Ancient Burmese amber often holds the answers to the greatest scientific questions.
Chinese and British paleontologists have described an unusual sample of Burmese amber that is about 100 million years old and contains a beetle of a previously unknown species. The insect is surrounded by pollen grains of a flowering plant, and next to the insect are two coprolites consisting of pollen. As the researchers note in their article, the find supports the hypothesis that beetles were one of the first pollinators of flowering plants: they visited flowers to eat pollen while transferring it from one plant to another.
The world we are used to is based on thousands of ecological ties. One of the most important among these is the collaboration of flowering plants and pollinating insects such as bees, butterflies, and flies. Biologists estimate that this mutually beneficial relationship began about a hundred million years ago.
However, under what circumstances insects began to pollinate plants is not yet completely clear. This is not surprising, since it is not easy to reconstruct the ecological features of long-extinct species.
Fortunately, sometimes in the hands of paleontologists are perfectly preserved specimens of fossil-pollinating insects, thanks to which you can learn more about ancient ecosystems.
Examining samples of Burmese amber aged 98.17 million years, scientists saw in one of them a well-preserved beetle from the family of flower sequins ( Kateretidae ), which turned out to be a representative of a previously unknown genus and species.
The ancient insect was very small – its body length was only 1.27 millimeters. Nevertheless, the find attracted considerable interest from paleontologists. The fact is that in the amber around the beetle, scientists examined about a hundred pollen grains belonging to a flowering plant from the extinct genus Tricolpopollenites. Four clusters of grains are located next to the beetle, and at least two grains have adhered to the belly of the insect.
According to the researchers, this indicates that the beetle carried pollen from flower to flower, similar to the present-day flower glitter. An additional argument in favor of this idea is the presence of setae on the beetle’s limbs and abdomen, to which pollen grains could easily attach. Based on the assumption that the insect was a pollinator, scientists selected an appropriate scientific name for it: Pelretes vivificus.
The generic name comes from the Old Bohemian word for pollen (one of the authors of the article is from the Czech Republic), and the specific name is translated from Latin as “giving life” – an allusion to the possible role of the beetle in plant reproduction.
In the same amber sample, the team discovered two cylindrical coprolites, which are composed of pollen grains of Tricolpopollenites. Judging by their structure and age of the find, they belong to some kind of beetle. Since the fossil excrement is located next to P. vivificus (the closest is at a distance of two millimeters from the insect), paleontologists decided that it was he who produced them.
Thus, representatives of this species could visit the flowers of plants from the genus Tricolpopollenites to eat pollen. At the same time, they carried away part of the grains on the abdomen and legs to other flowers of the same species, providing pollination.
Paleontologists have long assumed that pollen-eating beetles were the first pollinators of flowering plants. Probably, initially, these insects (together with representatives of some other groups) carried the pollen of gymnosperms such as cycads, and then, in the middle of the Cretaceous period, switched to flowering plants.
Subsequently, other insects began to pollinate the flowers, and the flowering plants themselves learned to produce nectar. This hypothesis is confirmed by samples of Burmese amber, in which the beetles survived together with the pollen of gymnosperms and flowering plants.
However, prior to the discovery of P. vivificus and its coprolites, experts did not have such solid evidence that dinosaur-era beetles visited flowers and fed on their pollen.
Interestingly, P. vivificus is already the third species of beetles from Burmese amber, for which a connection with the pollen of flowering plants has been noted. This indicates that, in the Middle Cretaceous, several groups of these insects at once mastered feeding on pollen grains of flowering plants and became their pollinators.
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Sources:
• EurekAlert. (n.d.). Scientists uncover the last meal of a cretaceous pollinator.
• Manduffie, D. (2021, April 12). A prehistoric beetle may provide new evidence of ancient pollinators.
• Science X Staff. (2021, April 12). Unusual fossil reveals last meal of prehistoric pollinator.
• Tihelka, E., Li, L., Fu, Y., Su, Y., Huang, D., & Cai, C. (2021, April 12). Angiosperm POLLINIVORY in a CRETACEOUS BEETLE.
• University of Bristol. (n.d.). Unusual fossil reveals last meal of prehistoric pollinator.
