A study in 2018 found that "Megachirella", an extinct genus of lepidosaur that lived about 240 million years ago during the Middle Triassic, was a stem-squamate, making it the oldest known squamate. The phylogenetic analysis was conducted by performing high-resolution microfocus X-ray computed tomography (micro-CT) scans on the fossil specimen of "Megachirella" to gather detailed data about its anatomy. This data was then compared with a phylogenetic dataset combining the morphological and molecular data of 129 extant and extinct reptilian taxa. The comparison revealed "Megachirella" had certain features that are unique to squamates. The study also found that geckos are the earliest crown group squamates not iguanians.