The Lower Permian fossiliferous infills of the Dolese Brothers Limestone Quarry, near Richards Spur, Oklahoma, have preserved the most diverse assemblage of Paleozoic terrestrial vertebrates, including small-bodied reptiles and lepospondyl anamniotes. Many of these taxa were previously known only from fragmentary remains, predominantly dentigerous jaw elements and numerous isolated skeletal elements. The recent discovery of articulated skulls and skeletons of small reptiles permits the recognition that dentigerous elements, previously assigned at this locality to the anamniote lepospondyl Euryodus primus, belong to a new captorhinid eureptile, Opisthodontosaurus carrolli gen. et sp. nov. This mistaken identity points to a dramatic level of convergence in mandibular and dental anatomy in two distantly related and disparate clades of terrestrial tetrapods and sheds light on the earliest instance of durophagy in eureptiles.

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Captorhinids are Paleozoic eureptiles that originated in the Late Pennsylvanian in Laurasia and dispersed across the major landmasses of Pangaea by the late Permian. Their evolutionary success as omnivorous and herbivorous members of Permian terrestrial communities has been attributed to the evolution of multiple marginal tooth rows. Multiple tooth rows evolved at least twice within Captorhinidae: once in the omnivorous Captorhinus aguti and again in the diverse subfamily of herbivorous moradisaurines. The earliest known moradisaurines co-occured with C. aguti in lower Permian strata of Texas; however C. aguti is also known from much older fissure fills in the famous Dolese Brothers quarry near Richards Spur, Oklahoma, suggesting that C. aguti preceded any other multiple-rowed captorhinid. Here we report on new material of multiple-rowed captorhinids from the lower Permian fissure fills of the Bally Mountain locality in Oklahoma, only 55 kilometers from Richards Spur. Some of this material is referable to Captorhinikos valensis, which was previously only known from younger strata in Texas, making this species the geologically and phylogenetically oldest moradisaurine. Furthermore, we determined that Ca. valensis co-existed with C. aguti at Bally Mountain and we explore the potential for niche partitioning in these early captorhinids. Lastly, we assess the potential temporal and environmental differences between Bally Mountain and Richards Spur, in order to explain the abundance of herbivorous moradisaurines at Bally Mountain and the complete lack of moradisaurines at the neighbouring Richards Spur locality.

Permian millipedes are rare, especially so considering the relative abundance of millipedes in Carboniferous rocks. We report an early Permian millipede fauna containing three new genera and species of millipedes (Oklahomasoma richardsspurense new genus new species, Karstiulus fortsillensis new genus new species, and Dolesea subtila new genus new species) found in fossil-producing pockets of the Fort Sill fissures exposed in the Dolese Quarry near Richards Spur, southwest Oklahoma, USA. These are the first new genera of invertebrates to be described from this site, one of the most prolific fossil-vertebrate sites in the world. We also comment on taxa with morphological similarities and note previously described occurrences of Permian millipedes as well as occurrences of fossil myriapods (millipedes and centipedes) in karst deposits (caves and fissure fills) in Europe, Africa, Asia, North America, and the Caribbean. In contrast with the forms found at Richards Spur, most of these previous accounts of millipedes found in caves and fissure fills are of Pleistocene forms that are closely allied to modern taxa. The taxa from Richards Spur bear some similarities to Pennsylvanian forms. Karst (cave and fissure) faunas should be ranked with concretion faunas, cannel coals, and amber faunas as a major source of fossil myriapods. UUID: http://zoobank.org/5d58e1fb-4e5b-4597-9cd9-5cc9e2096b4d