Oldest nerves found in China, offering clues to land evoluti
Mar 1, 2016 8:44:57 GMT 9.5
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Post by Willow on Mar 1, 2016 8:44:57 GMT 9.5
Oldest nerves found in China, offering clues to land evolution
Scientists have solved part of the mystery about how life evolved on land after finding what are thought to be the world’s oldest nerves preserved in Chinese rock.
An international study has revealed individual nerve fibres in a fossil of a caterpillar-like prawn that lived about 515 million years ago.
The discovery, outlined this morning in the journal Proceedings of the National Academy of Sciences, demonstrates how nervous systems became simplified during the Cambrian explosion — an extraordinary burst of evolution that transformed the early Earth’s bacteria, plankton and algae into complex creatures.
The remains of the “Chengjiangocaris kunmingensis”, a proto-crustacean with a broad head shield and a long body with differently sized pairs of legs, were found in southwestern China’s Yunnan province. The animal was an ancestor of modern arthropods, which include insects, spiders and crustaceans.
This specimen had been fossilised upside down, allowing an unprecedented view of the soft tissue — including the brain — which is normally hidden by the hard shell covering the head. The team made further discoveries after chipping at the rock around the fossil with a fine needle and using fluorescence microscopy to examine the nerve structure.
It found dozens of nerves, each less than one-hundredth of a millimetre in length, connected to each “ganglia” — beadlike masses of nervous tissue that separately controlled each pair of legs.
“We confirmed that the fibres were individual nerves, fossilised as carbon films, offering an unprecedented level of detail,” said co-author Javier Ortega-Hernandez of Cambridge University’s zoology department. “This is a unique glimpse into what the ancestral nervous system looked like.”
Cambridge said this type of nervous system structure was unknown in any living organism, although some aspects appeared similar to modern priapulids. The discovery represents the first time individual nerves have been found from the period before land creatures emerged from the sea.
Dr Ortega-Hernandez said an extraordinary bunch of coincidences had contributed to the find.
Soft tissue preservation was possible only in low-oxygen environments where animals had been buried rapidly by fine sediment, and left unmolested.
“It has been suggested that the water chemistry of the oceans was a bit different from today, which may explain to an extent why the Cambrian period has so many sites with exceptional preservation,” he told The Australian.
Scientists have solved part of the mystery about how life evolved on land after finding what are thought to be the world’s oldest nerves preserved in Chinese rock.
An international study has revealed individual nerve fibres in a fossil of a caterpillar-like prawn that lived about 515 million years ago.
The discovery, outlined this morning in the journal Proceedings of the National Academy of Sciences, demonstrates how nervous systems became simplified during the Cambrian explosion — an extraordinary burst of evolution that transformed the early Earth’s bacteria, plankton and algae into complex creatures.
The remains of the “Chengjiangocaris kunmingensis”, a proto-crustacean with a broad head shield and a long body with differently sized pairs of legs, were found in southwestern China’s Yunnan province. The animal was an ancestor of modern arthropods, which include insects, spiders and crustaceans.
This specimen had been fossilised upside down, allowing an unprecedented view of the soft tissue — including the brain — which is normally hidden by the hard shell covering the head. The team made further discoveries after chipping at the rock around the fossil with a fine needle and using fluorescence microscopy to examine the nerve structure.
It found dozens of nerves, each less than one-hundredth of a millimetre in length, connected to each “ganglia” — beadlike masses of nervous tissue that separately controlled each pair of legs.
“We confirmed that the fibres were individual nerves, fossilised as carbon films, offering an unprecedented level of detail,” said co-author Javier Ortega-Hernandez of Cambridge University’s zoology department. “This is a unique glimpse into what the ancestral nervous system looked like.”
Cambridge said this type of nervous system structure was unknown in any living organism, although some aspects appeared similar to modern priapulids. The discovery represents the first time individual nerves have been found from the period before land creatures emerged from the sea.
Dr Ortega-Hernandez said an extraordinary bunch of coincidences had contributed to the find.
Soft tissue preservation was possible only in low-oxygen environments where animals had been buried rapidly by fine sediment, and left unmolested.
“It has been suggested that the water chemistry of the oceans was a bit different from today, which may explain to an extent why the Cambrian period has so many sites with exceptional preservation,” he told The Australian.