A New Specimen of Lariosaurus Xingyiensis (Reptilia, Sauropterygia) from the Ladinian (Middle Triassic) Zhuganpo Member, Falang

Home , Ceresiosaurus, Lariosaurus, Neusticosaurus, Nothosauridae

A New Specimen of Lariosaurus xingyiensis (Reptilia, Sauropterygia) from the Ladinian (Middle Triassic) Zhuganpo Member, Falang Formation, Guizhou, China Author(s): Wen-Bin Lin, Da-Yong Jiang, Olivier Rieppel, Ryosuke Motani, Cheng Ji, Andrea Tintori, Zuo-Yu Sun, and Min Zhou Source: Journal of Vertebrate Paleontology, 37(2) Published By: The Society of Vertebrate Paleontology URL: http://www.bioone.org/doi/full/10.1080/02724634.2017.1278703

BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.

BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Journal of Vertebrate Paleontology e1278703 (10 pages) Ó by the Society of Vertebrate Paleontology DOI: 10.1080/02724634.2017.1278703

ARTICLE

A NEW SPECIMEN OF LARIOSAURUS XINGYIENSIS (REPTILIA, SAUROPTERYGIA) FROM THE LADINIAN (MIDDLE TRIASSIC) ZHUGANPO MEMBER, FALANG FORMATION, GUIZHOU, CHINA

WEN-BIN LIN,1,2 DA-YONG JIANG,*,1,2 OLIVIER RIEPPEL,3 RYOSUKE MOTANI,4 CHENG JI,5 ANDREA TINTORI,6 ZUO-YU SUN,1,2 and MIN ZHOU1,2 1Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education, Peking University, Beijing 100871, People’s Republic of China; 2Department of Geology and Geological Museum, Peking University, Beijing 100871, People’s Republic of China, [email protected]; 3Center of Integrative Research, The Field Museum, Chicago, Illinois 60605-2496, U.S.A., orieppel@ﬁeldmuseum.org; 4Department of Earth and Planetary Sciences, University of California, Davis, California 95616-8605, U.S.A., [email protected]; 5Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, People’s Republic of China, [email protected]; 6Dipartimento di Scienze della Terra ‘A. Desio,’ Universita degli Studi di Milano, Via Mangiagalli 34-20133 Milano, Italy, [email protected]

ABSTRACT—A new specimen of Lariosaurus xingyiensis is described and provides new information on the dermal palate of the skull and the postcranial skeleton. Based on a comprehensive comparison with the holotype specimen, an amended diagnosis of L. xingyiensis is given on the basis of the following features: a medium-sized species of Lariosaurus with jugal absent, longitudinal diameter of upper temporal fenestra about 1.7 times longitudinal diameter of orbit, retroarticular process elongate, clavicles without anterolaterally expanded corners, posterior scapular process (blade) slender and elongate, humerus distinctly shorter than femur, and dorsal process of ilium with distinct tubercular ornamentation. Two phylogenetic analyses of Nothosauridae demonstrate that Nothosaurus as previously conceived is not monophyletic whereas Lariosaurus is a monophylum. Three species previously referred to Nothosaurus are more closely related to Lariosaurus and are hereby reassigned to Lariosaurus, namely, L. juvenilis, L. youngi, and L. winkelhorsti.

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

Citation for this article: Lin, W.-B., D.-Y. Jiang, O. Rieppel, R. Motani, C. Ji, A. Tintori, Z.-Y. Sun, and M. Zhou. 2017. A new specimen of Lariosaurus xingyiensis (Reptilia, Sauropterygia) from the Ladinian (Middle Triassic) Zhuganpo Member, Falang Formation, Guizhou, China. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1278703.

INTRODUCTION southwestern China (Jiang et al., 2005, 2006a; Jiang, Maisch, Nothosauridae is a monophyletic taxon that includes the gen- Sun, et al., 2006). However, the material from the Ladinian of era Nothosaurus and Lariosaurus (Rieppel, 1998, 2000). They Xingyi City of southern China seems to blur the taxonomic were mainly reported from the Middle and lower Upper Triassic boundary between Nothosaurus and Lariosaurus (Rieppel et al., of the western Tethys until 2002, when abundant and complete 2003; Ji et al., 2014). In recent studies of N. zhangi reported skeletons were found from the Middle Triassic in southern from the Anisian of Luoping County, Yunnan Province, China China. Thus far, five valid Chinese taxa have been erected, (Liu et al., 2014), and L. vosseveldensis from the early Middle including L. xingyiensis (Li et al., 2002; Rieppel et al., 2003), L. Anisian of the Germanic Basin, Winterswijk, the Netherlands hongguoensis (Jiang et al., 2006b), N. youngi (Li and Rieppel., (Klein et al., 2016), respectively, the monophyletic Nothosaurus 2004; Ji et al., 2014), N. yangjuanensis (Jiang et al., 2005, 2006a; collapsed with N. youngi and N. winkelhorsti more closely Yin et al., 2014), and N. zhangi (Liu et al., 2014). related to Lariosaurus than to the remaining species of Notho- Nothosaurus and Lariosaurus were well distinguished by some saurus. Klein et al. (2016) further stated that Lariosaurus may characters on the basis of European specimens. The western indeed turn out to be monophyletic should the lariosaurian affin- Tethyan Nothosaurus typically has a larger upper temporal ity of N. juvenilis, N. youngi, and N. winkelhorsti be revealed fenestra that is 2 or more times the longitudinal diameter of the through reevaluation. This suggests that a revision is necessary orbit, whereas the same ratio in Lariosaurus is less than 2. The regarding the diagnosis of the two genera based on the recently latter genus also has a more evenly curved and flattened humerus discovered material. and a distinctly broadened ulna (Rieppel, 1998, 2000). These fea- Lariosaurus xingyiensis was originally erected by Li et al. tures can also be applied to separate the Anisian Nothosaurus (2002) and later redescribed in detail by Rieppel et al. (2003) and Lariosaurus found in Panxian County of Guizhou Province, based on a distorted skeleton from the Xingyi Fauna. Here, we report a new specimen of this taxon from the Zhuganpo Member of Falang Formation (Ladinian, Middle Triassic) at Xingyi, *Corresponding author. Guizhou Province. It was excavated in 2011 by a collaborative Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-2) research team comprising the Geological Museum of Peking containing all traditional members of Lariosaurus. We therefore University, the Department of Earth and Planetary Sciences of find it reasonable to expand the range of the genus and assign the University of California (Davis), the Dipartimento di Scienze ‘N. juvenilis’toLariosaurus because it shares diagnostic charac- della Terra ‘A. Desio’ of the Universita degli Studi di Milano, ters of the genus that are listed in the emended diagnosis above. and the Field Museum (Chicago). This new specimen has a ‘Nothosaurus juvenilis’ retains a concave ventral margin of the three-dimensionally preserved skull, offering hitherto unknown pubis (character 70, state 1), unlike other Lariosaurus species, in information on the palate. Its postcranial skeleton also provides which the margin is convex. However, this character state new knowledge about its anatomy, resulting in a revised diagno- appears to be synapomorphic for Nothosauridae (Rieppel, 2000) sis of this species. In addition, we conduct two phylogenetic anal- and therefore is not useful for generic diagnosis. ‘Nothosaurus yses to test the monophyly of the genera Nothosaurus and juvenilis’ was previously diagnosed on the basis of two features, Lariosaurus, and the relationships among their constituent a small ratio of the diameters of upper temporal fenestra and species. orbit and a narrow postorbital arch. Both features suggest an affinity with Lariosaurus rather than with Nothosaurus. The low MATERIALS AND METHODS upper temporal fenestra/orbit ratio (1.58) of ‘N. juvenilis’is clearly smaller than in any species of Nothosaurus but fits well The specimen (XNGM WS-30-R19) described herein was col- within the range for Lariosaurus. The narrow postorbital arch of lected from the Zhuganpo Member of the Falang Formation ‘N. juvenilis’ is also distinct from other Nothosaurus but is here (Middle Triassic) at the main excavation quarry in Nimaigu Vil- considered to be a diagnostic feature of Lariosaurus. Moreover, lage, Wusha Town, Xingyi City, Guizhou Province, China, in this species was erected based only on an incomplete skull (Riep- 2011. It is deposited in the collection of the Xingyi National Geo- pel, 1994). The exceptionally small size of the holotype material park Museum and has been accessible to researchers since 2011. raised the possibility that the specimen represents a juvenile indi- It has been exhibited in the museum for public viewing since the vidual of another species. However, Rieppel (1994) suggested museum opened on September 21, 2016. The specimen was that it was not immature based on the degree of ossification of mechanically prepared by two preparators (Y.-Z. Wang and M.- the skull. Therefore, ‘N. juvenilis’ is still regarded as a valid spe- Y. Wang) of the museum. Measurements were collected using cies in this study. digital calipers with a precision of 0.02 mm and are provided in Table 1 and Table 2. LARIOSAURUS XINGYIENSIS Li, Liu, and Rieppel, 2002 The phylogenetic analysis was performed using a heuristic (Figs. 1–4) search (ADDSEQ D RANDOM, NREPS D 1000, HOLD D 10, with other default settings) as implemented in PAUP 4.0b10 Holotype—IVPP V11866, a nearly complete skeleton. (Swofford, 2002). In the first analysis, the holotype and addi- Referred Specimen—XNGM WS-30-R19, a nearly complete tional specimens of N. youngi (XNGM WS-30-R24) and L. xing- skeleton lacking the right hind limb. yiensis (XNGM WS-30-R19 of this study) were coded separately Horizon and Locality—Middle Triassic, Zhuganpo Member, to test the generic assignment of the two species. Modification of Falang Formation; Wusha Town, Xingyi City, Guizhou Province, the character definitions and coding are explained in China. Appendix 1. The second analysis was performed at the species The exact locality and horizon of the holotype is unknown. level to test the taxonomic relationships within the family The new specimen was found about 0.6 m below the base of (Appendix 2). The data matrix consisted of 74 characters and 24 ammonite Haoceras xingyiensis Zone (middle late Ladinian, and 22 taxa, respectively (Supplementary Data1). Multistate Middle Triassic) at the main excavation quarry in Nimaigu Vil- characters were treated as unordered, and all characters were lage, Wusha Town, Xingyi City, Guizhou Province, China, as equally weighted. reported by Zou et al. (2015). The specimen was found in layer Institutional Abbreviations—IVPP, Institute of Vertebrate 30 of the lower faunal assemblage, together with Keichousaurus Paleontology and Paleoanthropology, Chinese Academy of Sci- and Nothosaurus youngi, as well as the actinopterygian fishes ences, Beijing, People’s Republic of China; XNGM, Xingyi Asialepidotus and Habroichthys (Tintori et al., 2015). National Geopark Museum, Xingyi City, Guizhou Province, Emended Diagnosis—(Modified after Rieppel et al., 2003.) A People’s Republic of China. medium-sized species of Lariosaurus; jugal absent; longitudinal diameter of upper temporal fenestra about 1.7 times longitudinal SYSTEMATIC PALEONTOLOGY diameter of orbit; retroarticular process elongate (autapomorphy SAUROPTERYGIA Owen, 1860 among Nothosauria); clavicles without anterolaterally expanded NOTHOSAURIA Seeley, 1882 corners; posterior scapular process (blade) slender and elongate NOTHOSAURIDAE Baur, 1889 (autapomorphy among Nothosauria); humerus distinctly shorter LARIOSAURUS Curioni, 1847 than femur; dorsal process of ilium with distinct tubercular ornamentation (autapomorphy among Nothosauria). Type Species—Lariosaurus balsami Curioni, 1847. Emended Definition—The last common ancestor of Lariosau- rus juvenilis and Lariosaurus hongguoensis, and all its DESCRIPTION descendants. Emended Diagnosis—(Modified after Rieppel, 2000.) Small- The anterior half of specimen XNGM WS-30-R19 is exposed to medium-sized nothosaurian with longitudinal diameter of in ventral view, whereas the rest is exposed in dorsal view upper temporal fenestra less than 2 times longitudinal diameter (Fig. 1). This is because the specimen was split between two suc- of orbit (autapomorphy among Eusauropterygia); distance from cessive beds, which we numbered 30 and 31. The anterior part of posterior margin of external naris to anterior margin of orbit the skeleton was retrieved from the underlying bed 30, whereas more than 1.7 times width of postorbital arch; zygapophyseal the posterior part was broken off along with the overlying bed pachyostosis present; four or more sacral ribs; dorsal wing of 31. The preserved length of the skeleton is 70.5 cm (Table 1). ilium reduced to stout process; ulna broadened at mid-diaphysis The skull (Fig. 2) was prepared in dorsal and ventral views; its (convergent in Keichousaurus); five or more carpal ossifications. length is 99.2 mm (from the snout tip to the margin of the skull Remarks—In the strict consensus trees resulting from phylo- table). The new specimen is smaller than the holotype, being genetic analyses, ‘N. juvenilis’ appears as sister taxon to the clade about 63.2% in skull length and 52.6% in humerus length Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-3)

FIGURE 1. A new specimen of Lariosaurus xingyiensis (XNGM WS-30-R19) from the Xingyi Fauna. Each scale bar unit equals 1 cm.

(Table 1). It is an adult judging from its fully fused frontal and The rostrum consists of the paired premaxillae (Fig. 2A, B). parietal and well-ossified carpals. The premaxilla defines the anterior margin of the external naris. The nasal processes of the premaxillae extend backwards along the midline to separate the anterior processes of the nasals. Post- erolaterally, the premaxillae meet the maxillae at the level of the Skull anterior margin of the external nares in a posteriorly concave The skull is nearly three-dimensionally preserved and only suture. slightly compressed dorsoventrally, enabling more reliable meas- The large maxilla forms the lateral margin of the external naris urements than the holotype (Fig. 2). The rostrum is elongate and and the anterior margin of the orbit. Posteromedial to the exter- blunt. The rostral constriction is weakly expressed as in the holo- nal naris, the maxilla meets the nasal in an interdigitating suture, type (Rieppel et al., 2003). The ratio between preorbital and pre- and more posteriorly it meets the prefrontal in a convex suture. narial lengths is 1.83, similar to that of other Lariosaurus species A foramen (for the superior alveolar nerve) is present at the bot- (Rieppel, 1998). The external naris is oval. The ratio of its longi- tom of a shallow anteroposteriorly extending depression on the tudinal diameter to its transverse diameter is 2. The orbit is of right maxilla lateral to the external naris, as is typical of most rounded contours, and the upper temporal fenestra is elongate species of Nothosaurus (Rieppel and Wild, 1996). Posteriorly, and oval. The ratio longitudinal diameter of the upper temporal the maxilla extends to about the level of the anterior margin of fenestra to that of the orbit is 1.69. The upper temporal fenestra the upper temporal fenestra. is thus relatively smaller than that of the holotype, the latter of Compared with the holotype, the nasal-prefrontal-maxilla which has almost the same ratio as N. youngi. However, this is contact is better preserved in the new specimen (Fig. 2A, B). probably a result of taphonomic deformation due to the skull of The paired and leaf-shaped nasals extend between the exter- the holotype being distorted (Rieppel et al., 2003:fig. 1). nal nares and the orbits. Anteriorly, a slender anterior process of the nasal lines the entire medial margin of the external TABLE 1. Measurements (in mm) of the skull of Lariosaurus xingyien- naris. Laterally, the nasal meets the maxilla and defines the sis (XNGM WS-30-R19). posterior margin of the external naris. Posterolaterally, it meets the prefrontal in a posteromedially trending suture, sep- Distance from the tip of the snout to occipital condyle 99.2 arating the maxilla from the frontal. Posteromedially, the Distance from the tip of the snout to back end of skull table 86.0 nasal narrows to a pointed tip and is embraced by the antero- Distance from the tip of the snout to anterior margin of external 18.0 lateral and anteromedial processes of the frontal at the level naris of the anterior margin of the orbit. Distance from the tip of the snout to anterior margin of orbit 33.0 The prefrontal has limited dorsal exposure, located at the Distance from the tip of the snout to anterior margin of upper 54.0 temporal fenestra anteromedial corner of the orbit and defining the anterodor- Distance from posterior margin of external naris to anterior margin 10.7 sal margin of the orbit. Anterolaterally, the prefrontal meets of orbit the maxilla in a concave suture. It is convex and elevated Distance from posterior margin of orbit to anterior margin of upper 4.5 posteriorly, forming a ridge along with the frontal and post- temporal fenestra frontal around the orbit. Posteriorly, the prefrontal is sepa- Longitudinal diameter of external naris 9.0 rated from the postfrontal by the frontal that enters the Transverse diameter of external naris 4.5 Longitudinal diameter of orbit 19.5 dorsal margin of the orbit. Transverse diameter of orbit 13.0 The frontal is unpaired and rather elongate, defining the dorsal Longitudinal diameter of upper temporal fenestra 33.0 margin of the orbit. Anteriorly, the frontal bears two distinct Transverse diameter of upper temporal fenestra 11.0 anterolateral processes that enter between the prefrontal and Longitudinal diameter of parietal foramen 2.5 the nasal and together with the anteromedial process embrace Maximal width of skull at rostrum 14.2 Maximal width of skull at rostral constriction 14.1 the posterior process of the nasal. Anterolaterally, the frontal Maximal width of skull at level between orbit and upper temporal 37.7 contacts the prefrontal along a nearly straight suture. Posteriorly, fenestra it meets the parietal in a deeply interdigitating suture that is Maximal width of skull at posterior end of squamosal 46.6 located at the level of the anterior margin of the upper temporal Minimal width of bony bridge between external nares 4.0 fenestra. Minimal width of bony bridge between orbits 4.7 The nearly triangular postfrontal forms the posteromedial Length of mandibular symphysis 11.9 Width of mandibular symphysis 13.0 margin of the orbit and remains excluded from the anteromedial margin of the upper temporal fenestra by a relatively broad Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-4)

FIGURE 2. Skull of Lariosaurus xingyiensis (XNGM WS-30-R19). A, B, dorsal view; C, D, ventral view. Abbreviations: a, angular; ana, atlas neural arch; art, articular; at, atlas; ax, axis; bo, basioccipital; cn, coronoid; d, dentary; ec, ectopterygoid; eo, exoccipital; f, frontal; hy, hyoid; j, jugal; ma, maxilla; n, nasal; op, opisthotic; p, parietal; pa, palatine; pf, postfrontal; pm, premaxilla; po, postorbital; prf, prefrontal; pt, pterygoid; q, quadrate; r, rib; sa, surangular; so, supraoccipital; sq, squamosal; v, vomer.

contact between the postorbital and the parietal. Medially, the magnum is not visible. Posteriorly, the supraoccipital meets the postfrontal meets the frontal in a curved suture. Laterally, the exoccipital in a concave suture. suture between the postfrontal and the postorbital is concave The exoccipital contacts the supraoccipital anterodorsally and anteriorly and straight posterolaterally. meets the opisthotic laterally. Its pedicel rests on the dorsolateral The postorbital defines the posterior margin of the orbit and aspect of the basioccipital. The laterodorsal portion of the opis- the anterior and nearly half of the lateral margin of the upper thotic is visible, but the paroccipital process is not visible. The temporal fenestra. Medially, it contacts the parietal along a opisthotic meets the squamosal anterodorsally. The oval basioc- straight suture. Along the ventral margin of the upper temporal cipital is exposed behind the pterygoid, forming the occipital fenestra, the postorbital tapers posteriorly to a point at a level condyle without contribution from the exoccipitals. slightly anterior to the midpoint of the upper temporal fenestra. The vomer is an elongate element, forming the anterior and Anterolaterally, the postorbital meets the maxilla in an interdigi- medial margins of the internal naris (Fig. 2C, D). It contacts the tating suture and is overlapped to a certain degree by the latter. palatine posterolaterally, thus excluding the pterygoid from the The jugal is absent as in the holotype. margin of the internal naris. Posterior to the internal naris, the The parietal is fused. It forms the medial margin of the upper vomers extend to embrace the anterior tips of the pterygoids. temporal fenestra. The pineal foramen is situated close to the The internal naris is obscured by the dentary and the splenial posterior margin of the skull roof, at the level of the posterior laterally. It is bordered by the vomer anteriorly and medially and one third of the upper temporal fenestra. Posteriorly, the parietal the palatine posteriorly. diverges laterally to meet the squamosal at the posteromedial The palatines are well preserved on both sides and separated margin of the upper temporal fenestra. The posterior margin of from each other by the vomers and the pterygoids. Anteriorly, the skull table is separated from the occipital surface by a distinct the palatine defines the posterior margin of the internal naris occipital crest, which is laterally continued by the squamosal. In and meets the pterygoid in a long, curved suture medially. Poste- occipital view, the parietal develops a distinct but short sagittal riorly, it extends to contact the ectopterygoid along a concave crest, which cannot be observed in the holotype. suture. The squamosal forms the posterior half of the upper temporal The pterygoid is paired. It is the longest element of the palate, arch, within which the squamosal meets the postorbital along an with an anteroposterior extension of 75.7 mm. The two ptery- elongate suture. Posterolaterally, the lateral process of the squa- goids are remarkably elevated anteromedially and form a narrow mosal descends to contact the quadrate. Posteroventrally, the and long groove along the midline. Laterally, the pterygoid squamosal contacts the supraoccipital medially and the opis- forms a weakly developed transverse process, which together thotic laterally. with the ectopterygoid composes the pterygoid flange. Postero- The supraoccipital is horizontally oriented. It meets the parie- medially, the pterygoids meet in an interdigitating sagittal suture, tal anterodorsally and the squamosal further laterally. Contrary their surface becoming concave towards the midline. At the pos- to the description of Rieppel et al. (2003), the sagittal crest on terior margin, the pterygoid contacts the occipital condyle. the surface of the supraoccipital plate is only composed of one The quadrate shows a relatively broad condylar region. It con- pronounced and low ridge, which almost contacts the sagittal tacts the squamosal dorsally. In ventral view, the quadrate ramus crest of the parietal anteriorly. The border of the foramen of the pterygoid narrows posterolaterally and forms a slender Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-5) ridge, broadly contacting the pterygoid ramus of the quadrate zygapophyses. The neural arches are broad, and the neural vertically lateral to the occipital region. There is no evidence for spines are low. Pachyostosis is distinct in the prezygapophyses a quadratojugal. and postzygapophyses. The dorsal ribs are single-headed and The ectopterygoid is well preserved, forming most of the pter- curved distally. Their proximal parts are pachyostotic. The last ygoid flange. Medially, it meets the pterygoid in a slightly convex dorsal rib is straight and distinctly shorter than the preceding suture. Posteriorly, it tapers to a narrow projection. dorsal ribs, with a narrow distal end. It does not trend toward the The lower jaw is complete, and each element can be identified ilium. on both sides (Fig. 2C, D). The two dentaries meet anteriorly, The sacrum comprises five vertebrae (Fig. 3C). Compared forming a robust mandibular symphysis. Dividing the length of with the last dorsal rib, the sacral ribs are slightly longer, with the symphysis by the width of the symphysis in the constriction blunt and expanded distal ends. There are 22 caudal vertebrae yields a ratio of 0.92, in contrast to that observed in the holotype, preserved exposed in dorsal view. The first caudal rib is nearly as where it is 1.32. This difference may be the result of distortion of stout as the preceding sacral rib. A total of 16 caudal ribs are the lower jaw in the holotype. The splenial is excluded from the present in association with the caudal vertebrae, whereas only 15 formation of the mandibular symphysis, and it can be seen ven- caudal ribs are preserved in the holotype. This difference is tral to the dentary on both mandibular rami. The angular forms ascribed to intraspecific variation (Carroll and Gaskill, 1985). most of the posteroventral part of the mandible and the ventro- They are swollen in the middle region and taper towards the dis- lateral edge of the retroarticular process. The surangular covers tal end. the posterodorsal portion of the mandible and the lateral surface The gastral ribs appear at the level of the ninth dorsal verte- of the retroarticular process. It extends anteriorly to contact the bra, each comprising five elements. The mid-ventral element is dentary in a slightly concave suture, where the coronoid is angled and more robust, whereas the corresponding two collat- exposed, located on the dorsal margin of the surangular just eral elements of each side are more slender and spindle-shaped. below the anterior margin of the upper temporal fenestra. The The pectoral girdle is exposed in ventral view (Fig. 3A, B). coronoid process is about 2.4 mm in height. The articular is slen- The interclavicle is triangular, and the anterior end is complete der and elongated, forming the dorsal surface of the retroarticu- with a pointed tip. Its posterior edge is smoothly concave with a lar process. As described by Rieppel et al. (2003), a shallow much reduced midline projection. It is slightly different from longitudinal groove is present on the dorsal surface of the that of the holotype, which is almost straight posteriorly. How- articular. ever, this is possibly due to intraspecific variation as is also On the right side, five premaxillary fangs are preserved known in other eosauropterygians (Rieppel, 1989). The clavicle (Fig. 2A, B). Posterior to these, there are three small precanine is long and straight, without strong medial constriction or antero- maxillary teeth, followed by paired maxillary fangs that are dis- lateral expanded corner. The two clavicles do not meet in front tinct on both sides. Posteriorly, the maxillary teeth gradually of the interclavicle. become smaller. The exact number of maxillary teeth cannot be The right scapula is exposed in ventral view, whereas the left assessed because of the occlusion of the jaws. Therefore, the den- scapula is well exposed in medial view. It shows a concave ven- tal formula is 5 for the premaxilla and at least 3 C 2 for the max- tral surface of the broadened ventral (glenoidal) portion and a illa. The left mandibular ramus shows three anterior fangs. distinctly elongated posterodorsal process as in the holotype, However, the gaps between the three fangs are very wide. Thus, but it is stouter than in the latter. The coracoids are preserved it is possible that two small teeth were present, because five fangs in articulation, with a deeply concave anterior margin, a weakly are observed in the holotype. The total number of dentary teeth concave posterior margin, and a central constriction. The cannot be established in the specimen.

Postcranial Skeleton The vertebrae are well preserved in articulation. Twenty cervical centra are located anterior to the clavicular-interclavicular complex. The elements of the atlas-axis complex are discernible (Fig. 2). The atlantal centrum is exposed between the occipital condyle and the axial centrum. It is short, being only about half of the axis centrum in length. The paired atlantal neural arches are laterally convex and constricted medially. The neural spine is not developed on the atlas. The axial centrum is approxi- mately as long as wide, only slightly shorter than the following centrum. The axial neural arch has essentially the same shape as that of the rest of the cervical vertebrae. The length of the cervical centra gradually increases from the third to the 20th. The cervical centra are slightly constricted in a lateral direction in ventral view, but the ventral ridge is not distinct. The atlas rib is well preserved. It is a roughly triangular element. The length of the cervical ribs from the axis through the ninth cervical is nearly constant but increases distinctly from the 10th ver- tebra backwards. The cervical ribs are double-headed, with a free anterior process. A total of 24 dorsal vertebrae can be counted. Therefore, the presacral vertebral count is 44, a higher count than that esti- FIGURE 3. The pectoral and pelvic girdles and hind limbs of Lariosau- mated by Rieppel et al. (2003) for the holotype. The anterior 12 rus xingyiensis (XNGM WS-30-R19). A, B, pectoral girdle in ventral vertebrae are exposed in ventral view, and the remaining dorsal view; C, pelvic girdle and hind limbs in dorsal view. Abbreviations: cl, vertebrae are exposed in dorsal view. As in all nothosaurs, the clavicle; co, coracoid; cr1, first caudal rib; dr, dorsal rib; icl, interclavicle; vertebral centra are platycoelous (Rieppel, 2000). The transverse fe, femur; fi, fibula; il, ilium; is, ischium; pu, pubis; sc, scapula; sr, sacral processes project laterally and only slightly beyond the rib; ti, tibia. Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-6) medial margin of the coracoid is nearly straight and contacts its TABLE 2. Measurements (in mm) of the appendicular skeleton of Lar- counterpart along an elongate facet. The lateral margin of the iosaurus xingyiensis (XNGM WS-30-R19). coracoid is much expanded, and the notch for the coracoid foramen is weakly developed, unlike in the holotype where it is Bone Length Proximal width Minimal width Distal width distinct. Right humerus 42.0 10.8 12.0 14.0 The pelvic girdle is exposed in medial view but mostly over- Left humerus 41.5 10.6 11.8 13.6 lapped by the vertebrae and ribs (Fig. 3C). The ilium consists of Right radius 23.0 7.2 4.5 6.7 a roughly triangular acetabular portion and a dorsal blade. The Right ulna 23.0 12.0 7.5 10.1 dorsal iliac blade is reduced, with distinct ornamental tubercles Left femur 55.0 12.0 7.4 8.7 on the surface, as is also observed in the holotype (Rieppel et al., Left tibia 26.9 9.0 7.9 9.8 Left fibula — 6.5 5.5 — 2003:fig. 5B). The width of the ilium is much smaller than the total width of the distal ends of the five sacral ribs. Only the proximal (acetabular) ends of the pubes are visible. Therefore, it is difficult to identify the nature of the obturator foramen in the and resembles that of other Lariosaurus. It is evenly curved pos- pubis. The exact contour of the ischium is unclear, but it seems teriorly, and the deltopectoral crest is weakly developed. It grad- that the ischium expands to form a fan-shaped blade posteriorly. ually gets broader distally without constriction in its mid-shaft, Both humeri are completely exposed in ventral view (Fig. 4A, as is characteristic of Lariosaurus. The ectepicondylar groove is B). The humerus is distinctly shorter than the femur (Table 2) present at the distal end of the humerus near its anterior margin, and the entepicondylar foramen is distinct, located close to the posterior margin (Fig. 4A, B). The radius is slender and nearly equal in length to the ulna. It shows a sigmoidal pre axial margin, and the proximal end is more distinctly expanded than the distal end. The ulna is flattened dorsoventrally and is much broader than the radius, with a nearly straight postaxial margin. The preaxial margin of the ulna is concave, enclosing the spatium interosseum with the concave preaxial margin of the radius. Its proximal end is more expanded than the distal end. Five carpal ossifications are present in the right manus, including the kidney-shaped intermedium, the rounded ulnare, and three distal carpals. The intermedium has a slightly concave anterior margin. It is intercalated between the radius and ulna and is the largest element of the five. The ulnare is slightly smaller than the intermedium and located distal to the ulna. Dis- tal carpals III and IV are nearly equal in size, whereas distal carpal V is much smaller, only half the diameter of the former two. The metacarpals are all slender and constricted medially. Metacarpal I is shortest and broadest, with an expanded proximal end. Metacarpal III is the longest of the five, and its distal margin is slightly narrower than the proximal one. Metacarpal II is slightly shorter than metacarpal IV. Metacarpal V is partially damaged and is possibly shorter than metacarpal II. The phalan- ges are incomplete, with a preserved phalangeal formula of 2-2- 3-2-?. The hind limbs are not completely preserved, leaving only the left femur, tibia, and fibula, and a partially preserved right femur (Fig. 3C). Therefore, the following description is mainly based on the left hind limb. The femur is long, slender, and slightly sigmoidally curved. Its proximal end is broader than the distal one. The internal trochanter, if present, would be much reduced, as is indicated by the flat proximal head of the femur. The tibia is straight and broader than the fibula. The proximal end of the tibia is slightly shorter than the distal end. The distal part of the fibula is missing. The fibula appears to be a little longer than the tibia. It is curved postaxially, forming the spatium interosseum with the tibia. It is impossible to count the number of ossifications in the tarsus or the phalangeal formula of the pes.

PHYLOGENETIC ANALYSIS In order to assess the ingroup relationships of Nothosauridae and test the phylogenetic relationships of Lariosaurus and Nothosaurus, we conducted two analyses based on a revision of the data matrix of Liu et al. (2014). The ﬁrst analysis resulted in seven equally parsimonious trees. The topology of the strict con FIGURE 4. Right forelimb of Lariosaurus xingyiensis (XNGM WS-30- sensus tree is similar to that of Liu et al. (2014) and revealed the R19) in ventral view. A, photo; B, interpretative drawing. Abbreviations: new specimen to be sister to the holotype of L. xingyiensis and dc, distal carpal; hu, humerus; int, intermedium; mc, metacarpal; ra, specimen XNGM WS-30-R24 to be sister to that of N. youngi radius; u, ulna; ul, ulnare. Scale bar equals 1 cm. (Fig. 5A), thereby conﬁrming the generic assignment of the Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-7)

FIGURE 5. Strict consensus trees resulting from the phylogenetic analyses of Nothosaur- idae interrelationships (see text for more details). A, result of the ﬁrst analysis (7 MPTs, TL D 239, CI D 0.3682, and RI D 0.5325); B, result of the second analysis (7 MPTs, TL D 221, CI D 0.3937, and RI D 0.5162). Values above branches leading to the nodes represent Bremer support, and the values below the branches are bootstrap values 50% (1000 replicates).

XNGM specimens given earlier. The analysis does not support species of the genus Lariosaurus are recognized (Rieppel, 1998, the monophyly of Nothosaurus or Lariosaurus, respectively, as 2000; Li et al., 2002; Rieppel et al., 2003; Jiang et al., 2006a; traditionally defined. Nothosaurus youngi and N. winkelhorsti Jiang et al., 2006b), among which Lariosaurus xingyiensis and L. are more closely related to lariosaurs than to nothosaurs as in hongguoensis were collected from deposits in southwestern Liu et al. (2014) and Klein et al. (2016), the former being the sis- China. Lariosaurus hongguoensis is based on a complete skele- ter taxon of L. xingyiensis and the latter sister to L. buzzii. ton from the Upper Member (middle Anisian) of the Guanling Nothosaurus juvenilis is the sister taxon of the clade that includes Formation of Panxian County in Guizhou Province. It differs all species of Lariosaurus and the aforementioned two species of from L. xingyiensis by the small prefrontal, the more extensive Nothosaurus. The second analysis returned the same result as frontal, the presence of the jugal, a broader parietal skull table, seen in the first analysis (Fig. 5B). and probably at least seven premaxillary teeth. The proximal end of the radius in L. xingyiensis is more expanded than the distal one, whereas both ends of the radius in L. hongguoensis are COMPARISON AND DISCUSSION almost equally expanded. Specimen XNGM WS-30-R19 was excavated from the same Lariosaurus xingyiensis also differs from the lariosaurs of the area as the holotype, and can be referred to that species on the western Tethys in some features. Regarding features of the skull, basis of the following features: retroarticular process elongate; the parietal skull table of L. balsami and L. curionii shows a dis- clavicles without anterolaterally expanded corners; posterior tinct constriction in the posteriormost part (Rieppel, 1998, 2000), scapular process (blade) slender and elongate; humerus distinctly which is absent in L. xingyiensis. Furthermore, the absence of a shorter than femur; and dorsal process of ilium with distinct rostral constriction and the relatively small postfrontal of L. curi- tubercular ornamentation. However, the new specimen shows onii are also different from L. xingyiensis. Lariosaurus stensioei some features that are not present or cannot be ascertained in has a small and rounded upper temporal fenestra with the parie- the holotype. There is a shallow anteroposteriorly extending tal foramen displaced to the anterior position in the parietal, depression with a foramen on the maxilla close to the ventral whereas in L. xingyiensis the upper temporal fenestra is larger margin of the external naris in the new specimen. The nasal and more elongate and the parietal foramen is located close to meets the prefrontal, thus excluding the maxilla from contact the posterior margin of the parietal. Moreover, the sagittal crest with the frontal, which is different from the holotype (Rieppel on the supraoccipital of L. xingyiensis is slender and low, in con- et al., 2003). Furthermore, in occipital view, a short sagittal crest trast to that of L. stensioei, which shows a prominent, knob-like is present on the parietal, but in dorsal view the supraoccipital process. The fused nasals, broad parietal, the central position of plate displays a single pronounced ridge. Due to the overlapping the parietal foramen, and the low upper temporal fenestra/orbit clavicular-interclavicular complex and coracoid, the exact num- ratio of L. buzzii are clearly dissimilar to L. xingyiensis. Com- ber of presacral vertebrae could not be established for the holo- pared with L. xingyiensis, L. calcagnii has the parietal foramen type, whereas it is discernible in the new material with a total of displaced to the posterior extremity of the parietal skull table 44 presacrals. and L. valceresii has a relatively large upper temporal fenestra/ Information derived from the new specimen allows us to bet- orbit ratio. In addition to the smaller skull size, L. vosseveldensis ter distinguish L. xingyiensis from other lariosaurs. To date, nine is different from L. xingyiensis by its fused premaxillae and Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-8) nasals, the contact of the prefrontal with the postfrontal, the support the monophyly of Lariosaurus, whereas the monophyly presence of the jugal, broad parietal, as well as the frontoparietal of the traditional Nothosaurus is not supported. Furthermore, suture being placed anteriorly (Klein et al., 2016). ‘N. juvenilis,’ ‘N. youngi,’ and ‘N. winkelhorsti’ are reassigned to In reference to the postcranial skeleton, there are six carpals Lariosaurus,asL. juvenilis, L. youngi, and L. winkelhorsti, present in L. balsami, but only five in L. xingyiensis. The postax- respectively. Although the phylogenetic relationships of the spe- ial margin of the ulna in L. curionii is concave, unlike in L. xin- cies of Lariosarus are fully resolved, many clades have low boot- gyiensis, where the postaxial margin of the ulna is nearly strap support values (lower than 50%) and low Bremer support straight. The humerus of L. buzzii lacks an entepicondylar fora- (Fig. 5), mainly because the complete postcranial skeleton is men, which is present in L. xingyiensis. The heightened neural unknown for Germanosaurus, as well as for many species of spines in the proximal caudal region, the humerus distinctly lon- Nothosaurus and Lariosaurus. The interpretation of the phyloge- ger than the femur, and the ulna without distinctly broadened netic hypothesis is necessarily based on the currently available proximal head of L. calcagnii are different from conditions in material only and might be subject to revisions along with L. xingyiensis. Lariosaurus valceresii differs from L. xingyiensi the discovery of additional specimens in the future. In conclu- in the absence of rib pachyostosis and a relatively longer and dis- sion, more information on complete specimens is necessary tinctly preaxially angulated humerus. to further clarify the phylogenetic relationships among Triassic In addition, with an increasing number of articulated skeletons Nothosauridae. of Nothosaurus and Lariosaurus collected in southwestern China, comparisons of the entire skeleton are becoming possible. Detailed observations and comparisons of all relevant species of ACKNOWLEDGMENTS Nothosaurus and Lariosaurus revealed that three species that Y.-Z. Wang and M.-Y. Wang prepared the specimen. We were previously assigned to Nothosaurus were no longer refer- thank C. Li and Q.-H. Shang of IVPP for providing access to the able to that genus. Nothosaurus youngi from the Ladinian of specimens under their care. Projects 41372016, 41402014, and south China exhibits a morphology that was reported to show 40920124002 were supported by the National Natural Science diagnostic features of Lariosaurus in the postcranium (Ji et al., Foundation of China. Project 123102 was supported by State 2014), such as the presence of pachyostotic dorsal ribs, four Key Laboratory of Palaeobiology and Stratigraphy (Nanjing sacral vertebrae, the anterior margin of its humerus without a Institute of Geology and Palaeontology, Chinese Academy of distinct angulation, and the presence of five ossified carpals. Sciences). Project 20120001110072 was supported by the Therefore, it is logical to conclude that N. youngi is more closely Research Fund for the Doctoral Program of Higher Education. related to Lariosaurus than to Nothosaurus. Additionally, both Editor R. O’Keefe, reviewer J. Liu, and an anonymous reviewer N. youngi and L. xingyiensis are found in the Zhuganpo Member offered very helpful suggestions and comments. of Falang Formation. The referred specimen of N. youngi (XNGM WS-30-R24, formerly WS-30-R24) was actually discovered in the same bed as L. xingyiensis during the excavation at LITERATURE CITED Nimaigu village. Nothosaurus winkelhorsti is only represented by a small skull (46 mm long) from the Lower Muschelkalk (early Baur, G. 1889. Palaeohatteria Credner, and the Proganosauria. American Anisian) locality of Winterswijk, the Netherlands. It is the small- Journal of Science 3:310–313. Carroll, R. L., and P. Gaskill. 1985. The nothosaur Pachypleurosaurus est skull among Triassic nothosauroids, but so far its juvenile sta- and the origin of plesiosaurs. Philosophical Transactions of the tus cannot be unequivocally confirmed (Klein and Albers, 2009). Royal Society of London B Biological Sciences 309:343–393. In addition, the low upper temporal fenestra/orbit ratio (1.65), Curioni, G. 1847. Cenni sopra un nuovo saurio fossile dei monti di Per- the broad parietal, and the parietal foramen located close to the ledo sul Lario e sul terreno che lo racchiude. Giornale del’ J.R. central part of the parietal in N. winkelhorsti all indicate lario- Instituto Lombardo di Scienze, Lettre ed Arti 16:159–170. saur affinity. The holotype and only known specimen of N. juve- Hanni,€ K. 2004. Die Gattung Ceresiosaurus. Hochschulverlag, Zurich, nilis from the Hauptmuschelkalk of Germany was redescribed Switzerland, 147 pp. by Rieppel (1994). The ratio of the longitudinal diameter of the Ji, C., D.-Y. Jiang, O. Rieppel, R. Motani, A. Tintori, and Z.-Y. Sun. upper temporal fenestra to that of the orbit is 1.58 in N. juvenilis. 2014. A new specimen of Nothosaurus youngi from the Middle Tri- assic of Guizhou, China. Journal of Vertebrate Paleontology This value is lower than that of other species of Nothosaurus but 34:465–470. fits well into the range of the species of Lariosaurus. Further, its Jiang, D.-Y., M. W. Maisch, W.-C. Hao, Y.-L. Sun, and Z.-Y. Sun. 2006a. relatively narrow postorbital arch also resembles that of other Nothosaurus yangjuanensis n. sp. (Reptilia, Sauropterygia, Notho- Lariosaurus, again indicating lariosaur affinity. sauridae) from the middle Anisian (Middle Triassic) of Guizhou, Based on morphological and phylogenetic affinity, N. juvenilis, southwestern China. Neues Jahrbuch fur€ Geologie und N. youngi, and N. winkelhorsti should be assigned to the genus Palaontologie,€ Monatshefte 2006:257–276. Lariosaurus. Therefore, Lariosaurus is redefined as a monophy- Jiang, D.-Y., M. W. Maisch, Z.-Y. Sun, Y.-L. Sun, and W.-C. Hao. 2006b. A letic clade including the most recent common ancestor of L. juve- new species of Lariosaurus (Reptilia, Sauropterygia) from the Middle nilis and L. hongguoensis and all of its descendants. The clade is Anisian (Middle Triassic) of Guizhou, southwestern China. Neues Jahrbuch fur€ Geologie und Palaontologie,€ Monatshefte 242:19–42. supported by five unambiguous synapomorphies (i.e., supported Jiang, D.-Y., M. W. Maisch, W.-C. Hao, H. U. Pretzschner, Y.-L. Sun, by both ACCTRAN and DELTRAN optimization): 1(1), ratio and Z.-Y. Sun. 2005. Nothosaurus sp. (Reptilia, Sauropterygia, of condylobasal skull length to longitudinal diameter of upper Nothosauridae) from the Anisian (Middle Triassic) of Guizhou, temporal fossa between 3.0 and 3.4; 2(1), ratio of longitudinal southwestern China. Neues Jahrbuch fur€ Geologie und diameter of upper temporal fossa to that of orbit between 1.0 Palaontologie,€ Monatshefte 2005:565–576. and 2.0; 4 (0), ratio of distance from posterior margin of external Klein, N., and P. C. H. Albers. 2009. A new species of the sauropsid rep- naris to anterior margin of orbit to the width of the postorbital tile Nothosaurus from the Lower Muschelkalk of the western Ger- arch more than 1.7; 17(0), parietal extending beyond the anterior manic Basin, Winterswijk, The Netherlands. Acta Palaeontologica margin of upper temporal fossa; and 71(1), obturator foramen of Polonica 54:589–598. Klein, N., D. F. A. E. Voeten, A. Haarhuis, and R. Bleeker. 2016. The pubis open in adult. earliest record of the genus Lariosaurus from the early middle Ani- In summary, the new specimen of L. xingyiensis provides com- sian (Middle Triassic) of the Germanic Basin. Journal of Vertebrate prehensive morphological information for this species and neces- Paleontology 36:4, e1163712, doi: 10.1080/02724634.2016.1163712. sitates the emendation of previous diagnoses. Phylogenetic Li, J.-L., and O. Rieppel. 2004. A new nothosaur from Middle Triassic of analyses of the Nothosauridae based on the new specimens Guizhou, China. Vertebrata PalAsiatica 42:1–12. Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-9)

Li, J.-L., J. Liu, and O. Rieppel. 2002. A new species of Lariosaurus (Sau- (67) Carpal ossifications, number: two or three (0); four (1); five ropterygia: Nothosauridae) from Triassic of Guizhou, Southwest (2); six (3). This revised definition of character states reflects China. Vertebrata PalAsiatica 40:114–126. the result of gap coding (see Supplementary Data 1 for Liu, J., S.-X. Hu, O. Rieppel, D.-Y. Jiang, M. Benton, N. Kelley, J. Aitch- more details). ison, C.-Y. Zhou, W. Wen, J.-Y. Huang, T. Xie, and T. Lv. 2014. A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Trias- sic of SW China and its implication for the Triassic biotic recovery. Coding Changes Scientific Reports 4:7142. doi: 10.1038/srep07142. Owen, R. 1860. Palaeontology; or, a Systematic Summary of Extinct Ani- mals and Their Geologic Remains. Adam and Charles Black, Edin- Pachypleurosauria: character 67 is changed from state (1) to burgh, U.K., xv C 420 pp. (0) because there are two or three carpals present in the Rieppel, O. 1989. A new pachypleurosaur (Reptilia: Sauropterygia) from taxon. the Middle Triassic of Monte San Giorgio, Switzerland. Philosophi- Simosaurus: character 67 is changed from state (1) to (0) because cal Transactions of the Royal Society of London B Biological Scien- there are three carpals present in the taxon. ces 323:1–73. Rieppel, O. 1994. The status of the sauropterygian reptile Nothosaurus Germanosaurus: character 2 is changed from state (2) to (1) juvenilis from the Middle Triassic of Germany. Palaeontology because the ratio of upper temporal fossa to orbit is between 37:733–745. 1.0 and 2.0. Rieppel, O. 1998. The status of the sauropterygian reptile genera Ceresio- N. yangjuanensis: character 2 is changed from state (3) to (2) saurus, Lariosaurus, and Silvestrosaurus from the Middle Triassic of because the ratio of upper temporal fossa to orbit is greater Europe. Fieldiana: Geology 38:1–46. than 2; character 67 from (0) to (1) because there are four car- Rieppel, O. 2000. Sauropterygia I: Placodontia, Pachypleurosauria, pals present in the taxon. Nothosauroidea, Pistosauroidea. Encyclopedia of Paleoherpetol- N. marchicus: character 2 is changed from state (3) to (2) because ogy, Volume 12A. Verlag Dr. Friedrich Pfeil, Munich, 134 pp. the ratio of upper temporal fossa to orbit is greater than 2; Rieppel, O., and R. Wild. 1996. A revision of the genus Nothosaurus (Repti- lia, Sauropterygia) from the Germanic Triassic, with comments on the character 67 from (1) to (0) because there are three carpals status of Conchiosaurus clavatus. Fieldiana Geology 34:1–82. present in the taxon. Rieppel, O., J.-L. Li, and J. Liu. 2003. Lariosaurus xingyiensis (Reptilia: N. mirabilis: character 2 is changed from state (4) to (2) because Sauropterygia) from the Triassic of China. Canadian Journal of the ratio of upper temporal fossa to orbit is greater than 2. Earth Sciences 40:621–634. N. giganteus: character 2 is changed from state (4) to (2) because Seeley, H. G. 1882. On Neusticosaurus pusillus (Fraas), an amphibious the ratio of upper temporal fossa to orbit is greater than 2; reptile having affinities with terrestrial Nothosauria and with marine character 67 from (0) to (1) because there are four carpals Plesiosauria. Quarterly Journal of the Geological Society of London present in the taxon. 38:350–366. N. tchernovi: character 2 is changed from state (3) to (2) Tintori, A., Z.-Y. Sun, P.-G. Ni, C. Lombardo, D.-Y. Jiang, and R. Motani. 2015. Oldest stem Teleostei from the Late Ladinian (Mid- because the ratio of upper temporal fossa to orbit is dle Triassic) of Southern China. Rivista Italiana di Paleontologia e greater than 2. Stratigrafia 121:285–296. N. youngi: character 67 is changed from state (0) to (2) because Yin, C., W.-Y. Hao, Z.-Y. Sun, Y.-L. Sun, and D.-Y. Jiang. 2014. New there are five carpals present in the taxon (Ji et al., 2014). material of Nothosaurus yangjuanensis from the Middle Anisian N. jagisteus: character 2 is changed from state (3) to (2) because (Middle Triassic) of Guizhou Province, Southwestern China. Acta the ratio of upper temporal fossa to orbit is greater than 2; Scientiarum Naturalium Universitatis Pekinensis 50:467–475. [Chi- character 67 from (1) to (0) because there are three carpals nese, with English abstract] present in the taxon. Zou, X.-D., M. Balini, D.-Y. Jiang, A. Tintori, Z.-Y. Sun, and Y.-L. Sun. N. edingerae: character 2 is changed from state (3) to (2) because 2015. Ammonoids from the Zhuganpo Member of the Falang For- mation at Nimaigu and their relevance for dating the Xingyi Fossil- the ratio of upper temporal fossa to orbit is greater than 2. Lagerstatte€ (Late Ladinian, Guizhou, China). Rivista Italiana di L. hongguoensis: character 2 is changed from state (2) to (1) Paleontologia e Stratigrafia 121:135–161. because the ratio of upper temporal fossa to orbit is between 1.0 and 2.0; character 8 from (0) to (1), maxilla with depression Submitted July 13, 2016; revisions received October 15, 2016; at lateral margin of external naris and a foramen at its bottom accepted November 17, 2016. for the exit of a lateral branch of the superior alveolar nerve; Handling editor: Robin O’Keefe. character 16 from (1) to (0), foramen located within a deep trough absent; character 29 from (0) to (1), quadratojugal APPENDIX 1. List of characters modified from Liu et al. absent; character 53 from (1) to (0), medial gastral rib ele- (2014), coding changes made to that matrix, and codings for two ments with a single lateral process; character 60 from (1) to additional taxa. (0), humerus, insertional crest for latissimus dorsi muscle reduced; character 67 from (0) to (2) because there are five Modified Characters carpals present in the taxon. L. buzzii: character 2 is changed from state (0) to (1) because the (2) Ratio of longitudinal diameters, upper temporal fossa to ratio of upper temporal fossa to orbit is between 1.0 and 2.0. orbit: 1.0 or less (0); more than 1.0 but less than 2.0 (1); 2.0 L. calcagnii: character 2 is changed from state (0) to (1) because or more (2). It has been known historically that Nothosau- the ratio of upper temporal fossa to orbit is between 1.0 and rus typically has a larger upper temporal fenestra, with a 2.0; character 67 from (0) to (3) because there are six carpals longitudinal diameter that is 2 or more times that of the present in the taxon (Hanni,€ 2004). orbit, whereas the same ratio in Lariosaurus is between 1.0 L. balsami: character 67 is changed from state (0) to (3) because and 2.0 and less than 1.0 in Pachypleurosauria (see Supple- there are six carpals present in the taxon. mentary Data 1 for more details). L. valceresii: character 2 is changed from state (2) to (1) because (32) Supraoccipital, sagittal crest: absent (0); reduced (1); well the ratio of upper temporal fossa to orbit is between 1.0 and developed (2); knob-like (3). The character originally 2.0; character 67 from (0) to (2) because there are five carpals included a fourth character state: knob-like (3). However, present in the taxon. none of the taxa in the data set exhibited this character L. xingyiensis: character 2 is changed from state (2) to (1) state. Accordingly, the character state was deleted. because the ratio of upper temporal fossa to orbit is Lin et al.—New specimen of Lariosaurus xingyiensis (e1278703-10)

between 1.0 and 2.0; character 21 from (?) to (1), jugal APPENDIX 2. List of coding changes made to the matrix of the absent; character 29 from (?) to (1), quadratojugal absent; ﬁrst analysis. character 67 from (0) to (2) because there are ﬁve carpals N. youngi: character 2 is changed from state (2) to (1/2); char- present in the taxon. acter 11 from (0) to (0/1); character 26 from (1) to (0/1); character 32 from (1) to (1/2); characters 35, 36, 37, and 46 from (0) to Additional Taxa (0/1); character 52 from (?) to (1); character 53 from (1) to (0/1); character 56 from (0) to (0/1); character 57 from (2) to (0/2); character 58 from (0) to (0/1); characters 59, 61, and 62 from (?) XNGM WS-30-R19 11001 00100 11001 00210 11010 11110 12010 01011 to (0); characters 65 and 68 from (?) to (1); character 71 from (0) 11212 00011 12010 00110 00211 0211? ?01? to (0/1). L. xingyiensis: character 1 is changed from state (2) to (1/2); XNGM WS-30-R24 character 12 from (0) to (0/1); character 35 from (1) to (0/1); 21001 00100 11001 10201 01010 01110 12001 11111 character 45 from (?) to (2); character 59 from (0) to (0/1); char- 11112 10001 11000 10100 00211 121?0 1001 acter 66 from (1) to (0/1).