The latest discovery of amber in Ecuador's Amazon forest, which contains a wealth of preserved fossils of wasps, midges, flies, beetles, and other insects, provides insight into a South American ecosystem that was teeming with life 112 million years ago, during the dinosaur era.
Amber is tree resin that has fossilized. Amber can occasionally contain bioinclusions, which are creatures, fungi, and plants that became stuck in the sticky substance before it solidified and eventually fossilized.
Bioinclusions of insects and even a portion of a spider's web were found in the amber fragments that researchers discovered in a quarry close to the town of Archidona in Ecuador's Napo Province. Nearby, fossilized plant remains were discovered in the sediment.
The Ecuador discovery is the largest amber deposit from the dinosaur era discovered in South America to date, with nearly all of the major amber deposits discovered so far being in the Northern Hemisphere.
The area was a part of the vast ancient landmass known as Gondwana, which later divided into the Indian subcontinent, the Arabian Peninsula, Antarctica, Australia, South America, and Africa.
Paleoentomologist Xavier Delclòs of the University of Barcelona, lead author of the study published in the journal Communications Earth & Environment, "Finding a new site of this importance in the ancient continent of Gondwana provides very valuable information from a region where we previously had little data about the organisms that lived there."
Aphids, wasps, caddisflies, beetles, and midges—both biting and non-biting—were among the insects the researchers found in the amber.
According to paleoentomologist and study co-author Mónica Solórzano Kraemer of the Senckenberg Research Institute in Frankfurt, Germany, the insects found in the amber offer insight into the ecosystem they inhabited based on knowledge of the ecology of similar insects that are still alive today.
For example, the biting midges probably consumed the blood of the dinosaurs that were then roaming the area.
"Amber essentially preserves the exoskeletons of small organisms from the past. The preservation of these outer structures is so excellent that, under a microscope, they can look like freshly dead organisms, yet they are millions of years old," Delclòs said.
Delclòs added, "Resin is sticky and is produced by trees to block pathogens, so it traps anything living in or around the tree. Once exposed to air, the resin polymerizes and hardens, and if it is then buried in an oxygen-free environment for millions of years, it transforms into amber. Organisms without mineralized skeletons are rare in the fossil record, but amber preserves many of them in exceptional condition, like no other rock can."
The fossils come from a significant period of change in Earth's flora, when flowering plants were taking over. Some of the flora that existed at the location at the time was revealed by the fossilized plant remains. According to the fossils, approximately 37% of the flora was made up of flowering plants.
About 80% of all plants on Earth are flowering plants, or angiosperms, making them the largest and most varied plant group. They originated during the Cretaceous, the final period of the dinosaur era, and produce flowers and fruits from which they produce their seeds.
The gymnosperms, a group that predates them on Earth and includes conifers and a few others, are their closest relatives.
According to Delclòs, the fossils' discovery in Ecuador "opens a window into how the transition from gymnosperm forests to today's forests dominated by angiosperms took place."
