Parvoblongoolithus
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| Parvoblongoolithus Temporal range: | |
|---|---|
Egg fossil classification  | |
| Oofamily: | incertae sedis |
| Oogenus: | †Parvoblongoolithus |
| Oospecies | |
Parvoblongoolithus is an oogenus of fossil dinosaur egg whose small size and unusual shape suggest the possibility that it is a dwarf egg.[1]
The sole known Parvoblongoolithus jinguoensis specimen was found in the Upper Cretaceous Chichengshan Formation in Tiantai County, Zhejiang.[1]
Description
Parvoblongoolithus known 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, the P. jinguoensis has 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 of Parvoblongoolithus is two-layered. Additionally, its pore system is prolatocanaliculate, unlike the angusticanaliculate pores of bird eggs (such as Laevisoolithidae or Gobioolithidae) and its microstructures are much more similar to those of stalicoolithids, Mosaicoolithus, and Paraspheroolithus.[1]