A 53-million-year-old ecosystem
The Fushun Amber Fossil Lagerstätte offers an exceptionally detailed look into a subtropical forest ecosystem from 50 to 53 million years ago. This amber is not a product of pine trees, but rather the fossilized resin of extinct trees from the cypress family, Cupressaceae. The deposits are found within the Guchengzi Formation, layered with massive coal seams in what was once Asia's largest open-pit coal mine.
The amber formed during the Early Eocene Climatic Optimum (EECO), a prolonged period of high global temperatures. This interval is considered a potential analog for future climate change scenarios. The rock layers in the Fushun basin record the EECO but also a series of smaller, transient global warming events called hyperthermals. The environment preserved in the amber was a humid subtropical forest, providing a direct record of life that thrived under greenhouse conditions.
Life in the Eocene forest
The scientific value of Fushun amber comes from its biological inclusions. Researchers have identified fossils from over 22 orders and more than 80 families of arthropods. The diversity of eusocial insects, such as ants, bees, and termites, is significant. Finds include new genera of social bees, such as Thyreomelikertes, which show the evolution of social colonies.
Beyond insects, the amber preserves a wide range of forest life. Spiders are found, sometimes with fragments of their webs intact. Microscopic life, including fungi, is also preserved. One remarkable specimen shows a parasitic fungus, Allocordyceps baltica, erupting from the rectum of a carpenter ant. Plant materials like leaves, flowers, and wood fragments from genera such as Metasequoia are also common, allowing for a detailed reconstruction of the Eocene flora. These fossils demonstrate a biotic interchange between the eastern and western parts of the Eurasian continent during this warm period.