Small mammal taphonomy of three Miocene localities from Damiao, Nei Mongol, China

摘要: Predation is the most common cause of death in small mammals. It also causes the greatest modification on their remains. Other postmortem processes, such as weathering, trampling, and transportation all modify bones and contribute to the forming assemblage. Here we examined three Miocene localities from Damiao, Nei Mongol, China with different fluvial subenvironments. The ages span from early Miocene to early late Miocene (ca 21–11.6 Ma). We describe the sedimentary context and taphonomic features of the small mammal assemblages, and identify the responsible agents for the fossil accumulations. Our study reveals predation as primary means of accumulation for all three localities. However, there is overprinting of other means of accumulation such as fluvial transportation and possibly signs of trampling at the two younger localities. Results indicate possibly different predators for all localities; owls for the oldest one, and diurnal birds of prey or mammalian agents for the younger two. We also show that systematic excavation for small mammals can be done, and in this way it may be possible to reduce some of the damage collecting always produces. 捕食是小哺乳动物死亡最常见的原因，也导致被捕食动物遗骸发生明显改变。动物死亡后的风化、踩踏、搬运等过程也会改变动物的骨骼并影响到化石组合的形成。本文研究了内蒙古大庙三个中新世化石地点，时代从早中新世到晚中新世早期(约21~11.6 ma)。通过分析各小哺乳动物化石组合的沉积背景以及埋藏学特征识别化石埋藏的主要成因。结果显示出捕食是三个地点小哺乳动物化石埋藏的基本成因，而在两个年轻的地点中也有流水搬运与可能的踩踏因素的叠加。三个地点可能存在不一样的捕食者：早中新世地点以猫头鹰捕食为主，中、晚中新世地点则以日间活动的鸟类或哺乳类为主要捕食者。研究还显示小哺乳动物的系统发掘是可行的，在一定程度上可以减少采样过程中产生的破坏。