Undulatoolithus
Undulatoolithus is an oogenus of Chinese fossil dinosaur egg belonging to Elongatoolithidae. It is very similar to "Macroolithus", but has different ornamentation. Like other elongatoolithids, it was probably laid by oviraptorosaurs. Distribution. "Undulatoolithus" is found in the Zhoutian Formation, in the Pingxiang Basin of Jiangxi. It is dated to the Upper Cretaceous. History. The Pingxiang Basin, in Jiangxi, was first excavated for fossils in 2002. Several fossil eggs, egg clutches, and dinosaur bones were discovered, including those later described as "Undulatoolithus" in 2013 by Chinese paleontologists Wang Qiang, Zhao Zikui, Wang Xiaolin, Li Ning, and Zou Songlin. The type  and only known specimen of "Undulatoolithus" was the first elongatoolithid egg clutch discovered in the Pingxiang basin. Description. Like all elongatoolithids, "Undulatoolithus" eggs are elongated and asymmetrical, and have a two-layered eggshell (consisting of the cone layer and the columnar layer). The only known "Undulatoolithus" specimen is a nest consisting of five complete eggs and three partial eggs. The eggs are paired and arranged radially, similar to other elongatoolithids. They average about long and across. The eggshell is nearly 1.5 mm thick, including ornamentation. The boundary between the two eggshell layers in "Undulatoolithus" is gradual. The cone layer is  relatively thin, ranging from one fourth to one eighth the width of the columnar layer. The most notable characteristic of "Undulatoolithus" is the ornamentation on the surface of the eggshell. Like most elongatoolithids it is covered with nodes and ridges, but they are much more prominent than other oospecies and make up nearly half the total eggshell thickness. Paleobiology. "Undulatoolithus" has not been associated with embryos or skeletal remains, so the identity of the egg-laying dinosaur is unknown. However, all embryos or adult skeletons that have been associated with other elongatoolithids are oviraptorids. Like other elongatoolithids, "Undulatoolithus" probably received  intensive parental care. Parataxonomy. "Undulatoolithus" is classified as within Elongatoolithidae. It is very similar to "Macroolithus," but has much more prominent eggshell ornamentation.