Data from: No deep diving: evidence of predation on epipelagic fish for a stem beaked whale from the late Miocene of Peru

Although modern beaked whales (Ziphiidae) are known to be highly specialized toothed whales that predominantly feed at great depths upon benthic and benthopelagic prey, only limited palaeontological data document this major ecological shift. We report on a ziphiid–fish assemblage from the Late Miocene of Peru that we interpret as the first direct evidence of a predator–prey relationship between a ziphiid and epipelagic fish. Preserved in a dolomite concretion, a skeleton of the stem ziphiid Messapicetus gregarius was discovered together with numerous skeletons of a clupeiform fish closely related to the epipelagic extant Pacific sardine (Sardinops sagax). Based on the position of fish individuals along the head and chest regions of the ziphiid, the lack of digestion marks on fish remains and the homogeneous size of individuals, we propose that this assemblage results from the death of the whale (possibly via toxin poisoning) shortly after the capture of prey from a single school. Together with morphological data and the frequent discovery of fossil crown ziphiids in deep-sea deposits, this exceptional record supports the hypothesis that only more derived ziphiids were regular deep divers and that the extinction of epipelagic forms may coincide with the radiation of true dolphins.

尽管现代喙鲸科（Ziphiidae）是高度特化的齿鲸类，主要于深海水域以底栖及底中层猎物为食，但记录这一重大生态转变的古生物学资料却极为有限。本研究报道了一件采自秘鲁晚中新世的喙鲸-鱼类化石组合，经分析认为其首次直接证实了喙鲸与大洋上层鱼类间的捕食者-猎物互作关系。该标本赋存于白云石结核之中，包含一具基干喙鲸类格雷戈里梅萨皮克鲸（Messapicetus gregarius）的骨架，以及大量与现生太平洋沙丁鱼（Sardinops sagax）亲缘关系密切的鲱形目鱼类骨架。基于鱼类个体沿该喙鲸头部与胸部的分布位置、鱼类遗骸未检出消化痕迹，以及个体尺寸均一的特征，我们推测该化石群形成于该鲸从单一鱼群捕获猎物后不久死亡的事件，其死亡原因可能为毒素中毒。结合形态学数据以及深海沉积中频繁发现的冠群喙鲸化石记录，这一罕见的化石记录支持如下假说：仅更为特化的喙鲸类才是常规深海潜水觅食者，而上层洄游型喙鲸类的灭绝或与真海豚类的辐射演化同步发生。