In a breakthrough that could shed light on the development of life on our planet, scientists in Germany have isolated a veritable "micro world" of bacteria , fungi and other tiny organisms dating back 220 million years in tiny nuggets of amber.
The microbes existed in the Triassic period, at the time of the first dinosaurs. They have given scientists a unique insight into the evolution and ecology of ancient micro-organisms.
A key discovery was that many microbes appear to have changed very little in the last 200 million years.
One amoeba found in the amber, Centropyxis hirsuta, is identical to a species that survives today. Amber is solidified tree sap, which can preserve small creatures and plants and freeze them in time.
Flies, beetles, ants and spiders dating back many millions of years have been found trapped in amber.
But soft bodied amber specimens older than 135 million years are very rare. Until now, no microbial inclusions had been found dating back this far.
The amber in question was discovered near the town of Cortina d'Ampezzo in the Italian Dolomites. Thousands of amber drops, measuring just about one millimetre across, were uncovered there.
The most abundant microbes found in the drops were bacteria. Also discovered were fungi, algae and single-celled animals including ciliate protozoa and amoebas.
The scientists, led by Alexander Schmidt, from the Museum fur Naturkunde der Humboldt-Universitat zu Berlin, in Germany, wrote in the journal Nature: "Our findings show that different genera, and even species, of microbial taxa have been able to survive geological epochs.
"Higher levels in food webs, on the other hand, have been shaped by environmental changes.
"Unchanged since the Lower Mesozoic, protozoans survived the entire era of the dinosaurs, as well as the diversification of angiosperm, (flowering plants), birds and mammals."