The discovery of anguimorph embryos inside rigid-shelled eggs was rather unexpected as this
mode of reproduction was thought to be an exclusive specialisation of gekkonid among squamates [5,7–9,34] (Fig 9). The similarities observed between the rigid-shelled eggs of modern
gekkonids and the Phu Phok anguimorphs are likely the result of an evolutionary convergence
as leathery-shelled eggs are predominant in all other squamate clades [5,35,36] (Fig 9). Unlike
rigid-shelled eggs, eggs of most oviparous squamates present a leathery aspect which consists
of a variable and thin coating of calcite overlying a fibrous shell membrane [35]. The rigid type