Procolophonomorpha is an order or clade of early reptiles that appeared during the Middle Permian. It constitutes a diverse assemblage that includes a number of lizard-like forms, as well as more diverse types such as the pareiasaurs. The most important subclade, Procolophonia, is traditionally thought to be ancestral to (and hence to include) turtles. Lee 1995, 1996, 1997 argues that turtles evolved from pareiasaurs, but this view is by no means held unanimously. Rieppel and deBraga 1996 and deBraga and Rieppel, 1997 argue that turtles evolved from sauropterygians.
The following cladogram is simplified after the phylogenetic analysis of MacDougall and Reisz (2014) and shows the placement of Procolophonomorpha within Parareptilia and its interrelationships. Relationships within bolded terminal clades are not shown.
- Carroll, R. L., 1988: Appendix; Vertebrate Classification. in Carroll, R. L. 1988: Vertebrate Paleontology and Evolution, W. H. Freeman and Company, New York
- deBraga M. and O. Rieppel. 1997. "Reptile phylogeny and the interrelationships of turtles". Zoological Journal of the Linnean Society 120: 281–354.
- deBraga, M. and Reisz, R. R., 1996: "The Early Permian reptile Acleistorhinus pteroticus and its phylogenetic position". Journal of Vertebrate Paleontology: Vol. 16, #3, pp. 384–395
- Laurin, M., and Gauthier, J. A., 1996 Phylogeny and Classification of Amniotes, at the Tree of Life Web Project
- Lee, M. S. Y. 1995. "Historical burden in systematics and the interrelationships of 'Parareptiles'". Biological Reviews of the Cambridge Philosophical Society 70: 459–547.
- Lee M. S. Y. 1996. "Correlated progression and the origin of turtles". Nature 379: 812–815.
- Lee, M. S. Y., 1997: "Pareiasaur phylogeny and the origin of turtles". Zoological Journal of the Linnean Society: Vol. 120, pp. 197–280
- Rieppel O. and M. deBraga. 1996. "Turtles as diapsid reptiles". Nature 384: 453–455.