Tianzhenosaurus chengi sp. nov.
A new ankylosaurid specimen was discovered in the Upper Cretaceous second member of Huiquanpu Formation on the Kangdailiang mountain(1 262 meters above sea level) at the juncture from the north of Yangyuan County, Hebei Province and the South of Tianzhen County, Shanxi Province. The skull of the new specimen was low and flat, the skull roof is covered with irregular dermal bony tuberetes [tubercules?], occipital was round and slightly exceeds the skull roof, dermal bony projection of posterior side was short, small, flat with occipital region and extend upward at a 45-degree angle. These characters of the skull are clearly different with Tianchisaurus of the Middle Jurassic from Xinjiang in China, Shamosaurus of the Early Creteceous from Mongolia, Ankylosaurus of the Late Jurassic and the Late Cretaceous Euoplocephalus from North America, as well as Pinacosaurus from the Late Cretaceous in China and Mongolia. Besides the shape of the skull, range of the skull roof covered with dermal bony tuberetes, the stretch direction and angle of dermal bony tubertes in posterior of tow [top?] side and occipiter region transverse axis also clearly different with Saichania, Talarurus of the Late Cretaceous from Mongonia and Tarchia from Inner Mongolia as well as Shanxia from same horizon from Wujiashan of Tianzhan County, Shanxi province. The correlative characters of skull are very consistent with Tianzhenosaurus in same locality and horizon, so belongs to the genus Tianzhenosaurus. But comparing with Tianzhenosaurus youngi, the new specimen character: the dermal bony tuberetes are fairly small, low and flat; the occipital region slight incline to upper; the basioccipital was round, raised, with underside wide and round; the occipital foramen was big and round; the orbital foramen was big, elongate; the peripheral zone was low and flat; the pterygoid and vomer nearly vertical; the vomer was thin and long; the caudal vertebrae were thick and strong. So we established a new species: Tianzhenosaurus chengi sp. nov. based on the new specimen. The new species discovery not only furnished materials of rare Ankylosaur fossils in China, but also significantly in studying the taxonomy, migration, evolution of Ankylosaurus as well as the relationship and paleobiogeography of the Cretaceous dinosaur faunas.
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