Paradictyoolithusis anoogenusofdictyoolithiddinosaur eggfrom theZhejiang Province,China.They are nearly spherical eggs, measuring up to 13.9 cm (5.5 in) in diameter, and have a thin eggshell. Their shells are made up of three or four superimposed layers of eggshell units. The two known oospecies are distinguished mainly by their pore structure.[1]
| Paradictyoolithus Temporal range:
| |
|---|---|
Egg fossil classification
| |
| Basic shell type: | †Dinosauroid-spherulitic |
| Oofamily: | †Dictyoolithidae |
| Oogenus: | †Paradictyoolithus Wanget al.,2013 |
| Oospecies | |
| |
Distribution
editBothParadictyoolithusoospecies are from theChichengshan FormationinTiantai County,Zhejiang,China.[1]This formation was determined to be 91 to 94 million years old (earlyUpper Cretaceous) byUranium–lead dating.[2]
Discovery
editPrior to 2013, descriptions of dictyoolithids were brief due to the scarcity of material. However, in 2013 the Chinese paleontologists Wang Qiang, Zhao Zi-Kui, Wang Xiao-Lin, Zhang Shu-Kang from theChinese Academy of Sciencesworking together with Jiang Yan-Gen from the Tiantai Bureau of Land and Resources of Zhejiang Province, described several new dictyoolithid specimens, including both oospecies ofParadictyoolithus.[1]
Description
editParadictyoolithuseggs are roughly spherical, measuring 10.8–13.9 cm (4.3–5.5 in) in diameter. Their eggshell is thin, measuring only 1.8 to 2.2 mm thick (compared to 2.5 to 2.8 mm in its close relative,Dictyoolithus). The shell consists of three or four layers of superimposed eggshell units. A radial cross section of the eggshell reveals the net-like (or reticulate) arrangement of the eggshell units, typical of dictyoolithid eggs. The shell units are slender and irregularly shaped.[1]
Paradictyoolithuscontains two oospecies:P. zhuangqianensisandP. xiaxishanensis.The two oospecies are primarily distinguished by their pore structure.P. zhuangqianensishas pores which all connect to each other in irregular patterns; the walls of the pores are separated into disconnected blocks.P. xiaxishanensis,on the other hand, has well-separated pore canals which look like ahoneycombin cross-section. Also,P. zhuangqianensisis slightly larger thanP. xiaxishanensis,but has a thinner shell.[1]
A fossilizedegg clutchcontaining six eggs and an egg impression reveals thatP. xiaxishanensiseggs were arranged irregularly in their nest.[1]The only known clutch ofP. zhuangqiensisis not well enough preserved to determine how the nest was organized.[1]
References
edit- ^abcdefgWang, Qiang; Zhao, Zikui; Wang, Xiaolin; Zhang, Shukang; Jiang, Yan'gen (2013)."New forms of dictyoolithids from the Tiantai Basin, Zhekiang Province of China and a parataxonomic revision of dictyoolithids"(PDF).Vertebrata PalAsiatica.51:43–54.
- ^Huaiyu He, Xiaolin Wang, Qiang Wang, Shunxing Jiang, Xin Cheng, Jialiang Zhang, Zhonghe Zhou, Zikui Zhao, Yangen Jiang, Fangming Yu, Chenglong Deng, Jinhui Yang, Rixiang Zhu (2013). "SIMS zircon U–Pb dating of the Late Cretaceous dinosaur egg-bearing red deposits in the Tiantai Basin, southeastern China."Journal of Asian Earth Sciences,62, 654-661.