| Beibeilong | |
|---|---|
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| Skeleton and line drawing of Baby Louie | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Superfamily: | †Caenagnathoidea |
| Family: | †Caenagnathidae |
| Genus: | †Beibeilong Pu et al., 2017 |
| Type species | |
| †Beibeilong sinensis Pu et al., 2017
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Beibeilong (Chinese: 贝贝龙, transl. baby dragon) is a genus of large caenagnathid dinosaurs that lived in China during the Late Cretaceous epoch, about 96 million to 88 million years ago. The genus contains a single species, Beibeilong sinensis. The species was named and described in 2017 through analysis of an embryonic skeleton (nicknamed Baby Louie) and partial nest with large eggs that were discovered in the Gaogou Formation of China (Henan Province) between 1992 and 1993.
Beibeilong was a notably large caenagnathid and among the largest oviraptorosaurs, estimated at 7.5 m (25 ft) long (extrapolated from the large embryo and eggs) with a ponderous weight of about 1.5–2 metric tons (1.7–2.2 short tons), based on comparisons with the closely related Gigantoraptor. Its jaws—in a similar fashion to most other oviraptorosaurs—were toothless and developed a horny beak (also known as rhamphotheca). Most of the anatomical traits of Beibeilong are consistent with caenagnathids rather than oviraptorids, another diverse oviraptorosaur family. Within Caenagnathidae it occupies a basal (primitive) position.
Beibeilong laid one the largest known types of dinosaur eggs, Macroelongatoolithus. Its eggs measured around 40–45 cm (16–18 in) in length and had ruggedly ornamented eggshell surfaces. The typical Macroelongatoolithus nest was ring-shaped with one or two layers of eggs, and the center was largely devoid of eggs. Giant caenagnathids (like Beibeilong) may have sat directly in the empty center to avoid egg-crushing because of their massive body dimensions. The paleoenvironments in which Beibeilong lived consisted of relatively mesic (humid, well-watered) floodplains crossed by rivers with semi-arid to tropical climates.