Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt-am-Main, Germany.
Eur J Protistol. 2011 May;47(2):59-66. doi: 10.1016/j.ejop.2010.12.003. Epub 2011 Jan 26.
The mid-Cretaceous amber of France contains thousands of protist-like inclusions similar in shape to some ciliates, flagellates and amoebae. The sheer abundance of these inclusions and their size variation within a single amber piece are not concordant with true fossil protists. French amber is coniferous in origin, which generally does not preserve well protists without cell walls. Thus, it would be surprising if French Cretaceous amber had preserved millions of protists. Here, we present a survey of the protist-like inclusions from French amber and attempt to elucidate their origins. Diverse Cretaceous ambers (from Spain, Germany and Lebanon), also derived from conifer resins, contain thousands of protist-like inclusions. In contrast, Tertiary ambers and modern resins are poor in protist-like fossils. This suggests these inclusions originated from early Cretaceous plant resins, probably secreted with the resin by trees that did not survive after the Cretaceous (such as the Cheirolepidiaceae). A review of the recent literature on amber microfossils indicates several protist-like inclusions that are unlikely to have a biological origin have already been described as real fossil protists. This is problematic in that it will bias our understanding of protist evolution.
法国白垩纪中期琥珀中含有数千种类似原生动物的内含物，其形状与某些纤毛虫、鞭毛虫和变形虫相似。这些内含物的数量之多，以及它们在一块琥珀内的大小变化，与真正的化石原生动物并不相符。法国琥珀源于针叶树，而一般来说，没有细胞壁的原生动物很难保存下来。因此，如果法国白垩纪琥珀保存了数百万种原生动物，那将令人惊讶。在这里，我们对法国琥珀中的类似原生动物的内含物进行了调查，并试图阐明其起源。来自西班牙、德国和黎巴嫩的不同白垩纪琥珀（也来自针叶树树脂）也含有数千种类似原生动物的内含物。相比之下，第三纪琥珀和现代树脂中则缺乏类似原生动物的化石。这表明这些内含物起源于早白垩世植物树脂，可能是由那些在白垩纪后灭绝的树木（如南洋杉科）与树脂一起分泌的。对琥珀微化石的最新文献的回顾表明，已经有一些不太可能具有生物起源的类似原生动物的内含物被描述为真正的化石原生动物。这是有问题的，因为它会影响我们对原生动物进化的理解。
