Shixingoolithus

Shixingoolithus is an oogenus of dinosaur egg from the Cretaceous of Nanxiong, China.[1][2]

Shixingoolithus
Temporal range: Maastrichtian
Egg fossil classification
Basic shell type: †Dinosauroid-spherulitic
Oofamily: †Stalicoolithidae
Oogenus: †Shixingoolithus
Zhao et al., 1991
Oospecies
  • †S. erbeni

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.[2][3]

Paleobiology

Shixingoolithus probably represents eggs of an ornithopod dinosaur.[4][5] They are known from the Pingling Formation (from the Upper Maastrichtian), but are absent from the Yuanpu Formation, indicating that they disappeared in the last 200,000 to 300,000 years of the Cretaceous.[6][7]

Parataxonomy

Shixingoolithus was initially described as a Spheroolithid on the basis of its spherical shape, and similarities to other Spheroolithid eggs.[6][2] In 2012, Wang et al. classified Shixingoolithus in a new oofamily, Stalicoolithidae, alongside Stalicoolithus and Coralloidoolithus, because of the secondary eggshell units found in its pore canals.[8] However, these secondary shell units may in fact simply be taphonomic 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.[5]

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See also
  • List of dinosaur oogenera

References
  1. 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
  2. Carpenter, K. 1999. Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana.
  3. 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
  4. Konstantin E. Mikhailov, Emily S. Bray & Karl E. Hirsch (1996). "Parataxonomy of fossil egg remains (Veterovata): basic principles and applications". Journal of Vertebrate Paleontology. 16 (4): 763–769. doi:10.1080/02724634.1996.10011364. JSTOR 4523773.
  5. 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.
  6. 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
  7. 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.
  8. 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. 57: 3740-3747. doi: 10.1007/s11434-012-5353-2


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