India ‘may not have been an isolated island-continent 50mn yrs ago’
By ANITuesday, October 26, 2010
WASHINGTON - Scientists have discovered amber deposits containing bees, termites, spiders, and flies - the find has challenged the assumption that India was an isolated island-continent in the Early Eocene, or 52-50 million years ago.
The amber is also the oldest evidence of a tropical broadleaf rainforest in Asia.
“We know India was isolated, but when and for precisely how long is unclear,” said David Grimaldi, curator in the Division of Invertebrate Zoology at the American Museum of Natural History.
“The insects trapped in the fossil resin cast a new light on the history of the sub-continent,” said Jes Rust, professor of Invertebrate Paleontology at the Universit�t Bonn in Germany.
Grimaldi, Rust, and colleagues describe the Cambay amber as the oldest evidence of tropical forests in Asia. It belongs to a family of hardwood trees that currently makes up 80 percent of the forest canopy in Southeast Asia.
Fossilized wood from this family was found as well, making this deposit the earliest record of these plants in India and showing that this family is nearly twice as old as was commonly believed.
Also found were 100 arthropod species that represent 55 families and 14 orders. Some of these species are early relatives of highly social, or eusocial, insects like honey bees and stingless bees, rhinotermitid termites, and ants, suggesting that these groups radiated during or just prior to the early Eocene.
“What we found indicates that India was not completely isolated, even though the Cambay deposit dates from a time that precedes the slamming of India into Asia,” said Michael Engel at the University of Kansas.
Climate might have also played a role in the fauna found in the Cambay amber. The Early Eocene was a time of great climatic warmth: the tropics reached the poles. The researchers predict that the climate would have had an effect on the distribution of arthropods.
The discovery is published this week in Proceedings of the National Academy of Sciences. (ANI)
