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Osteology of the Large Dissorophid Temnospondyl Anakamacops Petrolicus from the Guadalupian Dashankou Fauna of China

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Osteology of the Large Dissorophid Temnospondyl Anakamacops Petrolicus from the Guadalupian Dashankou Fauna of China Journal of Vertebrate Paleontology ISSN: 0272-4634 (Print) 1937-2809 (Online) Journal homepage: https://www.tandfonline.com/loi/ujvp20 Osteology of the large dissorophid temnospondyl Anakamacops petrolicus from the Guadalupian Dashankou Fauna of China Jun Liu To cite this article: Jun Liu (2018) Osteology of the large dissorophid temnospondyl Anakamacops petrolicus from the Guadalupian Dashankou Fauna of China, Journal of Vertebrate Paleontology, 38:5, e1513407, DOI: 10.1080/02724634.2018.1513407 To link to this article: https://doi.org/10.1080/02724634.2018.1513407 View supplementary material Published online: 05 Nov 2018. Submit your article to this journal Article views: 172 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=ujvp20 Journal of Vertebrate Paleontology e1513407 (11 pages) # by the Society of Vertebrate Paleontology DOI: 10.1080/02724634.2018.1513407 ARTICLE OSTEOLOGY OF THE LARGE DISSOROPHID TEMNOSPONDYL ANAKAMACOPS PETROLICUS FROM THE GUADALUPIAN DASHANKOU FAUNA OF CHINA JUN LIU Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, CAS Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China, [email protected] ABSTRACT—Dissorophidae are terrestrial temnospondyls with conspicuous armor. All known Guadalupian dissorophid species, including Anakamacops petrolicus, are established based on incomplete materials. Here two new dissorophid specimens from the Guadalupian Dashankou Fauna of China are described and referred to A. petrolicus. They provide much more new osteological information of this species. Anakamacops petrolicus has the largest skull among all known dissorophid species. It exhibits knobby exostoses on the skull roof and mandible, a high suborbital bar that is greater than half of the skull height, a triangular, posteriorly closed otic notch with the anteroposterior length greater than the width, relatively smooth vomer with a few denticles on the lateral margin, two nuchal (occipital) ridges with short overlap where the right one is anterior to the left one, the interpterygoid vacuity far from the choana, low coronoid process, the medial ridge of the adductor fossa close to the ventral margin of the mandible, and the first inner osteoderm nearly triangular with concave margins in dorsal view. The Guadalupian dissorophid species form a monophyletic clade, Kamacopini, which was distributed in northeastern Pangaea, with the following synapomorphies to differentiate it from other dissorophids: suborbital bar high (subequal to or greater than the orbital height) and the interpterygoid vacuities far from the choanae. http://www.zoobank.org/urn:lsid:zoobank.org:pub:864C8AC9-89C1-41B8-BD33-D3DE5ABF5BBB SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Liu, J. 2018. Osteology of the large dissorophid temnospondyl Anakamacops petrolicus from the Guadalupian Dashankou Fauna of China. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1513407. INTRODUCTION acervalis and I. vorax measure ca. 20 cm in width, whereas the skull length of K. acervalis was estimated to be 25–30 cm The Olsoniformes are a clade of terrestrial temnospondyls from (Gubin, 1980). late Carboniferous and Permian environments (DeMar, 1966; A cladistic analysis of the Dissorophidae was initially carried Anderson et al., 2008; Reisz et al., 2009). Within this group, the out by Schoch (2012), and more recent studies show that the Dissorophidae are a taxonomically diverse and morphologically Dissorophidae include a few basal members and two major clades, distinct clade. These Paleozoic amphibians are characterized by the Dissorophinae sensu stricto and the Eucacopinae (Holmes their conspicuous armor (Williston, 1910). Their body lengths gen- et al., 2013; Schoch and Sues, 2013). The Eucacopinae are charac- erally range from 25 to 50 cm (Schoch and Sues, 2013). Most dis- terized by the abbreviated postparietal, the presence of an interna- sorophid species are known from the Cisuralian (early Permian) rial fenestra, a semilunar curvature on the squamosal, and a of North America (Carroll, 1964; Schoch, 2012), with only five transverse ridge on the postparietal (Schoch and Sues, 2013). The taxa having been reported from the Guadalupian (middle two Russian taxa, Kamacops and Zygosaurus, form a monophy- Permian) of Russia and China. In Russia, the first known dissoro- letic clade to the exclusion of Cacops (Schoch, 2012). Given that phid, Zygosaurus lucius, was reported from a heavily worn skull the known materials of Iratusaurus vorax (Paleontological (Eichwald, 1848). Later, two taxa, Kamacops acervalis and Institute, Russian Academy of Sciences, PIN 164/300) and Iratusaurus vorax, were established from incomplete skulls, and a Anakamacops petrolicus (Institute of Geology, Chinese Academy fragmentary specimen was tentatively referred to Alegeinosaurus of Geological Sciences, IGCAGS V365) are so fragmentary (Gubin, 1980, 1993). Anakamacops petrolicus, based on a left (Gubin, 1980; Li and Cheng, 1999), Schoch (2012) did not include snout, is the only dissorophid and the only temnospondyl known these two taxa in his original phylogenetic matrix. However, I. from the Permian of China (Li and Cheng, 1999). The vorax couldbereferredtoacladeincludingCacops, Kamacops, Guadalupian dissorophids from Russia and China are significantly and Zygosaurus basedonthepresenceofaclosedoticnotch. larger compared with the older ones. The skull of Z. lucius meas- The Dashankou tetrapod fauna derives from the Qingtoushan uresca.17cminlengthandca.11cminwidth.Thepreorbital Formation of Yumen, Gansu Province, China, and it is dominated length is 7 cm in the holotype of A. petrolicus, resulting in a com- by therapsids such as Sinophoneus yumenensis Cheng and Ji, plete skull length estimate of greater than 20 cm. The skulls of K. 1996, Biseridens qilianicus Li and Cheng, 1997,andRaranimus dashankouensis Liu, Rubidge, and Li, 2009. The fauna also Color versions of one or more of the figures in the article can be includes Belebey chengi Muller,€ Li, and Reisz, 2008 found online at www.tandfonline.com/ujvp. (Bolosauridae), Gansurhinus qingtoushanensis Reisz, Liu, Li, and Published online 05 Nov 2018 Liu—Anakamacops from Dashankou Fauna (e1513407-2) Muller,€ 2011 (Captorhinidae), Anakamacops petrolicus Li and fenstra ovalis; imf, inframeckelian fossa; j,jugal;l,lacrimal;lep, Cheng, 1999 (Dissorophidae), Yumenerpeton yangi Jiang, Ji, and laterally exposed palatine; m, maxilla; mco, middle coronoid; nr, Mo, 2017 (Bystrowianidae), Ingentidens corridoricus Li and nuchal ridge; on,oticnotch;ot,oticcapsule;p, parietal; par,pre- Cheng, 1999,andPhratochronis qilianensis Li and Cheng, 1999 articular; pco, posterior coronoid; pl, palatine; po,postorbital; (Chroniosuchidae). The age of the fauna is regarded as Roadian pof, postfrontal; pop, paroccipital process; pp, postparietal; prf, (Liu et al., 2009) or Wordian (Rubidge, 2005). Among the previ- prefrontal; ps, parasphenoid; psl, postsplenial; pt, pterygoid; ptf, ously unstudied materials from this locality are two specimens posttemporal fossa; q, quadrate; qj, quadratojugal; qpt,quadrate that can be referred to Dissorophidae. These specimens are larger ramus of pterygoid; sa, suprangular; sm, sphenethmoid; sq, than all other known dissorophid specimens. Herein, I describe squamosal; st, supratemporal; t,tabular;v,vomer. the new specimens, tentatively referring them to A. petrolicus, and examine the phylogenetic position of that species among Dissorophidae. SYSTEMATIC PALEONTOLOGY Institutional Abbreviations—IGCAGS, Institute of Geology, TEMNOSPONDYLI Zittel, 1888 Chinese Academy of Geological Sciences, Beijing, China; IVPP, DISSOROPHOIDEA Bolt, 1969 Institute of Vertebrate Paleontology and Paleoanthropology, DISSOROPHIDAE Boulenger, 1902 Chinese Academy of Sciences, Beijing, China; PIN, EUCACOPINAE Schoch and Sues, 2013 Paleontological Institute, Russian Academy of Sciences, KAMACOPINI, new taxon Moscow, Russia. Anatomical Abbreviations—I, channel for the olfactory Definition—The most inclusive clade that includes nerve; V, recess for exit of trigeminal nerve; a, angular; art, Kamacops acervalis, but not Cacops woehri. articular; bo, basioccipital; bs, basisphenoid; bt, basal tubera; ctf, chorda tympanic foramen; d,dentary;ec, ectopterygoid; eo,exoc- ANAKAMACOPS PETROLICUS Li and Cheng, 1999 cipital; ep, epipterygoid; f, frontal; fm, foramen magnum; fo, (Figs. 1–8) FIGURE 1. Anakamacops petrolicus, IGCAGS V365, holotype. Photos and drawings of the snout in A, lateral, B, dorsal, and C, ventral views. Drawings from Li and Cheng (1999:fig. 3). Scale bars equal 2 cm. Liu—Anakamacops from Dashankou Fauna (e1513407-3) Holotype—IGCAGS V365, left side of a snout (Fig. 1). complete skull is estimated to have been ca. 40 cm in midline Referred Specimens—IVPP V 23862, an incomplete poster- length, based on the skull shape of Cacops (Reisz et al., 2009). ior half of the skull with incomplete lower jaws, an intercen- The skull is relatively wide but low and trapezoid in occipital trum, and two osteoderms; IVPP V 23863, posterior end of a view, with the cheek at an angle of ca. 130 –140 with the skull right lower jaw. table (Figs.
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