A small beetle trapped in amber could show how the land masses moved

After carefully cutting and polishing amber, Yamamoto determined that this insect, smaller than the charger of an iPhone, was a new species for science. The beetle, which lived 99 million years ago, is a parent of living insects that live under the bark of trees and gives scientists clues as to how the landmasses of the Earth were laid out millions of years ago.

"This is a very rare discovery," said Yamamoto, a researcher at the Field Museum and lead author of an article in Journal of Systematic Palaeontology describing the new species. The fossil beetle is one of the oldest members of his family: his name, Propiestus archaicus, refers to the fact that it is a former parent of the bark beetle Piestus kind today which now dominates South America.

While the dinosaurs roamed much of the Earth 99 million years ago during the Upper Cretaceous, Propiestus, with its flattened body and short legs, was busy conquering a smaller turf beneath the surface. bark of rotten trees. Its long, thin antennae clearly indicated to Yamamoto that Propiestus lived in this environment, similar to the mountain beetle.

"The antennas probably had an extremely sensitive sensory organ capacity," said Yamamoto. Structures resembling smaller hair, attached perpendicular to the antennas, would have increased its ability to detect the environment. "There would not have been much space available in the beetle habitat, so it was important to be able to detect everything," he says.

Propiestus is just one of hundreds of thousands of Amber inclusions from Burma – another word for objects trapped inside this amber – on which scientists have been extensively documented over the past 15 years . Many small insects that lived during the Cretaceous met their creator in the hands of tree sap that engulfed insects and hardened to become amber. The insects trapped inside have fossilized and remained frozen for millions of years, unaffected by the passage of time. The hardened amber, covered with earth, rotting leaves and other organic matter eventually melted into its environment.

Because of this, the nature of amber does not look like that of jewelry – in fact, it does not look like anything special. The small masses of unpolished amber look like rocks, which means that only people with experience in identifying amber, mostly local miners, are able to find them.

After mining by amber miners, the clumps are either sold in the jewelery trade, or to scientists like Yamamoto to study inclusions. For Yamamoto's amber piece, he used sandpaper to carefully polish the amber just enough to make it Propiestus clearly visible.

"It was very exciting because the cutting process is very sensitive," Yamamoto said. "If you cut too fast or apply too much pressure, you destroy the inside inside very quickly."

Once polished amber, the beetle was clearly visible, which allowed Yamamoto and his colleagues to study it and determine his closest relatives alive. PropiestusThe cousins ​​of the beetle are mostly living in South America, with the exception of one species in southern Arizona. Myanmar, where Propiestus was found, is literally on the other side of the world. But it has not always been like that.

Millions of years ago, Myanmar and South America were actually very close to each other, all merged into the Gondwana megacontinent, which formed at the time of the rupture of the first megacontinent, Pangea. Gondwana has itself broken down, helping to form the continents that we recognize today on a map.

Scientists have a clear idea of ​​the current continents and sub-continents that would have made up Gondwana and that would have made up its sister continent, Laurasia. However, the detailed calendar and structure of Gondwana's division into several continents is debatable. Searching supporting or contrasting evidence means analyzing fossils, some as small as Propiestus, to compare their similarities with other organisms discovered in the world that would have inhabited the same space for a long time.

"Like koalas and kangaroos today, some animals that we think have lived in Gondwana are only found in one part of the world.Although Propiestus has long since disappeared, our findings probably show astonishing links between Southern Hemisphere and Myanmar, "said Yamamoto. "Our conclusion is consistent with the assumption that, unlike what is happening today, Myanmar was once located in the southern hemisphere."

Many inclusions in Burmese amber that have been the focus of research over the last 15 years, including Propiestus, show signs that show common traits with Gondwana insects. By studying these tiny creatures trapped in amber, we find answers to questions about the structure of the Earth and the life it supported millions of years ago.

"This fossil helps us understand life in the Mesozoic era," he said. "We have to think of everything from that moment on, big and small."

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