T70 Links between Mesozoic Climate and Biodiversity

Sunday, 31 October 2010
1:30 PM - 5:30 PM
Room 603

UNTANGLING THE RELATIONSHIP BETWEEN CLIMATE AND BIODIVERSITY IN MESOZOIC TERRESTRIAL VERTEBRATES

Paper number: T70-3
Program: Technical Sessions
Time: 2:05 PM – 2:20 PM

Authors

Abstract

In the modern world, the relationship between climatic variation and biodiversity is well known and appreciated. Current climatic conditions maintain a unimodal biodiversity gradient that peaks around the equator, decreasing with increasing latitude. This pattern is observed in various groups of plants, vertebrates, and insects as well as in terrestrial, freshwater, and marine environments. The modern biodiversity gradient is assumed to be ancient, stretching back at least 65 my or more. However, prior to the recent icehouse there were several hothouse intervals in Earth’s history in which the temperature gradient was more relaxed, leading to climatic conditions unseen in many modern ecosystems. It may therefore be unrealistic to expect the distribution of biodiversity to have remained static during these intervals. In fact, studying past distribution patterns may prove vital to understanding the relationship between climatic variables and current species diversity.

Here we present part of an ongoing study into Mesozoic climates and terrestrial vertebrate distribution patterns in which we explore the relationship between body fossils and climate simulations. Fossil distribution data comes from the Paleobiology Database while abiotic parameters (temperature, precipitation, etc.) are derived from Fast Ocean Atmospheric Model (FOAM) simulations for 220, 195, 155, 120, 90, and 70 mya. Throughout much of the Mesozoic, terrestrial vertebrate diversity (especially dinosaurs) appears to follow a bimodal distribution pattern. Likewise, the climate during this time was characterized by strong continentality and a relaxed temperature gradient. The bimodal pattern weakens as continentalality breaks down with Pangean disassembly during the Cretaceous. This suggests that strongly seasonal environments played an important role in supporting biodiversity during the Mesozoic, lending important insights into the ecology of terrestrial ecosystems during this time. Changes in taxonomic diversity over time may also be related then to the expansion or contraction of certain key climate zones and have implications for understanding extinction patterns. Although much work remains to be done, this method presents a promising way for exploring the connection between Earth’s climate and biota.