Science. 1993 Jan 8;259(5092):222-4. doi: 10.1126/science.259.5092.222.
Protozoa, cyanobacteria, sheathed algae, sheathed fungi, germinating pollen or spores, and fungal spores have been found in amber 220 to 230 million years old. Many of these microorganisms can be assigned to present-day groups. This discovery of terrestrial, soft-bodied protists that can be referred to modern groups indicates that morphological evolution is very gradual in many protists and that both structural and probably functional stasis extend back at least to the Upper Triassic period.
在 2.2 亿至 2.3 亿年前的琥珀中发现了原生动物、蓝藻、鞘藻、鞘菌类、萌发的花粉或孢子以及真菌孢子。其中许多微生物可以归为现代类群。在陆地上发现的这些可归入现代类群的柔软原生动物表明，许多原生动物的形态进化非常缓慢，结构和可能的功能停滞至少可以追溯到上三叠纪时期。
