''Undulatoolithus'' is an

oogenus Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of t ...

of Chinese fossil

dinosaur egg Dinosaur eggs are the organic vessels in which a dinosaur embryo develops. When the first scientifically documented remains of non-avian dinosaurs were being described in England during the 1820s, it was presumed that dinosaurs had laid eggs be ...

belonging to

Elongatoolithidae Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs (with the exception of the avian ''Ornitholithus''). They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and b ...

. It is very similar to ''

Macroolithus ''Macroolithus'' is an oogenus (fossil-egg genus) of dinosaur egg belonging to the oofamily Elongatoolithidae. The Type (biology), type oospecies, ''M. rugustus'', was originally described under the now-defunct oogenus name ''Oolithes''. Three o ...

'', but has different ornamentation. Like other elongatoolithids, it was probably laid by

oviraptorosaurs Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or w ...

.Q. Wang, Z. Zhao, X. Wang, N. Li, and S. Zou. (2013
A new form of Elongatoolithidae, Undulatoolithus pengi oogen. et oosp. nov. from Pingxiang, Jiangxi, China.
''

Zootaxa ''Zootaxa'' is a peer-reviewed scientific mega journal for animal taxonomists. It is published by Magnolia Press ''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view ...

'' 3746(1):194-200

Distribution

''Undulatoolithus'' is found in the

Zhoutian Formation Zhoutian or Zhou Tian may refer to: * ''Zhoutian'' (周田 zhōu-tián), a dialect of Shaozhou Tuhua, a Chinese language * ''Zhoutian'' (周田镇 zhōu-tián-zhèn), a town in Huilai County, Jieyang, Guangdong, China; see List of township-level div ...

, in the

Pingxiang Basin Pingxiang () is a medium-sized prefecture-level city located in western Jiangxi province, People's Republic of China. Geography and climate Pingxiang is a city situated near the border of Jiangxi with Hunan province. Approximately 110 kilometer ...

Jiangxi Jiangxi (; ; formerly romanized as Kiangsi or Chianghsi) is a landlocked province in the east of the People's Republic of China. Its major cities include Nanchang and Jiujiang. Spanning from the banks of the Yangtze river in the north into h ...

. It is dated to 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'', ...

History

The Pingxiang Basin, in

, was first excavated for fossils in

2002 File:2002 Events Collage.png, From left, clockwise: The 2002 Winter Olympics are held in Salt Lake City; Queen Elizabeth The Queen Mother and her daughter Princess Margaret, Countess of Snowdon die; East Timor gains independence from Indonesia and ...

. Several fossil eggs, egg clutches, and dinosaur bones were discovered, including those later described as ''Undulatoolithus'' in 2013 by Chinese paleontologists Wang Qiang,

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 ...

Wang Xiaolin Wang may refer to: Names * Wang (surname) (王), a common Chinese surname * Wāng (汪), a less common Chinese surname * Titles in Chinese nobility * A title in Korean nobility * A title in Mongolian nobility Places * Wang River in Thailand ...

Li Ning Li Ning (born March 10, 1963 in Liuzhou, Guangxi) is a Chinese retired gymnast, billionaire entrepreneur, and the founder of the eponymous sportswear company Li-Ning. Gymnastics career Li started training at the age of eight and was sele ...

, and

Zou Songlin Zou or ZOU may refer to: Places * Zou (state), Chinese state that existed during the Zhou Dynasty * Zou, Ivory Coast, town and sub-prefecture in Ivory Coast * Zou Department of Benin * Zou River of Benin * Zoucheng, formerly Zou County, in Jining, ...

. The type and only known specimen of ''Undulatoolithus'' was the first

elongatoolithid Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs (with the exception of the avian ''Ornitholithus''). They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and b ...

egg clutch discovered in the Pingxiang basin.

Description

Like all elongatoolithids, ''Undulatoolithus'' eggs are elongated and asymmetrical, and have a two-layered eggshell (consisting of the cone layer and the columnar layer). The only known ''Undulatoolithus'' specimen is a nest consisting of five complete eggs and three partial eggs. The eggs are paired and arranged radially, similar to other elongatoolithids. They average about long and across. The eggshell is nearly 1.5 mm thick, including ornamentation. The boundary between the two eggshell layers in ''Undulatoolithus'' is gradual. The cone layer is relatively thin, ranging from one fourth to one eighth the width of the columnar layer. The most notable characteristic of ''Undulatoolithus'' is the ornamentation on the surface of the eggshell. Like most elongatoolithids it is covered with nodes and ridges, but they are much more prominent than other oospecies and make up nearly half the total eggshell thickness.

Paleobiology

''Undulatoolithus'' has not been associated with embryos or skeletal remains, so the identity of the egg-laying dinosaur is unknown. However, all embryos or adult skeletons that have been associated with other elongatoolithids are

oviraptorid Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between on ...

s. Like other elongatoolithids, ''Undulatoolithus'' probably received intensive parental care.Simon, D. J. (2014).
Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications.
(Master's thesis,

Montana State University Montana State University (MSU) is a public land-grant research university in Bozeman, Montana. It is the state's largest university. MSU offers baccalaureate degrees in 60 fields, master's degrees in 68 fields, and doctoral degrees in 35 fiel ...

, Bozeman). p. 19-22

Parataxonomy

''Undulatoolithus'' is classified as within Elongatoolithidae. It is very similar to ''

,'' but has much more prominent eggshell ornamentation.

References

{{Taxonbar, from=Q22287019 Fossil parataxa described in 2013 Egg fossils Fossils of China Late Cretaceous reptiles of Asia Elongatoolithids