禄丰古猿蝴蝶种下第四前臼齿釉质-齿质交界面的三维几何形态

禄丰古猿蝴蝶种 (Lufengpithecus hudienensis) 也称蝴蝶古猿,是重要的早期人科成员,化石产自云南元谋盆地竹棚-小河及雷老两个地点群,其年代为中新世晚期。上世纪八、九十年代的发掘工作共获得幼年个体颅骨1具、残上颌骨10件、残下颌骨17件及1500多枚单个牙齿。受限于当时的技术条件,蝴蝶古猿牙齿内部结构及三维形态一直未有报道和对比研究。本文首次使用高精度CT配合三维几何形态测量方法,对6枚产自小河地点的蝴蝶古猿下颌第四前臼齿的釉质-齿质交界面形态进行了观察和对比,对比材料包括步氏巨猿、猩猩（化石）、大猩猩、黑猩猩及现代人。多变量分析显示,蝴蝶古猿釉质-齿质交界面几何形态接近于本文所涉及的大型猿类对比标本,但并没有表现出与某一特定类群的相似性;咬合面轮廓狭长,前凹尺寸明显小于后凹;整体形态介于齿质尖较高的大猩猩和齿质尖较低、釉质-齿质交界面形态扁平的巨猿、猩猩和黑猩猩之间。本文所观察到的类群之间的异同可能与趋同演化有关,也需要更多数据的进一步验证。将釉质-齿质交界面的三维几何形态和其他牙齿内部结构的信息（如釉质厚度及其三维分布规律等）综合,有助于进一步讨论蝴蝶古猿的分类学、系统发育和食性。

Geometric morphometry of the enamel-dentine junction interface of Lufengpithecus hudienensis lower fourth premolars

The dental endostructural morphology of the Miocene hominid, Lufengpithecus hudienensis from Yuanmou basin remains largely undocumented. Here we first use micro-CT scanning and landmark-based, 3D geometric morphometric tools to conduct a preliminary study on the enamel-dentine junction (EDJ) morphology of Lufengpithecus hudienensis lower fourth premolars(n=6), with a comparative sample of fossil and extant great apes (n=26) and modern humans(n=10). Multivariate analysis of the shapes of the EDJ ridge curves suggests that L. hudienensis as membership in the hominids, it has slender occlusal outline and smaller fovea anterior than posterior, which is a relatively primitive feature (compared with Homo) widely expressed among great apes and early hominins. In the between-group PCA (bgPCA) plot, L. hudienensis is placed at an intermediate position between Gorilla (sharp dentine horns and elevated topology) and other hominid taxa with relatively flattened EDJ represented by Pan, fossil Pongo and Gigantopithecus blacki, such similarities may reflect functional adaptation rather than phylogenetic signals, but further analysis with a large sample is needed before drawing a conclusion. Interspecific overlap between L. hudienensis and comparative samples is minor. The morphological affinity between L. hudienensis and comparative samples is investigated. The possible implications for dietary inferences in light of EDJ morphology and previously documented enamel thickness data are discussed.