The Huainan biota is a collection of macroscopic organisms discovered in the early 1980s in the Precambrian deposits of China (Huainan City, Anhui Province), that represent a transitional period in evolution. [1]
The Huainan biota is a collection of macroscopic organisms discovered in the early 1980s in the Precambrian deposits of China (Huainan City, Anhui Province), that represent a transitional period in evolution. [1]
Huainan biota organisms were discovered by Wang Guixiang and Sun Weiguo in the 1980s in Precambrian rock formations near Huainan City. [1] The organisms date back to 840-740 million years ago (Ma). [2] This falls into to the Tonian period, which marks a transitional phase in Earth's history where life began evolving from tiny micro-organisms to larger organisms. [3]
In the Huainan area, the Neoproterozoic rock layers are classified in three main groups; the Huainan Group, Feishui Group, and the Fengtai Formation. [3] They each represent a different sedimentary cycle. [3] The Huainan group is made up of siliciclastic rocks like sandstone and shale. [3] The Feishui group consists of carbonate rocks, like limestone and dolomite, and includes fossil-bearing formations, such as the Jiuliqiao Formation, where the Huainan Biota was found. [3] The Fengtai Formation is composed of glacial deposits of diamictites. [3]
Two types of Huainan biota were found in the Jiuliqiao Formation, a geological rock unit ranging from 26 to 119 meters thick, dating to the Ediacaran Period. [4] Their difference being in their fossil shapes. The first type of biota consists of a worm-like, tubular structure. [4] The second type of biota consists of solitary discs with a central opening. [4] Both fossil types vary between 0.5-2 mm in size. [4]
A similar biota, about 1 billion years old, was found by M. B. Gnilovskaya in Russia on the Timan Ridge. [5] It is only known that its constituent organisms ( Protoarenicola , Pararenicola , Sinosabellidites ) reached several centimeters in size (which is significantly inferior to the Ediacaran ones) and, apparently, had the shape of segmented tubes, often goblet-shaped, with extensions at the end. [5] Huainan biota do not contain jellyfish-like "discs" (as seen in the Ediacaran biota), nor any forms close to sponges.
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