Friday, April 17, 2020

[Paleontology • 2019] Xingtianosaurus ganqi • A New Caudipterid from the Lower Cretaceous of China with Information on the Evolution of the Manus of Oviraptorosauria

Xingtianosaurus ganqi
Qiu, Wang, Wang, Li, Zhang & Ma, 2019

Illustration: Dmitry Tokalchik

Caudipteridae is a basal clade of Oviraptorosauria, all known species from the Early Cretaceous Jehol Biota of northeastern China. They were one of the first feathered dinosaur groups discovered, and possessed avian-like pennaceous remiges and rectrices. Their discovery provided significant information on early oviraptorosaurian evolution and the origins of birds and feathers. Here we describe a new caudipterid species Xingtianosaurus ganqi gen. et sp. nov. from the Lower Cretaceous Yixian Formation of Liaoning Province, China. This new taxon differs from other caudipterids by a small pleurocoel close to the dorsal edge of the lateral surface of the dorsal vertebrate centrum, a humerus longer than the scapula, a proportionally long ulna, a relatively small radiale angle, and a relatively short metacarpal I. The phylogenetic results shows X. ganqi is an early diverging caudipterid. It exhibits a mosaic morphology, providing new morphological information on early manual evolution of Oviraptorosauria, and giving new light on the evolution of radiale angle among Coelurosauria.

Figure 1: The holotype of Xingtianosaurus ganqi gen. et sp. nov. (IVPP V13390).
(a) Photograph. (b) line drawing.
Scale bar: 100 mm. cdv, caudal vertebrate; dv, dorsal vertebrate; fe.l left femur; fe.r, right femur; fi.l left fibula; fi.r, right fibula; gas, gastralia; hu.l left humerus; hu.r, right humerus; il.l, left ilium; is.l left ischium; mcI.l left metacarpal I; mcI.r, right metacarpal I; mcII.l left metacarpal II; mcII.r, right metacarpal II; mcIII.l left metacarpal III; mcIII.r, right metacarpal III; mtI.l left metatarsal I; mtI.r, right metatarsal I; mtII.l left metatarsal II; mtII.r, right metatarsal II; mtIII.l left metatarsal III; mtIII.r, right metatarsal III; mtIV.l left metatarsal IV; mtIV.r, right metatarsal IV; mtV.l left metatarsal V; ph3d32.r, right phalanx II-3; ph3d3.r, right phalanx III-3; ph3d4.r, right phalanx III-4; pu, pubis; ra.l left radius; ra.r, right radius; sca.l, left scapula; st, sternum; ti.l left tibia; ti.r, right tibia; ul.l left ulna; ul.r, right ulna. 
(Photograph by Gao Wei, drawing by R.Q).

Systematic palaeontology
Oviraptorosauria Barsbold, 1976
Caudipteridae Zhou et Wang, 2000

Xingtianosaurus gen. nov

Etymology: XingTian, a Chinese deity recorded in Shanhaijing who continued to fight even after his head had been cut off, in reference to the skull-less holotype; saurus, Greek for lizard.

Type species: Xingtianosaurus ganqi

Diagnosis: A caudipterid dinosaur distinguished from other caudipterid taxa by the following combination of characters: small pleurocoel close to the dorsal edge of the lateral surface of the dorsal vertebral centrum, humerus longer than the scapula, proportionally long ulna (as long as humerus), relatively small radiale angle (39°, compared to >48° in other oviraptorosaurs with known radiale angle), extremely short metacarpal I (<40% length of the metacarpal II), small ligament pits on the manual phalanges.

Xingtianosaurus ganqi sp. nov.

Etymology: Ganqi, the weapon of Xingtian recorded in Shanhaijing.

Holotype: IVPP (Institute of Vertebrate Paleontology and Paleoanthropology) V13390 (Fig. 1). A partial skeleton, missing the skull, cervical vertebrae, anterior dorsal vertebrae and coracoids.

Locality and horizon: Wangjiagou, Yixian County, Liaoning Province. The Dakangpu Bed (same horizon to Dawangzhangzi Bed) of Yixian Formation, Lower Cretaceous (Fig. 2).


Rui Qiu, Xiaolin Wang, Qiang Wang, Ning Li, Jialiang Zhang and Yiyun Ma. 2019. A New Caudipterid from the Lower Cretaceous of China with Information on the Evolution of the Manus of Oviraptorosauria. Scientific Reports. 9, 6431. DOI: 10.1038/s41598-019-42547-6