Data_Sheet_1_Sexual Dimorphism and Body Reconstruction of a Hornless Rhinocerotid, Plesiaceratherium gracile, From the Early Miocene of the Shanwang Basin, Shandong, China.pdf

We investigated the sexual dimorphism and reconstructed the body of Plesiaceratherium gracile based on the numerous new specimens from the Early Miocene Shanwang Basin, China. The sexual dimorphism of P. gracile is reflected by the size of both the lower incisor i2 [length male/female (M/F) ratio = 2.69, width M/F = 1.63] and the upper incisor I1 (length M/F = 1.63). Other mensural variations reveal their ranges greatly overlapping on both genders, with a low M/F ratio; hence, they cannot be interpreted as sexual dimorphism. The large-sized body and the strong sexual difference of incisors suggest that P. gracile is polygynous and has a solitary lifestyle. When we reconstructed the body of P. gracile, we found that the head-body length is 2,796–3,117 mm, the shoulder height is 1,476–1,627 mm, and the body weight is about 1,198 kg. All skeletons have the ventral edge of the thorax at the level of the olecranon of the ulna. The spinous processes of the posterior thoracic vertebrae and the lumbar vertebrae are always vertical, the metatarso-femur ratio and the tibio-femur ratio are high, and the two joint angles between the scapula, the humerus, and the radius are 102°–143° and 115°–160°, respectively, indicating that P. gracile has a mediportal limb and a horse-gallop running type. Furthermore, the limb-segment comparisons of P. gracile and other rhinoceroses demonstrate that the proximal long bones, including the scapula, the humerus, and the femur, are important for the body height, regardless of whether their body is large or small-sized; the distal parts of the limb, including the metacarpus and the metatarsus, are sensitive to body mass changes.

本研究对始新世山旺盆地的众多新标本进行了研究，重构了优雅长角犀（Plesiaceratherium gracile）的性别二形性和身体结构。优雅长角犀的性别二形性体现在下颌门齿i2（长度男/女比=2.69，宽度男/女比=1.63）和上颌门齿I1（长度男/女比=1.63）的大小上。其他测量数据的差异表明，性别之间的范围有显著重叠，男/女比较低；因此，它们不能被解释为性别二形性。大型身体和牙齿的强烈性别差异暗示了优雅长角犀为多妻制且具有独居的生活方式。在重构优雅长角犀的身体时，我们发现其头体长为2,796–3,117毫米，肩高为1,476–1,627毫米，体重约为1,198公斤。所有骨骼的胸廓腹侧边缘位于尺骨桡骨头的水平处。后胸椎和腰椎的棘突始终垂直，跖骨-股骨比和胫骨-股骨比较高，肩胛骨、肱骨和桡骨之间的两个关节角度分别为102°–143°和115°–160°，这表明优雅长角犀具有中侧肢体和马奔跑型。此外，优雅长角犀与其他犀牛的肢体段比较表明，包括肩胛骨、肱骨和股骨在内的近端长骨对于身体高度至关重要，无论其体型大小；肢体远端部分，包括掌骨和跖骨，对体重变化敏感。