Evidence from ammonoids and conodonts for multiple Early Triassic mass extinctions

Area of Science:

• Paleontology
• Marine Biology
• Geochemistry

Background:

• Ammonoids and conodonts exhibit high origination/extinction rates, making them sensitive to environmental shifts.
• Global environmental crises, particularly carbon isotopic excursions, intensify extinction rates.
• Early Triassic negative carbon isotopic excursions mirrored Permian mass extinction events.

Observation:

• Ammonoids and conodonts experienced significant mass extinctions during three Early Triassic negative carbon isotopic excursions.
• These taxa demonstrated rapid rediversification between extinction events, consistent with their high origination rates.
• Other marine taxa with lower origination rates were less impacted but remain poorly studied.

Findings:

• High origination/extinction rate taxa like ammonoids and conodonts are vulnerable to global crises but recover quickly.
• Early Triassic crises led to mass extinctions in ammonoids and conodonts, similar to Permian events.
• Less-studied marine taxa with low origination rates showed modest diversity changes, obscured in the fossil record.

Implications:

• The study highlights the differential impact of mass extinctions on marine taxa based on their intrinsic rates of origination and extinction.
• Understanding ammonoid and conodont recovery provides insights into ecosystem resilience after environmental crises.
• Further research on less-studied taxa is needed to fully comprehend the scope of Early Triassic marine life responses to global change.