The Cambrian Explosion and Its Evolutionary Significance

The Region’s Geological Formation and Fossil Beds

The region, which dates back to around 520 million years ago, is one of the common preservation sites today with its well-preserved fossils of trilobites, and most scientists have moved to conduct extensive researches in the area. As compared to other types of biotas, this location comprises of deep water deposition and labile soft tissues. In terms of its geological formation, the location contains major fossil beds comprising of soft tissue preserving locations, and it is classified as one in two of the locations comprising of the trilobites across the globe (Jago & Cooper, 2011). The three common fossil localities with this form of fauna are known as the Cambrian explosion, an aspect that describes the time when metazoan animals existed, and with their hard parts, it was easy for the fossils to appear on fossil records. GARCÍA‐BELLIDO et al. (2009) explains that the lower Cambrian region offers critical information about the existence of early animal communities, and among the most intriguing issues it raises about the discoveries is that its biota is taxonomically the same as that of Burgess Shale-type in terms of the disparate preservation styles and deposition settings.

The Discovery of Fossils in Emu Bay Shale’s Lower Regions

Recently, there was a discovery of some fossils from Emu Bay Shale’s lower regions, specifically in the Kangaroo Island of Southern Australia. The island is known for its natural and splendor environment, together with the ancient relics forming the marine life. These discovery of the fossils have led to scientists developing critical insights into the origin and evolution of animals around the area. Generally, fossils indicate the existence of certain species during history, and researchers conduct extensive tests and experiments to ascertain the types of species that lived in the region. For instance, there are some insights indicating the evolution of arthropods with compound eyes, and they could have extended their geographical range to the margin of East Gondwanan (Paterson et al., 2016). The discovery of such fossils holds great potentials for scientists, who want to enhance the taphonomic pathways and describe the visual nature of Anomalocaris animals, with the notion that these animals have a close relationship with arthropods. Besides, the discovery of fossils indicates that the advanced arthropod eyes might have evolved over time before the animals developed hardened exoskeletons and joint legs.

Species Diversity and Depositional Environment

Of the more than fifty species discovered from the EBS, around thirty percent of them comprise of biomineralized structures and the rest are soft-bodied (McKirdy et al., 2011). Though, based on their relative abundance, the biomineralized ones prevail in terms of their trilobite dominance, with their species diversity comprising a majority of panarthropods. Daley et al. (2013) note that as of today, there are around 28 species of panarthropods recorded. The other classifications of species identified in the area include the brachiopods, sponges, a single annelid species, cycloneuralian worms, and molluscs. In terms of its depositional environment, the region has a shallow water deposition, indicating the existence of fibrous calcium carbonate or blocky apatite. Some of them also include old phosphatized tissues in their quotas.

The Evolution and Preservation of Species in Emu Bay Shale

Emu Bay Shale offers important information regarding the evolution of different species, their ecology and biogeography faunas based on the East Gondwanan view. In general, EBS creates an impression that it could have lived in an environment with well-oxygenated water columns subjected to fluctuating oxycline. As a result, an exaerobic zone was developed on the sea floor, which later inhabited these species and acted as the preservation point for the taxa species. Even though the location is made of Burgess Shale-type biota, it has exceptional modes of preservation along its nearshores, thus being able to reshape how soft body fossils are preserved at Cambrian.

References

Daley, A. C., Paterson, J. R., Edgecombe, G. D., García‐Bellido, D. C., & Jago, J. B. (2013). New anatomical information on Anomalocaris from the Cambrian Emu Bay Shale of South Australia and a reassessment of its inferred predatory habits. Palaeontology, 56(5), 971-990.

GARCÍA‐BELLIDO, D. C., Paterson, J. R., Edgecombe, G. D., Jago, J. B., Gehling, J. G., & Lee, M. S. (2009). The bivalved arthropods Isoxys and Tuzoia with soft‐part preservation from the Lower Cambrian Emu Bay Shale Lagerstätte (Kangaroo Island, Australia). Palaeontology, 52(6), 1221-1241.

Jago, J. B., & Cooper, B. J. (2011). The Emu Bay Shale lagerstätte: a history of investigations. Australian Journal of Earth Sciences, 58(3), 235-241.

McKirdy, D. M., Hall, P. A., Nedin, C., Halverson, G. P., Michaelsen, B. H., Jago, J. B., ... & Jenkins, R. J. F. (2011). Paleoredox status and thermal alteration of the lower Cambrian (series 2) Emu Bay Shale Lagerstätte, South Australia. Australian Journal of Earth Sciences, 58(3), 259-272.

Paterson, J. R., García-Bellido, D. C., Jago, J. B., Gehling, J. G., Lee, M. S., & Edgecombe, G. D. (2016). The Emu Bay Shale Konservat-Lagerstätte: a view of Cambrian life from East Gondwana. Journal of the Geological Society, 173(1), 1-11.