Fig. 1. Summary of the evolution of acoustic communication across tetrapods.

Pie diagrams at select nodes indicate proportional likelihoods of each state, with acoustic communication present (black) or absent (white). The tree includes 1799 species and is based on the Hackett³⁰ backbone tree within birds. Reconstructions were based on the ARD model (with different rates for gains and losses). Major clades are indicated by colored rings on the outside of the tree; concentric circles (and associated numbers) indicate clade ages in millions of years before present²². Images of representative species are from Aijing Li, Jundong Tian, Xiaofei Zhai, Xiaowei Hong, and Yanjun Zhu. Reconstructions for all nodes and using alternative models and trees are shown as Supplementary Data 5–8 (this tree and model correspond to Supplementary Data 8). Source data are provided in Supplementary Data 3.