Australia: The Land Where Time Began

A biography of the Australian continent 

Bilaterian Animals with Complex Behaviours from the Ediacaran - Trace Fossil Evidence

See Bilaterian – Oldest Specimen Found in the Ediacaran of South Australia

According to the authors¹ it can be a challenge to distinguish between trace fossils from the Ediacaran and tubular body fossils and this uncertainty has previously resulted in a number of Ediacaran fossils being interpreted as animal traces and later reinterpreted as tubular body fossils. There are true Ediacaran trace fossils, though there are relatively few and they are morphologically simple, and they are dominated by horizontal trails and shallow burrows. Such simple morphologies have been interpreted as evidence of modest behavioural complexity and limited geobiological impact of animal bioturbators prior to the Cambrian explosion. In this paper the authors¹ report on 3 trace fossil types - horizontal tunnels, surface tracks or trails, and traces that are vertical - that have been found in the latest Dengying Formation of Ediacaran age, 551-541 Ma, in the Yangtze Gorges area in South China. The authors¹ suggest the presence of cross-cutting tunnels and scratch marks indicate that these traces are not likely to be tubular body fossils. It is suggested that these 3 types of traces are likely to record the activities of animals relating to feeding under mats, epibenthic locomotion, and temporary dwelling, respectively. The authors¹ claim to show that these 3 trace types were constructed by the same bilaterian animals that had interactions, that were moderately complex, with microbial mats to exploit resources of nutrients and O₂. These animals were the beginnings of a new age in ecosystem engineering, animal-sediments interaction, and biogeochemical cycling.

Sources & Further reading

1. Chen, Zhe, Chuanming Zhou, Mike Meyer, Ke Xiang, James D. Schiffbauer, Xunlai Yuan, and Shuhai Xiao. "Trace Fossil Evidence for Ediacaran Bilaterian Animals with Complex Behaviors." Precambrian Research 224, no. 0 (1// 2013): 690-701.