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This week in Current Biology, researchers report tiny nematodelike fossils from the Ediacaran period, dating to about 15 million years before the Cambrian forms.

Excavating a site in Australia that contains fossils of other Ediacaran organisms, they found 1-centimeter creatures they named Uncus dzaugisi.

His mother, University of California, Riverside, paleoecologist Mary Droser, was searching for fossilized remnants of animals from the Ediacaran era, stretching from approximately 635 million years ago to 541 million years ago, during which the first complex animals evolved.

"We know they didn't just appear out of nowhere, and so the ancestors of all ecdysozoans must have been present during the preceding Ediacaran period."

Yet ecdysozoan fossil animals have remained hidden among scores of animal fossils paleontologists have discovered from the Ediacaran Period.