门: 节肢动物门
纲: 大附肢纲
目: 林乔利虫目
科: 林乔利虫科
属：海妖虫属
种: 库特奈海妖虫
描述:
标本平均长度(包含大附肢）大约95.4 mm±21.2; 平均高度大约22.3 mm±4.1.共分为17节,其中头甲分4节，胸甲分12节以及有一个尾节.头甲轴向长度约占身体总长的1/4;比最前端的胸甲稍微宽阔; 边缘光滑并且缺少背部隆线.有两对共四只眼睛，眼柄退化较严重，四只眼睛均位于头部最前端: 两只侧眼稍大，位于背部前端中间的两只眼睛较小，后者方向朝前且位于侧眼前方，并且彼此相距比至侧眼的距离更近。头甲上共四对附肢，最前端一对不同于其他附肢的称为大附肢，其后两对附肢退化严重且鲜为人知–其中第一对要比第二对更短，还有一对类似躯干上附肢，为双肢型且发育完全。躯干除去尾节分还为十二节。当身体笔直时背甲轴部大约有1/4节长的部分重叠，肋部发育完全并且有相似的重叠发生;最后几节弯曲幅度稍微增加；倒数第三节体节肋部轮廓似裙摆且外端角度圆滑（其他体节肋部外端都有锋利的尖角）; 倒数第二节肋部作锋刃状指向后部; 最后一节无肋部，它的脊柱紧贴外皮。躯干上附肢从第2至12节均为关节硬化的双肢型附肢，可分为一个大的基节，一个外肢和一个桨状的内肢。与背甲肋部相似，附肢尺寸向后逐渐减小，从体长的2/9到高度退化（第十节）; 第十一节和十二节的内肢结构暂未被发现。尾节轴向上大约占身体总长的1/6，由倒三角形的尾部基节和尾叶两部分组成。
Phylum: Arthropoda
Class: Megacheira
Order：Leanchoiliida
Family: Leanchoiliidae
Genus：Yawunik
Specie: Yawunik kootenayi
Description:
Average length (excluding ‘great appendages’):95.4 mm±21.2; average height: 22.3 mm±4.1. Body 17-segmented with four-segmented cephalon, 12 thoracic segments and a telson.Length of cephalic shield ca. one-quarter of total body length; slightly wider than anteriormost thoracic segments; margins smooth and devoid of dorsal carinae.Four eyes, all with very reduced peduncles and all located in the anteriormost portion of the head: two larger antero-lateral eyes and two smaller antero-dorso-medial eyes, the latter oriented forward, located in front of the larger eyes and slightly closer together than they are to lateral eyes.Four pairs of cephalic appendages: an anterior highly differentiated pair of multichelate appendages (‘great
appendages’), two pairs of reduced and poorly known appendages–the first pair probably much shorter than the second–and a pair of trunk-like fully developed biramous appendages.Trunk divided into 12 segments, excluding telson. Tergo-sternites overlapping for approximately one-quarter of their length when body is straight forming a short spine postero-medially.Pleurae well-developed,similarly overlapping, decreasing in size antero-posteriorly;slight increase in curvature within the posteriormost segments; antepenultimate trunk segment with pleurae forming a ‘skirt’in outline with a rounded posterior angle, while other pleurae have sharp posterior angles; penultimate trunk segment with pleurae as sharp ‘blades’ pointed posteriorly; last trunk segment without pleurae,its spine appressed against the cuticle.Appendages from segments 2 to 12 arthrodized and biramous.Divided into a large basipod, an endopod and a paddle-shaped exopod. Similar to pleurae, appendages decreasing in size posteriorward, from long (>2/9th of body length) to highly reduced (segment 10) or vestigial; endopods of segments 11 and 12 unknown. Telson ca. one-sixth of body length, bipartite,composed of an articulating socket and flat telsal blade.
时代：中寒武系第三统第五阶，在厚史蒂芬组上部（布尔吉斯页岩）
主要产地: 加拿大不列颠哥伦比亚省库特奈国家公园大理石峡谷，布尔吉斯生物群
Age：Middle Cambrian (Series 3, Stage 5), upper part of the ‘thick’ Stephen Formation (Burgess Shale)
Principal localities: Burgess biota(Marble Canyon,Kootenay National Park, British Columbia)
Cédric Aria,Jean-Bernard Caron and Robert Gaines,2015.A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny.Palaeontology,Volume58, Issue4,pp.629-660.