小油櫛蟲

**小油櫛蟲**（學名：）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。

## 物種
* *Olenellus agellus* Resser & Howell, 1938
* *Olenellus chiefensis* , 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* , 1925, 異名 *O. alius*, *O. peculiaris*
* *Olenellus howelli* , 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* (, 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|Fremontella halli]]*
* *Olenellus altifrontatus* = *[[Bolbolenellus|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|Fallotaspis bondoni]]* 
* *Olenellus bonnensis* = *[[Mesonacis|Mesonacis bonnensis]]*
* *Olenellus brevoculus* = *[[Mesonacis|Mesonacis bonnensis]]*
* *Olenellus broegeri* = *[[Callavia|Callavia broegeri]]*
* *Olenellus bristolensis* = *[[Bristolia|Bristolia bristolensis]]*
* *Olenellus bristolensis* p.&nbsp;8. fig 1-11, non pl. 7, fig 1, 2, 5 = *[[Bristolia|Bristolia harringtoni]]*
* *Olenellus bufrontis* = *[[Bolbolenellus|Bolbolenellus sphaerulosus]]*
* *Olenellus callavei* = *Callavonia callavei*
* *Olenellus cylindricus* = *[[Mesonacis|Mesonacis cylindricus]]*
* *Olenellus eagerensis* = *[[Mesonacis|Mesonacis eagerensis]]*
* *Olenellus euryparia* = *[[Bolbolenellus|Bolbolenellus euryparia]]*
* *Olenellus forresti* = *[[Redlichia|Redlichia forresti]]*
* *Olenellus fremonti* pl. 15, fig. 18 = *[[Bristolia|Bristolia fragilis]]*
* *Olenellus fremonti* pl. 37, fig. 1, 4-5 = *[[Bolbolenellus|Bolbolenellus euryparia]]*
* *Olenellus fremonti* pl. 37, fig. 1-2 = *[[Mesonacis|Mesonacis fremonti]]*
* *Olenellus georgiensis*, p.&nbsp;220, pl. 5, fig. 7, non fig. 6 = *[[Mesonacis|Mesonacis vermontanus]]*
* *Olenellus gigas* = *Andalusiana cornuta*
* *Olenellus gilberti* = *[[Bristolia|Bristolia bristolensis]]*
* *Olenellus groenlandicus* = *[[Bolbolenellus|Bolbolenellus groenlandicus]]*
* *Olenellus halli* = *[[Fremontella|Fremontella halli]]*
* *Olenellus hamoculus* = *[[Mesonacis|Mesonacis hamoculus]]*
* *Olenellus hermani* = *[[Bolbolenellus|Bolbolenellus hermani]]*
* *Olenellus hyperboreus* = *[[Mesolenellus|Mesolenellus hyperboreus]]*
* *Olenellus insolens* = *[[Bristolia|Bristolia insolens]]*
* *Olenellus intermedius* = *[[Fritzolenellus|Fritzolenellus lapworthi]]* or *F. reticulatus*
* *Olenellus kentensis* = *[[Bolbolenellus|Bolbolenellus groenlandicus]]*
* *Olenellus lapworthi* = *[[Fritzolenellus|Fritzolenellus lapworthi]]*
* *Olenellus laxocules* = *[[Elliptocephala|Elliptocephala laxocules]]*
* *Olenellus logani* = *[[Elliptocephala|Elliptocephala logani]]*
* *Olenellus mickwitzi* = *[[Schmidtiellus|Schmidtiellus mickwitzi mickwitzi]]*
* *Olenellus mohavensis* = *[[Bristolia|Bristolia mohavensis]]*
* *Olenellus multinodus* = *[[Nephrolenellus|Nephrolenellus multinodus]]*
* *Olenellus paraocules* = *[[Elliptocephala|Elliptocephala paraocules]]*
* *Olenellus praenuntius* = *[[Elliptocephala|Elliptocephala praenuntius]]*
* *Olenellus reticulatus* = *[[Fritzolenellus|Fritzolenellus reticulatus]]*
* *Olenellus sequomalus* = *[[Elliptocephala|Elliptocephala sequomalus]]*
* *Olenellus sphaerulosus* = *[[Bolbolenellus|Bolbolenellus sphaerulosus]]*
* *Olenellus svalbardensis* = *[[Mesolenellus|Mesolenellus svalbardensis]]*
* *Olenellus terranovicus* = *[[Mesonacis|Mesonacis bonnensis]]*
* *Olenellus torelli* = *[[Schmidtiellus|Schmidtiellus mickwitzi torelli]]*
* *Olenellus truemani* = *[[Elliptocephala|Elliptocephala walcotti]]*
* *Olenellus truemani* = *[[Fritzolenellus|Fritzolenellus truemani]]*
* *Olenellus truncatooculatus* = *[[Mummaspis|Mummaspis truncatooculatus]]*
* *Olenellus vermontanus* = *[[Mesonacis|Mesonacis vermontanus]]*
* *Olenellus walcottanus* = *[[Wanneria|Wanneria walcottana]]*

## 圖片

Image:Olenellus NT small.jpg|*Olenellus thompsoni*的復原圖
Image:Olenellus fowleri CRF.jpeg|*Olenellus fowleri*
Image:Olenellus-fowleri.jpg|*Olenellus fowleri*
Image:Olenellus gilbert rightlight CRF.jpg|吉伯特氏小油櫛蟲（*Olenellus gilberti*）
Image:Olenellus yorkensis CRF.jpg|*Olenellus roddyi*
Image:Olenellus chiefensis cephalon CRF.jpg|*Olenellus chiefensis*
Image:Olenellus clarki 37mm CRF.jpeg|*Olenellus clarki*
Image:Olenellus nevadensis CRF.jpg|*Olenellus nevadensis*
Image:Olenellus terminatus Pyramid Shale Carrara Formation.jpg|*Olenellus terminatus*


## 參考文獻

## 外部連結
* ''Olenellus'' in the Paleobiology Database
* photograph of ''Olenellus chiefensis'' 
* photograph of ''Olenellus getzi''
* photograph of ''Olenellus gilberti''
* photograph of ''Olenellus terminatus'' 
* photograph of ''Olenellus thompsoni''
* photograph of ''Olenellus transitans''

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