‘Pompeii of prehistoric plants’ reveals the secret of evolution: study

Spectacular fossil plants preserved in a volcanic ash fall in China brought to light an evolutionary race 300 million years ago, which was eventually won by the seed plants that dominate so much of Earth today.

New research on fossils unearthed at the “Prehistoric Plant Pompeii” in Wuda, Inner Mongolia, reveals that plants, called Noeggerathiales, were highly evolved members of the lineage from which seed plants originated.

Noeggerathiales were important peat-forming plants that lived approximately 325 to 251 million years ago. Understanding of their relationships with other plant groups has so far been limited by poorly preserved examples.

Fossils found in China have allowed experts to establish that Noeggerathiales are more closely related to seed plants than to other groups of ferns.

No longer seen as an evolutionary dead end, they are now recognized as advanced tree ferns that developed complex cone-shaped structures from modified leaves. Despite their sophistication, the Noeggerathiales fell victim to the profound environmental and climatic changes of 251 million years ago that destroyed swamp ecosystems around the world.

The international research team, led by paleontologists from the Nanjing Institute of Geology and Paleontology and the University of Birmingham, today published their findings in the Proceedings of the National Academy of Sciences (PNAS).

Co-author Dr Jason Hilton, reader in paleobiology at the Forestry Research Institute, University of Birmingham, said: ‘Noeggerathiales were recognized as early as the 1930s, but scientists have treated them as a’ taxonomic football ‘, endlessly launched without anyone. identify their place in the history of life.

“The spectacular fossil plants found in China are increasingly recognized as the plant equivalent of Pompeii. Thanks to this slice of life preserved in the volcanic ash, we were able to reconstruct a new species of Noeggerathiales which finally regulates the affinity and the evolutionary importance of the group.

“The fate of the Noeggerathiales is a stark reminder of what can happen when even very advanced life forms are faced with rapid environmental change.”

Researchers studied whole Noeggerathiales preserved in a 26-inch-thick bed of volcanic ash formed 298 million years ago, smothering all plants growing in a nearby swamp.

The ashes kept the fossils from rotting or being consumed, and preserved many complete individuals in microscopic detail.

Senior author Jun Wang, professor of paleobotany at the Nanjing Institute of Geology and Paleontology, said, “Many specimens were identified during excavations in 2006-2007 when a few leaves were visible on the surface of the ashes. . from each other and a rod below – we revealed the crown on the spot, but then extracted the full samples to bring them back to the lab.

“It has taken many years to study these and the additional specimens we have found more recently. Whole trees are the most impressive fossil plants that I have seen and due to our painstaking work they are also among the most impressive. most important to science. “

The researchers also deduced that the ancestral lineage from which seed plants evolved diversified alongside early radiation from seed plants during the Devonian, Carboniferous, and Permian periods, and did not quickly die out as we thought so before.