Yunnanozoon lividum

Yunnanozoon lividum (from Yunnan, and Ancient Greek ζῷον (zôion), meaning "animal", with specific name coming from Latin lividum; (lead-coloured), referring to preserved colour of specimens) is an extinct species of bilaterian animal from the Lower Cambrian Chengjiang biota of Yunnan province, China. Its affinities have long been the subject of controversy.

== Description == left|thumb|Well preserved specimen and diagram of body anatomy|270x270px The body of Yunnanozoon was fusiform, with specimens ranging from in length. The body was strongly laterally compressed, meaning that it was taller than it was wide. A segmented dorsal unit was present on the top of the body. The first segment of which was triangular, while the other segments were approximately rectangular. Axial stripes also ran down the body in the region immediately below the dorsal unit. Towards the front of the animal were 7 pairs of filamentous arches. These arches were covered by sac-like structures which had openings between them. Towards the back of the body a tube-like structure was present, possibly the gut, with four pairs of enigmatic circular structures (possibly gonads) at the mid-point of the body. The front half of the body had rod-like structures running along the top and bottom, which were probably sclerotized.