''Dictyoolithus'' is an oogenus of dinosaur egg from the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. It is notable for having over five superimposed layers of eggshell units. Possibly, it was laid by

megalosauroid Megalosauroidea (meaning 'great/big lizard forms') is a superfamily (or clade) of tetanuran theropod dinosaurs that lived from the Middle Jurassic to the Late Cretaceous period. The group is defined as ''Megalosaurus bucklandii'' and all taxa sha ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

Distribution

''Dictyoolithus'' is known from Hongpo, a town in Xixia County,

Henan Henan (; or ; ; alternatively Honan) is a landlocked province of China, in the central part of the country. Henan is often referred to as Zhongyuan or Zhongzhou (), which literally means "central plain" or "midland", although the name is al ...

. This is in the

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eight ...

Sigou Formation. It has also been discovered in

Lishui Lishui (; Lishuinese: ''li⁶ syu³'' ) is a prefecture-level city in the southwest of Zhejiang province, People's Republic of China. It borders Quzhou, Jinhua and Taizhou to the north, Wenzhou to the southeast, and the province of Fujian to ...

Zhejiang Zhejiang ( or , ; , also romanized as Chekiang) is an eastern, coastal province of the People's Republic of China. Its capital and largest city is Hangzhou, and other notable cities include Ningbo and Wenzhou. Zhejiang is bordered by Jiang ...

, in the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

Chichengshan Formation.

History

''Dictyoolithus'' was first discovered and described in

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by Chinese paleontologist and pioneer of fossil eggshell classification,

Zhao Zikui Zhao may refer to: * Zhao (surname) (赵), a Chinese surname ** commonly spelled Chao in Taiwan or up until the early 20th century in other regions ** Chiu, from the Cantonese pronunciation ** Cho (Korean surname), represent the Hanja 趙 (Chine ...

. He named two oopsecies: ''D. hongpoensis'' and ''D. neixiangensis'' (now '' Protodictyoolithus neixiangensis''). However, since excavations were still going on at the time, his description was brief.Z.-K. Zhao. (1994) "Dinosaur eggs in China:On the structure and evolution of eggshells." In K. Carpenter, K. F. Hirsch, and J. R. Horner (eds.), ''Dinosaur Eggs and Babies,'' Cambridge University Press, Cambridge. Cambridge. pp. 184–203. In

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, a third oospecies was named, ''D. jiangi'',Liu, J., & Zhao, Z. (2004). A new oospecies of the dinosaur eggs (Dictyoolithus) from Laiyang, Shandong Province. Vertebrata Pal Asiatica, 42(2), 166–170. followed by a fourth, ''D. gonzhulingensis'' in 2006.Wang Qiang, Zan Shu-Qin, Jin Li-Yong, Chen Jun (2006). A New Oospecies, ''Dictyoolithus Gongzhulingensis'', from the Early Cretaceous Quantou Formation in the Central Jilin Province. ''Journal of Jilin University (Earth Science Edition)'', 36(2): 153–157. However, in

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Chinese paleontologists Wang Qiang, Zhao Zikui, Wang Xiaolin, Zhang Shukang, and Jiang Yan'gen did a reanalysis of the entire oofamily Dictyoolithidae, and split the oogenus ''Dictyoolithus'' into two, classifying ''"D." neixiangensis'' and ''"D." jiangi'' within a new oogenus: '' Protodictyoolithus''. Furthermore, they moved ''"D." gonzhulingensis'' into an entirely different oofamily and oogenus, reclassifying it as a member of ''

Similifaveoloolithus ''Similifaveoloolithus'' is an oogenus of fossil dinosaur egg from the Tiantai basin in Zhejiang Province, China. It is the sole known oospecies of the oofamily Similifaveoloolithidae.Wang Qiang, Zhao Zikui, Wang Xiaolin, Zhang Shukang, and Ji ...

''.Wang Qiang, Zhao Zikui, Wang Xiaolin, Zhang Shukang, and Jiang Yan'gen. (2013)
New forms of dictyoolithids from the Tiantai Basin, Zhejiang Province of China and a parataxonomic revision of the dictyoolithids.
''Vertebrata PalAsiatica'' 51:43–54.

Description

''Dictyoolithus'' eggs are roughly spherical and measure from in diameter.Jin X.S., Jackson F.D., Varricchio D.J., Y. Azuma, and He T. (2010) "The first Dictyoolithus egg clutches from the Lishui Basin, Zhejiang Province, China." '' Journal of Vertebrate Paleontology'', 30(1): 188–195 Their eggshell is between 2.5 and 2.8 mm thick. The surface ornamentation is smooth with a grainy texture, or has very low rounded nodes. The eggshell is notable for being composed of more than five superimposed layers of eggshell units. In some specimens, found at Lishui, no superimposed layers of eggshells were found. However, it is not certain that these specimens in fact represent ''Dictyoolithus''. The eggshell units have a reticulate organization.

Paleobiology

Since no embryos or adult remains have been found with ''Dictyoolithus'' eggs, it is uncertain what kind of dinosaur laid them.Varricchio, D. J. (2011). A distinct dinosaur life history?. Historical Biology, 23(01), 91–107. Chicago A cladistic analysis in 2010 by Jin '' et al.'' found ''Dictyoolithus'' to be basal theropod eggs. Similarly, Sellés and Galobart in

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found ''Dictyoolithus'' to be basal theropods, and considered it to be the eggs of megalosauroids.Sellés, A. G., & Galobart, À. (2015). "Reassessing the endemic European Upper Cretaceous dinosaur egg Cairanoolithus." ''Historical Biology,'' (ahead-of-print), 1–14. Unlike many dinosaur eggs, the calcareous and membranous parts of ''Dictyoolithus'' eggshells probably formed simultaneously in the oviduct, as in the modern

tuatara Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...

Parataxonomy

''Dictyoolithus'' is classified in the oofamily Dictyoolithidae, alongside ''Protodictyoolithus'' and '' Paradictyoolithus''. It contains only a single oospecies: ''D. hongpoensis''. Mikhailov (1997) suggested that it may actually be a dendroolithid.

References

{{Taxonbar, from=Q5274009 Egg fossils Fossil parataxa described in 1994 Cretaceous dinosaurs of Asia Dinosaur reproduction