''Protoceratopsidovum'' is an
oogenus of
dinosaur egg 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 millio ...
. Despite its name (which means "eggs of ''
Protoceratops''"
[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, but rather the eggs of
maniraptoran theropods.
[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 ...
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 least ...
''.
[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 Prismatoolithidae.
They were originally thought to be eggs of ''
Protoceratops'' (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 ch ...
in
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
maniraptorans.
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 lightweig ...
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, ...
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.
See also
*
List of dinosaur oogenera
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