Name: Doushantuo Formation Location: South China Age: 550-590 million years old (latest Precambrian)

3. Fauna and Flora

The fossils found in the Doushantuo Formation include spherical microfossils, acritarchs, and algae.

The spherical microfossils have been interpreted as early developmental stages of animals, although the group to which they belong is uncertain (Shen et al., 2000). However, the Doushantuo fossils are still important as they provide new information about the development of early animals (Shen et al., 2000; Zhang and Yuan, 1992).

The two main spherical microfossils, Megasphaera and Parapandorina, have been described as animal eggs and cleavage-stage embryos, respectively (Shen et al., 2000). The interpretations of other microfossils are not so certain, however (Shen et al., 2000). One of the controversies surrounding the Doushantuo embryos is that no gastrulas or adult animals have been found (Shen et al., 2000). This could be due to the animals travelling to the upper water column after the embryo stage, or maybe sediment reworking that sorted fossils by size (Shen et al., 2000).

Acritarchs (spherical organic-walled microfossils) have also been found in the Doushantuo Formation. Giant acritarchs diversified rapidly at this time due to a rise in sea level (Xiao et al., 1998a). These acritarchs could have grown to be giant due to high nutrient levels in surface waters (Xiao et al., 1998a).

Algae have been found in the Doushantuo Formation, and they: "range from simple colonies of undifferentiated cells to erect, branching forms characterized by tissue differentiation and specialized reproductive structures." (Zhang and Yuan, 1992, p. 556). These more complex forms are important for our understanding of algae development (Zhang and Yuan, 1992). More algal fragments have been found (Xiao and Knoll, 2000), which have been interpreted as brown algae.