Sphaerovumis anoogenusofdinosaur eggthat has only been discovered in South America.
| Sphaerovum Temporal range:
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|---|---|
Egg fossil classification
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| Basic shell type: | †Dinosauroid-spherulitic |
| Oofamily: | †Faveoloolithidae |
| Oogenus: | †Sphaerovum Mones,1980 |
| Oospecies | |
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History
editSphaerovumwas first described, along withTacuarembovum,in1980by paleontologistÁlvaro Mones,following their discovery at theAsencio Formationin Uruguay. This was one of the first discoveries of fossil dinosaur eggs in South America.[1]
Distribution
editFossils ofSphaerovumandSphaerovum-like eggs are known from thePuerto Yeruá,AllenandColorado Formationsin Argentina and theGuichónandAsencio Formationsof Uruguay.[2]They are always found inCampanian- orMaastrichtian-aged rocks, leading to their use asindex fossils.[3]
Description
editSphaerovumeggs 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.[2][1]The type specimen ofSphaerovum erbeniis toosilicifiedto make out its microstructure, however many specimens of South American fossil eggs showing superficial similarities toSphaerovumhave been found.[4]These specimens are resemble otherFaveoloolithidsin their filispherulitic structure and a multicanaliculate pore system. Unlike Faveoloolithids, however,Sphaerovumhas compactituberculate ornamentation more similar toMegaloolithids.[3][5]The high density of pores on the eggshell surface suggests that these eggs were laid in a humid environment.[3]
At theMercedes Formation,Sphaerovum-like eggs were found in large, closely packed groups indicating that they were buried in a shallow pit.[6]
Classification
editDue to their poor preservation, classification ofSphaerovumhas proven difficult.[4]
Parataxonomy
editTheholotypespecimen ofSphaerovumis heavilysilicified,making the eggshell structure unrecognizable and assignment to anyoofamilydifficult.[6][4]However, other specimens which have strong superficial resemblance toSphaerovumhave been found in Uruguay and Argentina. These specimens show morphology similar to members ofFaveoloolithidae,supporting the referral ofSphaerovumto that oofamily.[2][3]However, it is occasionally considered to be aMegaloolithid[7]on the basis of its ornamentation.[8]
Parentage
editIt is unknown what kind of dinosaur laidSphaerovumeggs because embryonic remains have not been found. However, they have long been considered to be the eggs oftitanosaurs.This would be consistent with the fact that titanosaurs were extremely common in theUpper Cretaceousof South America. Also, some eggshell fragments tentatively assigned toSphaerovumwere found loosely associated with the remains of aSaltasauridtitanosaur at theGuichón Formationin Uruguay.[2]
See also
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References
edit- ^abMones, 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 Aires1:265-277 (in Spanish)
- ^abcdSoto, 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 Sciences33(1):68-79. DOI: 10.1016/j.jsames.2011.08.003
- ^abcdCasadío, 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.
- ^abcSimón, M.E., (2006) "Cáscaras de huevos de dinosaurios de la Formación Allen (Campaniano e Maastrichtiano), en Salitral Moreno, provincia de Río Negro, Argentina."Ameghiniana43: 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
- ^abFaccio, G. (1994). "Dinosaurian eggs from the Upper Cretaceous of Uruguay." inDinosaur 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).