Paleontologists have screened 24-million-year-old fossil flowers and bees from the Late Oligocene of Enspel, Germany, and identified a new species of linden, Tilia magnasepala, as well as two new bumblebee species, Bombus (Kronobombus) messegus and Bombus (Timebombus) palaeocrater. The presence of the same Tilia pollen in flowers and adhering to the exterior of the bumblebees provides direct evidence for their interaction and the role of Bombus as a pollinator for Tilia by at least the Late Oligocene and persisting to the present.
Tilia magnasepala. Image credit: Christian Geier.
“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,” said Dr. Friðgeir Grímsson, a researcher at the University of Vienna.
“These microscopic pollen grains were made visible using UV and blue light and then extracted either individually or in clumps from flowers or the insects’ hair using a very small, fine needle in a minimally invasive procedure.”
After careful cleaning of the pollen grains, they were analyzed using high-resolution light and electron microscopy.
Some of the flowers examined came from the linden tree, and numerous bumblebees had visited linden flowers before they drowned in a former volcanic crater lake and fossilized.
“The newly-discovered linden flowers were named Tilia magnasepala,” said Christian Geier, a doctoral student at the University of Vienna.
“Two new bumble bee species were also named: Bombus (Kronobombus) messegus and Bombus (Timebombus) paleocrater.”
The fossils were found during excavations in the lake sediments of the former volcanic lake near Enspel in Rhineland-Palatinate, Germany.
“Tilia magnasepala flowers are the first of their kind from the European continent to be recorded and described according to palynological criteria — i.e. the science of pollen,” the researchers said.
“The fossil bumble bees are among the oldest representatives of their genus; only one species from Colorado, the United States, is older.”
“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,” Geier said.
“This type of research has great potential to shed light on our knowledge of pollinators of the past.”
The fossil record provides insights into dynamic developments in the past: changes due to climate change, species extinction and evolutionary adaptations.
The analysis of fossil animal and plant groups allows conclusions to be drawn about their behavior and their response to environmental changes.
“In our study, we were able to identify a certain degree of flower constancy in the bumble bees we studied,” Geier said.
“This means that they only visit one type of plant during a single flight.”
“Findings like these are important for better understanding the delicate interplay and resilience of today’s ecosystems.”
The study was published today in the journal New Phytologist.
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Christian Geier et al. 24 million years of pollination interaction between European linden flowers and bumble bees. New Phytologist, published online September 22, 2025; doi: 10.1111/nph.7053
