Palatodonta bleekeri (Neenan et al. 2013) is a basal placodont. Only the skull was described and the authors considered this a juvenile due to its small size and large orbit. Like its predecessor, Claudiosaurus, this may have been a small skull attached to a long neck and very much larger torso and tail. The resemblance to Phonodus is also striking. This taxon preceded Paraplacodus and the other placodonts, but did not yet develop the flat crushing teeth that characterizes that clade. Close kin also included Sinosaurosphargis and Stereosternum but these widely diverging taxa show how little is known about the base of the Enaliosauria.

The family tree of the Enaliosauria is here. The complete reptile family tree is here. A series on placodont and ichthyosaur palate evolution is here.

Pappochelys rosinae (Schoch and Sues 2015, Middle Triassic), was originally considered a stem turtle, but in the large reptile tree, Pappochelys nests with basal placodonts. Turtles, like Odontochelys, have a distinct and far removed ancestry.

Diandongosaurus acutidentatus (Shang et al. 2011) Olenekian, Early Triassic, IVPP V 17761, 30 cm in length) is a tiny taxon that nested at the base of the Placodontia but retained many of its pachypleurosaur traits.

Majiashanosaurus discocoracoidis (Jiang et al. 2014, Olenekian, Early Triassic, AGM-AGB5954, 47.4 cm in length) ironically nesting as as sister to the skull-only Palatodonta is the skull-less Majiashanosaurus.

Palacrodon browni (Brown 1906. Gow 1999; Early Triassic) was originally considered a rhynchocephalian, then an enigma. Here it nests as a basal placodont.

Broom R 1906. On a new South African Triassic rhynchocephalian. Transactions of the South African Philosophical Society 16: 379–380.

Gow CE 1999. The Triassic reptile Palacrodon browni Broom, synonymy and a new specimen. Palaeontologia Africana 35: 21–23.

Jiang et al. 2014. The Early Triassic Majiashanosaurus discocoracoidis, gen. et sp. nov. (Reptilia, Sauropterygia), from Chaohu, Anhui Province, People's Republica of China. Journal of Vertebrate Paleontology 34:1044-1052.

Neenan JM, Klein N and Scheyer TM 2013. European origin of placodont marine reptiles and the evolution of crushing dentition in Placodontia. Nature Communications 4:1621. - DOI: 10.1038/ncomms2633 |www.nature.com/naturecommunications.

Schoch RR and Sues H-D 2015. A Middle Triassic stem-turtle and the evolution of the turtle body plan. Nature (advance online publication) > doi:10.1038/nature14472 online

Shang Q-H, Wu X-C and Li C 2011. A new eosauropterygian from Middle Triassic of Eastern Yunnan Province, Southwestern China. Vertebrata PalAsiatica 49(2):155-171.

wiki/Palatodonta
wiki/Majiashanosaurus
wiki/Diandongosaurus
wiki/Pappochelys