The Chengjiang Biota inhabited a deltaic environment

Area of Science:

• Paleontology
• Sedimentology
• Geology

Background:

• The Chengjiang Biota represents the earliest Phanerozoic soft-bodied fossil assemblage.
• It provides a unique snapshot of the Cambrian Explosion, Earth's initial diversification.
• The precise sedimentary environment of the Chengjiang Biota remains debated.

Purpose of the Study:

• To investigate the sedimentary environment of the Chengjiang Biota.
• To understand the ecological conditions during the Cambrian Explosion.
• To re-evaluate the habitat of Burgess Shale-type faunas.

Main Methods:

• Analysis of a non-weathered core from the Yu'anshan Formation.
• Examination of the sedimentary succession preserving the Chengjiang Biota.
• Interpretation of sedimentologic data to infer environmental conditions.

Main Results:

• The Yu'anshan Formation succession was deposited in a delta influenced by storm floods.
• The Chengjiang animals inhabited an oxygen and nutrient-rich delta front environment.
• Key stressors included unstable salinity and high sedimentation rates.

Conclusions:

• The Chengjiang Biota inhabited a dynamic delta front environment, challenging previous assumptions.
• This finding necessitates a revision of the ecological interpretation of Burgess Shale-type faunas.
• Sedimentologic advances are crucial for understanding ancient ecosystems.