Australia: The Land Where Time Began

A biography of the Australian continent 

Bioturbation Through the Early Palaeozoic – Protracted Development

An important control on the character of modern marine sediments and biogeochemical cycling is exerted by bioturbation, the physical and chemical mixing of sediment by burrowing animals (1-9). This study has shown that until at least the Later Silurian, 120 Myr after the Precambrian-Cambrian transition the sediment mixing on marine shelves remained limited. In this paper iconological, stratigraphic and taphonomic data from a range of siliciclastic successions dating from the lower Phanerozoic that spanned 4 palaeocontinents are presented. Tarhan et al. say the protracted development of the sediment mixed layer is also consistent with sulphur and global sulphur model simulations. Evolutionary advances in sediment colonisation that occurred more rapidly than advances in the mixing of sediment is suggested by the slow rate of increase of bioturbation in the sediment record. Tarhan et al. concluded that the ecosystem restructuring that resulted from the onset of significant infaunal mobile deposit feeding (‘bulldozing’) occurred long after the Cambrian Explosion and the Great Ordovician Biodiversification Event.

Sources & Further reading

1. Tarhan, L. G., M. L. Droser, N. J. Planavsky and D. T. Johnston (2015). "Protracted development of bioturbation through the early Palaeozoic Era." Nature Geosci 8(11): 865-869.