''Protoceratopsidovum'' 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 ...

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 bec ...

from

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

. Despite its name (which means "eggs of ''

Protoceratops ''Protoceratops'' (; ) is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 75 to 71 million years ago. The genus ''Protoceratops'' includes two species: ''P. andrewsi'' and the larger ''P. hellenik ...

''"Zelenitsky, D., and Currie, P. (2004) "A Cladistic Analysis of Theropod Ootaxa." ''Journal of Vertebrate Paleontology.'' Vol. 24, Supplement 003: Abstracts of Papers Sixty-Fourth Annual Meeting Society of Vertebrate Paleontology Adams Mark Hotel Denver, Colorado November 3–6.), it does not represent the eggs of a

protoceratopsid Protoceratopsidae is a family of basal (primitive) ceratopsians from the Late Cretaceous period. Although ceratopsians have been found all over the world, protoceratopsids are only definitively known from Cretaceous strata in Asia, with most spec ...

, but rather the eggs of

maniraptoran Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Oviraptoros ...

theropods Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ca ...

.Carpenter, K. 1999. Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana.Zelenitsky, D. K. And Therrien, F. (2008),
Phylogenetic Analysis Of Reproductive Traits Of Maniraptoran Theropods And Its Implications For Egg Parataxonomy
" ''Palaeontology'', 51: 807–816.

Description

''Protoceratopsidovum'' eggs are extremely abundant in the Djadokhta and

Barun Goyot Formation The Barun Goyot Formation (also known as Baruungoyot Formation or West Goyot Formation) is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Pro ...

s.Mikhailov, K.E. (2000). "Eggs and eggshells of dinosaurs and birds from the Cretaceous of Mongolia." ''The age of dinosaurs in Russia and Mongolia.'' Cambridge University Press, Cambridge. pp. 560–572. ''P. sincerum'' and ''P. minimum'' eggs both have a smooth surface, whereas those of ''P. fluxuosum'' have fine ornamentation around the equatorial part. The eggs are elongated and asymmetrical, with a two-layered prismatic shell generally resembling the eggs of ''

Troodon ''Troodon'' ( ; ''Troödon'' in older sources) is a wastebasket taxon and a dubious genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Late Cretaceous period (about 77 mya). It includes at leas ...

''.Moreno-Azanza, M., Canudo, J. I., & Gasca, J. M. (2014). Spheroolithid eggshells in the Lower Cretaceous of Europe. Implications for eggshell evolution in ornithischian dinosaurs. C''retaceous Research'', 51, 75–87. They were laid in pairs.

Parataxonomy

The eggs of ''Protoceratopsidovum'' are classified in the

oofamily 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 ...

Prismatoolithidae Prismatoolithidae is an oofamily of fossil eggs. They may have been laid by ornithopods or theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on ea ...

. They were originally thought to be eggs of ''

'' (hence the name) because they are extremely common at the same sites as ''Protoceratops''. However, more recent research has cast doubt on this: a

cladistic analysis Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived chara ...

2008 File:2008 Events Collage.png, From left, clockwise: Lehman Brothers went bankrupt following the Subprime mortgage crisis; Cyclone Nargis killed more than 138,000 in Myanmar; A scene from the opening ceremony of the 2008 Summer Olympics in Beijing; ...

, by Zelenitsky and Therrien, found them to be the eggs of

Palaeobiology

The shape, structure, and arrangement of eggs of ''Protoceratopsidovum'' and its relatives provide some insight into the palaeobiology of fossil eggs. Their asymmetrical shape (resembling

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

eggs) suggests that the process of egg formation was similar to that of birds. Unlike bird eggs (which are laid one at a time), ''Protoceratopsidovum'' eggs were laid in pairs because the mother would have two functioning

oviduct The oviduct in mammals, is the passageway from an ovary. In human females this is more usually known as the Fallopian tube or uterine tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, o ...

s which would both lay a single egg simultaneously, contrasting with modern birds, which have only one functional oviduct. Though no fossils of parents incubating ''Protoceratopsidovum'' eggs have been found, their identification as maniraptoran eggs would imply that they were incubated.

References

{{Taxonbar, from=Q7251908 Egg fossils Dinosaur reproduction Campanian life Cretaceous Mongolia Fossils of Mongolia Barun Goyot Formation Djadochta fauna Fossil parataxa described in 1994

Description

Parataxonomy

Palaeobiology

See also

References