A skull of <i>Plesiaceratherium gracile</i> (Rhinocerotidae, Perissodactyla) from a new lower Miocene locality in Shandong Province, China, and the phylogenetic position of <i>Plesiaceratherium</i>

<p>A well-preserved fossil skull from a new locality in Jijiazhuang, Changle County, Shandong Province, China, is attributable to <i>Plesiaceratherium gracile</i>. Other rhinoceroses from the nearby Shanwang Basin of Linqu County, Shandong, formerly described as <i>Aceratherium</i> sp. and <i>Plesiaceratherium shanwangensis</i> are also referable to <i>P. gracile</i>. The new skull demonstrates the presence in <i>P. gracile</i> of the following characters: continuous labial cingula on lower cheek teeth; skull roof with nearly flat profile; and external auditory pseudomeatus ventrally closed, proceeding dorsocaudally in a shallow groove. Comparison of <i>Plesiaceratherium</i> with <i>Brachypotherium pugnator</i> Matsumoto, <a href="#cit0034" target="_blank">1921</a>, suggests that referral of the latter to <i>Plesiaceratherium</i> should be reconsidered. A phylogenetic analysis based on 314 characters scored for 39 terminal taxa places <i>Plesiaceratherium mirallesi</i> in a basal position within Rhinocerotidae, and recovers other species of <i>Plesiaceratherium</i> as a clade that is well separated from <i>B. pugnator</i> and is sister to the [<i>Subchilotherium</i> [<i>Acerorhinus</i> [<i>Shansirhinus, B</i>. <i>pugnator</i> [<i>Chilotherium</i>]]]] grouping. Based on this result and a reevaluation of the anatomy of ‘<i>P</i>.’ <i>mirallesi</i>, we propose that the genus <i>Dromoceratherium</i> should be revived to accommodate this species as <i>D. mirallesi</i>. The occurrence of <i>P. gracile</i> at Jijiazhuang indicates that the fossiliferous diatomaceous shales of this locality were deposited during the lower Miocene.</p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Lu, X., X. Zheng, C. Sullivan, and J. Tan. 2016. A skull of <i>Plesiaceratherium gracile</i> (Rhinocerotidae, Perissodactyla) from a new lower Miocene locality in Shandong Province, China, and the phylogenetic position of <i>Plesiaceratherium</i>. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1095201.</p

Suggested systematic position of <i>Zhuchengceratops inexpectus</i> among the Ceratopsia.

<p>A, the strict consensus of three most parsimonious trees produced by our analysis of Makovicky's (2010) matrix with <i>Zhuchengceratops inexpectus</i> added in; B, the strict consensus of six most parsimonious trees produced by our analysis of Chinnery and Horner's (2007) matrix with <i>Zhuchengceratops inexpectus</i> added in. Bremer support and bootstrap values are labeled (bootstrap values below 50% are not shown).</p

Selected measurements (in cm) of ZCDM V0015.

<p>*estimated length.</p>#<p>incomplete measurement.</p><p>all centrum heights were measured at the posterior end.</p

Left maxilla, pterygoid, ectopterygoid, and mandible of <i>Zhuchengceratops inexpectus</i> holotype (ZCDM V0015).

<p>Left maxilla, pterygoid, ectopterygoid, and mandible in dorsal (A), lateral (B), and medial (C) views; D, a pair of hyoid bones. Abbreviations: a, angular; bc, buccal crest; cn, coronoid; cp, coronoid process; ec, “Eustachian canal”; ep, ectopterygoid; f, fossa; g, groove; imf, internal mandibular fossa; lc, lateral condyle; mc, medial condyle; mg, Meckelian groove; mlp, mid-line process; mp, mandibular process; mr, maxillary ramus; pd, predentary; q, quadrate; qr, quadrate ramus; r, ridge; sa, surangular; sd, supradentary; sp, splenial; vp, ventral process; vr, ventral ridge.</p

Photographs of the pectoral girdle and forelimb of the <i>Linhevenator tani</i> holotype (LH V0021).

<p>A, right scapula in lateral view; right humerus in anterior (B), posterior (C), medial (D), and lateral (E) views. Abbreviations: ap, acromial process; dc, deltopectoral crest; enc, entepicondyle; gl, glenoid fossa; f, fossa; olf, olecranon fossa; r, ridge; tf, triangular fossa. Scale bar equals 10 mm.</p

Right maxilla, jugal, quadratojugal, ectopterygoid, and mandible of <i>Zhuchengceratops inexpectus</i> holotype (ZCDM V0015).

<p>Right maxilla and mandible in dorsolateral (A), lateral (B), and medial (C) views; right jugal, quadratojugal, and quadrate in lateral (D) and medial (E) views. Abbreviations: ap, articular facet for pterygoid; bc, buccal crest; ch, chamber within coronoid process; cn, coronoid; cp, coronoid process; de, dorsal embayment; f, fossa; fl, flange; g, groove; itf, infratemporal fenestra; ml, medial lamina; ob, orbit; pde, posterodorsal expansion; pp, postorbital process; ppm, posterior process on maxilla; r, ridge; ra, right angular; rd, right dentary; rm, right maxilla; ss, strap-like surface; ve, ventral embayment.</p

Photographs of the teeth of the <i>Linhevenator tani</i> holotype (LH V0021).

<p>Premaxillary tooth in labial (A), lingual (B), and distal (C) views; maxillary or posterior dentary tooth in labial (D) and lingual (E) views. Abbreviations: bc, basal constriction; dcs, denticles. Scale bar equals 5 mm.</p

<i>Zhuchengceratops inexpectus</i> holotype (ZCDM V0015).

<p>Line-drawings of <i>Zhuchengceratops inexpectus</i> holotype as preserved (A), and of left side of skull and mandible in lateral (B) and medial (C) views. The gray area in (A) represents the impression on the matrix made by the right maxilla. Abbreviations: a, angular; ar, articular; cn, coronoid; cv, cervical vertebrae; dv, dorsal vertebrae; ep, ectopterygoid; hb, hyoid bone; imf, internal mandibular fossa; jqq, jugal-quadratojugal-quadrate;ld, left dentary; m, maxilla; md, mandible; mg, Meckelian groove; mp, mandibular process; pd, predentary; pra, prearticular; q, quadrate; rd, right dentary; sa, surangular; sk, skull; sp, splenial.</p

Scorings for <i>L. tani.</i>

<p>Scorings for <i>L. tani.</i></p

Measurements of selected elements in <i>L. tani</i>, LH V0021 (in millimeters; * indicates estimated measurement).

<p>Measurements are lengths except where noted.</p