O. (M.) hyperborea (V. Poulsen, 1974) [Holmia hyperporea V. Poulsen, 1974]
   |     |--o †(Mesonacis) Walcott, 1885 [Fermontia Raw, 1936]
   |     |  |-- †O. (M.) vermontanus (Hall, 1859) [Olenus vermontanus Hall, 1859]
   |     |  `-- †O. (M.) fremonti Walcott, 1910 [Fermontia fremonti (Walcott, 1910) Raw, 1936
   |     `--o †(Paedeumias) Walcott, 1910
   |        `-- †O. (P.) transitans (Walcott, 1910) [Paedeumias transitans Walcott, 1910]
   |--o †Biceratopsinae Pack & Gayle, 1971 [taxonomic history]
   |  |--o †Biceratops Pack & Gayle, 1971
   |  |  `-- †B. nevadensis Pack & Gayle, 1971
   |  `--o †Peachella Walcott, 1910
   |     `-- †P. iddingsi (Walcott, 1884b) [Olenellus iddingsi Walcott, 1884b]
   |--o †Bristoliinae Palmer & Repina, 1993 [taxonomic history]
   |  |--o †Bristolia Harrington, 1956
   |  |  |-- †B. bristolensis (Resser, 1928) [Mesonacis bristolensis Resser, 1928]
   |  |  `-- †B. anteros Palmer & Halley, 1979
   |  |--o †Arcuolenellus Palmer & Repina, 1993
   |  |  `-- †A. arcuatus (Palmer in Palmer & Halley, 1979) [Olenellus arcuatus Palmer in Palmer & Halley, 1979]
   |  |--o †Bolbolenellus Palmer & Repina, 1993
   |  |  `--  †B. euryparia (Palmer in Palmer & Halley, 1979) [Olenellus euryparia Palmer in Palmer & Halley, 1979]
   |  `--o †Nephrolenellus Palmer & Repina, 1993
   |     |-- †N. multinodus (Palmer in Palmer & Halley, 1979) [Olenellus multinodus Palmer in Palmer & Halley, 1979]
   |     `-- †N. geniculatus Palmer, 1998
   |--o †Laudoniinae Palmer & Repina, 1993
   |  |?-o ?†Olenelloides Peach, 1894
   |  |  `-- †O. armatus (Peach, 1894) [Olenellus (Olenelloides) armatus Peach, 1894]
   |  `--o †Laudonia Harrington, 1956
   |     |-- †L. bispinata Harrington, 1956
   |     `-- †L. ampulata Fritz
   `--o †Wanneriinae Hupé, 1953 [taxonomic history]
      `--o †Wanneria Walcott, 1910
         `-- †W. walcottana (Wanner, 1901) [Olenellus (Holmia) walcottanus Wanner, 1901]

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