老挝黄金赌场南京古生物研究所罗慈航课题组，报道了白垩纪琥珀中特殊保存的海洋绦虫触手。相关论文于2024年3月22日发表在《地质学》杂志上。

研究报道了在Kachin(缅甸)白垩纪中期(ca.99Ma)琥珀中一块细长、具特殊图案的化石。该化石显示出独特的外部(甲胄图案)和内部(部分内陷的触手和无根钩)特征，与现存寄生于海洋板鳃类动物(主要是鲨鱼和鳐鱼)身上的锥虫绦虫类的触手相一致。该研究可能不仅提供了首个绦虫的部分身体化石，而且可以说是最令人信服的扁形虫身体化石。

此外，化石内部精致的内陷触须凸显了琥珀可以保存蠕虫的内部结构。值得注意的是，几乎所有现存的锥虫绦虫都是海洋板鳃动物的体内寄生虫，该研究提供了一个海洋内寄生虫特异性埋藏在陆地琥珀中的特殊例子。

据了解，寄生虫在现存的生态系统中无处不在，但在地质记录中保存得很少，尤其是寄生蠕虫(蠕虫肠虫)。其中一组是多节绦虫亚纲(绦虫类)，这是扁形动物(扁形虫)的一个特化体内寄生虫群。它们有一个复杂的生命周期，至少有两个宿主，感染所有主要的脊椎动物类群。然而，由于它们的栖息地较为隐蔽和软组织难以保存，化石记录非常稀少，在第四纪之前唯一被广泛接受的例子是在二叠纪的鲨鱼粪化石中发现的卵。身体化石的缺乏极大地阻碍了人们对其早期进化的理解。

附：英文原文

Title: Exceptional preservation of a marine tapeworm tentacle in Cretaceous amber

Author: Cihang Luo, Harry W. Palm, Yuhui Zhuang, Edmund A. Jarzembowski, Thet Tin Nyunt, Bo Wang

Issue&Volume: 2024-03-22

Abstract: Parasites are ubiquitous in extant ecosystems but rarely preserved in the geological record, especially parasitic worms (helminths). One such group is Cestoda (tapeworms), a specialized endoparasitic group of platyhelminths (flatworms). They have a complex lifecycle with at least two hosts, infecting all major groups of vertebrates. However, their fossil record is extremely sparse due to their soft tissue and concealed habitats, with the only widely accepted example before the Quaternary being eggs discovered in a shark coprolite from the Permian. The lack of body fossils greatly hampers our understanding of their early evolution. We report a slender, armed fossil from mid-Cretaceous Kachin (Myanmar) amber (ca. 99 Ma). This fossil displays unique external (armature pattern) and internal (partially invaginated tentacle and rootless hooks) features that are most consistent with the tentacles of extant trypanorhynch tapeworms that parasitize marine elasmobranchs (mainly sharks and rays). Our study thus probably provides not only the first partial body fossil of a tapeworm, but also arguably the most convincing body fossil of a flatworm. In addition, the exquisite invaginated tentacle inside the fossil highlights that amber can preserve the internal structure of helminths. Remarkably, nearly all extant trypanorhynchs are endoparasites of marine elasmobranchs, thus our study provides an exceptional example of a marine endoparasite trapped in terrestrial amber.

DOI: 10.1130/G52071.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G52071.1/636929/Exceptional-preservation-of-a-marine-tapewormredirectedFrom=fulltext