Most crocodilians rely on ambient warmth plus heat from rotting vegetation to incubate eggs. Paleosuchus trigonatus lives beside small streams under closed rainforest canopy, where sunlight is scarce and the forest floor is cool, so the usual budget is thin.
Field studies in Amazonia found that a substantial share of nests are constructed against active termite mounds, with the caiman piling leaf litter and soil around the structure. Termite colonies generate metabolic heat and regulate their mound climate, and nests built this way run warmer and more stable than the surrounding forest floor. Some nests recorded temperatures at the upper end of the viable range for the species.
Because crocodilian sex is set by incubation temperature, the choice of nest site has consequences beyond survival. How consistently the termite association shapes hatchling sex ratios across the range has not been established, and not every nest uses a mound.