Sunday, June 19, 2016

[Paleontology • 2013] Yulong mini • Chicken-sized Oviraptorid Dinosaurs from central China and their Ontogenetic Implications


Yulong mini  
Lü, Currie, Xu,Zhang, Pu & Jia, 2013


Abstract
Oviraptorids are a group of specialized non-avian theropod dinosaurs that were generally one to 8 m in body length. New specimens of baby oviraptorids from the Late Cretaceous of Henan Province are some of the smallest individuals known. They include diagnostic characters such as the relative position of the antorbital fenestra and the external naris, distinct opening in the premaxilla anteroventral to the external naris, antorbital fossa partly bordered by premaxilla posterodorsally, lacrimal process of premaxilla does not contact the anterodorsal process of the lacrimal, parietal almost as long as frontal; in dorsal view, posterior margin forms a straight line between the postzygapophyses in each of the fourth and fifth cervicals; femur longer than ilium. They also elucidate the ontogenetic processes of oviraptorids, including fusion of cranial elements and changes in relative body proportions. Hind limb proportions are constant in oviraptorids, regardless of absolute body size or ontogenetic stage. This suggests a sedentary lifestyle that did not involve the pursuit of similar-sized prey. The functional implications for bite force and therefore dietary preferences are better understood through the study of such small animals. The comparison of the measurements of 115 skeletons indicates that oviraptorids maintain their hind limb proportions regardless of ontogenetic stage or absolute size, which is a pattern seen more commonly in herbivores than in carnivores. This may weakly support the hypothesis that oviraptorids are herbivores rather than active carnivores.

Keywords: Baby oviraptorid, Yulong, Late Cretaceous, Henan Province


Fig. 1: a Photograph and b line drawings of  Yulong mini  (HGM 41HIII-0107).
cv cervical vertebrae, d dentary, fe femur, fi fibula, h humerus, il ilium, mt metatarsals, o orbital, po postorbital, rd radius, ul ulna, ti tibia.    DOI:10.1007/s00114-012-1007-0

Systematic paleontology

Oviraptorosauria Barsbold 1976
Oviraptoridae Barsbold 1976

Yulong mini gen. et sp. nov.

Etymology: Generic name derived from “Yu”, the abbreviated name for Henan Province, and “long” from Chinese, meaning dragon. The specific name refers to the small size of known specimens.

Holotype: Henan Geological Museum HGM 41HIII-0107, an exceptionally well-preserved skeleton with a skull and lower jaws.

Referred specimens: HGM 41HIII-0108, nearly complete skull with lower jaws; HGM 41HIII-0109, well-preserved skull, lower jaws and partial postcranial skeleton; HGM 41HIII-0110, partial skull, lower jaws and a few cervical centra; HGM 41HIII-0111, one complete left ilium.

Type locality and horizon: Qiupa Town, Luanchuan County, Henan Province; Upper Cretaceous, Qiupa Formation (Bureau of Geology and Mineral Resources of Henan Province 1989; Lü et al. 2007).

Diagnosis: Oviraptorid with the following characters: posterodorsal corner of the antorbital fenestra and the anteroventral corner of the external naris at the same level (similar conditions in Citipati osmolskae [MPC-D 100/978] and Citipati sp. [MPC-D 100/42]); distinct opening in the premaxilla anteroventral to the external naris; antorbital fossa partly bordered by premaxilla anterodorsally; lacrimal process of premaxilla does not contact the anterodorsal process of the lacrimal; parietal almost as long as frontal; in dorsal view, posterior margin forms a straight line between the postzygapophyses in each of the fourth and fifth cervicals; femur longer than ilium.



Lü, J.; Currie, P. J.; Xu, L.; Zhang, X.; Pu, H.; Jia, S. 2013. Chicken-sized Oviraptorid Dinosaurs from central China and their Ontogenetic Implications. Naturwissenschaften. DOI:10.1007/s00114-012-1007-0



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