Flowers Evolved 100 Million Years Earlier Than Thought: Plant Pollen Fossils Reveal All

Flowers are some of the most beautiful parts of nature. Their petals can be vibrant and their smells sweet. Yet flowering plants weren't always around; their particular evolution occurred millions of years ago. Now, researchers have uncovered new evidence about these plants. It turns out that they first evolved 100 million years early than previously thought.

Flowering plants had ancestors that were actually more closely related to conifers, ginkgos, cycads and seed ferns. Now extinct, these first plants left behind pollen grains that were then fossilized. In fact, an uninterrupted sequence of fossilized pollen from flowers begins in the Early Cretaceous, about 140 million years ago. This has led researchers to believe in the past that this is the time at which the first flowering plants evolved.

Now, it turns out that this might not be the case. The researchers studied two drilling cores from northern Switzerland. There, they discovered pollen grains that resemble fossil pollen from the earliest known flowering plants. Using Confocal Laser Scanning Microscopy, the scientists obtained high-resolution images across three dimensions of six different types of pollen.

Many studies have actually tried to estimate the age of flowering plants from molecular data. So far, though, no consensus has been reached. Estimates have ranged from the Triassic to the Cretaceous because molecular estimates typically need to be "anchored" in fossil evidence. Before now, such extremely old fossils have remained elusive. These new fossils, though, seem to show exactly when these plants emerged.

"We believe that even highly cautious scientists will now be convinced that flowering plants evolved long before the Cretaceous," said Peter Hochuli, one of the researchers, in a news release.

These primitive flowering plants in the Middle Triassic probably weren't like the flowers we know today. The region where the pollen was found was much drier than it is today and the plants occurred across a broad ecological range. The pollen's structure also suggests that the plants were pollinated by insects--most likely beetles.

The findings reveal a little more about the evolution of flowers. In particular, they show that these plants emerged far earlier than anyone expected--240 million years ago.

The findings are published in the journal Frontiers in Plant Science.