门: 绿藻门
纲: 未定
目: 未定
科: 未定
属: 约克那斯藻
种: 单型约克那斯藻
描述: 这种藻有很长的丝体，从一个短而宽的空心茎中长出，茎上覆盖着小的锥形板片。板片就就是藻体附着的位置。藻体与Dalyia有很强的相似性，表明这两个物种可能是同一个，其中Yuknesia是Dalyia的主干部分。单型约克那斯藻最大尺寸可达30mm。这种藻类非常罕见，仅占Walcott采石场生物群的0.04% (Caron and Jackson, 2008)。
Phylum: Chlorophyta (Green algae)
Class: Uncertain
Order：Uncertain
Family: Uncertain
Genus：Yuknessia
Specie: Yuknessia simplex
Description: This alga has long branches emerging from a short but wide hollow stem covered of small conical elements or plates. The plates were the attachment sites of the branches. The branches show strong similarities with Dalyia and suggest the two species might be synonymous, with Yuknessia representing the main stem structure of the Dalyia branches. The maximum size can reach 300mm. Yuknessia is very rare and represents only 0.04% of the Walcott Quarry community (Caron and Jackson, 2008).
时代：中寒武世，Bathyuriscus-Elrathina带到 Ptychagnostus punctuosus带，约5.05亿年前
主要产地: 加拿大布尔吉斯生物群
Age: Middle Cambrian, Bathyuriscus-Elrathina Zone to Ptychagnostus punctuosus Zone
(approximately 505 million years ago).
1.CARON, J.-B. AND
D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community,
Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.
2.CONWAY MORRIS,
S. AND R. A. ROBISON. 1988. More soft-bodied animals from the Middle Cambrian
of Utah and British Columbia. University of Kansas Paleontological
Contributions, 122 p.
3.WALCOTT, C.
1919. Cambrian Geology and Paleontology IV. Middle Cambrian Algae. Smithsonian
Miscellaneous Collections, 67(5): 217-260.
4.YANG, R., W.
ZHANG, L. JIANG AND H. GAO. 2003. Chengjiang biota from the Lower Cambrian
Niutitang Formation, Zunyi County, Guizhou Province, China. Acta Palaeontologica
Sinica, 77: 145-150.