page_title: Macroelongatoolithus
section_title: Paleobiology
hierarchical_section_title: Macroelongatoolithus / Paleobiology
caption_attribution_description: Macroelongatoolithus egg assigned to Tarbosaurus, Naturhistorisches Museum Wien
context_page_description: Macroelongatoolithus is an oogenus of large, fossil theropod eggs. They are known from Asia and from North America.
context_section_description: While they are occasionally considered to be the eggs of tyrannosaurs (like Tarbosaurus) on the basis of their huge size, most evidence suggests they are eggs of gigantic oviraptorids (like Gigantoraptor). The egg shape and structure closely resembles the eggs of Citipati, and many lines of fossil evidence (including association, embryonic remains, and eggs found within parents) link other elongatoolithids to oviraptorids. Also, a Macroelongatoolithus specimen named "Baby Louie" consisting of four fossil eggs and associated perinatal remains was discovered  in the Zoumagang Formation. Characteristics of the jawbone of this specimen resemble oviraptorids.
  The presence of Macroelongatoolithus in the United States indicates that there was likely a giant oviraptorid present in Cretaceous North America. Also, the fact that they have been found in both Asia and America is evidence of an Albian-Cenomanian interchange of fauna between the two continents.
  The gas conductance of the eggshells indicate that Macroelongatoolithus nests were buried in vegetation or sediments. Like other elongatoolithids, Macroelongatoolithus eggs are laid in pairs because the parents had two functional oviducts and thus laid two eggs simultaneously. The nests have unusually large volume of eggs compared to the body size of the parents, which could mean that multiple females would contribute to a single nest. Association of other oviraptorids with their eggs suggests extensive parental care was typical for elongatoolithids.
caption: Macroelongatoolithus eggs in the Naturhistorisches Museum Wien
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