门: 节肢动物门
纲: 大附肢纲
目：林乔利虫目
科:林乔利虫科
属：始虫属
种: 寒武始虫
描述:
标本长度大都在3-5cm之间。寒武始虫主要由一个头，11节体节和1个竹片状的尾节组成。头上具有一对腹侧的眼睛和三只中间的眼睛，一对带有三根长鞭节的大附肢和两对双肢型附肢。这些双肢型附肢与躯干上的附肢类似，都是由一个带刺的内肢和一个扁平且带有刚毛状修饰边的外肢组成。似乎有11对躯干附肢，每一对都对应一个体节（可据此推测体节）。扁平的尾节后部也带有宽刺修饰边。头部附近肠道弯曲呈U形；嘴巴位于第一对双肢型附肢的前端，朝向后方。头部后边肠道变宽并在躯干中一直保持这个宽度。肛门在尾节的前端，即尾节插入最后一节体节的节点后面。
Phylum: Arthropoda
Class: Megacheira
Order：Leanchoiliida
Family: Leanchoiliidae
Genus：Alalcomenaeus
Specie: Alalcomenaeus cambricus
Description:
The body of Alalcomenaeus cambricus consists of a cephalon, 11 trunk somites, and a spatulate telson. The cephalon bears a pair of ventral and three median eyes, a frontal appendage (the ‘great appendage’) bearing three long flagella,and two pairs of biramous appendages. These biramous appendages, like those of the trunk, consist of a spinose inner branch and a flat outer branch fringed by seta-like filaments. There appear to be 11 pairs of trunk appendages, one corresponding to each of the tergites (and hence presumably to the somites).The flat telson is fringed posteriorly with wide spines. The gut curves through a U near the anterior of the cephalon; the mouth lies just in front of the base of the first pair of biramous appendages, facing posteriorly.The gut widens in the posterior part of the cephalon, and maintains that width through the trunk. The anus is in the anterior part of the telson, just behind the point where the telson inserts into the last (11th) trunk somite.
时代：寒武系第三统第五阶，布尔吉斯页岩层
主要产地: 加拿大大不列颠哥伦比亚省，布尔吉斯生物群
Age：Cambrian Series 3, Stage 5(Burgess Shale)
Principal localities: Burgess biota（British Columbia，Canada）
Derek E.G.Briggs and Desmond Collins,1999.The arthropod Alalcomenaeus cambricus Simonetta, from the Middle Cambrian Burgess Shale of British Columbia. Palaeontology,Vol.42,pp.953-977.
Derek E.G.Briggs and H. B. Whittington,1985.Modes of life of arthropods from the Burgess Shale, British Columbia.Earth and Environmental Science Transactions of The Royal Society of Edinburgh,Volume 76,pp.149 - 160.