Tubercuoolithusis anoogenusofdinosaur eggfrom the earlyCampanianofMontana.[1]
| Tubercuoolithus Temporal range:
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|---|---|
Egg fossil classification
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| Oofamily: | incertae sedis |
| Oogenus: | †Tubercuoolithus Jackson and Varricchio, 2010 |
| Oospecies | |
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Distribution
editTubercuoolithusis so far known only from theTwo Medicine Formationin Montana, which is dated to the Campanian. The fossils were found inTeton County,at a locality dated to 80 million years old.[1]
Discovery
editFossil eggs are very common at the Two Medicine Formation, including the eggs ofTroodonandMaiasaura.However, until2010no eggs were known from the lower half of that formation. Then, two paleontologists at theUniversity of Montana,Frankie D. Jackson and David J. Varricchio, discovered a fossil egg site atSevenmile Hillnear the base of the formation. These discoveries includedTubercuoolithus,and constituted the oldest fossil eggs known from the Two Medicine.[1]
Description
editTubercuoolithusis similar to theMongolianelongatoolithidsin that its eggshell is composed of calcite and has two layers, a mammillary layer and a cryptoprismatic layer. However, it has quite distinctive ornamentation; the outer surface ofTubercuoolithus's eggshell is covered with domed nodes, arranged in long wavelike patterns (anastomotuberculate)[2]or irregular chains (ramotuberculate).[2]The eggshell thickness (including ornamentation) ranges between 831 μm and 1186 μm. The cryptoprismatic layer is roughly three times thicker than the mammillary layer. The pores are thin and straight.[1]
Because it is known only from fragments, the size and shape of a completeTubercuoolithusegg are unknown.[1]
Classification
editIt is uncertain whichoofamilyTubercuoolithusshould be classified in. It is similar in microstructure to Elongatoolithidae, but different in ornamentation. Its ornamentation is similar to that ofMontanoolithus.[1]
References
edit- ^abcdefJackson, Frankie; Varricchio, David (2010). "Fossil eggs and eggshell from the lowermost Two Medicine Formation of western Montana, Sevenmile Hill locality".Journal of Vertebrate Paleontology.30(4): 1142–1156.doi:10.1080/02724634.2010.483537.S2CID129461257.
- ^abCarpenter, Kenneth (1999). Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past), Indiana University Press;ISBN0-253-33497-7.p. 144