关键词: 古人类, 头骨, 梨状孔, 形态变异

Abstract:

When studying the Homo erectus fossils from Zhoukoudian in the 1940s, Weidenreich noticed that the lower border of the nasal aperture of Zhoukoudian hominins exhibited patterns different from those of modern populations from Europe, Australia, and Melanesia. In the 1960s, when studying the crania of Upper Cave, Wu Xinzhi proposed that the Late Pleistocene humans in China had wide nasal apertures. Even so, so far, no study of the circum-nasal region morphology of Chinese hominins has been conducted, and the morphological patterns and variabilities of the circum-nasal region in Chinese hominins remain unclear.

In this study, the morphological features in the circum-nasal region of 22 Chinese hominin fossils were described and compared. Our study indicates that the circum-nasal region morphology of Pleistocene humans in China exhibited marked evolutionary changes. Homo erectus, Middle Pleistocene humans, and Late Pleistocene early modern humans showed different patterns. In addition, there were intragroup variations among Chinese hominins from different chronological periods.

The nasal aperture of H. erectus exhibited some common morphological patterns: 1) a sharp lateral margin; 2) a sharp lower margin that formed a clear border dividing the naso-alveolar clivus and the nasal cavity; 3) the absence of a subnasal fossa, resulting in a flat upper portion of the naso-alveolar clivus; 4) a weak or absent anterior nasal spine.

The nasal apertures of late Middle Pleistocene hominins showed some specific patterns: 1) the nasal aperture was wide and low, with the horizontal size larger than the vertical size; 2) a sharp lateral margin; 3) a sharp lower margin forming a clear border; 4) all the specimens had a subnasal fossa that, together with the lower margin, divided the naso-alveolar clivus and the nasal cavity; 5) the anterior nasal spines were either weak or moderately developed; 6) the subnasal fossae showed different morphological patterns.

The nasal apertures of Late Pleistocene hominins also showed some common patterns: 1) the height of the nasal aperture increased; 2) the lower margin in most specimens was open, with a flat transition between the naso-alveolar clivus and the nasal cavity; 3) nearly all the specimens had a subnasal fossa, with the exception of Yahuaidong; 4) the anterior nasal spines were pronouncedly developed in most specimens; 5) the relative size of the nasal apertures seemed to be irregular; 6) the lower margins in some specimens (UC 101 and Maludong) exhibited a morphological pattern resembling that of late Middle Pleistocene hominins and different from those of other specimens from this time period.

Except for these characteristics of the nasal aperture mentioned above, compared with Holocene populations, the nasal apertures of Pleistocene hominins were lower. Both H. erectus and late Middle Pleistocene hominins had clear lower borders of the nasal aperture. The lower borders of the nasal aperture in most Late Pleistocene hominins were open, with a flat transition between the naso-alveolar clivus and the nasal cavity. The subnasal fossa seemed to appear from the late Middle Pleistocene. The anterior nasal spine also seemed to appear in the late Middle Pleistocene and became more pronounced gradually. Starting from the Late Pleistocene, the development of the anterior nasal spine showed variabilities, with the northern specimen of Upper Cave having a pronounced anterior nasal spine, and the southern specimens of Liujiang and Longlin showing weak anterior nasal spines.

Key words: hominins, skull, nasal aperture, morphological variations