Millions of years ago, bees and plants were already working together. An international research team has uncovered fossilized lime blossoms and bumble bees in 24-million-year-old lake sediments in Rhineland-Palatinate, Germany. Remarkably, preserved pollen grains revealed their direct interaction.
This discovery shows that bumble bees were already key pollinators of linden trees during that time, much like they remain today.
The finding is especially meaningful now, with pollinator populations facing severe decline worldwide. Understanding how pollination developed in the past could help us protect ecosystems for the future.
Pollen on bumble bee fossils
The project was led by Friðgeir Grímsson, a research scientist in the Division of Structural and Functional Botany at the University of Vienna.
“We examined hundreds, even thousands, of fossil flowers and insects for pollen in the hope of gaining insight into the evolution of flowers, flower visitors and pollination,” explained Grímsson.
The researchers used modern imaging methods to bring the ancient pollen into view. UV and blue light highlighted the microscopic grains, which were then extracted with an extremely fine needle.
After cleaning, scientists analyzed them under high-resolution microscopes. They found linden tree pollen clinging to the hairs of several fossilized bumble bees.
Naming new species
The team also described three entirely new species. “The newly discovered linden flowers were named Tilia magnasepala, meaning ‘linden tree with large sepals’,” explained doctoral student Christian Geier, lead author of the study.
Alongside the flowers, two bumble bee species were identified: Bombus (Kronobombus) messegus and Bombus (Timebombus) paleocrater.
The names reflect their age, features, and discovery site. All specimens came from sediments of a long-vanished volcanic lake near Enspel in Germany.
Fossils of flowers and bees
The fossils mark the first record of linden flowers on the European continent described with pollen science. The fossilized bumble bees belong to some of the earliest known species in their genus. Only one older species, found in Colorado, predates them.
“This is the first time worldwide that a fossil flower and its pollinating bees have been described from the same sediments and directly linked to each other using pollen,” said Geier. “This type of research has great potential to shed light on our knowledge of pollinators of the past.”
The study highlights how volcanic lake environments created ideal conditions for exceptional preservation.
Rapid burial in fine sediments prevented decay, locking insects and plants together in remarkable detail. This rare quality allowed researchers to observe not just morphology but also pollen traces, something rarely preserved in fossils.
Such deposits provide a unique window into ecological relationships, showing how pollination strategies evolved under ancient climates and environments. They capture interactions frozen in time, offering evidence beyond isolated plant or insect remains.
Lessons for today
Ancient fossils are not just relics; they hold valuable lessons about adaptation and survival. By studying past interactions, researchers gain insight into how species responded to climate shifts, extinctions, and environmental pressures.
“In our study, we were able to identify a certain degree of flower constancy in the bumble bees we studied. This means that they only visit one type of plant during a single flight,” noted Geier.
“Findings like these are important for better understanding the delicate interplay and resilience of today’s ecosystems.”
A long history of pollination
The findings also contribute to debates about the deep evolutionary history of pollination. They show that specialized relationships between bumble bees and linden trees existed far earlier than previously confirmed in Europe.
This pushes back evidence of mutualism, suggesting ecological networks were already well established during the early Miocene.
The research also emphasizes the importance of integrating fossil records with modern ecological studies. Pollination is central to biodiversity, agriculture, and climate resilience, and understanding its ancient roots adds context to current challenges.
Published in the journal New Phytologist, the research was part of the FWF project “Flower Power: can in-situ pollen link fossil plants to floral visitors?”
The results not only expand the fossil record but also highlight the long history of pollination – an interaction still vital for our world today.
Image Credit: Christian Geier
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