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.

关于新元古代早期真核生物（eukaryotes）的扩张，学界提出的一种解释为食真核生物捕食者（eukaryovorous predators）的出现——即一类以其他原生生物（protists）为食的原生生物。不过，该时期食真核生物捕食行为的相关证据均为间接证据，其依据包括性状状态重建（character state reconstructions）与分子钟（molecular clocks）推演，以及部分原生生物化石中发现的潜在防御结构。本文报道了采自美国亚利桑那州（Arizona）大峡谷（Grand Canyon）楚尔群（Chuar Group，时代约为7.8亿至7.4亿年）的7种有机壁微化石（organic-walled microfossils）中存在的0.1~3.4微米圆形孔洞；这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容物所形成的孔洞特征高度相似。尽管这类“类吸血鬼”行为在vampyrellid变形虫（vampyrellid amoebae）中最为典型，但该行为在真核生物中分布广泛，因此难以确切推断捕食者的具体类群。尽管如此，猎物的身份却清晰可辨：这些化石中的部分乃至全部均为真核生物。因此，这些孔洞是目前已知最早的真核生物捕食直接证据；此外，该地层上部花瓶状微化石（vase-shaped microfossils）中发现的约15~35微米半月形及圆形孔洞（也可能由“微型吸血鬼”类捕食者造成），共同表明古代楚尔海洋中存在多样的食真核生物捕食者类群。