杨氏天镇龙性双形现象的初步研究

通过对河北地质大学地球科学博物馆和山西大同博物馆收藏的4具杨氏天镇龙（甲龙类）骨架化石的研究，主要根据其头颅和尾锤的形态特征，认为杨氏天镇龙存在明显的性双形现象。雄性个体的鳞骨角粗大，向后上方两侧突伸；尾锤呈亚圆形，大而扁平。雌性个体的鳞骨角细小、低矮，向后侧方向突伸；尾锤呈亚圆形，小而扁平，表面具核桃纹纹饰。对甲龙类性双形现象的探讨为恐龙的研究提出了一种新的思路，可避免分类时出现同物异名的现象。

Preliminary study on the sexual dimorphism of Tianzhenosaurus youngi

This paper deals with 4 skeleton fossils of Tianzhenosaurus youngi (Ankylosauria) collected by the Museum of Earth Sciences of Hebei GEO University and the Datong Museum of Shanxi Province. Based on the characters of their skulls and tail clubs, Tianzhenosaurus youngi clearly shows sexual dimorphism. Male individuals have large and sturdy squamosal horns that protrude bilaterally upwards, and a large and flat sub-circular tail club. Female individuals have thinner, smaller and lower squamosal horns that protrude bilaterally backwards, and a small and flat sub-circular tail club with walnut-like decoration on its surface. This paper is the first study on the sexual dimorphism of ankylosaurs. It provides a new way for the study of dinosaurs in order to avoid the occurrence of synonym in classification.