Diadectes sideropelicus (Cope 1878a, b) (UC 706, UC 1078) Early Permian ~270 mya, 1.5-3 m in length, is widely considered a bulky pre-reptile, but here Diadectes nests in the middle of the Lepidosauromorpha. Derived from a sister to Orobates, Diadectes phylogenetically was a sister to Procolophon, a relationship that was never previously considered. Apparently Diadectes represents the last of its lineage.

Distinct from Orobates, the skull of Diadectes had rounder profile and more strongly descending cheek flanges. The posterior skull was strongly embayed. The orbit and naris were relatively smaller. The teeth were shorter.

The presacral column was reduced to 20 vertebrae. The neural spines were tallest near the pelvis. The ribs were widest anteriorly, as in Limnoscelis. The tail was shorter.

The legs were shorter and the feet were proportionately smaller.

Oradectes (Diadectes) sanmiguelensis is a sister to Diadectes.

Diadectes sideropelicus (UC675) is a derived diadectid with large premaxillary teeth. Colobomycter is a larger sister taxon at the base of the procolophonidae.

Diasparactus zenos FMNH UC 679

Berman DS, Sumida SS and Martens T 1998. Diadectes (Diadectomorpha: Diadectidae) from the Early Permian of central Germany, with description of a new species. Annals of Carnegie Museum 67:53-93.

Cope ED 1878a. Descriptions of extinct Batrachia and Reptilia from the Permian formation of Texas. Proceedings of the American Philosophical Society 17:505-530.

Cope ED 1878b. A new Diadectes. The American Naturalist 12:565.

Kissel R 2010. Morphology, Phylogeny, and Evolution of Diadectidae (Cotylosauria: Diadectomorpha). Thesis (Graduate Department of Ecology & Evolutionary Biology University of Toronto).

wiki/Diadectes