In Depth
Cloudina is one of those Cambrian animals that is both very exciting in evolutionary terms, yet much mystery still surrounds it. Cloudina represents one of the first examples of a creature known to have had a hard mineralised shell, and before the discovery of this genus, all other known creatures of the Ediacaran period were soft bodied. During this time much of the sea floor was covered in microbial mats which seem to have been the main living area for ocean life during this time. Cloudina however is usually found in areas where there would have been no microbial mat. Maybe Cloudina was among the first animals to venture away from the microbial mats, maybe they were uprooted by tidal current to dwell elsewhere, we don’t yet know for certain.
The shell of Cloudina resembled a series of upside down cones stacked on top of one another. The soft body of the organism was situated inside the shell, and in life the end of this soft body, perhaps with some kind of tendrils or filaments may have reached out to extract nutrients or organic matter passing by in the ocean currents. There is even speculation that in life the shell may have been flexible, though this is not yet certain. Even more telling about Cloudina though is that the shell, presumably evolved to be some kind of defence, sometimes shows sign of attack in the form of holes caused by boring. This suggests that even though Cloudina was ‘armoured’, some animals had already evolved an effective means of attack to penetrate the hard shell to eat the soft body inside.
Further Reading
- New shelly fossils from Nama Group, South West Africa. - American Journal of Science. 272 (8): 752–761. - G. J. B. Germs - 1972. - The early skeletal organism Cloudina: new occurrences from Oman and possibly China. - American Journal of Science. 290: 245–260. - S. Conway Morris, B. W. Mattes & M. Chen - 1990. - Shell structure and distribution of Cloudina, a potential index fossil for the terminal Proterozoic. - American Journal of Science. 290-A (290–A): 261–294. S. W. Grant - 1990. - Predatorial Borings in Late Precambrian Mineralized Exoskeletons. - Science. 257 (5068): 367–9. S. Bengtson & Y. Zhao - 1992. - Some observations on Cloudina, a terminal Proterozoic index fossil from Namibia. - Journal of African Earth Sciences. 33 (3): 475–480. - C. K. Brain - 2001. - Borings in Cloudina Shells: Complex Predator-Prey Dynamics in the Terminal Neoproterozoic. - PALAIOS. 18 (4–5): 454. - Hong Hua, Brian R. Pratt & Lu Yi Zhang - 2003. - A Revised Morphology of Cloudina with Ecological and Phylogenetic Implications. - A. J. Miller - 2004. - Skeletogenesis and asexual reproduction in the earliest biomineralizing animal Cloudina. - Geology. 33 (4): 277–280. - H. Hua, Z. Chen, X. Yuan, L. Zhang & S. Xiao - 2005. - Inconsistencies in proposed annelid affinities of early biomineralized organism Cloudina (Ediacaran): structural and ontogenetic evidences. - Carnets de G�ologie. - O. Vinn & M. Zatoń - 2012. - Transitional Ediacaran–Cambrian small skeletal fossil assemblages from South China and Kazakhstan: Implications for chronostratigraphy and metazoan evolution”. Precambrian Research. 285: 202–215. - Ben Yang, Michael Steiner, Maoyan Zhu, Guoxing Li, Jianni Liu & Pengju Lu - 2016. - The end of the Ediacaran: Two new exceptionally preserved body fossil assemblages from Mount Dunfee, Nevada, USA. - Geology. 44 (11): 911. - E. F. Smith, L. L. Nelson, M. A. Strange, A. E. Eyster, S. M. Rowland, D. P. Schrag & F. A. MacDonald - 2016. - Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period. - Nature Communications. 11 (205): 205. - James D. Schiffbauer, Tara Selly, Sarah M. Jacquet, Rachel A. Merz, Lyle L. Nelson, Michael A. Strange, Yaoping Cai & Emily F. Smith - 2020.
