{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T03:23:57Z","timestamp":1790047437057,"version":"4.0.1"},"reference-count":32,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2019,4,11]],"date-time":"2019-04-11T00:00:00Z","timestamp":1554940800000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Natural Sciences and Engineering Research Council (NSERC) of Canada"},{"DOI":"10.13039\/501100004032","name":"Jilin University","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100004032","id-type":"DOI","asserted-by":"crossref"}]},{"name":"University of Toronto Mississauga"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>The fossil record of caseids, a clade of faunivorous to large herbivorous Permian synapsids, is unusual in having a poorly documented history. Although Kungurian caseids are common in the well-known continental deposits of North America, and the fossil record of the group extends into the middle Permian (Guadalupian), with the presence of the large caseid<jats:italic>Ennatosaurus<\/jats:italic>in the Mezen Basin faunal assemblage, only two other occurrences are known in older Permian age sediments. One is an undescribed caseid from the Bromacker Quarry in Germany, and the second is<jats:italic>Oromycter<\/jats:italic>from the lower Permian of Richards Spur, Oklahoma. The former is known from several articulated skeletons, but the latter is known only from a handful of skeletal elements, including elements of the snout and lower jaw, some phalanges, and a few vertebrae. Here the fragmentary tooth bearing elements and dorsal vertebrae of another small caseid from Richards Spur are described, with a discussion of its significance in the context of caseid evolution, and the continuously expanding faunal list and taxic diversity at this locality.<\/jats:p>","DOI":"10.7717\/peerj.6615","type":"journal-article","created":{"date-parts":[[2019,4,11]],"date-time":"2019-04-11T08:45:40Z","timestamp":1554972340000},"page":"e6615","source":"Crossref","is-referenced-by-count":3,"title":["A small caseid synapsid,<i>Arisierpeton simplex<\/i>gen. et sp. nov., from the early Permian of Oklahoma, with a discussion of synapsid diversity at the classic Richards Spur locality"],"prefix":"10.7717","volume":"7","author":[{"given":"Robert R.","family":"Reisz","sequence":"first","affiliation":[{"name":"International Centre of Future Science, Jilin University, Changchun, Jilin, China"},{"name":"Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4443","published-online":{"date-parts":[[2019,4,11]]},"reference":[{"issue":"6","key":"10.7717\/peerj.6615\/ref-1","doi-asserted-by":"publisher","first-page":"e0156810","DOI":"10.1371\/journal.pone.0156810","article-title":"A re-description of \u2018Mycterosaurus\u2019 smithae, an early permian eothyridid and its impact on the phylogeny of pelycosaurian-grade synapsids","volume":"11","author":"Brocklehurst","year":"2016","journal-title":"PLOS ONE"},{"key":"10.7717\/peerj.6615\/ref-2","first-page":"198","article-title":"Oil in permian karst in the slick hills of Southwestern Oklahoma","volume":"93","author":"Donovan","year":"1992","journal-title":"Oklahoma Geological Survey Circular"},{"key":"10.7717\/peerj.6615\/ref-3","doi-asserted-by":"publisher","first-page":"293","DOI":"10.1669\/0883-1351(2000)015<0293:LPTPAV>2.0.CO;2","article-title":"Lower permian terrestrial paleoenvironments and vertebrate paleoecology of 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