PHILADELPHIA -- Ohio State University geologists have isolated complex organic molecules from 350-million-year-old fossil sea creatures -- the oldest such molecules yet found.
The molecules may have functioned as pigments, but the study offers a much bigger finding: an entirely new way to track how species evolved.
Christina O'Malley, a doctoral student in earth sciences at Ohio State, found orange and yellow organic molecules inside the fossilized remains of several species of sea creatures known as crinoids. The oldest fossils in the study date back to the Mississippian period.
She reported the find Wednesday at the meeting of the Geological Society of America in Philadelphia.
Crinoids still exist today. Though they resemble plants, they are marine animals. They cling to the seafloor and feast on plankton that float by.
The crinoids in this study had flower-like fronds capping skinny stalks about six inches high -- a look resembling "starfish on a stick," said William Ausich, professor of earth sciences and O'Malley's co-advisor with Yu-Ping Chin, also a professor of earth sciences.
Today's crinoids display a range of colors, some variegated shades of red, orange, and yellow, so the geologists weren't surprised that some of those colors turned up in the 350-million-year-old crinoids, Ausich said.
"People have suspected for a long time that organic molecules could be found inside fossils," he added. "This is just the first time that scientists have succeeded in finding them."
Though the organic molecules could be classified as pigments, nobody can be sure that they functioned as pigments inside these ancient animals, the geologists emphasized. They may have served some other purpose besides coloration -- perhaps to defend the animal from predators by making it less palatable.