Drilling cores from Switzerland have revealed the oldest known fossils of direct ancestors of flowering plants.
These beautifully preserved 240-million-year-old pollen grains are evidence that flowering plants evolved 100 million years earlier than previously thought, according to Researchers from the University of Zurich.
Flowering plants evolved from extinct plants related to conifers, ginkgos, cycads, and seed ferns. The oldest known fossils from flowering plants are pollen grains.
These are small, robust and numerous and therefore fossilize more easily than leaves and flowers.
An uninterrupted sequence of fossilized pollen from flowers begins in the Early Cretaceous, approximately 140 million years ago, and it is generally assumed that flowering plants first evolved around that time.
The present study documents flowering plant-like pollen that is 100 million years older, implying that flowering plants may have originated in the Early Triassic (between 252 to 247 million years ago) or even earlier.
Researcher Peter Hochuli and Susanne Feist-Burkhardt from Paleontological Institute and Museum, studied two drilling cores from Weiach and Leuggern, northern Switzerland, and found pollen grains that resemble fossil pollen from the earliest known flowering plants.
With Confocal Laser Scanning Microscopy, they obtained high-resolution images across three dimensions of six different types of pollen.
The samples from the present study were found 3000 km south of the previous site.
"We believe that even highly cautious scientists will now be convinced that flowering plants evolved long before the Cretaceous," said Hochuli.
In the Middle Triassic, both the Barents Sea and Switzerland lay in the subtropics, but the area of Switzerland was much drier than the region of the Barents Sea.
This implies that these plants arise in a broad ecological range. The pollen's structure suggests that the plants were pollinated by insects: most likely beetles, as bees would not evolve for another 100 million years.


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