DENVER--Scientists have excavated near the Arctic Circle in Russia what they believe are the oldest fossils of a mollusk-like animal. The fossils, dated between 550 million and 560 million years old, are the first examples of such animals in the Precambrian period, which has a notoriously sparse fossil record.
In a presentation at the Geological Society of America meeting here, grad student Bruce Waggoner of the University of California, Berkeley, said the living animal likely had a firm shell surrounded by softer ruffles that might have been gill-like structures. The fossils appear to have a mollusk-like mouth and may have had muscles under their shell similar to those of modern-day mollusks. To get an idea of what the 8-centimeter creature might have looked like, says Waggoner, imagine an Elizabethan person with a frilly collar "wearing a hard hat that's too large."
Waggoner and a team from the Paleontological Institute of the Russian Academy of Sciences in Moscow unearthed more than 20 fossils on the coast of the White Sea, just below the Arctic Circle, in 1994. The number of specimens allowed them to reconstruct with some confidence the shape of the living animal, which is 20 million to 30 million years older than the previously oldest known mollusk.
Paleontologists have gathered many fossils of what appear to be mollusk tracks from the Precambrian period, says University of California, Berkeley, biologist James Valentine, who's not affiliated with the group. "But this is the first time an actual body has been found," he says. The jury is still out, however, on whether Waggoner truly has found a mollusk. "It looks very promising, but it's hard to know for sure," says University of California, Los Angeles, geologist Bruce Runnegar.