Mandibular Morphology of Stegolophodon pseudolatidens (Proboscidea, Stegodontidae) from the Lower Miocene of Japan
Mandibular Morphology of Stegolophodon pseudolatidens (Proboscidea, Stegodontidae) from the Lower Miocene of Japan
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DOI：
10.2517/2020pr025
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发表时间：
2021-07
影响因子：
0.9
通讯作者：
Katsunori Iizumi;H. Ando;Kunihiro Suzuki;Yoshiki Koda
中科院分区：
文献类型：
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作者：
Katsunori Iizumi;H. Ando;Kunihiro Suzuki;Yoshiki Koda
抽象的。我们描述了在日本东北部中新世晚期（约 16.9–16.6 Ma）发现的两具保存完好的 Stegolophodon fakelatidens（哺乳动物、长鼻目、剑齿象科）下颌骨。 Sl的下颌骨。假乳齿兽在剑齿象科中是原始的，具有短的联合和下牙、四齿兽下臼齿和前段具有大背腹直径的下颌管。其特点是下颌支垂直（下颌支前缘与体背侧水平面几乎成直角），m3咬合面上近中方向有许多划痕，提示Sl.假乳牙似乎在咀嚼过程中获得了前颌运动。而Sl的下颌形态。 pseudolatidens 与 Stegolophodon 属的其他物种相当。缅甸中新世上部的剑齿象与这些物种的不同之处在于它们的联合较短，这是一种衍生条件。
Abstract. We describe two well-preserved mandibles of Stegolophodon pseudolatidens (Mammalia, Proboscidea, Stegodontidae) discovered from the lower Miocene (ca. 16.9–16.6 Ma) in Northeast Japan. The mandible of Sl. pseudolatidens is primitive within the Stegodontidae in having a short symphysis with lower tusks, tetralophodont lower molars, and a mandibular canal with the large dorsoventral diameter in the anterior segment. It is characterized by a perpendicular mandibular ramus (forming an almost right angle between the anterior margin of the mandibular ramus and the dorsal horizontal surface of the corpus), and many scratches in mesial direction on the occlusal surface of m3, implying that Sl. pseudolatidens appears to have acquired a proal jaw movement during mastication. While the mandibular morphology of Sl. pseudolatidens is comparable to that of other species of the genus that of Stegolophodon cf. stegodontoides from the upper Miocene of Myanmar differs from that of these species in having a shorter symphysis, which is a derived condition.