Here is the paper for which this article is based: https://www.pnas.org/doi/10.1073/pnas.0801918105 https://www.pnas.org/doi/10.1073/pnas.0801918105 The paper

Here is the paper for which this article is based: https://www.pnas.org/doi/10.1073/pnas.0801918105 https://www.pnas.org/doi/10.1073/pnas.0801918105 The paper is about megafauna rather than all mammels. This highly cited paper calculates the biomass of every class of organism, figure 1 is especially fascinating. https://www.pnas.org/doi/10.1073/pnas.1711842115 https://www.pnas.org/doi/10.1073/pnas.1711842115 Animals are tiny proportion of the world's biomass, with insects dominating that class, along with fish and molluscs.