1. University Museum of Zoology, Downing Street, Cambridge CB2 3EJ, UK

Correspondence to: Jennifer A. Clack¹ Correspondence and requests for materials should be addressed to the author (e-mail: Email: jac18@hermes.cam.ac.uk).

Abstract

Living (that is, crown-group) tetrapods represent the phylogenetic end-points of two lineages which diverged from each other during the mid/late Palaeozoic era. These two groups of tetrapods are the Amphibia (frogs, salamanders and caecilians), with their roots among temnospondyls¹,², and the Amniota (mammals, turtles, crocodiles, birds, lizards and snakes), with their roots among anthracosaurs³,⁴. The earliest representatives of both lineages, including a stem amniote, are known from the Viséan of East Kirkton, Scotland⁵. Here I describe a new taxon from this locality that not only combines characters of each lineage, but also represents the basal member of a third Palaeozoic group, the baphetids. The baphetids lie within the base of the crown clade of tetrapods and the morphology of the new taxon, their most primitive member, is a new benchmark for studying the polarity and evolution of crown tetrapod characters.

1. University Museum of Zoology, Downing Street, Cambridge CB2 3EJ, UK

Correspondence to: Jennifer A. Clack¹ Correspondence and requests for materials should be addressed to the author (e-mail: Email: jac18@hermes.cam.ac.uk).