小油櫛蟲（學名：_Olenellus_）是生存於寒武紀海洋中的一屬三葉蟲，是目前發現最古老（Cambrian Series 2 Stage 4）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，其中一個比其他的更顯眼。胸部呈錐狀往後逐漸變小。頭甲周圍有一圈窄小的晶體，與頰部棘刺連成一體。外骨骼的護膜很薄。牠們缺乏其他三葉蟲擁有的特徵 —— 背部表面的骨縫。



物種


* _Olenellus agellus_ Resser & Howell, 1938

* _Olenellus chiefensis_ 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, 1925, 異名 _O. alius_, _O. peculiaris_

* _Olenellus howelli_ 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, 1859)

* _Olenellus transitans_ (Walcott, 1910), 異名 _O. brachycephalus_, _Paedeumias perkinsi_

重新分配的物種

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_



圖片


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參考文獻



外部連結


* _Olenellus_ in the Paleobiology Database

* photograph of _Olenellus chiefensis_ （頁面存檔備份，存於網際網路檔案館）

* photograph of _Olenellus getzi_

* photograph of _Olenellus gilberti_

* photograph of _Olenellus terminatus_ （頁面存檔備份，存於網際網路檔案館）

* photograph of _Olenellus thompsoni_

* photograph of _Olenellus transitans_