MARCH 6 2012 02:25h
Earliest ancestor of humans described
The species Pikaia gracilens is a precursor to vertebrates, which makes it the direct ancestor of all members of the chordate family, which includes fish, birds, reptiles, amphibians and mammals -- and humans, researchers say.
The fossils where found in shale beds in Canada 100 years ago by American paleontologist Charles Doolittle Walcott, who suggested they could have been an early type of leech or worm.
Because they lacked a fully developed backbone, there remained doubts about exactly which category of species they should fall into.
A new analysis of specimens by Cambridge University scientists and Canadian colleagues has identified lumps of skeletal muscle tissue known as myomeres associated with a notochord, a simple type of primitive spinal chord, Britain's Daily Telegraph reported Monday.
"The discovery of myomeres is the smoking gun that we have long been seeking," lead study author Simon Conway Morris said.
"Now with myomeres, a nerve chord, a notochord and a vascular system all identified, this study clearly places Pikaia as the planet's most primitive chordate."
CAMBRIDGE, England, March 5 (UPI) -- A fossilized eel-like creature unearthed in Canada is the oldest life form found with a primitive spinal cord, making it man's earliest ancestor, experts say.