Turtles as diapsid reptiles

Recent molecular studies of amniote relationships show turtles to be diapsi d reptiles, related to the archosauromorph branch of saurian phylogeny. Thi s conflicts with palaeontological data which shows turtles to be related ei ther to anapsids, or to the lepidosauromorph branch within diapsids. Archos auromorph relationships of turtles have previously been proposed on the bas is of neontological (mostly soft anatomy) characters. This paper reviews th e neontological character evidence for turtle relationships and shows that most, but not all, of these characters are invalid in the reconstruction of turtle relationships within Amniota.