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，主要于深海底层及底中水层觅食，但目前仅存有限的古生物学数据可佐证这一重大生态位转变。本次研究报道了产自秘鲁晚中新世的一套喙鲸-鱼类化石组合，我们认为这是首个直接证实喙鲸与表层洄游鱼类间捕食关系的化石证据。该化石保存在一块白云岩结核中，一具基干喙鲸类（stem ziphiid）梅萨皮鲸属格雷戈里种（Messapicetus gregarius）的骨架与大量隶属于一类与现生太平洋沙丁鱼（Sardinops sagax）近缘的鲱形目鱼类的骨架一同被发现。结合鱼类个体在喙鲸头骨与胸部区域的分布位置、鱼类遗骸未发现消化痕迹，以及个体尺寸均一这几点，我们推测该化石组合形成于这头鲸从单个鱼群捕获猎物后不久死亡的场景，其死因可能为毒素中毒。结合形态学数据以及深海沉积中频繁出土的冠群喙鲸（crown ziphiids）化石记录，这一罕见化石证据支持以下假说：仅更为衍化的冠群喙鲸类才是常规的深潜觅食者，而表层洄游喙鲸类的灭绝或与真海豚类的辐射演化同步发生。