20 million years old
Proc Natl Acad Sci U S A. 2002 Feb 5;99(3):1410-3. Epub 2002 Jan 29.
Spirochete and protist symbionts of a termite (Mastotermes electrodominicus) in Miocene amber.
Department of Geosciences, University of Massachusetts, Amherst, MA 01003, USA.
Extraordinary preservation in amber of the Miocene termite Mastotermes electrodominicus has led to the discovery of fossil symbiotic microbes. Spirochete bacteria and wood-digesting protists were identified in the intestinal tissue of the insect. Fossil wood (xylem: developing vessel-element cells, fibers, pit connections), protists (most likely xylophagic amitochondriates), an endospore (probably of the filamentous intestinal bacterium Arthromitus = Bacillus), and large spirochetes were seen in thin section by light and transmission electron microscopy. The intestinal microbiota of the living termite Mastotermes darwiniensis, a genus now restricted to northern Australia, markedly resembles that preserved in amber. This is a direct observation of a 20-million-year-old xylophagus termite fossil microbial community.
PMID: 11818534 [PubMed - indexed for MEDLINE]PMCID: PMC122204Free PMC Article
Link Here- https://www.ncbi.nlm.nih.gov/pubmed/11818534