Placodontiformes

Placodontiformes is an extinct clade of sauropterygian marine reptiles that includes placodonts and the non-placodont Palatodonta. It was erected in 2013 with the description of Palatodonta. Placodontiformes is the most basal clade of Sauropterygia and the sister group of Eosauropterygia, which includes all other sauropterygians.^[2]

Placodontiforms Temporal range: Middle - Late Triassic, 246–201.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Skeleton of the placodontian placodontiform Henodus chelyops
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	†Sauropterygia
Clade:	†Placodontiformes Neenan et al., 2013
Subgroups
†Palatodonta †Atopodentatus?[1] †Placodontia

Phylogeny

Below is a cladogram from Neenan et al. (2013) showing the position of Placodontiformes within Sauropterygia:^[2]

Sauropterygia	Placodontiformes Palatodonta Placodontia Paraplacodus Placodus Cyamodontoidea Cyamodus Psephoderma Eosauropterygia Pistosauroidea Yunguisaurus Plesiosauria Pistosaurus Augustasaurus Corosaurus Cymatosaurus Nothosauroidea Diandongosaurus Pachypleurosauria

References

1. Wolniewicz, A. S.; Shen, Y.; Li, Q.; Sun, Y.; Qiao, Y.; Chen, Y.; Hu, Y.-W.; Liu, J. (2023). "An armoured marine reptile from the Early Triassic of South China and its phylogenetic and evolutionary implications". eLife. 12. doi:10.7554/eLife.83163. PMC 10499374. PMID 37551884.
2. Neenan, J. M.; Klein, N.; Scheyer, T. M. (2013). "European origin of placodont marine reptiles and the evolution of crushing dentition in Placodontia". Nature Communications. 4: 1621. Bibcode:2013NatCo...4.1621N. doi:10.1038/ncomms2633. PMID 23535642.