About the cover
The cover shows a reconstruction of Saccorhytus coronarius, a newly identified deuterostome dating back to the earliest Cambrian period in China. Deuterostomes constitute an array of organisms as varied as vertebrates, starfish, acorn worms and tunicates. But this range of forms, and a lack of extant morphological intermediates, makes it difficult to understand what early deuterostomes were like. The tiny fossils described by Simon Conway Morris and his Chinese colleagues reveal creatures with bag-like bodies and no anus. The primitive features seen in the remains have led the researchers to interpret them as the most basal known deuterostomes, suggesting that their earliest history lies among the meiofauna. Cover image: Jian Han/Dinghua Yan.