Fossil Flowers of Ancient Lianas Preserved in Amber Reveal the Evolution of Tropical Rainforests
Amber-preserved flowers from Southeast China show that lianas were already an established component of tropical rainforests 15 million years ago, during the Miocene. Researchers from China, France, Germany and Austria are using these exceptionally well-preserved fossils to reconstruct the biodiversity of a past ecosystem. The study has been published in the journal Annals of Botany.
Tiny flowers trapped in amber around 15 million years ago are offering scientists a rare glimpse into the plant life of a tropical rainforest in what is now Southeast China. Researchers have studied two exceptionally well-preserved fossil flowers from the Zhangpu flora. Their findings show that lianas already played an important role in the vegetation structure of tropical forests during the Middle Miocene.
“The fossils show not only that this plant group existed in Southeast China 15 million years ago,” says Eva-Maria Sadowski from the Museum für Naturkunde Berlin. “They also connect a Miocene plant lineage with its living relatives. This provides important insights into how plants evolved and how past ecosystems were composed.”
New fossil species
The fossils belong to the genus Ayenia (section Vahihara) in the mallow family (Malvaceae). One of the flowers is described as a new fossil species, Ayenia zhangpuensis, while the second specimen is assigned informally to Ayenia sp. Using light microscopy and X-ray tomography, the researchers were able to examine the delicate floral structures in detail.
“The exceptional preservation of these flowers allows us to identify features that are rarely preserved in fossil plants,” says Gongle Shi of the Nanjing Institute of Geology and Palaeontology in China. “Their similarity to living Ayenia species shows that the basic floral structure of this lineage has remained remarkably stable since at least the Middle Miocene.”
A window into an ancient rainforest
The Zhangpu flora from Fujian Province in Southeast China provides one of the most important windows into a tropical ecosystem of the Middle Miocene. During a period of globally warm climate, the region supported a highly diverse rainforest. Amber fossils from this period preserve numerous plants and animals in exceptional detail.
However, climbing plants are particularly difficult to identify in the fossil record. Their delicate structures often decay before they can be preserved under favourable conditions. As a result, their role in ancient forest ecosystems is often underestimated. The newly described flowers therefore add an important piece to the picture of the Zhangpu flora.
The discovery is more than a snapshot of a past rainforest. The close similarity between the fossil and living Ayenia flowers points to long-term continuity in floral form. At the same time, the fossils demonstrate how amber can help scientists reconstruct the evolutionary history of plants and the composition of ecosystems over millions of years.
Partners: The study was conducted in collaboration with researchers from the State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, University of Vienna; Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science,Freie Universität Berlin; Helmholtz-Zentrum Hereon, Museum national d'Histoire naturelle and University of Chinese Academy of Sciences.
Originalpublikation:
Xieting Wu, Simon Beurel, Julien B. Bachelier, Maria von Balthazar, Jörg U. Hammel, Eva-Maria Sadowski and Gongle Shi: Ayenia zhangpuensis sp. nov. (Malvaceae) from the Middle Miocene Zhangpu amber flora. Annals of Botany. DOI: 10.1093/aob/mcag220.
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