Perinate and eggs of a giant caenagnathid dinosaur from the Late Cretaceous of central China

The abundance of dinosaur eggs in Upper Cretaceous strata of Henan Province, China led to the collection and export of countless such fossils. One of these specimens, recently repatriated to China, is a partial clutch of large dinosaur eggs ( Macroelongatoolithus ) with a closely associated small theropod skeleton. Here we identify the specimen as an embryo and eggs of a new, large caenagnathid oviraptorosaur, Beibeilong sinensis . This specimen is the first known association between skeletal remains and eggs of caenagnathids. Caenagnathids and oviraptorids share similarities in their eggs and clutches, although the eggs of Beibeilong are significantly larger than those of oviraptorids and indicate an adult body size comparable to a gigantic caenagnathid. An abundance of Macroelongatoolithus eggs reported from Asia and North America contrasts with the dearth of giant caenagnathid skeletal remains. Regardless, the large caenagnathid- Macroelongatoolithus association revealed here suggests these dinosaurs were relatively common during the early Late Cretaceous. The fossil dinosaur embryo ‘Baby Louie’ and associated clutch of eggs were first discovered in the early 1990s, but were not formally described. Here, the authors identify the specimen as an embryo and eggs of the new large caenagnathid oviraptorosaur, Beibeilong sinensis , from the Late Cretaceous of China.