Curtin University PhD candidate Ines Melendez says the lipids are 380 million years old, or about 250 million years older than what had been the oldest known find of its kind.
"This is the first detailed molecular study … on a carbonate concretion from the Devonian Reef," she says.
Her supervisor, Professor Kliti Grice, says the fossil was originally a crustacean that died in the oceans around the time of the Devonian mass-extinctions (more than 360 million years ago).
It fed on smaller organisms in the oxygenated upper layer of water, and when it died it sank into a lower layer of anoxic water.
"Sulfate reducers degrade that organic matter anerobically, yielding hydrogen sulfide utilised in photosynthesis by organisms called Chlorobi at the interface between the oxygenated and anoxic layers," Prof Grice says.
Ms Melendez says these microbes then formed a community around the dead crustacean.
"There was so much organic matter that they didn't degrade everything," she says.
"The conditions helped these organisms to start to precipitate carbonate—whatever was left was encapsulated inside and wasn't used any more.
"In that way the concretion kept growing."
She analysed the fossil, finding molecules of 70 different steroids.
link.
No comments:
Post a Comment