Data from: Tiny vampires in ancient seas: evidence for predation via perforation in fossils from the ~780–740 million-year-old Chuar Group, Grand Canyon, USA

One explanation for the early Neoproterozoic expansion of eukaryotes is the appearance of eukaryovorous predators—i.e. protists that preyed on other protists. Evidence for eukaryovory at this time, however, is indirect, based on inferences from character state reconstructions and molecular clocks, and on the presence of possible defensive structures in some protistan fossils. Here I describe 0.1–3.4 µm circular holes in seven species of organic-walled microfossils from the ~780–740 million-year-old Chuar Group, Grand Canyon, Arizona, USA, that are similar to those formed today by predatory protists that perforate the walls of their prey to consume the contents inside. Although best known in the vampyrellid amoebae, this “vampire-like” behavior is widespread among eukaryotes, making it difficult to infer confidently the identity of the predator. Nonetheless, the identity of the prey is clear: some—and perhaps all—of the fossils are eukaryotes. These holes thus provide the oldest direct evidence for predation on eukaryotes, and together with ~15–35 µm half-moon-shaped and circular holes in vase-shaped microfossils from the upper part of the unit that may also be the work of “tiny vampires”, they suggest a diversity of eukaryovorous predators in the ancient Chuar sea.针对新元古代早期真核生物的扩张事件，现有一种解释为食真核生物捕食者的出现——即一类以其他原生生物为食的原生生物。然而，彼时食真核生物行为的相关证据均为间接证据，其依据来自性状状态重建与分子钟的推断，以及部分原生生物化石中疑似防御结构的存在。本文报道了采自美国亚利桑那州大峡谷地区约7.8亿至7.4亿年前丘尔群（Chuar Group）的7种有机壁微化石中的0.1至3.4微米圆形孔洞，此类孔洞与现今捕食性原生生物穿透猎物细胞壁以摄取内部内含物所形成的孔洞特征高度相似。尽管该行为以vampyrellid变形虫（vampyrellid amoebae）中的表现最为人熟知，但这种“类吸血鬼”的捕食行为在真核生物中广泛存在，因此难以确切推断捕食者的具体类群。不过，猎物的身份却十分明确：这些化石中的部分乃至全部均为真核生物。因此，这些孔洞为捕食真核生物的行为提供了迄今最古老的直接证据；此外，该地层上部的瓶形微化石中也存在约15至35微米的半月形与圆形孔洞，此类结构同样可能是“微型吸血鬼”捕食者的杰作，二者共同表明，远古丘尔海海域曾存在多样的食真核生物捕食者类群。