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Fossils Reveal Ancient Biodiversity |
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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 - 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. |
