Parvoblongoolithusis anoogenusof fossildinosaur eggwhose small size and unusual shape suggest the possibility that it is adwarf egg.[1]
| Parvoblongoolithus Temporal range:
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|---|---|
Egg fossil classification
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| Oofamily: | incertae sedis |
| Oogenus: | †Parvoblongoolithus |
| Oospecies | |
Distribution
editThe sole knownParvoblongoolithus jinguoensisspecimen was found in theUpper CretaceousChichengshan FormationinTiantai County,Zhejiang.[1]
Description
editParvoblongoolithusknown from only a single specimen. It is relatively small (measuring 45.5 mm (1.79 in) long by 34.4 mm (1.35 in) wide) with an asymmetrical shape, similar to modern bird eggs. The eggshell is 1.12 mm thick, with the barrel-shaped cones of the mammillary layer making up one-fifth of the total eggshell thickness. The pore system is prolatocanaliculate, meaning the pores vary in width along their length. The pore canals are thick and irregularly shaped. The outer surface of the eggshell is smooth.[1]
Despite having a bird-like shape and size, theP. jinguoensishas a very different microstructure, which bears a closer resemblance to non-avian dinosaur eggs than bird eggs.[2]Most significantly, all known Cretaceous bird eggs have a three-layered eggshell, whereas the eggshell ofParvoblongoolithusis two-layered. Additionally, its pore system is prolatocanaliculate, unlike the angusticanaliculate pores of bird eggs (such asLaevisoolithidaeorGobioolithidae) and its microstructures are much more similar to those ofstalicoolithids,Mosaicoolithus,andParaspheroolithus.[1]
Palaeobiology
editSince no skeletal remains were associated with its remains, the parentage ofParvoblongoolithusis unknown. However, its microstructure suggests it was laid by some kind of non-aviandinosaur,related to the parents of Stalicoolithidae,Paraspheroolithus,orMosaicoolithus.[1]
Parvoblongoolithusis remarkable for having an extremely thick shell (as thick as the shell oftitanosaureggs) despite being significantly smaller than its close relatives. This would have made it much more difficult for a baby dinosaur to break out of the egg without parental assistance. It is possible thatParvoblongoolithusactually represents a fossildwarf egg,a type of deformity occasionally observed in modern birds when a disturbance of the oviducts causes them to form a small, deformed egg. This would explain both the thick eggshell and unique shape ofP. jinguoensis.[1]
Parataxonomy
editParvoblongoolithushas not been classified into any oofamily. The eggshell resembles thespherulitic type,but it lacks the radial-tabular ultrastructure.[1]It is closely related toParaspheroolithus,Mosaicoolithus,and stalicoolithids.[1]
References
edit- ^abcdefghZhang, Shuakang; Jin, Xingsheng; O'Conner, Jingmai K.; Wang, Min; Xie, Junfang (2015). "A new egg with avian egg shape from the Upper Cretaceous of Zhejiang Province, China".Historical Biology.27(5): 595–602.doi:10.1080/08912963.2014.902451.S2CID85209671.
- ^"New dinosaur egg with avian egg shape discovered from the Upper Cretaceous of Zhejiang Province, China".phys.org. 28 May 2014.Retrieved27 March2016.