The Early Cretaceous terrestrial ecosystems of the Jehol Biota based on food-web and energy-flow models

The ancient terrestrial ecosystems of the Lower Cretaceous Yixian Formation and the Jiufotang Formation, consecutive components of the Jehol Group in Northeast China were reconstructed using an energy-flow and food-web model. This model can be used to quantitatively estimate population densities for ancient terrestrial vertebrates based on food webs, net primary productivity, and three categories of energy-transfer efficiency. The results indicate that densities reached 866 individuals km−2 and 4122 individuals km−2 in two ecosystems, respectively. The main component of the vertebrate fauna of the Yixian Formation consisted of large herbivorous dinosaurs, while much smaller avians dominated the Jiufotang fauna. The model also indicates a temporal transition in the dinosaur fauna from the Yixian fauna to the Jiufotang fauna in which theropods decreased and ceratopsids became more abundant. We then compared these estimates of biodiversity with the Early Cretaceous Choyr fauna of Mongolia, and Tetori fauna of Japan using Simpson's diversity indices. Those indices, based on biomass, indicate that the biodiversities of the Jehol fauna lay between those of the Choyr and Tetori faunas. This range in biodiversity seems attributable to fundamental differences in vegetation and the environment. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 836–853.