"Hundreds of millions of years before there was a chicken or an egg to debate, the first complex animals were evolving in parallel with Earth’s rising oxygen levels. But what came first — animals or oxygen? That question is the central theme of a special issue of Emerging Topics in Life Sciences published Sept. 28 by Portland Press. Titled “Early Earth and the Rise of Complex Life,” the issue was edited by UC Riverside’s Timothy Lyons, a distinguished professor of biogeochemistry, along with UCR professor Mary Droser and postdoctoral researcher Kimberly Lau, and Susannah Porter, a professor at UC Santa Barbara. Several of the 18 articles included in the collection were authored or co-authored by UCR researchers."