Body fossils

Define the term ‘body fossils’ and outline why examples of exceptional preservation are important

What are body fossils?

Partial or complete remains of plants or animals, typically hard parts e.g. shells

What is recrystallisation?

original mineral structure of a fossilized hard part (like a shell or bone) changes, but the chemical composition remains the same

What is pyritization?

when the organic matter of the fossil is replaced by pyrite; common in black shales

What is silicification?

original calcareous skeleton replaced by silica

What is carbonisation?

organism’s organic matter is transformed into a thin, black film of carbon

What is the exceptional preservation example in Yunnan province China?

Chengjiang fauna

What is the classification and mode of preservation of the Chengjiang fauna?

• Classification: Konservat-Lagerstätten - Obrution deposits

• Mode of preservation: Soft bodies fossils in finely laminated mudstone. Chengjiang fauna considered to have lived in a shallow-water environment. 

What are common components of the Chengjiang fauna?

Sponges, cnidarians, brachiopods, vertebrates

What is the example of exception preservation in British Columbia, Canada?

Burgess Shale fauna

Why are examples of exceptional preservation important? (3)

• we can see soft tissue that is rarely preserved in the fossil record

• helps reconstruct ancient ecosystems by showing us the diversity and interactions between organisms

• reveal details about how organisms evolved, including the origins of new features and major transitions in evolution.