1. The early-middle Cambrian period (Fortunian to Age 4) saw a significant increase in metazoan diversification and the expansion of arthropod- and echinoderm-rich biotas.
2. A new paleoredox analysis of Age 2-Age 4 Cambrian sections from the South China Craton suggests that mid-depth waters transitioned from anoxic conditions during Cambrian Age 2 to stable oxic conditions during Cambrian Age 4, indicating a stepwise expansion of oxic waters from shallow to deep settings during this time.
3. This study highlights the need for further research into the links between animal evolution, ecosystems, and marine redox conditions.
This article is generally reliable and trustworthy, as it is based on extensive research conducted by multiple authors with expertise in geology, biogeology, environmental geology, and geophysics. The authors provide detailed information about their methodology and results, which are supported by evidence from other studies. Furthermore, they acknowledge potential biases in their work and discuss possible counterarguments to their findings.
However, there are some potential issues with the article's trustworthiness and reliability. For example, while the authors discuss possible counterarguments to their findings, they do not explore them in depth or present both sides equally; instead they focus mainly on supporting their own conclusions. Additionally, while the authors note potential risks associated with their work (e.g., incomplete data sets), they do not provide any details about how these risks could affect their results or conclusions. Finally, there is some promotional content in the article; for example, the authors emphasize how their work provides "the unique opportunity" to investigate certain relationships between ocean redox evolution and metazoan diversification without providing any evidence for this claim or exploring alternative explanations for these relationships.