Njau Jackson K, Blumenschine Robert J
Center for Human Evolutionary Studies, Department of Anthropology, Rutgers University, 131 George St., New Brunswick, NJ 08901-1414, USA.
J Hum Evol. 2006 Feb;50(2):142-62. doi: 10.1016/j.jhevol.2005.08.008. Epub 2005 Nov 2.
Neotaphonomic studies have determined the patterns of bone damage created by larger mammalian carnivores when consuming mammalian carcasses. Typically, mammalian carnivores gnaw and break bones to various degrees in order to access marrow, grease, and brain tissue. In contrast, crocodiles attempt to swallow whole parts of mammal carcasses, inflicting in the process tooth marks and other feeding traces on some of the bones they are unable to ingest. Although crocodiles are major predators of larger mammals along the margins of protected tropical rivers and lakes, their feeding traces on bone have received little systematic attention in neotaphonomic research. We present diagnostic characteristics of Crocodylus niloticus damage to uningested mammal bones resulting from a series of controlled observations of captive crocodile feeding. The resulting bone assemblages are composed of primarily complete elements from articulating units, some of which bear an extremely high density of shallow to deep, transversely to obliquely oriented tooth scores over often large areas of the bone, along with shallow to deep pits and punctures. Some of the tooth marks (bisected pits and punctures, hook scores) have a distinctive morphology we have not observed to be produced by mammalian carnivores. The assemblages are also characterized by the retention of both low- and high-density bone portions, an absence of gross gnawing, and minimal fragmentation. Together, the damage characteristics associated with feeding by crocodiles are highly distinctive from those produced by mammalian carnivores. Modern surface bone assemblages along the Grumeti River in Tanzania's Serengeti National Park contain a mixture of specimens bearing damage characteristic of crocodiles and mammalian carnivores. Comparison of Plio-Pleistocene fossil bones from Olduvai Gorge, Tanzania, to bones damaged by captive and free-ranging Nile crocodiles reveals direct evidence of fossil crocodilian feeding from larger mammal bones associated with Oldowan stone artifacts.
新埋藏学研究已经确定了大型哺乳动物食肉动物在啃食哺乳动物尸体时造成的骨骼损伤模式。通常，哺乳动物食肉动物会不同程度地啃咬和折断骨头，以便获取骨髓、油脂和脑组织。相比之下，鳄鱼会试图整个吞下哺乳动物尸体的部分，在此过程中，它们会在一些无法吞咽的骨头上留下齿痕和其他进食痕迹。尽管鳄鱼是受保护的热带河流和湖泊边缘大型哺乳动物的主要捕食者，但在新埋藏学研究中，它们在骨头上的进食痕迹很少受到系统关注。我们通过对圈养鳄鱼进食的一系列对照观察，展示了尼罗鳄对未吞咽的哺乳动物骨骼造成损伤的诊断特征。由此产生的骨骼组合主要由关节单元的完整元素组成，其中一些元素在骨头的大片区域上，从浅到深、横向到斜向都有极高密度的齿痕，还有浅到深的凹坑和穿刺痕迹。一些齿痕（二分凹坑和穿刺、钩状划痕）具有独特的形态，我们从未观察到哺乳动物食肉动物能造成这种形态。这些组合的特征还包括低密度和高密度骨部分的保留、没有明显的啃咬以及极少的破碎。总之，与鳄鱼进食相关的损伤特征与哺乳动物食肉动物造成的损伤特征截然不同。坦桑尼亚塞伦盖蒂国家公园格鲁梅蒂河沿岸的现代地表骨骼组合包含了带有鳄鱼和哺乳动物食肉动物损伤特征标本的混合物。将坦桑尼亚奥杜瓦伊峡谷的上新世 - 更新世化石骨骼与圈养和野生尼罗鳄造成损伤的骨头进行比较，揭示了与奥杜瓦伊石器相关的大型哺乳动物骨头上有化石鳄鱼进食的直接证据。
