175 The Neoproterozoic Earth and Life Co-evolution, Part I

This session aims to enhance discussions and foster interdisciplinary collaborations to advance understanding of the Neoproterozoic Earth and life co-evolution. Contributions from paleontologists, geochemists, sedimentologists, Earth system modelers, and related fields are highly encouraged.

Tuesday, 21 October 2025
8:00 AM - 12:00 PM
HBGCC, 304A

The evolution of marine aerobic habitat for animals over the Neoproterozoic and Paleozoic

Paper number: 175-3
Program: Technical Sessions
Time: 8:35 AM – 8:55 AM

Authors

Abstract

Permissive environment hypotheses for early animal evolution require that marine environments in the Mesoproterozoic and early to mid-Neoproterozoic were aerobically unsuitable for Cambrian-style animals, and that these environments became irrevocably habitable near the Cambrian. Given that oxygen and temperature interact synergistically in determining an animal’s aerobic capacity, it is possible that any change from ‘non-permissive’ to ‘permissive’ aerobic environments was driven entirely by oxygen change, entirely by temperature change, or a combination of both. Here, we will first present new data demonstrating apparent physiological trade-offs such that animals cannot be both hypoxia tolerant and temperature-insensitive. Next, we examine different idealized scenarios for oxygen-temperature trajectories over the Neoproterozoic and into the Cambrian. These scenarios indicate multiple paths to sufficient aerobic habitat for animals, consistent with our understanding of animal ecophysiology, and also demonstrate that the most extreme estimates for atmospheric oxygen (e.g., <5% Present Atmospheric Levels) and temperature (e.g., tropical temperatures >40°C) were unlikely to have co-occurred in time after animals appear in the shallow-water fossil record. Finally, we combine published estimates of atmospheric oxygen and temperature change over the Paleozoic (and their associated uncertainty) to demonstrate how these variables controlled aerobic capacity for animals. The results highlight the need for more robust data records during early animal evolution (Ediacaran and Cambrian) and the necessity of considering oxygen and temperature in tandem when evaluating changes to aerobic habitat.   

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412540

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