Body size maxima in aquatic taxa correspond to lake level, with large body size observed in aquatic turtles, crocodylians, and hippopotamids during lake high stands on the north side of the Turkana Depression. However, these semi-aquatic groups display heterogenous trends over time and relationships to hydrologic proxies, indicating that their differential niches in these aquatic habitats were linked to different conditions and food resources. Terrestrial tortoises (Testudinidae) exceed 100 kg in mass in three members of the Shungura Formation, but are absent at large sizes between 2.3 Ma and 2.1 Ma, during the main period of hominid stone tool production. We tested for correlation between reptile maximum sizes, mammal maximum sizes and faunal metrics, δ18O and δ13C records from paleosols and mammal tooth enamel, and paleotemperature estimates across members of the Shungura Formation. After correction for multiple comparisons, no correlation tests between reptile size and paleoenvironment or mammal metrics are significant.