for National Geographic News
Scientists believe they have uncovered Earth's oldest known footprints in the mountains of Nevada—a fossil find that suggests animals have been walking around about 30 million years longer than previously thought, according to new research.
The controversial tracks—described by one skeptical scientist as "paired rows of dots"— may indicate animals had legs in the late Protozoic era, about 570 million years ago, according to lead researcher Loren Babcock.
The discovery is the strongest evidence to suggest animals were able to move about on their own appendages during the Ediacaran period, before the Cambrian period "explosion." During the Cambrian complex animals rapidly emerged and replaced simple multicellular animals, said the Ohio State University professor.
(Explore an interactive prehistoric time line.)
"We keep talking about the possibility of more complex animals in the Ediacaran—soft corals, some arthropods, and flatworms—but the evidence has not been totally convincing," he said in a statement.
"But if you find evidence, like we did, of an animal with legs—an animal walking around—then that makes the possibility much more likely."
Digging Up Dirt
The fossilized animal tracks were unearthed near Goldfield, Nevada, near Death Valley, in the Deep Spring rock formation.
The sedimentary formation—made of sandstone, siltstone, shale, and limestone layers—is about 600 million years old.
Babcock and others on his research team were analyzing rock dating back to the Ediacaran-Cambrian period when he flipped over a slab of sediment and found the supposed footprints.
"It was basically an accidental discovery," Babcock told National Geographic News after the findings were presented earlier this week at a meeting of the Geological Society of America in Houston, Texas.
The footprints are a couple of millimeters across and look like centipede leg marks, he said.
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