Next time when someone will ask which flowers are the oldest, you could answer the orchids, because the biologists at Harvard University have just discovered that they have co-existed with dinosaurs.

According to their findings, published this week in the journal Nature, the orchids arose some 76 to 84 million years ago. The scientists have identified the ancient fossilized remains of a pollen-bearing bee as the first hint of orchids in the fossil record.

The 15- to 20-million-year-old specimen of a worker bee carrying orchid pollinia, recovered by a private collector in the Dominican Republic in 2000, came to the attention of Ramírez and his colleagues at Harvard's Museum of Comparative Zoology in 2005.

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

Also Ramirez explained that the fossil record lacks evidence of orchids, because they bloom infrequently and are concentrated in tropical areas where heat and humidity prevent fossilization.

Until this study, the scientists believed that the orchids are at anywhere from 26 to 112 million years old. "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," Ramírez says. "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