The oldest clue of animal life, dating back at least 100 million years before the Cambrian period, when most major types of animals appear, has been found by University of California, Riverside (UCR) researchers.

The researchers have been tracking molecular signs of animal life, called biomarkers, as far back as 660–635 million years ago during the Neoproterozoic Era. They found a steroid compound produced only by sponges, which are among the earliest forms of animal life, in ancient rocks and oils from Oman, Siberia, and India.

The biomarker identified, a steroid compound named 26-methylstigmastane (26-mes), has a unique structure that is currently only known to be synthesized by certain species of modern sponges called demosponges.

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