The Science of Nature

, 106:2 | Cite as

Dimetrodon (Synapsida: Sphenacodontidae) from the cave system at Richards Spur, OK, USA, and a comparison of Early Permian–aged vertebrate paleoassemblages

  • Kirstin S. Brink
  • Mark J. MacDougall
  • Robert R. ReiszEmail author
Original Paper


The Early Permian Richards Spur locality is unique in preserving a highly diverse faunal assemblage in a cave system, composed of synapsids, reptiles, and anamniotes. However, the presence of Dimetrodon, the most common synapsid of Early Permian localities of the southwestern USA, has never been recorded from the site. Here, we describe for the first time the morphology and histology of a small neural spine with the distinctive figure-8 shape attributable to Dimetrodon. Additionally, histological analysis of previously described sphenacodontid teeth suggests the presence of a derived species of Dimetrodon at the Richards Spur locality. The presence of this derived synapsid, typical of the later occurring Kungurian localities of Texas and Oklahoma, is unexpected at the stratigraphically older Richards Spur locality. The cave system at Richards Spur preserves mainly basal synapsid taxa, including small caseid, varanopid, and sphenacodontid skeletal remains. The presence of a derived species of Dimetrodon suggests not only that this animal was more widespread than previously thought, but that there are different patterns of Early Permian synapsid evolution in different ecological settings.


Sphenacodontia Paleozoic Fissure fill Dentition Histology Paleobiogeography 



The authors wish to thank Bill May for the help in obtaining the neural spine and tooth specimens. For assistance with histology, the authors wish to thank Kentaro Chiba (Okayama University of Science) and Brian Iwama (ROM). For the help with specimen curation, the authors wish to thank Kevin Seymour (ROM).

Funding information

This research was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) PGS-D and Ontario Graduate Scholarship to Brink, NSERC PGS-D to MacDougall, and NSERC Discovery Grant to Reisz. Research was also supported by grants from the University of Toronto Mississauga (Canada) and Jilin University (China).


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of BiologyUniversity of Toronto MississaugaMississaugaCanada
  2. 2.Department of Oral Health Sciences, Faculty of DentistryUniversity of British ColumbiaVancouverCanada
  3. 3.Museum für Naturkunde Leibniz-Institute für Evolutions- und BiodiversitätsforschungBerlinGermany
  4. 4.International Center for Future ScienceJilin UniversityChangchunChina

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