Updated October 08, 2915 with a revision to the inclusion set of the Captorhinidae.
Figure 1. Labidosaurus, a derived member of a basal reptile clade, the Captorhinidae
It is widely known that captorhinids were basal reptiles that appeared during the Early Permian and disappeared during the Late Permian, evolving from single tooth-row forms to those with multiple tooth-rows. All may be considered herbivores perhaps derived from insectivores. The problem is, which taxa are indeed captorhinids, and which are not?
The Reisz et al. 2011 List
Reisz et al. (2011) published the most recent phylogeny of the captorhinids. They found Thuringothyris nested at the base followed by Concordia, Rhiodenticulatus, Romeria, Protocaptorhinus, Saurorictus, Captorhinus, Captorhinikos, Labidosaurus, Labidosaurikos, Moradisaurus, Rothaniscus and Gansurhinus. This closely matched the phylogeny of Sumida et al. (2010).
Greater Numbers of Taxa Provide Greater Resolution
Here, in the large reptile study, the phylogeny closely matches that of Reisz et al (2011) and Sumida et al. (2010) with the following exceptions. Here, Cephalerpeton, Reiszorhinus, Concordia and Romeria primus nested just outside of the Captorhinidae at the base of all other lepidosauromorphs. Saurorictus and Romeria texana nested at the base of the Captorhinidae.
Independent Phylogenies
When independent phylogenies match, that’s a good test of validity. The exceptions merely alert others to expand the taxon list to test the exceptions on their own time using their own character lists.
Late Surviving Taxa
The presence of Concordia in the Latest Pennsylvanian indicates an earlier branching of basal captorhinids. The discovered fossils probably represent some of the broadest numerical extent of each taxon.
References
Muller J and Reisz RR 2006. The phylogeny of early eureptiles: Comparing parsimony and Bayesian approaches in the investigation of a basal fossil clade.” Systematic Biology, 55(3):503-511. doi:10.1080/10635150600755396
Reisz RR, Liu J, Li JL and Müller J 2011. A new captorhinid reptile, Gansurhinus qingtoushanensis, gen. et sp. nov., from the Permian of China. Naturwissenschaften 98 (5): 435–441. doi:10.1007/s00114-011-0793-0. PMID 21484260.
Sumida SS, Dodick J, Metcalf A and Albright G. 2010. Reiszorhinus olsoni, a new single-tooth-rowed captorhinid reptile of the Lower Permian of Texas. Journal of Vertebrate Paleontology 30 (3): 704–714. doi:10.1080/02724631003758078
wiki/Captorhinidae
The Pterosaur Heresies 