The cranial characters of a new specimen of Yunguisaurus from Middle Triassic Ladinian Xingyi fauna, Guizhou
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摘要:
产自欧洲、北美洲和中国三叠纪的纯信龙次亚目，是连接鳍龙类"干群"和"冠群"的关键分子，也是探讨侏罗纪—白垩纪"冠群"蛇颈龙类起源和早期演化的关键环节类群。李氏云贵龙是中国华南地区发现的纯信龙次亚目中较原始的属种，也是目前发现保存最完好、数量最多的纯信龙类，但对其头骨骨骼形态学的认识依然存在不足。贵州兴义中三叠世拉丁期法郎组竹杆坡段中新发现的一件云贵龙完整头骨化石补充了云贵龙的骨骼学信息，如额骨未愈合、枕部存在开放空间等。经详细比较，新材料可能代表了目前发现的5件李氏云贵龙标本中体长最大的个体，推断额骨未愈合这一特征为云贵龙特有的鉴定特征，而非个体成年与否的判断依据。新材料显示，云贵龙的鳞状骨没有后内侧支，存在开放式枕部，同蛇颈龙类相似，指示了三叠纪纯信龙类同蛇颈龙类密切的亲缘关系。
Abstract:The Triassic Pistosauroidea from Europe, North America and China is the key to link the "stem-group" and "crown-group" Sauropterygia, and is important to reveal the origin and the early evolution of Jurassic-Cretaceous "crown-group" Sauropterygia, Plesiosaurus. Yunguisaurus is one of the most primitive genera of Pistosauroidea discovered in South China, with the most well-preserved specimens. However, the cranial osteology of Yunguisaurus is still lack of understanding. A new material of Yunguisaurus, excavated from the Zhuganpo Member(Ladinian) of Falang Formation, Xingyi Fauna in Guizhou Province, provides new detailed cranial information, such as the unfused frontals and the existence of an open space in the occipital region. Detailed comparison shows that the new material is the longest one among the five specimens of Yunguisaurus reported so far, indicating the unfused frontals should be a diagnosis of Yunguisaurus, rather than an ontogenic difference. There is no inner-posterior branch in squamosal of this new material, forming an open occipital part, which is similar to that of Plesiosaurus, indicating a close relationship with this genus.
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Keywords:
- Middle Triassic /
- Pistosauroidea /
- Yunguisaurus /
- Guizhou Province
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致谢: 感谢北京大学地球与空间科学学院江大勇教授在论文撰写过程中给予的指导和帮助，感谢北京大学地球与空间科学学院胡田芬技师帮助修理标本，感谢审稿专家在论文内容方面的宝贵意见和建议。
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图 1 鳍龙超目谱系关系(据Ma et al., 2015修改)
Figure 1. The phylogenetic relationships among sauropterygians
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图 2 兴义动物群地理位置(a)与泥麦古剖面照片(b) (据Lu et al., 2017修改)
Figure 2. Location of the Xingyi Fauna(a) and the photo of Nimaigu section(b)
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图 3 贵州兴义乌沙泥麦古剖面地层柱状图(菊石带划分据Zou et al., 2015修改)
Figure 3. The stratigraphic column of Nimaigu section, Wusha, Xingyi, Guizhou Province
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图 4 云贵龙新材料2(GMPKU-P-1528)头骨背侧视素描图
a —angular 隅骨；ar —articular 关节骨；axc —centrum of axis 枢椎；axna —neural arch of axis 枢椎神经弓；d —dentary 齿骨；en —external naris 外鼻孔；fr —frontal 额骨；j —jugal 颧骨；mx —maxilla 上颌骨；n —nasal 鼻骨；p —parietal 顶骨；pf —pineal foramen 顶孔；prf —prefrontal 前额骨；pm —premaxilla 前颌骨；pof —postfrontal 后额骨；po —postorbital 后眶骨；q —quadrate 方骨；pt —pterygoid 翼骨；sa —surangular 上隅骨；sq —squamosal 鳞状骨
Figure 4. Skull of the new specimen of Yunguisaurus (GMPKU-P-1528, dorsolateral view)
表 1 云贵龙新材料(GMPKU-P-1528)头骨测量数据
Table 1 Measurements of the skull of the new specimen (GMPKU-P-1528)
测量项 长度/mm 头骨长(吻端-鳞状骨后缘) 238 下颌骨长(齿骨前缘-关节骨后缘) 254 吻端-外鼻孔前缘 80 吻端-眼眶前缘 107 吻端-上颞孔前缘 147.9 吻部宽(垂直于鼻孔中线) 45.8 额骨中间宽 11 眼眶长(左) 32.9 眼眶宽(左) 32.8 眼眶后缘-鳞状骨后缘 103 外鼻孔长轴(左/右) 8.3/8.5 外鼻孔短轴(左/右) 5.5/5.2 上颞孔长(左/右) 83/83.7 上颞孔中间宽(左/右) 35/18 顶骨后部高 15.8 
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表 2 5件云贵龙标本解剖学数据对比
Table 2 Measurements of the five specimens of Yunguisaurus
对比项 正型标本*
NMNS 004529/F003862参考标本
ZMNH M8738参考标本
IVPP V 14993参考标本
XNGM XY-2013-R1新材料
GMPKU-P-1528头长/吻端-外鼻孔前缘 — 2.8 — 3.31 3.0 头长/吻端-眼眶最前缘 2.17 2.3 — 2.39 2.22 头长/上颞孔长 — 2.55 — 2.8 2.87 上颞孔长/眼眶长 — 1.95 — 2.3 2.52 额骨是否愈合 未愈合 未愈合 未愈合 — 未愈合 注：*数据据Sato et al.(2010)，其他为实际测量数据
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Cheng Y N, Sato T, Wu X C, et al. First complete pistosaurid from the Triassic of China[J]. Journal of Vertebrate Paleontology, 2006, 26: 501-504. doi: 10.1671/0272-4634(2006)26[501:FCPFTT]2.0.CO;2
Fabbri M, Vecchia F M D, Cau A. New information on Bobosaurus forojuliensis (Reptilia: Sauropterygia): implications for plesiosaurian evolution[J]. Historical Biology, 2014, 26(5): 661-669. doi: 10.1080/08912963.2013.826657
Laboury A, Scheyer T M, Klein N, et al. High phenotypic plasticity at the dawn of the eosauropterygian radiation[J]. Peer J., 2023, 9(11): e15776.
Lin W B, Jiang D Y, Rieppel O, et al. Panzhousaurus rotundirostris Jiang et al., 2019(Diapsida: Sauropterygia) and the recovery of the monophyly of Pachypleurosauridae[J]. Journal of Vertebrate Paleonology, 2021, 41(1): e1901730-2. doi: 10.1080/02724634.2021.1901730
Lu H, Jiang D Y, Motani R, et al. Middle Triassic Xingyi Fauna: showing turnover of marine reptiles from coastal to oceanic environments[J]. Palaeoworld, 2017, 27(2018): 107-116.
Ma L T, Jiang D Y, Rieppel O, et al. A new pistosauroid(Reptilia, Sauropterygia) from the late Ladinian Xingyi marine reptile level, southwestern China[J]. Journal of Vertebrate Paleontology, 2015, 35(1): 1-6.
Meyer H V. Mittheilung, an Professor Bronn gerichtet[J]. Neus Jahrbuch für Mineralogie, Geognosie. Geologie, und Petrefakten-Kunde, 1839: 559-560.
Rieppel O. Osteology of Simosaurus gaillardoti, and the phylogenetic interrelationships of stem-group Sauropterygia[J]. Fieldiana, 1994, 28: 1-85.
Rieppel O. Revision of the sauropterygian reptile genus Cymatosaurus v. Fritsch, 1894, and the relationships of Germanosaurus Nopcsa, from the Middle Triassic of Europe[J]. Fieldiana, 1997, 36: 1-38.
Rieppel O. Corosaurus alcovensis Case and the phylogenetic interrelationships of Triassic stem-group Sauropterygia[J]. Zoological Journal of the Linnean Society, 1998a, 124(1): 1-41. doi: 10.1111/j.1096-3642.1998.tb00568.x
Rieppel O. The status of the sauropterygia reptile generaCeresiosaurus, Lariosaurus, and Silvestrosaurus from the Middle Triassic of Europe[J]. Fieldiana(Geology), N.S., 1998b, 73(5): 1-46.
Rieppel O. The sauropterygian genera Chinchenia, Kwangsisaurus and Sanchiaosaurus from the Lower and Middle Triassic of China[J]. Journal of Vertebrate Paleontology, 1999, 19(2): 321-337. doi: 10.1080/02724634.1999.10011144
Rieppel O. Sauropterygia Ⅰ: Placodontia, Pachypleurosauria, Nothosauroidea, Pistosauroidea[C]//Handbuch der Paleoherpetology part 12A. München: Verlag Dr. Friedrich Pfeil, 2000: 1-134.
Rieppel O, Werneburg R. A new species of the sauropterygian Cymatosaurus from the lower Muschelkalk of Thuringia, Germany[J]. Palaeontology, 1998, 41(4): 575-589.
Sander P M, Klein N, Albers P C H, et al. Postcranial morphology of a basal Pistosauroidea(Sauropterygia) from the Lower Muschelkalk of Winterswijk, The Netherlands[J]. Paläontologische Zeitschrift, 2014, 88(1): 55-71. doi: 10.1007/s12542-013-0181-5
Sato T, Cheng Y N, Wu X C, et al. Osteology of Yunguisaurus Cheng et al., 2006(Reptilia; Sauropterygia), a Triassic Pistosauroid from China[J]. Paleontological Research, 2010, 14(3): 179-195. doi: 10.2517/1342-8144-14.3.179
Sato T, Zhao L J, Wu X C, et al. A new specimen of the Triassic pistosauroid Yunguisaurus, with implications for the origin of Plesiosauria(Reptilia, Sauropterygia) [J]. Palaeontology, 2014, 57(1): 55-76. doi: 10.1111/pala.12048
Shang Q H, Sato T, Li C, et al. New osteological information from a 'juvenile' specimen of Yunguisaurus(Sauropterygia; Pistosauroidea) [J]. Palaeoworld, 2017, 26(3): 500-509. doi: 10.1016/j.palwor.2016.05.008
Storrs G W. Function and phylogeny in sauropterygian(Diapsida) evolution[J]. American Journal of Science, 1993, 293(A): 63-90. doi: 10.2475/ajs.293.A.63
Storrs G W, Taylor M A. Cranial anatomy of a new plesiosaur genus from the lowermost Lias(Rhaetina/Hettangian) of Street, Somerset, England[J]. Journal of Vertebrate Paleontology, 1996, 16(3): 403-420. doi: 10.1080/02724634.1996.10011330
Storrs G W. Morphological and taxonomic clarification of the genus Plesiosaurus[C]// Callaway J M, Nicholls E. Ancient Marine Reptiles. San Diego: Academic Press, 1997: 145-190.
Wang X, Lu H, Jiang D Y, et al. A new specimen of Yunguisaurus(Reptilia; Sauropterygia) from the Ladinian(Middle Triassic) Zhuganpo Member, Falang Formation, Guizhou, China and the restudy of Dingxiaosaurus[J]. Palaeoworld, 2020, 29(1): 135-150.
Zhao L, Sato T, Chun L. The Most Complete Pistosauroid Skeleton from the Triassic of Yunnan, China[J]. Acta Geologica Sinica, 2008, 82(2): 283-286. doi: 10.3321/j.issn:1000-9515.2008.02.007
李锦玲, 刘俊, 奥利维尔·瑞博尔. 贵州兴义中三叠统法郎组竹杆坡段Lariosaurus一新种[J]. 古脊椎动物学报, 2002, 40(2): 114-126. https://www.cnki.com.cn/Article/CJFDTOTAL-GJZD200202002.htm 马乐天. 贵州兴义中三叠世拉丁期纯信龙次亚目新材料及纯信龙次亚目系统学研究[D]. 北京大学博士学位论文, 2014.
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