This video from the USA says about itself:
Rocks of the Proterozoic and Archean eras (The Precambrian) make up the inner gorge of the Grand Canyon on the Colorado Plateau. Proterozoic strata contains stromatolites, Chauria (small cap-like fossils) and Brooksella canyonensis, a fossil considered by some to be a fossil jellyfish and by others as a vendozoan (a group of puzzling late Precambrian firm impressions of what may be an extinct major category of life). The very hard rocks of the inner gorge belong to the Archean Era which in Arizona, may be younger in geologic time than nearer the continental nucleus where Archean rocks can be over three billion years old.From World Science:
Found: earliest known animal tracks?Ediacaran Siberian fossils: here.Oct. 5, 2008
Courtesy Ohio State University and World Science staff
Faint, fossilized tracks of an ancient aquatic creature suggests animals walked using legs at least 30 million years earlier than had been thought, some scientists say. But they admit the lack of a fossil of the creature itself will probably foster a healthy skepticism, and that researchers will need to look for additional evidence.
The tracks—two parallel rows of small dots, each about two millimeters wide—are dated to some 570 million years ago, to a period called the Ediacaran. That preceded the Cambrian period, when most major groups of animals evolved.
Scientists once thought that mainly microbes and simple multicellular animals existed before the Cambrian, but that idea is changing, said Loren Babcock, professor of earth sciences at Ohio State University.
He pronounced himself “reasonably certain” a centipede-like arthropod or a legged worm made the tracks. An arthropod is an invertebrate having jointed limbs and a segmented body—a group that includes insects.
Soo-Yeun Ahn, a doctoral student at Ohio State and a co-author of the research, presented the findings at the Geological Society of America meeting Sunday in Houston.
Babcock said he found the tracks while surveying rocks in the mountains near Goldfield, Nevada in 2000. “We came on an outcrop that looked like it crossed the Precambrian-Cambrian boundary…. We just sat down and started flipping rocks over. We were there less than an hour when I saw it.”
The creature must have stepped lightly onto the soft seabed, because its legs pressed only shallow pinpoints in it, Babcock said. But when he flipped over the rock bearing the little pits, the low-angle sunlight cast them in crisp shadow, he recalled. He couldn’t be sure of the creature’s length or number of legs, but he guessed it carried a centimeter-wide body on many spindly legs.
In 2002, other researchers reported a similar fossil trail from Canada that dated back to the middle of the Cambrian period, about 520 million years ago. Another set of tracks found in South China date back to 540 million years ago.
