Parataxonomic review of the Upper Cretaceous dinosaur eggshells belonging to the oofamily Megaloolithidae from India and Argentina

Abstract

The eggshell oospecies from India and Argentina are compared and reviewed in detail. These eggshells resemble each other in having a nodular outer surface ornamentation and clearly arched growth lines of the shell units. Microstructurally, the eggshell oospecies belonging to the oofamily Megaloolithidae shows fan-like shell units, which are sharply separated from each other throughout the thickness of the eggshell and can be traced up to the surface of the eggshell. Comparisons between four oospecies from India and Argentina reveal three groupings, which show similarities between megaloolithids of both countries: (1) Megaloolithus jabalpurensis, M. matleyi and M. patagonicus; (2) M. cylindricus, M. rahioliensis and Tipo 1d; (3) M. megadermus and Tipo 1e. The other two type of eggshell oospecies from India and Argentina shows partially fused external nodes and shell units. As a result growth lines enter into the adjacent shell units with a marked concavity. A new oogenera Fusioolithus have been erected due to fusion between shell units and prolatospherulitic morphotype, which include two new oospecies Fusioolithus baghensis and Fusioolithus berthei. Till date, morphostructurally, a total of fifteen eggshell oospecies belonging to different oofamilies have been recorded from India and seven eggshell from Argentina.