A tiny clue found in ancient sediment has unlocked big secrets about Greenland’s past and future climate.
Just beyond the northwest edge of the vast Greenland Ice Sheet, Northwestern University researchers have discovered lake mud that beat tough odds by surviving the last ice age. The mud, and remains of common flies nestled within it, record two interglacial periods in northwest Greenland. Although researchers have long known these two periods — the early Holocene and Last Interglacial — experienced warming in the Arctic due to changes in the Earth’s orbit, the mix of fly species preserved from these times shows that Greenland was even warmer than previously thought.
This information could help researchers better gauge Greenland’s sensitivity to warming, by testing and improving models of climate and ice sheet behavior. Those models could then improve predictions of how Greenland’s ice sheet, which covers 80 percent of the Arctic country and holds enough ice to equal 20 feet of global sea level, might respond to man-made global warming.
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INDEPENDENT.- Scientists in China have discovered what they claim are the oldest fossilised animal footprints ever found.
The parallel tracks were formed in mud up to 551 million years ago in southern China's Yangtze Gorges.
They potentially date to 10 million years before the Cambrian Explosion, when arthropod and other animal life rapidly flourished, and when creatures with pairs of legs capable of leaving such footprints were thought to have arisen.
Scientists from the Chinese Academy of Sciences' Nanjing Institute of Geology and Palaeontology, along with colleagues from Virginia Tech in the US, studies the tracks and burrows found within part of the Denying Formation, a fossil-rich area near the Yangtze River.
Asked how the teams knew the impressions were footprints, Dr Shuhai Xiao of Virginia Tech told The Independent: "If an animal makes footprints, the footprints are depressions on the sediment surface, and the depressions are filled with sediments from the overlying layer.
"This style of preservation is distinct from other types of trace fossils, for example, tunnels or burrows, or body fossils.
"The footprints are organised in two parallel rows, as expected if they were made by animals with paired appendages. Also, they are organised in repeated groups, as expected if the animal had multiple paired appendages."
Previously, no evidence of limbed animals had been discovered that pre-date the Cambrian Explosion, the sudden surge in diversity that occurred on Earth around 510 to 540 million years ago.
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