Exploring the drivers of early biomineralization

Area of Science:

• Paleontology
• Biomineralization
• Evolutionary Biology

Background:

• The earliest biomineralized hard parts, phosphatic plates, appeared approximately 810 million years ago (Ma).
• Large skeletons in diverse taxa, including early poriferans and cnidarians, emerged around 550 Ma in the terminal Ediacaran.
• A substantial increase in skeletal abundance, diversity, and mineralogy characterized the early Cambrian period.

Purpose of the Study:

• To investigate the origins and evolution of biomineralization from the Ediacaran to the early Cambrian.
• To explore the environmental and biological factors influencing the development of skeletal structures.
• To understand the transition from early biomineralization to more complex skeletal forms.

Main Methods:

• Analysis of fossilized skeletal biota from Ediacaran and early Cambrian carbonate and clastic settings.
• Examination of skeletal morphology to infer organic scaffolds and biomineralization processes.
• Correlation of biomineralization events with paleoceanographic conditions (e.g., Mg/Ca ratios, oxygen levels) and ecological pressures (e.g., predation).

Main Results:

• Ediacaran skeletal biota, like Cloudina and Anabarites, straddle the Ediacaran-Cambrian transition, with many found in carbonate settings and suggesting initial minimal biological control.
• Calcification appears to be a derived trait that arose independently in diverse groups, initially influenced by seawater chemistry.
• Early Cambrian skeletal diversification, particularly in clastic settings, suggests a response to increased predation pressure and greater biological control over biomineralization.

Conclusions:

• Biomineralization evolved independently in various lineages, with early forms showing limited biological control and dependence on environmental conditions.
• Changes in seawater chemistry (Mg/Ca ratios) and oxygen levels likely triggered Ediacaran-Cambrian biomineralization.
• The proliferation of diverse biomineralization styles in the Early Cambrian was likely driven by escalating predation pressure, leading to greater biological control.