A new small baurioid therocephalian from the Lower Triassic Jiucaiyuan Formation, Xinjiang, China

doi:10.19615/j.cnki.2096-9899.240726

Abstract

Abstract:

Several therocephalian species, mainly represented by cranial material from the late Permian, have been reported from China in recent years. Here we describe a tiny new baurioid therocephalian, Jiucaiyuangnathus confusus gen. et sp. nov., from the Jiucaiyuan Formation, Xinjiang, China. The new taxon is represented by a partial snout with occluded partial lower jaw and two postcranial skeletons. Although juvenile in stage, the new species is diagnosed by the following features: round pit in middle of lateral surface of maxilla; lacrimal contact nasal; fossa for dentary tooth on the posterior end of the premaxilla, lateral to the anterior choana; two small vertical triangular ridges extending dorsally and ventrally on the vomerine anterior portion, and bordering a thin vomerine foramen laterally; anterior projection of the lateral part of the frontal on the nasal; symphyseal region of the dentary projected anteriorly; 5 upper premaxillary teeth, upper and lower canines absent, diastema between the last premaxillary upper incisor and first maxillary tooth present, no diastema separating anterior from posterior dentition in the mandible, 10 maxillary teeth and 12 dentary teeth, posterior postcanine expands mesiodistally, having a main large cusps and tiny anterior and posterior accessory cusps in line; neural arches of the atlas fused by the neural spine, neural spine of the axis projected posteriorly, procoracoid foramen lies between procoracoid and scapula. Features of the dentition resembles those of the small baurioid Ericiolacerta parva from South Africa and Silphedosuchus orenburgensis from Russia. The specimens provide the rare opportunity to know in detail the postcranial skeleton of baurioids.

Key words: Jimsar, Xinjiang, Early Triassic, Jiucaiyuan Formation, Therocephalia, Baurioidea

摘要：

主要基于晚二叠世的头部材料，中国近年来报道了多个兽头类物种。记述了新疆韭菜园组的小型包氏兽超科(Baurioidea)新材料，包括一个头骨吻端及咬合的下颌以及两个头后骨架，并命名为迷惑韭菜园颌兽( Jiucaiyuangnathus confusus )。虽然标本为幼年个体，新种有以下鉴定特征：上颌骨侧面中部有小圆坑；泪骨与鼻骨接触；前颌骨后端在内鼻孔外侧有容纳下颌齿的窝；犁骨前部侧缘有小型三角形脊向背腹两侧延伸，组成细长的犁骨孔的侧缘；额骨有尖角延伸到鼻骨后侧部；齿骨的联合部收窄并指向前方；5枚前颌骨齿，上下犬齿缺失，前颌骨齿与上颌骨齿间有齿缺，下颌前部无齿缺，10枚上颌骨齿，12枚齿骨齿，后部齿加长，有大的主尖及小的前后副尖；寰椎神经弓与神经棘愈合，枢椎神经棘倒向后方，前乌喙骨孔位于前乌喙骨与肩胛骨间。齿系与小型包氏兽超科成员南非的 Ericiolacerta parva 及俄罗斯的 Silphedosuchus orenburgensis 类似。新的头后骨骼材料提供了难得的研究包氏兽超科成员头后骨骼的机会。

关键词: 新疆吉木萨尔, 早三叠世, 韭菜园组, 兽头类，包氏兽超科

CLC Number:

Q915.864

LIU Jun, Fernando ABDALA. A new small baurioid therocephalian from the Lower Triassic Jiucaiyuan Formation, Xinjiang, China. Vertebrata Palasiatica, 2024, 62(3): 201-224.

刘俊, Fernando ABDALA. 2024, 62(3): 201-224, 新疆下三叠统韭菜园组一新小型兽头类. 古脊椎动物学报.

Figures/Tables 10

Fig. 1 Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32945, holotype) from Jimsar, Xinjiang A-C. photo (A) and 3D rendering (B) of the left side of the snout in lateral and 3D rendering of the medial view of the left side of the snout (C);D. 3D rendering of the snout in posterior view showing the bones as preserved Abbreviations: afo. anteriormost foramen; cc. christa choanalis; F. frontal; L. lacrimal; l.c. lacrimal canal;M. maxilla; m. maxillary tooth; m.a. maxillary antrum; msf. maxillo-septomaxillary foramen;pdl. dorsal layer of palatine; pit. maxillary round pit; PL. palatine; PM. premaxilla;pml. medial layer of palatine; sH, sinus Highmore; SM. septomaxilla; V. vomer

Fig. 2 Snout of Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32945, holotype) from Jimsar, Xinjiang A. photo in dorsal view; B, C. 3D rendering of the left nasal and frontal in dorsal (B) and ventral (C) views; D, E. 3D rendering of the left side of the snout in ventral (D) and dorsal (E) views Abbreviations: cc. christa choanalis; ch. choana; F. frontal; f. fossa for lower anterior tooth; L. lacrimal; lpr. lacrimal-palatine ridge; M. maxilla; m. maxillary tooth; mpf. maxilla-palatine foramen; N. nasal; p. premaxillary tooth; pdl. dorsal layer of palatine; p.f. premaxillary fossa; PF. prefrontal; PL. palatine; PM. premaxilla; pml. medial layer of palatine; pvl. ventral layer of palatine; SM. septomaxilla

Fig. 3 3D rendering of Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32945, holotype) from Jimsar, Xinjiang A. the preserved snout in ventral view; B, C. vomer in dorsal (B) and ventral (C) views, vomer is reconstructed in the natural position in (C); D. left dentary in lateral view; E, F. mandibles in dorsal (E) and ventral (F) views Abbreviations: 1st ic. first incisor; ch. choana; D. dentary; d. dentary tooth; F. frontal; for vn. place for vomeronasal organ; M. maxilla; N. nasal; PL. palatine; PM. premaxilla; SP. splenial; V. vomer; v.f. vomerine foramen

Fig. 4 Posterior skeletons of Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32946) from Jimsar, Xinjiang A, B. photo of the slab; C, D. 3D rendering of bones Grey and light purple are bones of each specimen. Light blue uncertain. See online version for color

Fig. 5 3D rendering of Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32946-1) from Jimsar, Xinjiang A, B. the preserved skeleton in dorsal (A) and ventral (B) views; C. right femur in distal view; D-F. atlas and axis in anterior (D), left (E), and right (F) lateral views; G. four thoracic vertebrae in right lateral view; H, I. sacral region in lateral (H) and dorsal (I) views; J. caudal vertebrae Abbreviations: aic. atlas intercentrum; cdr. caudal rib; cdv. caudal vertebra; cr. cervical rib; FE. femur; lv. lumbar vertebra; ns. neural spine; sr. sacral rib; sv. sacral vertebra; tp. transverse process; tr. thoracic rib; tv. thoracic vertebra

Fig. 6 3D rendering of Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32946-2) from Jimsar, Xinjiang A, B. skeleton in dorsal (A) and ventral (B) views; C. part of thoracic vertebrae in left lateral view; D. two sacral and three anterior caudal ribs; E-H. sacral ribs of (D) in dorsal (E, G) and ventral (F, H) views;I-L. two smaller sacral ribs in dorsal (I, K) and ventral (J, L) views Abbreviations: cdr. caudal rib; mt. metatarsal; sr. sacral rib

Fig. 7 3D rendering of shoulder girdle of Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32946-2) from Jimsar, Xinjiang A-D. left scapula in anterior (A), lateral (B), posterior (C), and medial (D) views; E. partial right scapula in lateral view; F, G. left procoracoid in lateral (F) and medial (G) views Abbreviation: gl. glenoid

Fig. 8 3D rendering of pelvic girdles of Jiucaiyuangnathus confusus gen. et sp. nov. from Jimsar, Xinjiang IVPP V32946-1: A, B. left ilium in lateral (A) and medial (B) views; C, D. right ilium in lateral (C) and medial (D) views; E. relocated pubes and right ischium in ventral view; F. left pubis in dorsal view; G. right ischium in dorsal view. V32946-2: H, I. left ilium in lateral (H) and medial (I) views; J, K. right ilium in lateral (J) and medial (K) views; L-N. left ischium in ventral (L), lateral (M), and dorsal (N) views; O-Q. incomplete right pubis in dorsal (O), lateral (P), and ventral (Q) views; R. reconstructed left pelvis in lateral view based on the small individual (right ischium reversed). Scale bars equal 5 mm

Fig. 9 3D rendering of right femur of Jiucaiyuangnathus confusus gen. et sp. nov. (IVPP V32946-2) from Jimsar, Xinjiang in ventral (A), anterior (B), dorsal (C), posterior (D) and proximal (E) views Abbreviations: tr.int. internal trochanter; tr.maj. trochanter major; tr.min. trochanter minor

Fig. 10 Relationships of Baurioidea, showing the positions of Jiucaiyuangnathus when canines are coded as unknown Abbreviations: Chan. Changhsingian; Ind. Induan

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