Author: Carolyn Gramling / Source: Science News
Cholesterol clinched it: A group of strange Precambrian fossils are among the oldest known animals in the rock record.
Organic molecules preserved with fossils of the genus Dickinsonia confirm that the creatures were animals rather than fungi or lichen, a study in the Sept. 21 Science says. Researchers led by paleontologist Ilya Bobrovskiy of Australian National University in Canberra analyzed levels of steroids in the fossils, which date to between 571 million and 541 million years ago. The team found an abundance of cholesterol that points firmly to the animal kingdom.
The finding “gets rid of the more outlandish hypotheses about what these objects were,” says MIT geobiologist Roger Summons, who cowrote a related commentary in the same issue of Science. “You can’t argue with chemistry.”
Dickinsonia are part of the enigmatic Ediacara biota, the collective name for a burst of strange, alienlike life forms that flourished during the Precambrian Eon. Ediacarans, originally named for Australia’s Ediacara Hills, where they were first discovered, are now found in Precambrian-aged rocks around the globe.
HARD-WON
The new study was conducted on Ediacaran fossils extracted from a remote coastline in northwest Russia along the White Sea. The site is difficult to access — Bobrovskiy had…
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