[Paleontology • 2017] Beibeilong sinensis • Perinate and Eggs of A Giant Caenagnathid Dinosaur from the Late Cretaceous of central China

 Beibeilong sinensis

Pu, Zelenitsky, Lü, Currie, Carpenter, Xu, Koppelhus, Jia, Xiao, Chuang, Li, Kundrát & Shen, 2017DOI: 10.1038/NComms14952

Abstract

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.

Systematic palaeontology 

Theropoda Marsh 1881

Oviraptorosauria Barsbold 1976

Caenagnathidae Sternberg 1940

 Beibeilong sinensis gen. et sp. nov.

Figure 1: Photograph of eggs and skeleton of Beibeilong sinensis (HGM 41HIII1219).
Right image shows schematic overlay of approximate locations of individual eggs. Eggs 1 through 4 are in an upper layer just beneath the skeleton, whereas Egg 5 is in a lower layer of the block. Scale bar is in centimetre.

The fossil (left) and a digital overlay (right) shows where the eggs were placed before they broke and fossilized. Notice the skeleton of the embryo next to the ruler. 

Holotype. HGM 41HIII1219, a small, semi-articulated skeleton (‘Baby Louie’) associated with a partial nest of 6–8 eggs. The specimen is housed in the Henan Geological Museum (HGM), Zhengzhou, China.

the curled embryo of Beibelong on top of the eggs (eggshell is dark grey in color).

Photograph by Darla Zelenitsky, University of Calgary 

An illustration of Beibeilong embryo and egg fossil, with reconstruction of skeleton and fleshed-out models to the right. 

Figure 5: Reconstruction of Beibeilong embryo in ovo.
The drawing shows the approximate size of the Beibeilong embryo inside a Macroelongatoolithus egg.

drawn by Vladimir Rimbala

 Diagnosis. A large caenagnathid that has the following unique suite of features: antorbital fossa demarcated by sharply defined alveolar and dorsoposterior trending ridges, posterodorsal margin of lacrimal overlapped by frontal, subantorbital portion of the maxilla is inset medially, pronounced retroarticular process with a distinct concave posterior facet (roughly as tall at the base as it is wide), preacetabular process of the ilium longer than postacetabular process, posterior end of the postacetabular process truncated or broadly rounded, and accessory trochanter of the femur weakly developed.

 Locality and horizon. The specimen was discovered at a latitude/longitude of 33°15′30″ N, 111°43′41″ E in Heimaogou, 2 km east of Zhaoying Village, Yangcheng Township, Xixia County, Henan Province, People’s Republic of China. The locality is in the Upper Cretaceous Gaogou Formation (Cenomanian—Turonian)

Etymology. The generic name is derived from Chinese Pinyin ‘beibei’ for baby and ‘long’ for dragon. The specific name is derived from Latin referring to its discovery in China.

Beibeilong sinensis lived about 90 million years ago, during the Cretaceous period. The adults of this species were enormous, measuring up to 8 meters long from the snout to the end of the tail, and weighing up to 3,000 kilograms when fully grown at age 11.

Illustration: Zhao Chuang  

  

Hanyong Pu, Darla K. Zelenitsky, Junchang Lü, Philip J. Currie, Kenneth Carpenter, Li Xu, Eva B. Koppelhus, Songhai Jia, Le Xiao, Huali Chuang, Tianran Li, Martin Kundrát and Caizhi Shen. 2017. Perinate and Eggs of A Giant Caenagnathid Dinosaur from the Late Cretaceous of central China.  Nature Communications. 8, Article number: 14952. DOI: 10.1038/ncomms14952

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