Discovery of insects trapped in amber sheds light on ancient Amazon rainforest

WASHINGTON — Scientists have discovered prehistoric insects preserved in amber for the first time in South America, offering a fresh glimpse into life on Earth during a period when flowering plants were just beginning to diversify. The amber fragments were found at a sandstone quarry in Ecuador on the edge of today’s Amazon basin and date to about 112 million years ago, according to Fabiany Herrera, curator of fossil plants at the Field Museum in Chicago and a co-author of the study published in Communications Earth & Environment.

Almost all amber deposits from the past 130 million years have been in the Northern Hemisphere, and it has long been “an enigma” that researchers have found few in southern regions that once formed the supercontinent Gondwana, said David Grimaldi, an entomologist at the American Museum of Natural History who was not involved in the discovery. The researchers identified ancient beetles, flies, ants and wasps in fossilized tree resin and said the find could illuminate how flowering plants and insects interacted during the dinosaur era, according to Ricardo Pérez-de la Fuente, a paleoentomologist at the Oxford University Museum of Natural History who was not involved in the study.

At the Genoveva quarry, the source of the specimens, researchers uncovered hundreds of amber fragments, some containing insects, pollen and tree leaves. The finds indicate a mid-Cretaceous forest that included ferns and conifers, and they suggest that a Monkey Puzzle Tree — a species that no longer grows in Amazonia — once grew there, Herrera said.

Jaramillo, a study co-author at the Smithsonian Tropical Research Institute who helped locate the quarry, recalled that the site is rich in amber and more visible in the open quarry than it would be if hidden under dense vegetation. “There’s so much amber in the mines,” he said, “and it’s more visible in the open quarry than it would be if hidden under dense layers of vegetation.”

“Amber pieces are little windows into the past,” Grimaldi said. Pérez-de la Fuente added that the discovery will help researchers understand the evolving interactions between flowering plants and insects that lived during the era of the dinosaurs. “Amber tends to preserve things that are tiny,” Grimaldi said, and “the time when the relationship between flowering plants and insects got started” was one of the most successful partnerships in nature, Pérez-de la Fuente said.

Looking ahead, researchers plan to continue analyzing the amber trove to learn more about Cretaceous biodiversity, including the insects that fed on flowering plants and their broader ecological context in what was then a different Amazon basin. The study adds to our understanding of mid-Cretaceous Amazonia and the coevolution of plants and insects, offering a clearer picture of how this once-southern rainforest looked and functioned during a pivotal period in Earth’s history.