A new ootype of putative dromaeosaurid eggs from the Upper Cretaceous of southern China

Non-avian maniraptoran eggs are abundant in the Upper Cretaceous of China. Previous studies mainly focused on oviraptorosaur and troodontid eggs which can be classified into the oofamilies Elongatoolithidae and Prismatoolithidae, respectively. Here we report a new possible ootype of dromaeosaurid dinosaur recovered from the Lianhe Formation of the Ganzhou Basin. The new ootaxon, Gannanoolithus yingliangi oogen. et oosp. nov., is remarkable for its symmetrically elliptic shape and two structural layers with an abrupt and straight boundary. It shares a similar elongated shape, interlocked eggshell units, and an angusticanaliculate pore system with those of Deinonychus eggshell-like maniraptoran ootaxa reported from North America, Europe, and East Asia. The new phylogenetic analysis suggests the monophyly of dromaeosaurid and oviraptorosaurian eggs, and troodontid eggs are closely related to bird eggs. Paired eggs of Gannanoolithus might indicate that dromaeosaurid dinosaurs also have paired functional oviducts like oviraptorosaurs and troodontids. In addition, the porosity and EBSD analyses support that these eggs in the mound nests are buried.