Multiple tooth-rowed captorhinids from the Early Permian fissure fills of the Bally Mountain Locality of Oklahoma

Abstract

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.

A new small captorhinid reptile from the lower Permian of Oklahoma and resource partitioning among small captorhinids in the Richards Spur fauna

“…9; LeBlanc et al . , fig. 8), captorhinid species that are known from both the Richards Spur locality (thought then to be Sakmarian in age) and from Leonardian‐aged red beds localities in Texas.…”

“…In addition to being relatively common reptiles at lowland, red‐bed localities in the south‐western USA, captorhinids are the amniotes most commonly collected from the fissure fills at both Richards Spur and Bally Mountain in Oklahoma (Fox & Bowman ; LeBlanc et al . ). Whereas the latter fissure‐fill locality has been known for only five decades (originally as the ‘South Carnegie’ site in Olson ) and its accessibility has been intermittent during this time, Richards Spur has been visited regularly since at least the early 1930s (e.g.…”

Euconcordia nom. nov., a replacement name for the captorhinid eureptile Concordia Müller and Reisz, 2005 (non Kingsley, 1880), with new data on its dentition.

“…Recent studies of dental development and evolution among captorhinid eureptiles and Early Permian parareptiles (LeBlanc and Reisz 2015) have now allowed us to reinterpret the dental anatomy of this basal captorhinid. We therefore take this opportunity to reexamine the dental morphology of Euconcordia cunninghami, and also provide more complete visual information on the remarkable cranial remains of this taxon.…”

“…This small reptile is particularly important because its discovery has allowed palaeontologists to follow the evolutionary history of this clade, as it gradually transitioned from small insectivorous and carnivorous amniotes to omnivores (as seen in basal captorhinids) and eventually the highly derived herbivores (moradisaurine captorhinids) that we see in the Late Permian. There is convincing evidence that captorhinids are the first group of eureptiles to diversify significantly during the initials stages of amniote evolution (LeBlanc et al 2015;Modesto et al 2014). Unfortunately, the name Concordia is preoccupied by an extant hippolytid crustacean, Concordia Kingsley, 1880.…”

A Systematic and Ecomorphological Investigation of the Early Amniotes from Mazon Creek, Francis Creek Shale, Illinois, USA

“…The dentition of Cephalerpeton seems to represents an alternative approach to insectivorous durophagy contrasting with the very wide, teardrop-shaped dentition present in durophagous gymnarthrids, pantylids, the captorhinid Opisthodontosaurus, and durophagous modern squamates ). The ogival tooth morphology seen in other captorhinids is yet another example of durophagous dentition among early reptiles (Leblanc et al, 2015). This "captorhinid" type dentition could be convergently shared with CM 41714, the indeterminate reptile from Linton, Ohio.…”