Restoring Pintosaurus

Pintosaurus (Piñeiro et al. 2004)
was described as a basal procolophonid close to Coletta and Owenetta on the basis of a incomplete skull (Fig. 1). Cisneros (2008) nested Pintosaurus similarly.

Figure 1. Pintosaurus restored from Piñeiro et al. 2004.

Figure 1. Pintosaurus (Late Permian) restored from Piñeiro et al. 2004.

Here (Fig. 1) just a little color and phylogenetic bracketing adds in the missing pieces from the Pintosaurus skull. The upper portions had weathered away, but are here restored.

Distinct from sister taxa,
Pintosaurus had only three teeth in the premaxilla, and it appeared to have a posterolateral process of the premaxilla. The large palatal fangs on the palatine are also unique to this genus. But when Contritosaurus (aka Phaanthosaurus, Fig. 2) is added it shares the trait of three large premaxillary teeth, but the naris is anterior on a transverse premaxilla. This clade has an unusual narial fossa (depression).

Figure 2. Contritosaurus (aka Phaanthosaurus sinus), a sister to Pintosaurus. Note the narial fossa and palatine teeth.

Figure 2. Contritosaurus (aka Phaanthosaurus sinus), a sister to Pintosaurus. Note the narial fossa and palatine teeth.

Like their sister, Coletta (Fig. 3, Gow 2000, Modesto, Damiani and Sues 2002, Early Triassic, GHG 228), these genera likely had upper temporal fenestra. They nest as derived owenettids and stem lepidosauriformes.

Figure 3. Coletta nests with Pintosaurus and Contritosaurus in the large reptile tree. Note the small upper temporal fenestrae, marking this taxon as a stem owenettid.

Figure 3. Coletta nests with Pintosaurus and Contritosaurus in the large reptile tree. Note the small upper temporal fenestrae, marking this taxon as a derived owenettid and a stem lepidosauriform.

These are sisters to the ancestors of the gliding lepidosauriforms, and all lepidosaurs, including Sphenodon, pterosaurs, lizards and snakes.

References
Cisneros JC 2008. “Phylogenetic relationships of procolophonid parareptiles with remarks on their geological record”Journal of Systematic Palaeontology 6:345–366.
Cudinov PK and Vjushkov BP 1956. New data on small cotylosaurus from the Permian and Triassic of the USSR. Doklady Akademii Nauk SSSR 108:547-550.
Gow CE 2000. A new procolophonid (Parareptilia) from the Lystrosaurus Assemblage Zone, Beaufort Group, South Africa. Palaeontologia Africana 36:21–23.
Ivakhnenko MF 1974. New data on Early Triassic procolophonids of the USSR. Paleontological Journal 8:346-351.
Modesto SP, Damiana RJ and Sues H-D 2002. A reappraisal of Coletta seca, a basal procolophonid reptile from the lower Triassic of South Africa. Palaentology 45(5):883-895.
Piñeiro G, Rojas A and Ubilla M 2004. A new procolophonid (Reptilia, Parareptilia) from the Upper Permian of Uruguay. Journal of Vertebrate Paleontology 24:814-821.

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