Sphaerovum

Sphaerovum; Temporal range: Campanian-Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N
Egg fossil classification
Basic shell type:	†Dinosauroid-spherulitic
Oofamily:	†Faveoloolithidae
Oogenus:	†Sphaerovum; Mones, 1980
Oospecies
	†S. erbeni Mones, 1980 (type);

Sphaerovum is an

oogenus of dinosaur egg

that has only been discovered in South America.

History

Sphaerovum was first described, along with Tacuarembovum, in 1980 by paleontologist Álvaro Mones, following their discovery at the Asencio Formation in Uruguay. This was one of the first discoveries of fossil dinosaur eggs in South America.^[1]

Distribution

Fossils of Sphaerovum and Sphaerovum-like eggs are known from the

index fossils.^[3]

Sphaerovum eggs are 15-20 cm in diameter, with a shell between 4.2 and 5.5 mm thick. The ornamentation is compactituberculate, i.e. the eggshell is covered with dome-like nodes formed by the tops of the shell units.

silicified to make out its microstructure, however many specimens of South American fossil eggs showing superficial similarities to Sphaerovum have been found.^[4] These specimens are resemble other Faveoloolithids in their filispherulitic structure and a multicanaliculate pore system. Unlike Faveoloolithids, however, Sphaerovum has compactituberculate ornamentation more similar to Megaloolithids.^[3]^[5] The high density of pores on the eggshell surface suggests that these eggs were laid in a humid environment.^[3]

At the Mercedes Formation, Sphaerovum-like eggs were found in large, closely packed groups indicating that they were buried in a shallow pit.^[6]

Classification

Due to their poor preservation, classification of Sphaerovum has proven difficult.^[4]

Parataxonomy

The

oofamily difficult.^[6]^[4] However, other specimens which have strong superficial resemblance to Sphaerovum have been found in Uruguay and Argentina. These specimens show morphology similar to members of Faveoloolithidae, supporting the referral of Sphaerovum to that oofamily.^[2]^[3] However, it is occasionally considered to be a Megaloolithid^[7] on the basis of its ornamentation.^[8]

Parentage

It is unknown what kind of dinosaur laid Sphaerovum eggs because embryonic remains have not been found. However, they have long been considered to be the eggs of

Saltasaurid titanosaur at the Guichón Formation in Uruguay.^[2]

References

^ ^a ^b Mones, A. (1980) "Nuevos elementos de la paleoherpetofauna del Uruguay (Crocodilia y Dinosauria)." Actas II Congreso Argentino de Paleontologia y Bioestratigrafia y I Congreso Latinoamericano, Buenos Aires 1:265-277 (in Spanish)
^ ^a ^b ^c ^d Soto, M., Perea, D., and Cambiaso, A.V. (2012) "First sauropod (Dinosauria: Saurischia) remains from the Guichón Formation, Late Cretaceous of Uruguay" Journal of South American Earth Sciences 33(1):68-79. DOI: 10.1016/j.jsames.2011.08.003
^ ^a ^b ^c ^d Casadío, S., Manera, T., Parras, A., & Montalvo, C. I. (2002). "Dinosaur eggs (Faveloolithidae) from the Upper Cretaceous of the Colorado Basin, La Pampa Province, Argentina". Ameghiniana, 39(3), 285-293.
^ ^a ^b ^c Simón, M.E., (2006) "Cáscaras de huevos de dinosaurios de la Formación Allen (Campaniano e Maastrichtiano), en Salitral Moreno, provincia de Río Negro, Argentina." Ameghiniana 43: 513e528. [1]
^ Carpenter, K. (1999) Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana. p. 144
^ ^a ^b Faccio, G. (1994). "Dinosaurian eggs from the Upper Cretaceous of Uruguay." in Dinosaur eggs and babies, Edited by Kenneth Carpenter, Karl F. Hirsch, John R. Cambridge University Press. pp. 47-55.
^ Carpenter, K. (1999) Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana. p. 272
^ Batista, A. (2012). "Análisis morfológico y sistemático de Tacuarembovum oblongum Mones 1980 y otras ooformas similares (Dinosauria), cretácico tardío? de Uruguay: implicancias." Graduate Thesis for Universidad de la República (Uruguay).

[Mones_1980-1] Mones, A. (1980) "Nuevos elementos de la paleoherpetofauna del Uruguay (Crocodilia y Dinosauria)." Actas II Congreso Argentino de Paleontologia y Bioestratigrafia y I Congreso Latinoamericano, Buenos Aires 1:265-277 (in Spanish)

[Soto_et_al_2012-2] Soto, M., Perea, D., and Cambiaso, A.V. (2012) "First sauropod (Dinosauria: Saurischia) remains from the Guichón Formation, Late Cretaceous of Uruguay" Journal of South American Earth Sciences 33(1):68-79. DOI: 10.1016/j.jsames.2011.08.003

[Casadio_2002-3] Casadío, S., Manera, T., Parras, A., & Montalvo, C. I. (2002). "Dinosaur eggs (Faveloolithidae) from the Upper Cretaceous of the Colorado Basin, La Pampa Province, Argentina". Ameghiniana, 39(3), 285-293.

[Simon_2006-4] Simón, M.E., (2006) "Cáscaras de huevos de dinosaurios de la Formación Allen (Campaniano e Maastrichtiano), en Salitral Moreno, provincia de Río Negro, Argentina." Ameghiniana 43: 513e528. [1]

[Carpenter_1999_(2)-5] Carpenter, K. (1999) Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana. p. 144

[Faccio_1994-6] Faccio, G. (1994). "Dinosaurian eggs from the Upper Cretaceous of Uruguay." in Dinosaur eggs and babies, Edited by Kenneth Carpenter, Karl F. Hirsch, John R. Cambridge University Press. pp. 47-55.

[Carpenter_1999-7] Carpenter, K. (1999) Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana. p. 272

[Batista_2012-8] Batista, A. (2012). "Análisis morfológico y sistemático de Tacuarembovum oblongum Mones 1980 y otras ooformas similares (Dinosauria), cretácico tardío? de Uruguay: implicancias." Graduate Thesis for Universidad de la República (Uruguay).

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