Insects and spider webs, found locked in amber for 112 million years, have stories to tell

Insects trapped in ancient amber tree resin, discovered deep in Ecuador’s Amazon region, just changed what we know about South America’s prehistoric ecosystems.

This amber isn’t just old – it’s 112 million years old. It holds tiny creatures from a tropical rainforest that existed long before the Andes rose or the Amazon River flowed.

This is the first time anyone has found Mesozoic amber with preserved insects in South America. It’s a big deal because this means scientists now have a direct window into what life looked like in the middle of the Cretaceous Period.

This evidence is not from the well-studied north, but from the rarely-explored southern part of the ancient supercontinent, Gondwana.

Understanding amber fossils

When insects, spiders, or even tiny lizards got stuck in sticky amber resin many millions of years ago, the resin quickly covered them and protected their bodies from decay.

Over time, the resin fossilized into amber, preserving these creatures in remarkable detail.

Unlike most fossils, which are impressions in rock, amber fossils can hold actual tissues, hairs, or delicate features like wings and antennae, almost like nature’s time capsules.

Scientists study amber fossils because they provide direct evidence of ancient ecosystems.

By examining the organisms trapped inside, researchers can learn about what kinds of species existed, how they interacted, and even what plants and climates were like millions of years ago.

Insects frozen in ancient amber

The amber was unearthed in Napo province, at a site known as the Genoveva quarry. Now, the area belongs to the Amazon Basin’s lush surroundings. But back then, it was a dense, wet forest, full of life.

The amber formed from sticky, conifer resin that most probably belonged to trees from the Araucariaceae family. These are relatives of today’s monkey puzzle trees.

The resin flowed out, trapped insects, solidified, and got buried over time. Millions of years later, scientists have found some well-preserved samples that contain microscopic flies, beetles, wasps, and even fragments of a spider’s web.

“This is the largest Mesozoic amber deposit in South America and one of the richest in Gondwana with bioinclusions,” said Professor Xavier Delclòs, the lead author of the study.

What the insects reveal

The team studied 60 amber pieces and found 21 inclusions from at least five different insect orders, including flies (Diptera), beetles (Coleoptera), ants and wasps (Hymenoptera).

“Mostly chironomid and ceratopogonid dipterans were found, as well as springtails, coleoptera, hymenoptera, trichoptera, hemiptera and a fragment of a spider web,” said Enrique Peñalver from the IGME in Valencia.

Some of these insect families, like the now-extinct wasps †Stigmaphronidae, are extremely rare. Their presence suggests a rainforest ecosystem with freshwater streams and ponds.

Unlike other fossil sites from the same era, this one showed no signs of fire, which supports the idea that it was a very wet environment.

Leaf fossils also paint a picture

The amber comes from a fluvial-lacustrine setting – basically, an area where rivers and lakes shaped the landscape.

Surrounding rock layers from the same site also contained spores, pollen, and fossilized leaves from plants like ferns, cycads, and some of the earliest flowering plants (angiosperms).

“Everything indicates that the ancient ecosystem was wooded, humid and diverse, and has the oldest known association of angiosperm leaves in north-western South America,” said Delclòs.

Clues written in stone and resin

“The pollen and macrofossils identified in the rocks that contained the amber reveal a forest with pteridophytes (ferns and related species), Araucariaceae and Cheirolepidaceae conifers, cycads and early angiosperms,” said Carlos Jaramillo from the Smithsonian Tropical Research Institute (STRI).

He also noted the presence of epiphytic fungi and fungi that lived on the resin itself.

The amber itself came in two forms. One type formed underground around tree roots and had no inclusions.

The other formed above ground, in open air, and is the type that preserved the insects. Both types of amber were chemically altered due to the area’s proximity to oil deposits in the Hollín Formation.

“This amber is chemically mature and altered by exposure to oil, as the Hollín Formation is an oil source rock, and is currently commercially exploited,” explained César Menor Salván from the University of Alcalá.

New path to ancient ecosystems

The discovery doesn’t just tell us about a long-gone rainforest. It also fills a major gap in how we understand the breakup of Gondwana.

This is the ancient supercontinent that once included South America, Africa, Antarctica, and Australia.

“This study outlines a new framework for understanding equatorial ecosystems during the Cretaceous, and the biogeographical relationships of their components when the modern continents broke away from the supercontinent Gondwana,” the researchers wrote.

“Future excavations could help connect South American biodiversity with other regions of Gondwana, such as Antarctica, Australia and South Africa, where Cretaceous amber has also been found,” explained Monica Solórzano Kraemer from the Senckenberg Natural History Museum.

More insects in amber yet to be found

There’s still a lot to uncover at the Genoveva quarry. With just 60 amber pieces analyzed so far, scientists expect to find even more bioinclusions in future digs.

Every insect, every speck of pollen, and every tiny fossil could help answer questions about how life in tropical South America looked during the age of the dinosaurs.

And this is only the beginning. The discovery is a reminder that the past still has plenty of secrets. These may be buried deep in the rainforests that have stood for over 100 million years.

The full study was published in the journal Communications Earth & Environment.

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