Etymology.

Nankangia refers to the Chinese administrative unit Nankang City in Jiangxi Province.

Type species.

Nankangia jiangxiensis gen. et sp. nov. urn:lsid:zoobank.org:act: D3C8151C-970B-4944-AA4C-E913E73F64D8.

Diagnosis.

As for the type and only known species.

Etymology.

The specific name refers to Jiangxi Province, where the holotype site in Nankang City is located.

Holotype.

The holotype specimen (GMNH F10003) includes a partial lower jaw, five dorsal vertebrae, one and one-half sacral vertebrae, nine complete and two partial caudal vertebrae, both scapulocoracoids, incomplete furcula, a nearly complete right humerus, complete right ilium, most of the left ilium, complete right pubis and most of the left pubis, complete right ischium and a partial left ischium, both femora, right tibia, and some dorsal ribs. All specimens are housed at the Ganzhou Museum of Natural History, Ganzhou City of Jiangxi Province.

Type locality and horizon.

Longling of Nankang, Ganzhou City; Nanxiong Formation (Upper Cretaceous) [34].

Diagnosis.

Nankangia is distinguished by the following combination of characters: (1) the rostral end of the mandibular symphyseal region is not downturned (shared with caenagnathids, Incisivosaurus, Luoyanggia and Ganzhousaurus); (2) two infradiapophyseal fossae on the ventral surface near the base of the transverse process of the dorsal vertebrae; (3) pneumatic fossae on the sacral vertebrae slit-like; (4) neural spines of the cranial caudal vertebrae wider transversely than anteroposteriorly, forming a large posterior fossa with a rugose central area; (5) large fossa on the anterior surface (infraprezygapophyseal fossa) and another (infradiapophyseal fossa) on the ventral surface of the base of the transverse process of the cranial caudals; (6) femur longer than ilium (shared with Yulong and Khaan); (7) ratio of height to length of ilium 0.36; (8) femoral neck extending dorsomedially at about an angle of 90 to the shaft; (9) femur and tibia approximately the same length.

Lower jaw.

Both sides of the rostral part are preserved (Figure 2). In lateral view, the rostral end of the jaw is not downturned and the ventral margin of the dentary is nearly straight (Fig. 2A). Posteriorly, the dentary is divided into two branches that extend posterodorsally and posteroventrally, forming the anterior margin of the external mandibular fenestra. Many small nutrient openings are irregularly distributed on the lateral surface of the mandibular symphyseal region. In dorsal view, the cranial margin of the rostral end of the lower jaw is nearly straight; thus the mandibular symphyseal region is U-shaped, similar to that in Khaan mckennai and other oviraptorosaurs [12], but different from that of Luoyanggia liudianensis, where it is V-shaped [21]. The dorsal surface of the mandibular symphyseal region is smooth with several foramina along the margin of the jaw. The mandibular symphyseal suture is nearly straight. There is a distinct opening on the suture near the rostral end of the lower jaw. The margins of the rostral end are sharp. In posterior view, the sutural portion is convex, forming a distinct ridge. In ventral view, the symphyseal region is also U-shaped (Fig. 2B).

Dorsal vertebrae.

(Fig. 3 A; see Table S1). Five dorsal vertebrae are preserved. According to the position of the parapophysis, these vertebrae are mid-dorsal vertebrae. But their exact positions in the vertebral column are not clear, and thus these five dorsal vertebrae are referred to here as dorsal 1 to dorsal 5. The anterior articular end of the centrum is much more concave than the posterior articular end, which is moderately concave. The articular end is higher than wide and nearly rectangular. The five dorsal vertebrae are tightly articulated, and their lateral sides are covered by a portion of pubis on the left side and dorsal ribs on the right side. Thus, the detailed structure of the neural arches is not clear. The five articulated dorsal vertebrae curve dorsally. The position of the parapophysis moves upwards from the anterodorsal corner of the centrum on dorsal 1 to the neural arch on dorsal 5. The lengths of the centra increase from the cranial to the caudal vertebrae, as do the lengths of the lateral pneumatic fossae. A weak ventral ridge is present on the first two dorsal vertebrae. The ventral surfaces of the more caudal vertebrae become round. The facet of the parapophysis on dorsal 2 extends across the suture of the neural arch and the centrum, although its details are not clear. The facet of the parapophysis is concave and elongated, and its long axis is nearly vertical. The neural spine extends perpendicular to the centrum. Two distinct fossae (infradiapophyseal fossa: Infr f1 and Infr f2) are present on the lateral surface near the base of the transverse process (Fig. 3A). These two fossae are demarcated by three laminae: the anterior lamina originates from the posterolateral margin of the prezygapophysis and extends to the anteroventral surface of the transverse process; the middle lamina originates from the dorsal margin of the parapophysis and extends to the ventral surface of the transverse process; and the last lamina extends from the posterolateral margin of the centrum to the ventral side of the transverse process.

Sacral vertebrae.

(Fig. 3B; see Table S1 for measurements). There are only one and one half sacral vertebrae preserved. They represent the posteriormost two sacrals. The transverse processes are stout, with expanded distal ends that are fused together. The ventral surfaces of the centra are smooth. The suture between them is visible. The ventral surface of the last sacral centrum is rounded with a slight, shallow groove. The transverse process of this vertebra extends posterolaterally beyond the posterior articular end of the centrum. The posterior articular end of the posteriormost sacral vertebra is moderately concave and slightly wider than high. The neural canal is large and wider than high. The lateral surface of the last sacral vertebra is smooth with a small pneumatic fossa.

Caudal vertebrae.

(Fig. 3C; see Table S1 for measurements). Nine complete and two partial caudal vertebrae are preserved. A set of three and one half relatively large, articulated caudal vertebrae are cranial caudals. Another two and one half smaller vertebrae are distal caudals, and four isolated vertebrae belong to the middle portion of the tail.

The anterior articular ends of all completely preserved caudal vertebrae are moderately concave and their posterior articular ends are slightly concave. Because it is difficult to determine the exact positions of these vertebrae, they are here referred to as caudal 1 to caudal 9. Caudal 1 is relatively stout. The anterior articular end of its centrum is concave, although the margins are weathered and the articular end is not as concave as on the posterior caudals. The anterior articular end is circular. The ventral surface of the centrum is convex. The facet of the prezygapophysis faces anteromedially, and the prezygapophysis extends forward beyond the anterior articular end in lateral view. In anterior view, the neural canal is rectangular and higher than wide. The postzygapophysis does not extend beyond the posterior articular end. The pneumatic fossa is slit-like and smaller than those on the posterior caudal vertebrae (Fig. 3C). The transverse process extends posterolaterally. There is a distinct fossa (the infraprezygapophyseal fossa) on the lateral surface near the junction of the prezygapophysis and transverse process (Fig. 3D). Another triangular fossa (the infradiapophyseal fossa) is situated on the ventral surface near the base of the transverse process. This large fossa is demarcated by strong laminae known as the anterior and posterior centrodiapophyseal laminae in sauropod dinosaurs [35]. The neural spine is wider transversely than long anteroposteriorly. A distinct median vertical ridge (a structure that would be called a prespinal lamina in a sauropod) is present on the anterior surface of the neural spine, but this ridge disappears before reaching the dorsal margin of the neural canal. The neural spine extends posterodorsally and is triangular in lateral view. The posterior surface of the neural spine between the postzygapophyses is strongly concave, forming a large posterior fossa with a rugose area (Fig. 3E, pf) for the attachment of interspinal ligaments. The structures of the next two caudal vertebrae are similar to the first one, except for the pneumatic fossae and infraprezygapophyseal fossa, which become larger, and the infradiapophyseal fossa, which becomes smaller. The broken surfaces of the neural arches show that these structures are highly pneumatic.

The remaining caudal vertebrae are smaller than the first three caudals (Fig. 3F). Their centra have circular, concave anterior articular ends. They have distinct ventral grooves for contact with the hemal arches. A weak ventral groove is present on these distal caudal vertebrae. The prezyzapophysis overlaps a small part of the preceding vertebra. The hemal arch is wider than long. The hemal arch facets are distinct.

Scapulocoracoid.

(Figure 4; see Table S2 for measurements). Both the right and left scapulocoracoids are firmly attached to each other. The scapula and coracoid are highly fused and their sutures are not clear. The shaft of the scapula is narrow and curved medially. Its dorsal surface is weakly convex and its ventral surface is slightly concave in lateral view. Its dorsal margin is moderately thicker than its ventral margin. The distal end of the scapula is slightly expanded. The proximal end is much more expanded than the distal end. The acromion is very well developed. It is long and projects anteriorly. In lateral view, the ventral margin of the acromion smoothly transitions to the anterior surface of the proximal end of the scapula, forming a U-shaped configuration. The glenoid cavity faces posteroventrally. The coracoid is sutured with the scapula along a straight margin. Its anterior margin is missing. Its ventral margin is convex and its posterior margin is concave, forming a horn-like posteroventral process, which extends posteroventrally beyond the glenoid. The lateral surface of the coracoid is strongly convex with a distinct biceps tubercle near the center of the coracoid. The coracoid foramen is slit-like and its long axis nearly perpendicular to the scapula-coracoid suture. It is located anterodorsal to the biceps tubercle. The medial surface of the coracoid is strongly concave anterior to the posterior margin of the coracoid.

Furcula.

The bone is broken, and only parts of it are in contact with the acromion.

Humerus.

(Figure 5; see Table S2 for measurements). The right humerus is almost completely preserved, missing only a small portion of its distal end. It is slightly twisted. The deltopectoral crest is low, and its margin becomes thicker than the lateral margin of the proximal end of the humerus. The anterolateral surface of the proximal end of the humerus is concave. The posterior surface of the humerus is slightly convex. The lateral margin of the deltopectoral crest is straight. There is a distinct ridge that originates from the level of the distal margin of the deltopectoral crest nearly parallel to the apex of the deltopectoral crest, which is separated from it by about 2.5 cm. The apex of the deltopectoral crest is located on the proximal one-third of the shaft, which is different from the condition in some oviraptorids, where the apex of the deltopectoral crest is situated just proximal to the mid-length of the shaft [3]. The internal tuberosity expands medially. A distinct concave surface separates the internal tuberosity from the humeral head on the posterior surface. The humeral head is convex posteriorly but its opposite side is nearly flat. A portion of the distal end of the humerus is missing, thus the detailed structure of the condyles is not clear. The area of the olecranon fossa is flat on the posterior surface of the distal articular end of the humerus. There is a distinctly concave, round area near the middle portion of the distal end.

Ilium.

(Fig. 6A, B; see Table S3 for measurements). The right ilium is complete (Fig. 6B) and the left ilium (Fig. 6A) is missing its dorsal margin. The dorsal margin of the ilium is arched (Fig. 6B). In dorsal view, the preacetabular process extends anterolaterally, whereas the postacetabular process extends posteromedially; thus the ilium is weakly sigmoid in dorsal view. Although the ilia are not preserved together, the position of the medially curved central portion of the ilium may indicate that the dorsal margins of the opposing iliac blades were close to or even contacted each other along their medial sections. The preacetabular process of the ilium is slightly longer than the postacetabular process. The central portion of the lateral surface of the ilium is concave. The lateral surface of the postacetabular process is convex and that of the preacetabular process is nearly flat. The postacetabular process is much thicker than the preacetabular process. The preacetabular process is thin and plate-like, and its ventral margin is weakly expanded ventrally below the level of the dorsal acetabular margin. The ventral margin of the preacetabular process is mediolaterally wide and there is a distinct medial margin, which forms a shallow fossa. This cuppedicus fossa is near the base of the preacetabular process. The anteroventral extension of the preacetabular process is round. The postacetabular process narrows posteriorly and is pointed. The brevis fossa is short and wide on the ventral surface of the postacetabular process. The pubic peduncle is much deeper than the ischial peduncle, which is different from other oviraptorids where the pubic peduncle is as deep as the ischial peduncle [3]. The pubic peduncle is much longer anteroposteriorly than the ischial peduncle. The articular surface of the ischial peduncle is much smaller than that of the pubic peduncle. The pubis is fused with the ilium but the ischium is not fused. The articular surface on the ischial peduncle for the ischium is small, triangular, and located posteroventrally. The antitrochanter is located on the lateral surface near the ischial peduncle. There is no supracetabular crest. The acetabulum is wider on the lateral surface than the medial surface.

The medial surface of the ilium is slightly concave dorsoventrally. There are two short, distinct ridges extending dorsally above the middle dorsal margin of the acetabulum.

Pubis.

(Fig. 6C; see Table S4 for measurements). The right pubis is complete whereas the left pubis is missing its middle portion. The pubis is oriented vertically and its shaft is weakly concave anteriorly. The proximal end of the pubis forms the anteroventral margin of the acetabulum. The distal ends of both pubes are fused into a pubic boot. The anterior process of the pubic boot is longer than the posterior process. The ventral surface of the pubic boot is flat. Although the pubic apron is not well preserved, broken surfaces indicate that the apron occupied about two to thirds of the length of the pubis.

Ischium.

(Fig. 6A, 6B; see Table S4 for measurements). The right ischium is complete. The left ischium is missing a small portion of the middle of its shaft (Fig. 6A). The ischium has a very well developed, triangular obturator process whose tip is 15 cm away from the proximal end of the ischium (Fig. 6B). The articular surface for the ischial peduncle of the ilium is circular whereas the articular end for the pubis is elongated. The medial surface of the ischium is flat and its lateral surface, except for the obturator process, is slightly convex. The lateral surface of the obturator process is concave. The posterior margin of the ischium is thick, round, and distinctly concave. The anterior margin of the ischium is thin. There is no evidence for the fusion of the distal ends of the ischia.

Femur.

Both femora are well preserved (Fig. 7A–D, F; see Table S5 for measurements). A swollen area near the distal end of the right femur is probably pathological in origin. This area is about 9 cm away from the distal end of the femur. The right femur is shorter than the left femur, and this might be caused by this pathology. The femur is longer than the ilium. It is straight in anterior and posterior views but it curves anteriorly in lateral view. The femoral head is more or less oval and the femoral neck is distinct. The femoral neck extends medially at an angle of about 90 to the shaft. In posterior view, the femoral head bears a distinct ridge, which is separated from the femoral neck. There is a distinct foramen on the posterior surface near the middle of the proximal end. This foramen is larger on the left femur than on the right. At the proximal margin, there is a distinctly smooth, shallow area that separates the massive greater trochanter from the femoral neck. The greater trochanter extends anteroposteriorly. The lateral surface of the greater trochanter is smooth and flat. The anterior (lesser) trochanter is finger-like and its dorsal end is well distal to the greater trochanter. The anterior trochanter adheres closely to the greater trochanter but is separated from it by a distinct furrow that opens dorsally. It bears a pronounced ridge on its anterior surface. There is a distinct opening near the base of the anterior trochanter. About 11 cm from the proximal end of the right femur, a suboval area (about 2 cm long) is defined by a shallow groove near the medial margin of the posterior surface of the shaft. This region is not well preserved on the left femur. It is the fourth trochanter. On the distal end of the femur, the medial condyle is larger than the lateral condyle. The lateral condyle extends only slightly distal to the medial condyle, whereas, in oviraptorids, the lateral condyle extends well distal to the medial one [3]. Thus, when seen in anterior view, the distal margin of the femur is nearly horizontal. As in oviraptorids, there is a deep fossa that separates the well-developed tibiofibular crest from the large posterior surface of the medial condyle. In anterior view, the surface of the distal end is nearly flat. A distinct ridge is present on the anteromedial margin and may represent the medial epicondyle. There is a coarse area formed by short ridges and grooves on the distomedial surface of the distal end. This is possibly an anteromedial adductor muscle scar, although it is weak.

Tibia.

(Fig. 7D; see Table S5 for measurements). The right tibia, along with a small portion of the adherent right fibula, is well-preserved. The tibia is straight and 2 cm longer than the femur. The posterior surface of the shaft is slightly convex whereas its anterior surface is nearly flat. The cnemial crest is strongly developed occupying almost half the entire anteroposterior length of the proximal surface of the tibia. The medial surface of the proximal end is smooth and convex. The proximal articular surface of the tibia is angled obliquely posteriorly. The margins are expanded posteriorly; thus, the proximal end is clearly distinct from the tibial shaft. There is a foramen on the posterior surface just distal to the proximal margin. The fibular condyle of the tibia is oval, with a concave surface for articulation with the fibula. The fibular crest is short, extending for about 7 cm along the anterolateral margin of the proximal portion of the tibia. The distal end of the tibia is slightly expanded.

Tarsals.

The proximal tarsals (astragalus and calcaneum) are not fused but are tightly applied to each other and to the tibia. The calcaneum is small and disc-like. Its lateral surface for contact with the distal end of the fibula is concave. The astragalus is large. Its ascending process is taller than wide (5.5 cm wide, at least 8.5 cm tall). It extends for at least 21% of the length of the anterior surface of the tibia. There is a suboval fossa on the middle of the anterior surface of its articular end (Fig. 7E, f1). Two small, parallel, elongate fossae (Fig. 7E, f, f2) are present near the base of the astragalus; this may be similar to the well-marked central depression in other oviraptorids [3].