FIGURE 6 in To name or not to name: Criteria to promote economy of change in Linnaean classification schemes

FIGURE 6. Pros and cons of the time banding criterion as exemplified in two related reptile genera with radically different patterns of temporal diversification. Both the African Bradypodion and the Malagasy Brookesia are well diagnosable and clearly monophyletic units. While Bradypodion diversified in the Miocene-Pliocene, Brookesia dates back to the Cretaceous. Several morphologically extremely similar sister species of miniaturized Brookesia, such as B. tuberculata and B. tristis have an age almost doubling that of the entire genus Bradypodion. Attempts of adapting classification on the basis of age would mean an extreme oversplitting of Brookesia with numerous non-diagnosable genera, or merging Bradypodion into a larger unit of unstable monophyly and low diagnosability. Within Brookesia, arguments might in the future be brought forward that the B. nasus group (light blue) should be recognized as a distinct genus and the two sister clades would obtain the rank of genus (light and dark blue dots). This decision would bring an even more stable monopyhly and better diagnosability. However, such a splitting would still leave units of much older age than Bradypodion. Abbreviations: Cret = Cretaceous; Pal = Paleocene; Eo = Eocene; Oli = Oligocene; Mio = Miocene; Pl = Piocene + Pleistocene + Quaternary. Timetrees redrawn after Tolley et al. (2006) and Townsend et al. (2009, 2011).