(CN) - Deep in an Ecuadorian quarry, a 112-million-year-old fly sits preserved in amber, marking the first discovery of ancient insects trapped in fossilized tree resin in South America.
The find, published Thursday in Communications Earth & Environment, opens a window into Gondwana's rainforests, revealing for the first time the types of creatures that lived in South America's forests during the age of dinosaurs.
Until now, almost all major amber discoveries containing ancient life have come from the Northern Hemisphere, leaving scientists largely in the dark about what insects and other small creatures lived in the southern continents at that time.
Xavier Delcls, a paleontologist at the University of Barcelona who led the research, worked with an international team of scientists from nine countries including Argentina, Brazil, Colombia, Ecuador, Germany, Panama, Sweden and the United States. They extracted the amber from Ecuador's Genoveva quarry, where the Hollin Formation preserves layers of rock dating back to a time when Earth was much warmer and wetter than today and flowering plants were beginning to appear.
The team identified two distinct types of amber in the formation. One type formed underground around the roots of resin-producing plants, while the other - less common aerial amber - formed from resin exposed to air. The aerial amber trapped insects and other small creatures as the resin dripped from trees, while the underground amber generally did not.
The size difference between the two types is significant. Aerial amber pieces are usually small (less than 7 cm) and stalactitic in shape, while root-derived amber can be up to 40 cm and is typically subspherical or kidney-shaped.
From 60 aerial amber pieces, scientists extracted 21 tiny ancient animals representing at least six orders, including various flies from multiple families, beetles, wasps and a fragment of spider web. They also identified a wide variety of plant fossils in the rock samples, including spores, pollen and other remains.
The fly specimens included multiple families: Ceratopogonidae (biting midges), Chironomidae (non-biting midges), Scatopsidae, and Dolichopodidae. The researchers found six chironomid specimens alone, suggesting freshwater bodies or persistently moist conditions in the ancient forest.
They found tiny wasps that likely hunted other insects. Two families, Stigmaphronidae and Scelionidae, were identified, and these small wasps likely laid their eggs in or on other insects, acting as parasites.
In order to determine the types of trees that produced the amber, the scientists conducted advanced chemical analyses. Their tests indicated the amber came from Araucariaceae, ancient relatives of today's monkey puzzle trees and Norfolk pines.
The fossil record also indicates the forest was highly diverse. The Hollin Formation at the Genoveva quarry preserves what the researchers described as "the earliest documented association of angiosperm leaves from north-western South America." Pollen analysis showed the taxonomic composition of the ancient flora was dominated by pteridophytes, which include ferns and fern allies (42% of taxa), followed by flowering plants (37%), gnetophytes (13%), and conifers (8%).
The insect inclusions suggest the forest was humid and swampy.
"The presence of relatively abundant chironomid flies and one trichopteran as bioinclusions - both insect groups with aquatic larval stages - further supports the interpretation of predominantly humid conditions," the researchers wrote in their study.
Delcls and his team believe this discovery is only the start. Ongoing digs in Ecuador could turn up more amber specimens, giving scientists a clearer picture of how life in South America changed after the breakup of Gondwana.
"Future fieldwork exploration in the Hollin Formation of the Napo region is expected to yield new fossil bioinclusions, which may improve our understanding of the biogeographic relationships between the South American fauna and flora and those of other Gondwana regions," the researchers said.
Source: Courthouse News Service
