We plotted the largest as-preserved or estimated length of skull, lower jaw, and/or carapace of turtles and crocodylians from each of the neotropical Neogene to Quaternary fossil sites, putting them in context with the global climatic curve of Zachos et al. (46) and the major geological and geographical events of northern South America. We included the following lineages of turtles: Erymnochelyinae, Podocnemidinae, Chelidae, and Testudinidae, and for the crocodylians: Alligatoridae, Gavialidae, and Crocodylidae (Fig. 6, fig. S9, and table S3), adding also the largest reported extant representatives. We excluded from this plot very recently immigrant lineages of turtles: Geoemydidae, Kinosternidae, Emydidae, and Chelydridae, and turtles that occasionally reached South America, for example, Trionychidae, as well as sea turtles and the extant Galápagos tortoises (gigantism due to phylogenetic history and island isolation). The extremely fragmentary Charactosuchus spp. were also excluded considering that they are still controversial if they are truly members of Crocodylidae (67).