Schematic views of the seven different gekkotan and representative derived squamate eggshells.

Abstract

<p>Most of the terminology followed [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199496#pone.0199496.ref002" target="_blank">2</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0199496#pone.0199496.ref015" target="_blank">15</a>] and otherwise new terms are proposed in this study. The light gray areas in <i>Gekko gecko</i> (A), <i>Paroedura stumpfii</i> (C), and <i>Phelsuma grandis</i> (D) eggshells show the location and shape of “dark bands”. The dark gray areas in rigid gecko eggshells (A–D) signify the shape of extinction pattern under polarized light. The jargon “calcareous layer” is used in soft gekkotan eggshell to refer to stem-like and cap-like structures, collectively. The figures are not drawn to scale. In <i>Gekko gecko</i> eggshell (A), a pore-like and bulbous structures are associated with the ornamentation. The eggshell of <i>Paroedura stumpfii</i> has a peculiar porous layer (C). The mixed layer of <i>Rhacodactylus leachianus</i> eggshell (F) can be further differentiated into two sub-layers. The protein fibers in <i>Eublepharis macularius</i> eggshell (G) are undulated unlike other soft eggshells (E, F). Note that soft eggshells of derived squamates do not have stem-like structure that extends to the shell membrane (H).</p