Strange fossils, including some that could be predecessors to modern animals, found in China shed new light on the evolution of large, complex organisms, and indicate that they may have diversified earlier than thought.
Researchers believe that the rocks containing these fossils, found in southern Anhui Provence, date between 635 million and 580 million years ago. The new types of organisms discovered in them include two that are fan-shaped, as long as 2 inches (5 centimeters), and resemble seaweed, as well as three other new types of organisms that are difficult to classify as animal or plant.
“Some of my colleagues are more leaning toward the animal interpretation,” said study researcher Shuhai Xiao, a professor of geobiology at Virginia Polytechnic Institute and State University. “But my personal view is that we still don’t know what they are.”
One of the three could be interpreted as resembling the early life stage of a polyp, or a sea anemone. The other two mysterious organisms have tube-like structures that could represent the digestive system of worm-like animals. For one of these, the call for plant or animal depends on perspective.
You could interpret the bulbous structure at one end of its stalk as a holdfast, which seaweed use as an anchor, making the organism a plant. Or you could see a proboscis, a tube-like feeding structure, and a simple, worm-like animal, the authors write in today’s (Feb. 17) issue of the journal Nature.