Arctic Ice and the Ecological Ascent of the Dinosaurs

• Main Author: Olsen, Paul E.
• Format: Text
• Language: unknown
• Published: Montclair State University Digital Commons 2020
• Subjects: Environmental Sciences; Sustainability; Arctic
• Online Access: https://digitalcommons.montclair.edu/sustainability-seminar/2020/spring2020/12; https://digitalcommons.montclair.edu/context/sustainability-seminar/article/1082/viewcontent/20200218_olsen.pdf

Despite the extremely high levels of atmospheric CO2 (+2000 ppm) in the Late Triassic and earliest Jurassic (~232-199 million years ago), there is evidence of seasonally freezing conditions in the Arctic of that time. This evidence consists of abundant icerafted debris in lake sediments. Based on phylogenetic bracket analysis, dinosaurs at this time were insulated, and could take advantage of the rich Arctic deciduous and evergreen vegetation, even under freezing winter conditions. Transient volcanic winters caused by the eruptions of the Central Atlantic Magmatic Province led to a mass extinction at 201.6 million years ago, at the close of the Triassic, that decimating all medium- to large-sized non-dinosaurian, uninsulated animals on land. In contrast, the insulated dinosaurs, already adapted to cold temperatures, not only survived but underwent a rapid adaptive radiation and ecological expansion in the Jurassic, taking over regions formerly dominated by large uninsulated reptiles.