Early Paleozoic brachiopod larva: true larva, not a juvenile

The ontogeny of extinct brachiopods is often reconstructed from specimens with well-preserved juvenile shells. However, paleontological reconstructions based on the fossil material contradict the reconstruction of the evolution of brachiopod life cycles based on the analysis of the ontogeny of recent brachiopods. If the paleontological reconstructions suggest a planktotrophic stage with a shell as the initial type of the brachiopod ontogeny, the biologists suppose true planktotrophic larva to be the basic stage of the brachiopod life cycles. In the present paper, the paleontological data are considered in correspondence with the data on the different developmental stages of recent brachiopods. The large size and presence of the impressions of larval setal sacks are interpreted as evidence of the stage of true planktotrophic larva in the ontogeny of the Early Paleozoic brachiopods.