Erratus sperare, a new species of ancient marine arthropod from eastern Yunnan, China, had unique trunk appendages that represent an intermediate stage of biramous limb evolution. The ecological reconstruction of Erratus sperare, showing the nektonic life style; the initial situation of trunk limbs, as flaps associated with weakly sclerotized endopods indicates a swimming rather than fully benthic habit. Image credit: Fu et al., doi: 10.1098/rstb.2021.0034. Erratus...
