A revision of the eggshell fragment of Spheroolithus megadermus from Laiyang, Shandong Province, China

摘要: In 1958, a special type of dinosaur egg was discovered in Zhaotuan, Laiyang, Shandong Province, China. Although only a large eggshell fragment was collected, its extremely large thickness indicated that the eggshell fragment represented a new ootaxon. In previous studies, it was named Spheroolithus megadermus and assigned to the oogenus Spheroolithus under the oofamily of the Spheroolithidae based on the microstructure in radial view. However, a comparative study of the microstructure in tangential views between the large eggshell fragment from Laiyang and the recently reported Multifissoolithus from Zhejiang Province, China and Yamaguchi, Japan revealed that all of them have roughly paralleled and wavy clefts. Therefore, this study reassigned the large eggshell fragment from Laiyang to Multifissoolithus of the Dongyangoolithidae and discussed its unique compact layer near the eggshell’s inner surface, as well as the chronological and spatial distribution of dongyangoolithid eggs. The reassignment of the holotype of Spheroolithus megadermus also indicates that the referred specimen of Spheroolithus megadermus from Changtu, Liaoning Province becomes the holotype of a new oospecies Spheroolithus quantouensis.