fourth trochanter overlooks a depression which is split in two by a thin ridge. The femur is extended and narrows significantly towards its broken and eroded lower extremity. This contrasts with other lagerpetids, which have a femur that expands towards the knee. Tibia fragments are slightly curved and expanded near the knee, similar to other lagerpetids. A pair of long and closely appressed bones have been identified as metatarsals, though this is uncertain due to the unusually bent appearance of one of the bones. Pedal phalanges (toe bones) are hourglass-shaped and have strongly developed joints. The long and narrow caudal (tail) vertebra has a concave lower edge and fused neurocentral sutures. Classification To test its relationships to other reptiles, Kongonaphon was placed in a phylogenetic analysis modified from Müller et al. 2019. This analysis did not originally include Scleromochlus, a tiny archosaur often considered distantly related to pterosaurs. The first iteration of the analysis found Kongonaphon and other lagerpetids to be the earliest-diverging dinosauromorphs, more closely related to dinosaurs than to pterosaurs. This result is common among archosaur-focused analyses. The following cladogram illustrates the first iteration: Scleromochlus was added in the second iteration of the analysis. Unusually, lagerpetids shifted from dinosauromorphs to pterosauromorphs (closer to pterosaurs) in this iteration. Pterosauromorpha is justified by several synapomorphies (shared derived characteristics) of the maxilla and ankle, though some of these are unknown in lagerpetids. As a result, further study is required to justify the placement of lagerpetids within Pterosauromorpha. This is also the case for Scleromochlus, which is coded into the analysis based on latex casts of sandstone molds. The following cladogram illustrates the second iteration: Paleobiology The teeth of Kongonaphon are similar to those of insect-eating modern animals in both shape and texture. This is among the most convincing evidence for an insectivorous diet in early avemetatarsalians, especially lagerpetids (for which teeth were previously unknown). This diet has also been suggested for Silesaurus based on referred coprolites, but Silesaurus's tooth wear suggests it was primarily herbivorous. Histology and development A histological study on a tibia fragment of UA 10618 has helped clarify the animal's bone structure, growth, and development. The tibia is fairly thin-walled, with a cortex (dense outer layer) making up about 20% of the diameter. Vascular canals are common in the cortex, and are primarily longitudinally oriented (parallel to the bone's shaft and circular in cross-section). There is some organized