小油櫛蟲

小油櫛蟲（學名：Olenellus）是生存於寒武紀第二世第四期的一屬三葉蟲，是目前發現最古老的三葉蟲品種之一。這類原始的三葉蟲生活在海底，不怎麼活躍。牠們的尾部較小，頭及眼大，並有眾多長有棘刺的胸節，其中一節特別顯眼。胸部呈錐狀、往後逐漸變小。頭甲周圍有一圈窄小的縫，與頰刺連成一體。外骨骼的護膜很薄。牠們沒有背部表面的骨縫——這是其他三葉蟲擁有的特徵。 Olenellus agellus Resser & Howell, 1938 Olenellus chiefensis Palmer（英语：Allison R. Palmer）, 1998 Olenellus clarki (Resser, 1928), 異名 Paedeumias clarki Olenellus crassimarginatus Walcott, 1910, 異名 O. thompsoni crassimarginatus, O. wanneri, O. latilimbatus Olenellus fowleri Palmer, 1998 Olenellus getzi Dunbar（英语：Carl Owen Dunbar）, 1925, 異名 O. alius, O. peculiaris Olenellus howelli Meek（英语：Fielding Bradford Meek）, 1874 Olenellus nevadensis (Walcott, 1910), 異名 Paedeumias nevadensis, Callavia nevadensis Olenellus parvofrontatus Fritz, 1991 Olenellus puertoblancoensis Lochman, 1952 Olenellus robsonensis Burling, 1916, 異名 Paedeumias robsonensis Olenellus roddyi Resser & Howell, 1938, 異名 O. similaris, O. nodosus, O. nitidus, O. jonasae, Paedeumias glabrum, P. yorkense, P. eboracense Olenellus romensis Resser & Howell, 1938, 異名 O. buttsi Olenellus terminatus Palmer, 1998 Olenellus thompsoni (Hall（英语：James Hall (paleontologist)）, 1859) Olenellus transitans (Walcott, 1910), 異名 O. brachycephalus, Paedeumias perkinsi 以下的物種現時已被置入其他屬。 Olenellus alabamensis = Fremontella halli Olenellus altifrontatus = Bolbolenellus altifrontatus Olenellus argentus pl. 40, fig 12, 13, 15, 16, non fig. 14 = Grandinasus argentus Olenellus argentus pl. 40, fig 14, non fig. 12, 13, 15, 16 = Holmiella falx Olenellus bondoni = Fallotaspis bondoni Olenellus bonnensis = Mesonacis bonnensis Olenellus brevoculus = Mesonacis bonnensis Olenellus broegeri = Callavia broegeri Olenellus bristolensis = Bristolia bristolensis Olenellus bristolensis p. 8. fig 1-11, non pl. 7, fig 1, 2, 5 = Bristolia harringtoni Olenellus bufrontis = Bolbolenellus sphaerulosus Olenellus callavei = Callavonia callavei Olenellus cylindricus = Mesonacis cylindricus Olenellus eagerensis = Mesonacis eagerensis Olenellus euryparia = Bolbolenellus euryparia Olenellus forresti = Redlichia forresti Olenellus fremonti pl. 15, fig. 18 = Bristolia fragilis Olenellus fremonti pl. 37, fig. 1, 4-5 = Bolbolenellus euryparia Olenellus fremonti pl. 37, fig. 1-2 = Mesonacis fremonti Olenellus georgiensis, p. 220, pl. 5, fig. 7, non fig. 6 = Mesonacis vermontanus Olenellus gigas = Andalusiana cornuta Olenellus gilberti = Bristolia bristolensis Olenellus groenlandicus = Bolbolenellus groenlandicus Olenellus halli = Fremontella halli Olenellus hamoculus = Mesonacis hamoculus Olenellus hermani = Bolbolenellus hermani Olenellus hyperboreus = Mesolenellus hyperboreus Olenellus insolens = Bristolia insolens Olenellus intermedius = Fritzolenellus lapworthi or F. reticulatus Olenellus kentensis = Bolbolenellus groenlandicus Olenellus lapworthi = Fritzolenellus lapworthi Olenellus laxocules = Elliptocephala laxocules Olenellus logani = Elliptocephala logani Olenellus mickwitzi = Schmidtiellus mickwitzi mickwitzi Olenellus mohavensis = Bristolia mohavensis Olenellus multinodus = Nephrolenellus multinodus Olenellus paraocules = Elliptocephala paraocules Olenellus praenuntius = Elliptocephala praenuntius Olenellus reticulatus = Fritzolenellus reticulatus Olenellus sequomalus = Elliptocephala sequomalus Olenellus sphaerulosus = Bolbolenellus sphaerulosus Olenellus svalbardensis = Mesolenellus svalbardensis Olenellus terranovicus = Mesonacis bonnensis Olenellus torelli = Schmidtiellus mickwitzi torelli Olenellus truemani = Elliptocephala walcotti Olenellus truemani = Fritzolenellus truemani Olenellus truncatooculatus = Mummaspis truncatooculatus Olenellus vermontanus = Mesonacis vermontanus Olenellus walcottanus = Wanneria walcottana Olenellus thompsoni的復原圖 Olenellus fowleri Olenellus fowleri 吉伯特氏小油櫛蟲（Olenellus gilberti） Olenellus roddyi Olenellus chiefensis Olenellus clarki Olenellus nevadensis Olenellus terminatus Walker, Cyril; Ward, David. Fossils. Smithsonian Handbooks revised, illustrated. Dorling Kindersley. 2002: 56. ISBN 0789489848.  Lieberman, B.S. Systematic Revision of the Olenelloidea (Trilobita, Cambrian) (PDF). Bulletin of the Peabody Museum of Natural History. 1999, 45 [2017-11-29]. （原始内容存档 (PDF)于2016-06-24）.  Palmer, A.R. Terminal Early Cambrian Extinction of the Olenellina: Documentation from the Pioche Formation, Nevada. Journal of Paleontology. 1998, 72 (4): 650–672. JSTOR 1306693.  Cowie, J.; McNamara, K.J. Olenellus (Trilobita) from the Lower Cambrian Strata of North-West Scotland (PDF). Palaeontology. 1978, 21 (3): 615–634 [2017-11-29]. （原始内容存档 (PDF)于2012-05-26）.  Walcott, C.D., Olenellus and other genera of the Mesonacidae, Smithsonian Miscellaneous Collections, 1910, 63 (6): 231–422  Riccio, J.F., The Lower Cambrian Olenellidae of the Marble Mountains, California, Bulletin of the Californian Academy of Sciences, 1952, 51: 25–49  Resser, C.E.; Howell, B.F., Lower Cambrian Olenellus zone of the Appalachians, Bulletin of the Geological Society of America, 1938, 49: 195–248  Fritz, W.H., Lower Cambrian Trilobites from the Sekwi Formation type section, Mackenzie Mountains, northwestern Canada, Bulletin of the Canadian Geological Survey, 1972, 212: 1–90  Walcott, C.D., Cambrian geology and paleontology, No. 11, New Lower Cambrian subfauna, Smithsonian Miscellaneous Collections, 1913, 67 (11): 309–326  Olenellus in the Paleobiology Database（英语：Paleobiology Database） photograph of Olenellus chiefensis （页面存档备份，存于互联网档案馆） photograph of Olenellus getzi photograph of Olenellus gilberti photograph of Olenellus terminatus （页面存档备份，存于互联网档案馆） photograph of Olenellus thompsoni photograph of Olenellus transitans