The postcranial variability of Quaternary European rhinoceroses: the case study of Stephanorhinus hundsheimensis from the Middle Pleistocene site of Contrada Monticelli (Apulia, southern Italy)

Five rhinoceros species, mainly distinguishable through cranial, mandibular and dental morphology, were recognized during the Quaternary across Europe. The postcranial morphology of these taxa is quite variable, with strong superposition among species, especially between Stephanorhinus etruscus and Stephanorhinus hundsheimensis. Here, the complete sample including 25 postcranial bones from the early Middle Pleistocene site of Contrada Monticelli (Apulia, southern Italy) is described and compared through morphological and biometric analyses. A few bones, in addition to cranial and mandibular remains from this site, have been previously referred to Stephanorhinus hundsheimensis. We explored the morphological variability of Stephanorhinus hundsheimensis from Contrada Monticelli against the diagnostic characters described in the literature. The size variation of the Contrada Monticelli sample is also investigated, through a comparison with other Quaternary European rhinoceros samples. Our results indicate a wide morphological variability with several distinct characters and a strong morphological affinity between Stephanorhinus etruscus and S. hundsheimensis. Our results suggest that Stephanorhinus hundsheimensis from Contrada Monticelli is a species with a high degree of intraspecific variability, possibly a hybrid population or a population including two morphotypes of the same species.欧洲第四纪地层中已识别出5种犀牛，它们主要通过颅骨、下颌骨及牙齿形态进行区分。上述分类群的颅后形态颇具变异性，物种间存在较强的形态重叠现象，尤以Stephan犀属（Stephanorhinus）的埃特鲁斯犀（Stephanorhinus etruscus）与洪谢伊姆犀（Stephanorhinus hundsheimensis）之间为甚。 本次研究通过形态学与生物测量学分析，对采自意大利南部普利亚大区孔塔达·蒙蒂切利（Contrada Monticelli）早中更新世遗址的25件完整颅后骨骼标本进行了描述与对比。此前该遗址出土的部分颅骨、下颌骨及骨骼标本曾被归入洪谢伊姆犀。 我们基于文献中记载的鉴别特征，对孔塔达·蒙蒂切利遗址出土的洪谢伊姆犀的形态变异性展开了探究。此外，通过与欧洲其他第四纪犀牛标本集合的对比，我们还分析了该遗址标本的尺寸变异情况。 研究结果显示，该类群存在广泛的形态变异性，兼具多处独特特征，且埃特鲁斯犀与洪谢伊姆犀之间存在极强的形态亲缘关系。本研究结果表明，孔塔达·蒙蒂切利遗址出土的洪谢伊姆犀种内变异性极高，其可能为杂交种群，或是包含同一物种两种形态型的种群。