Abstract

Paleoclimate simulations that utilize realistic paleogeography and paleotopography and are strenuously tested against the geologic record become multi-purpose vehicles for studying more involved geologic, paleontologic and economic questions. In this study we focus on the first two questions and use a simulation that models Kimmeridgian-Tithonian (154.7-145.6 Ma) paleoclimate. The results provide challenging paleoecological implications for faunal province distributions, migrations and habitats.

The Kimmeridgian-Tithonian distribution of four herbivorous dinosaur orders and the carnivorous Theropoda can be grouped into 33 localities worldwide. The majority of localities occur in the northern hemisphere on all continents in the subtropic to temperate paleolatitudes. Most localities in Gondwana are in similar paleolatitudes. These dinosaur sites are not found associated with their aquatic reptilian relatives. Dinosaur remains do exist in regions subject to wide ranging summer and winter temperature fluctuations as well as limited net moisture supply. The distribution of localities in a paleoclimate framework reflect their preferred habitats, feeding habits, point strongly to seasonal migrations and/or can suggest that certain dinosaurian orders could regulate their body temperatures.

The marine shelf margins and epeiric seas hosted a widely distributed and diverse ammonoid fauna which are reported from 47 localities worldwide. Ammonoids changed from being cosmopolitan in the Kimmeridgian to being strongly provincial by late Tithonian. A region of the equatorial Tethys that includes most of the present Arabian Peninsula contains neritic platform facies but lacks ammonoids. Results from modeled seasonal sea surface temperature, sea ice distribution, precipitation-evaporation and wind-driven upwelling permit the evaluation and quantification of paleoenvironmental factors favorable as well as pernicious for ammonoid distribution.