In an Ecuadorian quarry, researchers have uncovered an exceptional fossil treasure: 112-million-year-old amber containing perfectly preserved insects. This discovery opens a unique window onto the tropical forests that covered the supercontinent Gondwana during the Cretaceous, a crucial period in Earth's history when modern continents were beginning to separate.
Amber, this fossilized tree resin, has the remarkable property of trapping and preserving living organisms with incredible detail. While most known amber deposits are found in the northern hemisphere, this discovery in Ecuador fills an important gap in our understanding of the ancient biodiversity of the southern hemisphere. Scientists have identified two distinct types of amber: one formed deep underground around tree roots, the other exposed to the open air before fossilization.
This beetle likely fed on fungi in a Cretaceous forest.
Credit: Enrique Peñalver The meticulous analysis of 60 aerial amber samples revealed 21 remarkable biological inclusions. Among these treasures frozen in time, researchers identified representatives from five different insect orders, including Diptera (flies), Coleoptera (beetles) and Hymenoptera (which includes ants and wasps). A fossilized spider web completes this picture of exceptionally well-preserved ancient biodiversity.
The characteristics of these biological inclusions, combined with the study of surrounding plant fossils - spores, pollen and other remains - allow scientists to reconstruct the environment of that time. They describe a humid, dense forest dominated by resin-producing trees, located in the southern part of Gondwana. This discovery thus offers a detailed portrait of a Cretaceous tropical ecosystem.
This study, published in
Communications Earth & Environment, represents a major advance for paleontology. It enables the study of fragile organisms like insects and arachnids that rarely fossilize under other conditions.
Amber: a natural time capsule
Amber forms when resin secreted by certain trees, mainly conifers, undergoes a fossilization process over millions of years. This organic material gradually hardens while maintaining its transparency, allowing observation of the inclusions it contains.
Fresh resin acts as a natural trap for small organisms. Its initial viscosity prevents their escape, and its gradual solidification permanently imprisons them. The anaerobic environment created by encapsulation prevents decomposition, thus preserving the most delicate structures.
Unlike conventional fossils where only hard parts are preserved, amber can preserve extremely fine anatomical details: membranous wings, sensory hairs, and even cells and organic molecules in some exceptional cases. This preservation makes it a valuable tool for studying evolution.