Coleoptera in amber from Cretaceous resiniferous forests
By: David Peris
Summarized by: Austin Spencer
Bio: Austin Spencer is a geology major at the University of South Florida and is currently a senior. Once he earns his degree, he plans to work for the Florida Department of Environmental Protection with the Florida Geological Survey and eventually would like to work at a community college teaching an introductory geology class to help teach a new generation of potential geologists. When he is not studying geology, he enjoys reading, hiking, and cycling in his free time.
What data were used? Beetle fossils discovered in Cretaceous-age amber from around the world. The age and location of these Cretaceous amber deposits are shown in Figure 1 on the stratigraphic chart of the Cretaceous. It is important to point out that no new materials from Myanmar were collected for this study. Paleontological associations have come together against buying and collecting fossils from Myanmar due to the human rights violations that are occurring in the country. You can read more here: Statement from the Society of Vertebrate Paleontology.
Methods: This study used a digital microscope to create up close images of fossil beetles in amber, as well as information from other scientific papers to create a taxonomic list of new beetle species found in various deposits of Cretaceous amber up to 2019. The taxonomic list can be found in the papers Appendix A.
Results: Coleoptera is an order that contains all species of beetles. This study highlights newly discovered species of coleoptera that are preserved in amber, which is fossilized tree sap, from the Cretaceous Period (~129-66 Ma). This study has revealed that there have been 364 new species discovered from Cretaceous-age amber. When an insect is preserved in amber, it is often preserved in great detail. This allows researchers to study the beetles as they were millions of years ago. This has led to ecological discoveries found from these new fossils. Some of the fossils discovered have shown a feeding structure called a spore brush, which is used to eat spores from fungi. These spore brushes have been observed in some modern mycophagous beetles, which are fungal feeding beetles. This discovery shows that fungal feeding beetles have been around since the Cretaceous. Another discovery from the study of Cretaceous fossil beetles is their role as pollinators. Today, bees and butterflies are known as the main pollinators; however, before bees and butterflies evolved to be pollinators, beetles were important insect pollinators. Researchers have found in the fossil record from these Cretaceous beetles that there are patterns of adaptations shown from the Early Cretaceous to modern pollinating beetles. Ancient beetles have also been thought as one of the causes of large-scale resin production from trees that go on the form the Cretaceous amber deposits, however, this has never been proven. The study uses an example from a beetle known as an ambrosia beetle, from Miocene Epoch (~23-5 Ma). These beetles are known to bore into wood and deposit ambrosia fungus into the wood, which they use as a food source. These beetles are known to be abundant in Miocene-age amber, which leads researchers to believe that beetles could be the cause of damage to resin-producing trees in other time periods as well.
Why is the study important? Coleoptera includes more than 400,000 species of beetles, which makes up about 25% of all living organisms. Beetles are important organisms for many different ecological interactions around the world. Beetles are pollinators, decomposers, and primary consumers. Since beetles are such an important part of ecosystems it is important that we understand the evolution of these organisms throughout history and how they interacted with past ecosystems to get a better understanding of modern beetles and their importance.
The big picture: This study highlights the abundance of beetles found recently in Cretaceous amber. With the discovery of these new species more research can be done to better understand how these organisms interacted with Cretaceous ecosystems as well as the evolution of beetles to modern day, though it is important to ensure ethical collection of amber fossils. This study will hopefully lead to new discoveries of Coleoptera and their supposed involvement in resin production in Cretaceous forests as well.
Citation: Peris, D., Coleoptera in amber from Cretaceous resiniferous forests, Cretaceous Research Vol. 113 (2020), https://doi.org/10.1016/j.cretres.2020.104484