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Vertebrata Palasiatica ›› 2011, Vol. 49 ›› Issue (2): 241-252.

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EVOLUTION OF CRANIAL CAVITIES IN GIANT PANDAS (AILUROPODA, CARNIVORA, MAMMALIA)

DONG Wei, ZHANG Jue-Fei   

  • Online:2011-06-15 Published:2011-06-15

大熊猫颅内腔的演化

董为,张觉非   

Abstract: Three-dimensional virtual cranial endocasts of the Early Pleistocene Ailuropoda microta, the Late Pleistocene A. baconi, extant A. melanoleuca and Ursus maritimus were described and compared. The morphologies of cranial endocasts of giant pandas are generally similar to each other, but quite different from that of the polar bear. The intracranial volumes appear the smallest in A. microta, intermediate in A. melanoleuca, and the largest in A. baconi. The sulci and gyri impressions are developed on cranial endocasts of the giant pandas, more so in A. melanoleuca than in A. microta. On the contrary, they are not developed on the cranial endocast of the polar bear, but the blood vessel impressions are developed on the lateral occipital sides in the polar bears. The ventral longitudinal groove on olfactory endocast is developed in A. microta, weak in A. baconi, nearly absent in A.melanoleuca, but well developed in Ursus maritimus. The encephalization quotient is similar among A.microta, A. baconi and A. melanoleuca, but it is much greater for giant pandas than in the polar bear. The morphology of the paranasal sinuses is also similar among giant pandas, but different from that of the polar bear. The frontal sinuses of giant pandas are rather long, quite high and dorsally ridgy, but those of the polar bear are shorter, relatively lower, wider and dorsally flat. The maxillary sinuses of giant pandas are relatively wide, but those of the polar bear are narrow. The sphenoid sinuses of giant pandas are all small, but those of the polar bear are large and cover the anterior portion of the braincase. These endocranial differences between giant pandas and the polar bear support the classification of giant pandas as an independent family.

摘要: 描述比较了早更新世大熊猫小种(Ailuropoda microta)、晚更新世大熊猫巴氏种(A. baconi)、现生大熊猫(A. melanoleuca)和北极熊(Ursus maritimus)的虚拟三维颅内模。大熊猫脑窝内模的形态在小种、巴氏种和现生种之间大致相似,而与北极熊区分明显。大熊猫的脑窝内模容积从小种到巴氏种呈增大趋势,但从巴氏种到现生种呈减小趋势。大熊猫的大脑沟回在脑窝内模上留下的印痕非常明显,并从小种经巴氏种到现生种则呈稳定增长趋势。相反,北极熊的大脑沟回在脑窝内模上留下的印痕不明显,而血管印痕在脑窝枕区的两侧很明显。嗅球窝内模腹部的纵沟在大熊猫小种发育,在巴氏种较弱,在大熊猫现生种几乎不存在,而在北极熊较发育。大熊猫的脑量商在小种、巴氏种和现生种之间差别不大,但大熊猫的脑量商明显大于北极熊。大熊猫的副鼻窦在小种、巴氏种和现生种之间的差别不大,但与北极熊差别较大。大熊猫的额窦很长、较高、背侧脊形,而北极熊的额窦长度相对较短、高度较低、宽度稍大、背侧平缓。大熊猫的上颌窦较宽,而北极熊的则较窄。大熊猫的蝶窦很小,而北极熊的则较大,覆盖在脑腔前侧。大熊猫这3个不同时期的种与北极熊在颅内腔上这些明显的差异支持将大熊猫从熊科中独立出来的分类。