Figure 4.

Relationship of body mass to gastrolith mass in birds and dinosaurs. Data were compiled for 27 bird species of several families (ostriches, wild birds and domesticated; see electronic supplementary material) as well as for the theropod Caudipteryx and the three sauropod finds with the highest mass of associated gastroliths (type specimens of Seismosaurus, Cedarosaurus and Dinheirosaurus). Note that values of relative gastrolith mass in sauropods lie well below the regression line for birds and the Caudipteryx data.