An international team led by Prof. Bo Wang and Prof. Gongle Shi from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) with the participation of dr hab. Jacek Szwedo, prof. UG from the Laboratory of Evolutionary Entomology and the Amber Inclusion Museum, published the results of a long-term study conducted between 2010 and 2019 on a diverse and perfectly preserved assemblage of plant and animal fossils from the Middle Miocene Fotan Group, Zhangpu, Fujian Province in southeastern China. The article was published on April 30 this year. - Wang B. et al. (2021) The mid-Miocene Zhangpu biota reveals an outstandingly rich rainforest biome in East Asia. Science Advances 7 (18), eabg0625.
The fossil site, known as the Zhangpu biota, has yielded about 25,000 amber samples containing fossils and about 5,000 collected plant fossils. The Zhangpu fauna from the middle Miocene (lang) is the richest tropical rainforest biota discovered to date. It is a postcard from the past, showing the extraordinary species diversity that exists in a 14.7 million-year-old tropical rainforest and sheds light on rainforest evolution. The site is unique in that the materials are not commercially extracted and used, so the species list is minimally skewed by human selectivity. Furthermore, the exact age of the layers with fossils is well separated by radioisotopic dating, and the associated plant fossils, imprints, allow for quantitative reconstruction of past climate.
The diverse fruits of Dipterocarpaceae and legumes (Fabaceae) preserved in the fossils, as well as the leaves of 78 different deciduous trees, show that tropical seasonal rainforests extended further north than they do today, offering insights into what changes might occur in a future, warmer world if ecosystems are able to adapt to them. Inclusions in amber from Zhangpu show a diverse, perfectly preserved fauna of fossil arthropods as well as numerous plant and other inclusions such as fungi, snails and even feathers. Phytoinclusions include Bryophytes (liverworts and mosses) and a variety of flowering plants. Arthropod inclusions include an impressive array of over 250 families, including various Araneae, Acari, Julidae and at least 200 insect families from 20 orders.
The extremely high arthropod diversity makes the Zhangpu amber biota one of the four richest in the world, along with the well-known fauna of Cretaceous amber from Kachin (> 568 families), Eocene Baltic amber (> 550 families) and Miocene Dominican amber (205 families). Insect inclusions in Zhangpu amber indicate the presence of many taxa of ants, Apidae, Chrysopidae, Phasmatidae, Termitoidae and Orthoptera that are now restricted to tropical Southeast Asia and/or New Guinea.
These results suggest that Asian rainforest insect assemblages have been stable since the middle Miocene (at least 15 million years ago). They also highlight that tropical rainforests act as 'museums of biodiversity' at a general level. The relative ecological stability of such mega thermal environments facilitates the continued accumulation of species diversity and makes them even more valuable than previously thought. Compared to the modern climate of Zhangpu, the most notable difference is that the climate of the middle Miocene was characterised by warmer winters, resulting in relatively stable temperatures throughout the year. In global warming scenarios, winter warming is usually more pronounced than summer warming and has a larger and more widespread impact on terrestrial and marine ecosystems. It reduces winter losses and is beneficial for animal reproduction and tropical plant growth.
dr hab. Jacek Szwedo, prof. UG