PALEOECOLOGICAL RECOVERY OF EARLY TRIASSIC ECHINOIDS: A TEST OF THE HABITABLE ZONE HYPOTHESIS WITH MEMBERS OF THE MODERN FAUNA

Confronted with global climate change and ocean acidification, our collective knowledge of ecosystem response during times of environmental crisis in Earth’s ancient past may provide insights towards combating ecological degradation in modern oceans. Early Triassic marine environments were characterized by oceanic warming due in part to elevated levels of atmospheric CO₂ and periodic intervals of localized anoxia, resulting in an overall restructuring of faunal dominance, distribution, and biodiversity. Re-assembly of ecological communities during the Early Triassic are largely unknown; however, a previous paleoecological study by Tyler Beatty et al. (2008), suggests that post-extinction recovery length was minimized in shallow marine habitable zones. To further expand upon the investigations of Beatty et al., we will use Early Triassic echinoids as a case study for understanding paleoecology on the eastern margin of Panthalassa. We hypothesized that amidst the deleterious environmental conditions of the Early Triassic, echinoids thrived within the habitable zone as an abundant member of the Modern Fauna. The environmental conditions required for sustaining diverse and well-established paleocommunities given the harsh marine conditions of the Early Triassic may become more apparent by using echinoids as a paleoecological proxy.

Early Triassic echinoids of the western United States appear exclusively within shallow marine shelves, all of which contain evidence of frequent storm activity. The observed strata contain bivalves, brachiopods, gastropods, and echinoderms, indicating that these habitats were well oxygenated enough to support paleocommunities of moderate diversity. The oceans of the Early Triassic provide only an approximate analogue for modern oceans; however, analysis of Early Triassic ecosystems via quantification of echinoid abundance and diversity may help reveal important patterns necessary in understanding the rapidly shifting ecosystems of our modern, warming oceans.