''Shixingoolithus'' 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 ...

of Nanxiong,

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 ...

.Z. Zhao, J. Ye, H. Li, Z. Zhao, and Z. Yan. 1991. Extinction of the dinosaurs across the Cretaceous-Tertiary boundary in Nanxiong Basin, Guangdong Province. Vertebrata PalAsiatica 29(1):1-20Carpenter, K. 1999. Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana.

Description

''Shixingoolithus'' eggs are nearly spherical, and about 12 cm in diameter, with a shell thickness of 2.3-2.6 mm. The shell is made up of tall, prismatic units, and has narrow, irregular pore canals. Its cone layer (mammillae) is approximately a fourth of the shell thickness.Zhao, Z.K. (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. In K. Carpenter, K. F. Hirsch, and J. R. Horner (eds.), Dinosaur Eggs and Babies, Cambridge University Press, Cambridge 184-203

Paleobiology

''Shixingoolithus'' probably represents eggs of an

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...

dinosaur.Moreno-Azanza, M., J.I. Canudo, and J.M. Gasca. (2014). "Spheroolithid eggshells in the Lower Cretaceous of Europe. Implications for eggshell evolution in ornithischian dinosaurs." ''Cretaceous Research'' 51:75-87. They are known from the Pingling Formation and Chishan Formation (from the Upper

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

), but are absent from the Yuanpu Formation, indicating that they disappeared in the last 200,000 to 300,000 years of the Cretaceous.Zhao, Z.-k., X. Mao, Z. Chai, G. Yang, P. Kong, M. Ebihara, and Z.-h. Zhao. (2002). "A possible causal relationship between extinction of dinosaurs and K/T iridium enrichment in the Nanxiong Basin, South China: evidence from dinosaur eggshells. ''Palaeogeography, Palaeoclimatology, Palaeoecology 178:1-17.

Parataxonomy

''Shixingoolithus'' was initially described as a member of the

Spheroolithidae Spheroolithidae is an oofamily of dinosaur eggs. It contains ''Guegoolithus'', ''Spheroolithus'', and '' Paraspheroolithus''. Like modern birds, the eggshell membrane formed before the calcareous part of the shell.Z.-K. Zhao. (1994) "Dinosaur egg ...

on the basis of its spherical shape, and similarities to other spheroolithid eggs.Z. Zhao, J. Ye, H. Li, Z. Zhao, and Z. Yan. 1991.
Extinction of the dinosaurs across the Cretaceous-Tertiary boundary in Nanxiong Basin, Guangdong Province
" ''Vertebrata PalAsiatica'' 29(1):1-20 In 2012, Wang et al. classified ''Shixingoolithus'' in a new oofamily,

Stalicoolithidae Stalicoolithidae is an oofamily of fossil eggs.Wang Q, Wang X L, Zhao Z K, and Jiang Y G. (2012).A new oofamily of dinosaur egg from the Upper Cretaceous of Tiantai Basin, Zhejiang Province, and its mechanism of eggshell formation Chinese Scienc ...

, alongside ''

Stalicoolithus ''Stalicoolithus'' is an oogenus of dinosaur egg from the Sanshui and Chichengshan Formations of the Tiantai Basin in Zhejiang Province. It is known from a single, complete fossil egg, notable for its spherical shape.Wang Q, Wang X L, Zhao Z K, ...

'' and ''

Coralloidoolithus ''Coralloidoolithus'' is an oogenus of dinosaur egg from the Tiantai Basin in Zhejiang Province, containing a single known oospecies ''C. shizuiwanensis''. Formerly, it was classified in the oogenus '' Paraspheroolithus''; however, it was consi ...

'', because of the secondary eggshell units found in its pore canals.Wang Q, Wang X L, Zhao Z K, and Jiang Y G. (2012).
A new oofamily of dinosaur egg from the Upper Cretaceous of Tiantai Basin, Zhejiang Province, and its mechanism of eggshell formation

Chinese Science Bulletin ''Science Bulletin'' () is a multidisciplinary scientific journal co-sponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China. It is published by Elsevier on behalf of Science in China Press and focuses on ...

. 57: 3740-3747. doi: 10.1007/s11434-012-5353-2 However, these secondary shell units may in fact simply be

taphonomic Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov t ...

artifacts. It has also been speculated to in fact be a dendroolithid, but a more complete description must be made before its classification can be resolved.Moreno-Azanza, M., J.I. Canudo, and J.M. Gasca. (2014). "Spheroolithid eggshells in the Lower Cretaceous of Europe. Implications for eggshell evolution in ornithischian dinosaurs." ''Cretaceous Research'' 51:75-87.

References

Dinosaur reproduction Fossil parataxa described in 1991 Stalicoolithids {{eggshell-stub

Description

Paleobiology

Parataxonomy

See also

References