This fossilized fly was discovered in a Peruvian amber deposit
Credit: Darío de Franceschi
Fossils Reveal Ancient Biodiversity
By Julio Godoy
A fascinating amber deposit in Peru containing fossilized flies, wasps and spiders proves that the rich diversity of Amazon species dates back much further than previously thought. Tierramérica spoke with the international team that made the discovery.
PARIS, Sep 25 (Tierramérica).- The discovery of an amber deposit formed in the Amazon during the Miocene epoch proves that the region's rich biological diversity dates back some 16 million years, members of the research team that made the finding told Tierramérica
The Miocene era encompasses the period of Earth's development between 23 million and five million years ago.
In 2004, a group of researchers from the United States, France, Britain, Mexico and Peru discovered a small amber deposit embedded with insect fossils and plant matter in the Western Amazon, close to the northern Peruvian city of Iquitos.
The preliminary findings were announced Aug. 28 in Paris by the team, which is coordinated by Pierre Olivier Antoine, a geology researcher with the Paul Sabatier University in Toulouse, France.
The insects found fossilized in the amber -- wasps, weevils, flies, tiny mites and even a spider caught in its own web -- belong to 13 different families, compelling evidence of the region's rich biodiversity during the middle Miocene. In contrast, today's average garden hosts insects from a mere three families.
"The amber contained several kinds of insects, such as coleoptera, psocoptera, diptera, hemiptera and arachnids, as well as microfossils such as spores, pollen and algae," Rodolfo Salas Gismondi, a Peruvian paleontologist on the team, told Tierramérica.
Aquatic larvae and plant matter were also found trapped in the amber.
"The samples contain four unknown insect species. We couldn't identify them more specifically -- insect fossils are rare, so not many classification parameters are available, especially for something 15 million years old," added Salas Gismondi, who works at the Natural History Museum of the National University of San Marcos de Lima.
Antoine called the discovery "extraordinary".
"Amber (fossilized tree resin) is abundant in many parts of the world, especially in the northern hemisphere, but it is rare to find fossils in amber in South America,” the French expert told Tierramérica.
"Before our discovery, fossil-bearing amber had been found in three areas -- Patagonia, eastern Brazil and French Guyana -- but never in the Amazon region," he said.
"The pieces of amber we found are so small that they fit in a box of matches. Yet they represent a vast biological diversity," he said.
Antoine said the discovery suggests that during the middle Miocene era the western Amazon basin was a hot, humid and densely forested place teeming with a variety of ancient species comparable to today's biodiversity. The Amazon basin is considered the world's richest biotope.
This discovery disproves the theory that the Amazon's biodiversity developed only after the Miocene period, following the last ice age (approximately 10 million years ago).
"The amber we found confirms one of our hypotheses: that this epoch (the middle Miocene) was one of the most megadiverse times of all in the Amazon and was the foundation for today's rich biodiversity," said Salas Gismondi.
The discovery also suggests that biological evolution in what is now modern-day South America occurred separately from similar processes in North America, given that during the middle Miocene the current subcontinent was an isolated land mass. The Central American isthmus has bridged the two hemispheres only for the last three million years.
"During this period, South America was a huge island and a huge inland ocean, called the Pebas Sea, covered most of the Amazon region," said the Peruvian expert.
Palaeontologists called the chance discovery "a lucky break."
"Our team was looking for plant matter and fossils of large vertebrates to study climate evolution in the western Amazon basin. But we did not expect to find insect remains, because they have no skeletons and therefore are rarely preserved as fossils," said Antoine.
The investigation is part of a larger program run by France's National Center for Scientific Research (CNRS), called "Neogenic evolution of the Western Amazon basin and biodiversity and their relationship with the geological dynamic of the Andes."
"Because the Amazon basin forest is so dense, there are few paleontological and geological studies of the region that focus on this period," explained Antoine.
The fossils are currently undergoing DNA and protein analysis in Paris, in order to catalog their phylogenetic and taxonomic characteristics, and in 2007 the amber will be moved to Lima's Natural History Museum. CNRS research on the fossils will continue until 2008.
* Julio Godoy is an IPS correspondent.