Orchids co-existed with dinos 80 million years ago

The fossil of a 15- to 20-million-year-old specimen of a worker bee preserved in amber with a mass of orchid pollen on its back has scientists excited, for it shows that orchids co-existed with dinosaurs 80 million years ago.

London, Aug 30 : The fossil of a 15- to 20-million-year-old specimen of a worker bee preserved in amber with a mass of orchid pollen on its back has scientists excited, for it shows that orchids co-existed with dinosaurs 80 million years ago.

The finding of the fossilised bee, the researchers from Harvard University state, is exciting because while orchids are the largest and most diverse plant family on the planet, there exists very little direct evidence of pollination in the fossil record.

"Since the time of Darwin, evolutionary biologists have been fascinated with orchids' spectacular adaptations for insect pollination. But while orchids are the largest and most diverse plant family on Earth, they have been absent from the fossil record," Nature magazine quoted lead author Santiago R. Ramirez, a researcher in Harvard's Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, as saying.

The finding is important as it means that the exotic flowers are much older than they were previously thought to be.

"Our analysis places orchids far toward the older end of the range that had been postulated, suggesting the family was fairly young at the time of the extinction of the dinosaurs some 65 million years ago. It appears, based on our molecular clock analyses, that they began to flourish shortly after the mass extinction at the so-called 'K/T boundary' between the Cretaceous and Tertiary periods, which decimated many of Earth's species," Ramírez said.

According to Ramirez, the reason why evidence of orchids is lacking in the fossil record is because the flowers not only bloom infrequently but also because they are concentrated in tropical areas where heat and humidity prevent fossilization.

As a result, their pollen is dispersed not by wind, but only by animals.

Another thing that makes fossilization difficult is that the pollen disintegrates upon contact with the acid used to extract pollen from rocks.

The fossilised bee, Proplebeia dominicana, was recovered by a private collector in the Dominican Republic in 2000, and came to the attention of the researchers in 2005.

While this particular species of stingless bee is now extinct, the analysis of pollen it carries firmly places the flower within one of five extant subfamilies of orchids.

Even the placement of the pollen on the bee's back has boffins excited, for it not only confirms that the grains were placed through active pollination -- as opposed to a random encounter with an orchid -- but also sheds light on the exact type and shape of orchid flower that produced the pollen all those million years ago.

By applying the so-called molecular clock method, the scientists also estimated the age of the major branches of the orchid family. To their surprise, they found that certain groups of modern orchids, including the highly prized genus Vanilla, evolved very early during the rise of the plant family.

"This result is puzzling and fascinating at the same time because modern species of Vanilla orchids are locally distributed throughout the tropical regions of the world. But we know that tropical continents began to split apart about 100 million years ago, and thus our estimates of 60 to 70 million years for the age of Vanilla suggest that tropical continents were still experiencing significant biotic exchange much after their dramatic split," says Ramirez.

The scientists' analysis is published this week in the journal Nature.

ANI