505 Million Year Old Fossil Linked To Humans
March 6, 2012

505 Million Year Old Fossil Linked To Humans

A team of researchers have discovered that a 505 million-year-old fossil is actually an ancient relative to humans.

Researchers from the University of Cambridge, University of Toronto and the Royal Ontario Museum (ROM) confirmed that the extinct Pikaia gracilen found in Burgess Shale fossil beds in Canada's Yoho National Park is the most primitive form of all known vertebrates, including humans.

Pikaia was first described by American paleontologist Charles Doolittle Walcott in 1911 as a possible annelid worm.

However, scientists determined that Pikaia had a very primitive notochord, which goes on to make up part of the backbone in vertebrates.

“The discovery of myomeres is the smoking gun that we have long been seeking,” the study´s lead author, Professor Simon Conway Morris of the University of Cambridge, said in a press statement (http://www.cam.ac.uk/research/news/humans-oldest-ancestor-found/).

“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. So, next time we put the family photograph on the mantle-piece, there in the background will be Pikaia.”

The eel-like animal averaged about two-inches in length, and had a flattened body that was divided into a series of segmented muscle blocks seen as S-shaped lines that lie on either side of the notochord.

The team said that it likely swam above the sea floor by moving its body in a series of side-to-side curves.

The researchers examined 114 Pikaia fossils using a range of imagery techniques to help reveal the fine details of the animal.

“It´s very humbling to know that swans, snakes, bears, zebras and, incredibly, humans all share a deep history with this tiny creature no longer than my thumb,” Jean-Bernard Caron, an assistant professor of ecology and evolutionary biology at the University of Toronto, said.

The research was published in the British scientific journal Biological Reviews on March 5.


Image Caption: Pikaia gracilens. Image credit J.B. Caron


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