Fossil sheds light on buttercups' origins

A 125-million-year-old fossil has unveiled new information about the evolution of flowering plants, thanks to an international group of scientists that includes IU biologist David Dilcher.

Dilcher first met his Chinese colleague Ge Sun in 1986. The two shared an office at the British Museum of Natural History in London.

Ge Sun and Dilcher started working together doing research in the 1990s, and they published a major paper in science in 1998 and 2002 titled “The First Flower in the World,” which featured information about a particular area in northeast China that feathered dinosaurs and the earliest birds and mammals once inhabited.

“It’s a special place with a lot of really interesting animals and interesting plants,” Dilcher said.

Dilcher and Ge Sun have published four “First Flower” features, the latest of which was published in Nature Magazine about a eudicot fossil found to be proof of a shared species origin of most flowering plants.

A eudicot is a species of a flowering plant. Eudicot plants make up a large percentage of plants worldwide. Various types include water lilies; buttercups and maple, oak and tulip trees. This fossil is part of the Ranunculaceae (buttercup) family.

Dilcher, who is also the co-author of the Nature article, said he believes this 6.3-inch-tall fossilized plant dates back 125 million years. A single stem branches out into five leaves, one of which leads to a fully developed flower. The small, cup-shaped flower has five petals.  

It was believed to be found in the Daxinfangzi Bed of the middle part of the Yixian Formation. The bed is mainly composed of yellowish-gray and gray sandstone implanted with gray silt stone, tuffaceous silt and fine-grained sandstone.

“This is the only specimen that has ever been found and is extremely rare,” Dilcher said.

Dilcher, Zhiduan Chen (Chinese Academy of Sciences) and Hongshan Wang (Shenyang Normal University) belonged to the group of scientists who named the fossil Leefructus mirus in adoration of Li Shiming, a nonscientist who obtained the specimen and kept it in his home but later donated the fossil to Ge Sun’s new museum of paleontology in Liaoning Province. Ge Sun led the group in research.

“I have a botanical background so I can put things in perspective in terms of evolution,” Dilcher said. “(Ge Sun) has a geology background and can put things in terms of stratigraphy and where they are. We take strengths along with the other co-authors.”

Ge Sun’s new museum is said to become the biggest museum in China. The museum is also dedicating the fossil in mid-May. Dilcher said a few of his IU colleagues have been invited, along with IU President Michael McRobbie.

Dilcher said he believes this discovery is important because the world is curious about the major origins of groups today.

“It gives us a good handle or foothold as to where was the beginning of radiation of these major eudicots.”