Aug 29, 2007
Ancient orchid pollen found attached to a bee trapped in amber suggests the "supermodels of the plant world" were blooming at the time of the dinosaurs.
The discovery indicates that orchids arose between 76 and 84 million years ago, making them far older than experts had previously thought.
Experts used the fossil pollen grains to estimate the ages of major branches of orchids living today.
Details of the research by a team in the US are published in Nature journal.
Despite being the most diverse plant group on Earth, orchids are rare finds in the fossil record.
The authors of the Nature paper describe a mass of orchid pollen found stuck to the body of an extinct bee that lived 15-20 million years ago.
The remains of the bee were trapped and preserved in amber from the Dominican Republic.
Dating the fossil allowed lead researcher Santiago Ramirez to calibrate a "molecular clock" which uses mutations, or changes, in the plants' DNA to estimate the time of divergence between living organisms.
By building a "family tree" of orchids, the scientists could move back in time to see when the species first appeared, as well as where and how it spread.
They found that the most recent common ancestor of all modern-day orchids lived in the twilight of the dinosaurs, during the Late Cretaceous period.
"It is the first identifiable fossil orchid ever found," Mr Ramirez said.
"And it is the first case in which an insect-orchid interaction has been observed in the fossil record."
The new orchid species, identified from the morphology of the pollen, has been dubbed Meliorchis caribea.
The age of the first orchids has proven a controversial topic. Previous estimates have ranged from 26 to 110 million years ago.
The Orchidaceae family is the largest in the plant kingdom, numbering at least 25,000 species.