A Newly Discovered Amber Deposit in South America

Amber is a fossilized form of tree resin. Because organisms can become trapped within the resin and preserved in remarkable detail, amber has long served as an invaluable resource for paleontological research. Although the origin of amber dates back to the Carboniferous period about 320 million years ago, amber containing preserved organisms did not become common until the early Cretaceous, roughly 125 million years ago. Such biologically rich amber deposits persisted until around 72 million years ago, after which they largely disappeared and only reappeared during the Cenozoic.

Most amber deposits containing biological inclusions are found in the northern supercontinent Laurasia. In contrast, amber fossils from the southern supercontinent Gondwana are comparatively rare. Only a few regions, such as Lebanon, Jordan, and the Congo, contain amber deposits of sufficient scale to support paleontological research. For this reason, each newly discovered amber site within Gondwana is highly valuable for reconstructing the ecosystems of ancient Gondwanan forests.

Amber locality in Ecuador（圖片來源：Delclòs, X et al. (2025).，採用 CC BY-NC-ND 4.0 授權。）

A study published in 2025 described a large amber deposit discovered in Ecuador. This site represents the largest Mesozoic amber deposit yet identified in South America. The amber formed during the early Cretaceous, approximately 112 million years ago. Importantly, it also represents the first known Mesozoic amber in South America that contains terrestrial arthropods, giving the discovery considerable scientific significance.

Analysis indicates that the amber from this locality formed in two distinct ways. One type developed near tree roots, where resin secreted underground accumulated within a relatively enclosed environment. This root-derived amber accounts for the majority of the deposit but rarely contains preserved organisms. The second type formed in open air from resin secreted by tree trunks or branches. Although less abundant, some pieces of this aerial amber contain trapped organisms.

Two types of amber: a–c formed from tree roots, while the others formed from resin exposed to the air（圖片來源：Delclòs, X et al. (2025).，採用 CC BY-NC-ND 4.0 授權。）

So far, researchers have identified 21 amber pieces containing biological inclusions. Most specimens are well preserved and consist primarily of arthropods. These include members of Collembola, Insecta, and Arachnida. Within the insects, the assemblage includes eleven Diptera, one Coleoptera, one Trichoptera, four Hymenoptera, and two Hemiptera. Among the dipterans, six specimens belong to the family Chironomidae. Because the larvae of these insects require freshwater habitats, their presence indicates that the forest in which the resin formed likely existed in persistently humid conditions or near standing freshwater bodies.

Various arthropods preserved within amber（圖片來源：Delclòs, X et al. (2025).，採用 CC BY-NC-ND 4.0 授權。）

No plant fragments have yet been found preserved directly inside the amber. However, the surrounding strata contain abundant fossils of pollen, spores, and leaves, allowing researchers to reconstruct the composition of the ancient forest. The flora included various ferns, cycad relatives, and other gymnosperms. Particularly significant is the presence of leaf fossils belonging to angiosperms. These represent the earliest known angiosperm leaf fossils from northwestern South America. Microscopic analysis has also revealed several kinds of epiphytic fungi growing on the fossil leaves.

Fossil plant leaves and pollen from the locality（圖片來源：Delclòs, X et al. (2025).，採用 CC BY-NC-ND 4.0 授權。）

These plant fossils indicate that during the early Cretaceous, the low-latitude region of northwestern Gondwana supported a species-rich and humid forest ecosystem. Numerous fern species and related plants likely occupied the forest understory or areas close to water. The dominant trees appear to have belonged to the Araucariaceae, and the amber itself was probably produced primarily by these conifers.

The presence of chironomid larvae and trichopteran larvae in the amber further supports the interpretation of a wet environment, since both groups require aquatic habitats during development. In addition, the geological layers at the site show no evidence of wildfire activity. This contrasts strongly with many northern hemisphere amber deposits, where charcoal is frequently found and suggests more fire-prone ecosystems.

The amber described in this study provides important insights into the arthropod communities that inhabited forests on the western side of Gondwana. It also has broader global importance. Continued exploration of the deposit is expected to uncover additional amber pieces containing biological inclusions. Such discoveries may help scientists better understand the biogeographic relationships between South America and other Gondwanan regions, including Antarctica, Africa, Australia, and New Zealand. Further research will be necessary to fully reveal the ecological and evolutionary implications of this remarkable site.

（Author: Bai Leng）

Reference:

Delclòs, X., Peñalver, E., Jaramillo, C., Cadena, E., Menor-Salván, C., Román, J. L., Castaño-Cardona, R. F., Peris, D., Carvalho, M., Quiroz-Cabascango, D., Carvalho, M. R., Blomenkemper, P., Herrera, F., Santamarina, P., Santer, M., Carrera, G., Solórzano-Kraemer, M. M. (2025). Cretaceous amber of Ecuador unveils new insights into South America’s Gondwanan forests. Communications Earth & Environment.