Annotated Bibliography

Marshall, Charles R. ‘Explaining the Cambrian “Explosion” of Animals’. Annual Review of Earth and Planetary Sciences, vol. 34, no. 1, Annual Reviews, May 2006, pp. 355–384, https://doi.org10.1146/annurev.earth.33.031504.103001.

Marshall goes into detail about exactly what the Cambrian explosion was and what could have potentially caused it. He explains how important this time in evolutionary history was due to the first appearance of many different body plans. Marshall combines many disciplines in order to get a clear view of how the Cambrian explosion came to be and what we understand about it through the fossil record. 

Liu, Jianni, et al. ‘A Cambrian Fossil from the Chengjiang Fauna Sharing Characteristics with Gilled Lobopodians, Opabiniids and Radiodonts’. Frontiers in Earth Science, vol. 10, Frontiers Media SA, July 2022, https://doi.org10.3389/feart.2022.861934.

The article describes the discovery of a new fossil dating back to the Cambrian period which does not taxonomically fit into the previously established groups of animals. The fossil appears to have physical characteristics similar to both radiodonts and lobopodians. The authors debunk theories of the fossil belonging to a juvenile radiodont and explain why it would not make sense for the fossil to fall under lobopodian. They also go into detail about the taxonomy of related groups to help the reader better understand the connections the new fossil may have to previously recorded fossils.

Schwab, I. R. ‘The Evolution of Eyes: Major Steps. The Keeler Lecture 2017: Centenary of Keeler Ltd’. Eye, vol. 32, no. 2, Feb. 2018, pp. 302–313, https://doi.org10.1038/eye.2017.226.

Schwab’s article goes into detail about how eyes evolved over billions of years. From single-celled organisms to primates, there are many different types of ocular lenses that developed. He describes how the evolution of sight was not promised and occurred by chance. Only 7 of 36 different phyla have the ability to form images through sight, although this includes 96% of species. Schwab discusses the first known eyes seen through fossils from the Cambrian explosion and the beginning of compound eyes. Many animal phyla known today first evolved during the Cambrian, and they possessed varying forms of eye structures.

Royal Ontario Museum. (2022, July 8). 500-million-year-old fossilized brains of stanleycaris prompt a rethink of the evolution of insects and spiders. ScienceDaily. www.sciencedaily.com/releases/2022/07/220708123631.htm

This article discusses how scientists at the Royal Ontario Museum have revealed new research into a fossil recovered from the Burgess Shale which contains a preserved brain and nervous system. The fossilized Stanleycaris offers insight into how animals half a billion years ago functioned as well as how they were related to modern animals. Stanleycaris was an ancient arthropod related to insects and spiders, and by being able to know how their brain and body were segmented we can better understand the evolution of radiodonts in general. The fossil allows us to know more about what animals at the time looked like and their importance in the ancient food web. Now realizing that Stanleycaris had a third eye in addition to its stalked eyes helps us to understand the complexity of the animal’s visual abilities and the way it lived. 

Nedin, Christopher. ‘Anomalocaris Predation on Nonmineralized and Mineralized Trilobites’. Geology, vol. 27, no. 11, Geological Society of America, 1999, p. 987, https://doi.org10.1130/0091-7613(1999)027<0987:aponam>2.3.co;2.

Nedin uses fossil analysis to assess how some anomalocaridids used their jaws and appendages during predation. He assesses fossilized trilobite species from the period that contain damage to their tough shields in order to determine if the injuries were caused by an anomalocaridid. He discovered that in order for Anomalocaris to break the shield of a trilobite, it would need to repeatedly flex its appendages with the shield between its appendages and its jaws. 

Hazlehurst, Kate, and Lisa Hendry. “Eyes on the Prize: The Evolution of Vision.” Natural History Museum, https://www.nhm.ac.uk/discover/eyes-on-the-prize-evolution-of-vision.html. 

This article describes fossilized animals from the Cambrian which have preserved neural networks. Being able to study their brains allows for more information on the visual processing of ancient animals. They go into detail about compound eye structure and how eyes evolved over millions of years.

Fox, Douglas. “What Sparked the Cambrian Explosion?” Scientific American, Nature Magazine, 16 Feb. 2016, https://www.scientificamerican.com/article/what-sparked-the-cambrian-explosion1. 

This article discusses various possibilities for what caused the Cambrian Explosion. This includes an increase in oxygen and the acquisition of new behaviors. They also go into how an increase in oxygen is unlikely to be the main cause for such an explosion of life due to recent research.