Call it a 100-million-year-old piece of voyeurism, but scientists have found a fossilized piece of amber containing an extinct flower species in the act of copulating.

The amber, which contains a cluster of 18 small flowers from the Cretaceous Period, includes the newly-named Micropetasos burmensis, which contains the pollen tubes from two grains of pollen penetrating the female plant's stigma, setting the stage for the reproductive process.

"This is the beauty of amber fossils. They are preserved so rapidly after entering the resin that structures such as pollen grains and tubes can be detected with a microscope," said George Poinar, Jr., a professor emeritus in the Department of Integrative Biology at Oregon State University.

This fossilized picture of plant copulation shows that flowering plants, otherwise known as angiosperms, reproduced in the same way back then as they do today. The sticky pollen also indicates that they used insects to transport them.

"The evolution of flowering plants caused an enormous change in the biodiversity of life on Earth, especially in the tropics and subtropics," Poinar said.

"New associations between these small flowering plants and various types of insects and other animal life resulted in the successful distribution and evolution of these plants through most of the world today. It's interesting that the mechanisms for reproduction that are still with us today had already been established some 100 million years ago."

It was during the Cretaceous Period that some of the world's first flowering plants began to appear on the scene after millions of years of mostly conifers, ferns, mosses, and cycads.

You can read the full published study detailing the findings in the Journal of the Botanical Research Institute of Texas.