Portland, Ore. — A scientist has found a 100 million-year-old bee trapped in amber, making it possibly the oldest bee ever found.

"I knew right away what it was, because I had seen bees in younger amber before," said George Poinar, a zoology professor at Oregon State University.

The bee is about 40 million years older than previously found bees. The discovery of the ancient bee may help explain the rapid expansion and diversity of flowering plants during that time.

Poinar found the bee in amber from a mine in the Hukawng Valley of northern Myanmar, formerly known as Burma. Many researchers buy bags of amber from miners to search for fossils. Amber, a translucent semiprecious stone, is a substance that begins as tree resin. The sticky resin entombs and preserves insects, pollen and other small organisms.

Also embedded in the amber are four kinds of flowers. "So we can imagine this little bee flitting around these tiny flowers millions of years ago," Poinar said.

An article on his discovery will appear Friday in the journal Science, co-authored by bee researcher Bryan Danforth of Cornell University.

In the competing journal Nature this week, there is an article about the unraveling of the genetic map of the honeybee. The recently completed sequencing of the honeybee genome already is giving scientists fresh insights into the social insects.

Poinar's ancient male bee, Melittosphex burmensis, is not a honeybee and not related to any modern bee family.

The pollen-eating bee has a few features of meat-eating wasps, such as narrow hind legs, but the body's branched hairs are a key feature of pollen-spreading bees.

The bee -- about one-fifth the size of today's worker honeybee -- has a heart-shaped head.

But the ancient bee was probably an evolutionary dead end and may not have given rise to modern bees, scientists said.

"It's exciting to see something that seems so different from what we think of as modern bees," Danforth said. "It's not an ancestor of honeybees, but probably was a species on an early branch of the evolutionary tree of bees that went extinct."