Fossils rarely retain evidence of an organism’s original color, but these 99-million-year-old amber fossils found in Myanmar reveal the vibrant hues of another world.
New investigation Published today in Proceedings of the Royal Society B highlights dozens of amber fossils from the Cretaceous period that still contain evidence of the original colors of their occupants. Bursting into metallic blues, purples and greens, these ancient insects are bizarre and strangely familiar.
It goes without saying that nature is very colorful. Unfortunately, however, fossils often provide a dull, monochromatic view of the past. That said, paleontologists are finding ways to extract colors from well-preserved fossils, either dinosaurs and flying reptiles or old snakes and mammals.
Determining the color of extinct species is important because it can tell paleontologists one or two things about the animal’s behavior, such as whether it used flamboyant colors to attract mates or prevent potential predators, camouflage to hide or hide, or colors that helped with temperature regulation. Color can also shed light on ancient environments and ecosystems, particularly when it comes to camouflage.
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For the new study, a research team from the Nanjing Institute of Geology and Paleontology at the Chinese Academy of Sciences (NIGPAS) studied 35 individual samples of amber with fantastically preserved insects trapped inside. The fossils were found in an amber mine in northern Myanmar.
“Amber is from the Middle Cretaceous, approximately 99 million years old, dating back to the golden age of dinosaurs,” said Cai Chenyan, an associate professor at NIGPAS and lead author of the new study, in a press release. “It is essentially resin produced by ancient coniferous trees that grew in a tropical jungle environment. Animals and plants trapped in the thick resin were preserved, some with real fidelity. “
Colors in nature tend to fall into three main categories: bioluminescence, pigments, and structural colors. These amber fossils retain structural colors, which tend to be intense and quite striking (including metallic colors), and are produced by microscopic light scattering structures located on the heads, bodies, and limbs of animals.
“The type of color preserved in amber fossils is called structural color,” said Pan Yanhong, co-author of the study and professor at NIGPAS. “The surface nanostructure scatters light of specific wavelengths” which “produces very intense colors,” said Pan, adding that this “mechanism is responsible for many of the colors we know of in our daily lives.”
These amber fossils retained evidence of their structural colors, but not before careful preparation, as the authors explain in their article:
For standard observation, the fossils were polished using different grades of sandpaper and diatomite powder, to get as close as possible to the [fossils] as possible without damaging them. Where it helped observation, some pieces were polished into very thin slices, making the insect [fossils] clearly observable and the surrounding amber matrix almost transparent to bright light.
For you photographers out there:
Pictures were taken with various backgrounds using a Canon EOS 5D Mark III digital camera, equipped with a Canon MP-E 65mm (F2.8, 1–5X) macro lens, and with an attached Canon MT-24EX dual flash. Focus stacking software (Zerene Stacker, v. 1.04) was used to increase depth of field.
The images were edited in Photoshop, but only to adjust the brightness and contrast.
Cuckoo wasps were particularly impressive, with their heads, thorax, abdomen, and legs in shades of metallic greenish-blue, yellow-red, purple, and green. Fascinatingly, these color patterns matched the cuckoo wasps alive today, according to the research. Other highlights include blue and purple beetles, and metallic dark green soldier flies. The greenish-blue colors were attributed to camouflage, but other functions, such as thermoregulation, could not be ruled out.
To test whether the observed colors were caused by the nanostructures, the scientists made some theoretical models. They studied a selected wasp sample using an electron microscope, which allowed them to combine patterns with specific colors. Specifically, the reflectance wavelengths at 514 nanometers corresponded to the teal color as seen under white light, which matched very well with his own eyes.
The colors seen in these amber samples are therefore indicative of how these insects actually appeared during the Cretaceous, according to the research.
“[Our] observations strongly suggest that the color preserved in some amber [fossils] it may be the same as insects show when they are alive, about 99 million years ago, “the authors wrote in the study.” This is further corroborated by the fact that metallic blue-green coloration is frequently found in existing ones. [living] cuckoo wasps. “
The authors also looked at amber fossils in which color was not preserved. In these cases, the nanostructures suffered severe damage, resulting in a brownish-blackish coloration.
This is an exciting result, Because it means that other amber fossils can also produce structural colors. It’s time for scientists to revisit some old specimens.
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