164-million-year-old plant fossil is the oldest example of a flower bud

The Fossilized Florigerminis jurassica plant with definite stem, bulbous fruit and fossilized flower bud (marked by the white arrow). (Image credit: NIGPAS)

Researchers have discovered the first example of a flower bud in a 164 million year old plant fossil in China. The discovery firmly postpones the emergence of flowering plants in the Jurassic periodbetween 145 million and 201 million years ago.

The fossil, which was discovered in the Inner Mongolia region of China, measures 1.7 inches (4.2 centimeters) long and 0.8 inches (2 cm) wide. It contains a stem, a leafy branch, a bulbous fruit and a tiny flower bud about 3 millimeters square. The researchers named the new species Florigerminis jurassica.

There are two main types of plants: flowering plants, called angiosperms, and non-flowering plants, called gymnosperms. Both the flower bud and the fruit of the fossil are clear indicators that F.jurassica was an angiosperm and not a gymnosperm, which was the dominant plant type during the Jurassic period. So far, fossil evidence has shown that angiosperms only appeared in Cretaceous periodbetween 66 million and 145 million years ago, but the new fossil is the most compelling evidence yet that this was not the case.

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Close-up images of the fossilized flower bud (left) and fruit (right). (Image credit: NIGPAS)

“Many paleobotanists are surprised [by the fossil]because it is quite different from what is said in the books,” lead author Xin Wang, a researcher at the Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences (NIGPAS), told Live Science in an email. “But I’m not that surprised,” he added.

The new fossil is not the oldest example of a fossilized flower ever discovered. In 2018, in a study published in eLiferesearchers have described 174 million year old flowers of a plant of the genus Nanjinganthusalso found in China, Previously reported Live Science.

However, some researchers have questioned whether Nanjinganthus can truly be considered an angiosperm because the flowers were not complex enough to distinguish them from the leafy structures seen in gymnosperms, ScienceAlert Reported. The flowers are also extremely delicate and difficult to fossilize, which can make it difficult to distinguish them from other plant matter, Wang said.

But the flower bud and fruit of the new fossil prove beyond any doubt that F.jurassica was definitely an angiosperm, he says. The fossil “therefore underlines the presence of angiosperms in the Jurassic and calls for a rethinking of the evolution of angiosperms”, according to the researchers. written in a statement.

Wang believes that several other known plant genera from the Jurassic period, including Nanjinganthus, Juraherba, Youhania, Jurafruits, Xingxueanthus and Schmeissneria, could also potentially be angiosperms, but he says there’s no way to tell for sure without fossil evidence. Until now, scientists had simply assumed that these genera were gymnosperms because they appeared in the Jurassic period.

However, if angiosperms were present in the Jurassic, they would have been very rare compared to gymnosperms and geographically isolated, making the discovery of other such well-preserved flower buds highly unlikely, he said.

Alternatively, it is also possible that F.jurassica may be one of the earliest evolutionary links between ancient angiosperm-like plants, such as Nanjinganthusand more recent true angiosperms discovered in the Cretaceous, Wang said.

The study was published online Jan. 6 in the Journal of the Geological Society of London.

Originally posted on Live Science.