Eggshell structure, parataxonomy and phylogenetic analysis: some notes on articles published from 2002 to 2011

Different aspects of using eggshell structure in description of fossil eggs and in phylogenetic analysis are critically discussed. One of the lines of discussion is that correct identification of the so-called squamatic ultrastructure (important feature of the spongy layer in ornithoid type of eggshell) is a key point for the results of the analysis. The complex biocrystalline nature of the so-called squamatic ultrastructure is under particular consideration. The other line concerns the use of parataxonomy and the role of structural typifications (eggshell basic types and morphotypes) as an adequate concise language for fossil egg description. The importance of these questions is illustrated on the examples of the last finds of Cretaceous eggs from the territory of the Gobi Desert in Mongolia. Finally, some recommendations for the future development of paleoology are proposed. Development of the accessible photobase of all described oogenera and oospecies, with comparable illustrations of the eggs, eggshell surface and eggshell structure, is an important step in this direction.