Abstract:  A single large theropod tooth was recovered from the middle Upper Cretaceous Majiacun Formation, Henan Province, China. The morphology of the tooth strongly suggests that it belongs to a baryonychine spinosaurid theropod based on the following features: long, conical tooth with a sub-circular cross-section, slight recurvature along the length of the tooth and numerous fine denticles on both anterior and posterior carinae. This tooth therefore may represent the first record of the baryonychines in Asia, and the first in the Late Cretaceous. This suggests that the baryonychines were more widely distributed both geographically and temporally than previously thought. Based on the gross morphology and inferred ecology of spinosaurids as a whole, we note that these animals are surprisingly rare in the fossil record compared to other theropod clades. This suggests that in life they may have been genuinely rare animals, perhaps as a result of their extreme morphological specialisation.

摘要： 中国河南省晚白垩世中段地层马家村组发现了一枚大型兽脚龙类牙齿。该牙牙体长，呈圆锥状，横断面卵圆形，沿长轴微向后缘弯曲，前后缘均有大量锯齿状突起，这些特征显示其很可能是重爪龙类牙齿。这可能代表了重爪龙类在亚洲地区的首次发现，也是该类恐龙在晚白垩世地层中的首现，由此表明重爪龙类在时间和地域分布上较之前研究观点更为广泛。综合棘龙科的化石形态学以及推知的生态学证据看，较之其他兽脚类，棘龙类化石记录很少，很可能意味该类动物数量确实稀少，造成这种现象的原因可能是其过分特化的身体形态。