Squamata is the reptile lineage containing lizards, snakes and amphisbaenians. It belongs within lepidosaurs, whose other living branch is represented by the tuatara. Snakes are nested among lineages commonly called lizards, so excluding snakes does not leave a complete evolutionary branch.
The relationships require evidence beyond superficial similarity: elongated, limbless bodies can arise in different lineages. A 2015 analysis combined hundreds of anatomical characters with dozens of genes from living and fossil groups to compare competing arrangements.[ref]
Integrated Analyses Resolve Conflicts over Squamate Reptile Phylogeny and Reveal Unexpected Placements for Fossil Taxa by Tod W. Reeder and others. Abstract: integrated morphology and molecular data
This makes Squamata a useful example of how phylogenetics tests anatomical interpretations against molecular evidence while retaining fossils that have no recoverable sequence data. New to topics? Read the docs here!