Huracan qiui, Jiangzuo & Flynn & Wang & Hou & Deng, 2023

Jiangzuo, Qigao, Flynn, John J., Wang, Shiqi, Hou, Sukuan & Deng, Tao, 2023, New Fossil Giant Panda Relatives (Ailuropodinae, Ursidae): A Basal Lineage of Gigantic Mio-Pliocene Cursorial Carnivores, American Museum Novitates 2023 (3996), pp. 1-72 : 33-38

Huracan qiui , sp. nov.

ETYMOLOGY: Species name in honor of Zhanxiang Qiu, for his outstanding contributions to Chinese Cenozoic paleontology and stratigraphy, especially in the Linxia Basin. TYPE SPECIMEN: HMV 2005, a nearly complete skull with little deformation ( fig. 17 ), collected by local villagers from the Wangjiashan fossil locality, which yields the Qingbushan Fauna.

DIAGNOSIS: Huge ailuropodine bear with weakly hypercarnivorous features; P2–3 double rooted; P4 slightly shorter than M1, with subdivided hypocone; M1 elongate with large metastyle; and M2 slightly elongate.

DIFFERENTIAL DIAGNOSIS: Differs from both Huracan coffeyi and H. schneideri in having a narrower cranium; more developed anterior premolars; longer M1 and M2, with proportionally longer M2 talon.

TYPE LOCALITY: Wangjiashan , Linxia Basin, Gansu Province, China; Baodean ALMA (late Miocene) .

OCCURRENCE: Known only from the type locality.

DESCRIPTION: HMV 2005 represents a nearly complete cranium, lacking the zygomatic arches and the posterior part of the sagittal crest, and with a broken occipital condyle. The braincase was slightly dorsoventrally depressed postmortem. The preserved part is ~ 475.7 mm in length, and the total skull length is estimated at ~ 485–495 mm. Since HMV 2005 is the only specimen known for the species, its sex is unknown, which is important for comparisons among sexually dimorphic species (most ursids). Its large size could indicate that the individual is a male, whereas the low cranium, relatively small canine (CL/M1L = 0.87), weak expansion of the rostrum at the level of canines, and poorly developed sagittal crest instead could indicate a female of a very large-bodied species.

postorbital process of frontal major palatine foramen

DORSAL VIEW: The cranium is elongate. Judging from the preserved part of the anterior root of the zygomatic arch, the cranium is not wide. The anterior part of the rostrum is constant in width, but the rostrum widens posteriorly at the level of the P4. The anterior border of the nasal is broken, and the posterior border nearly reaches the level of the postorbital process of the frontal. The length of the nasal is ~ 120 mm, and it gradually narrows and tapers in width posteriorly. The surface of the nasal is slightly dorsally domed. The suture between the maxilla and frontal reaches the level of the midpoint of the orbit. The nasal is separated from the maxilla by a wide bridge (11.82 mm at the middle part) composed of the posterior process of the premaxilla and the anterior process of the frontal. The premaxilla and frontal meet at the level of the P4 paracone. The forehead is wide, slightly exceeding the width of the rostrum across the canine. A postorbital process of the frontal is present but not distinct. Temporal ridges are moderately developed; the ridges from both sides unite into the sagittal crest at the anterior part of the braincase. The postorbital constriction is indistinct. The braincase is widest in its middle part, and is significantly wider than the postorbital constriction.

LATERAL VIEW: The cranium is not high. The dorsal contour of the cranium forms a gentle curve, with the highest point located in the middle part of the cranium, at the level of the postorbital constriction. The anterior contour of the naris opening is very slightly concave posteriorly, and forms a very small angle with the dorsal contour of the nasal bone. The anterior border of the nasal lies at the level of the P1. The upper toothrow is distinctly concave ventrally from P3 to M2. The lateral surface of the lower side of the maxilla undulates along the tooth roots. The infraorbital foramen is vertically oriented, and located at the level of the P4 metacone; its dorsoventral diameter is 15.42 mm on the left side and 12.22 mm on the right. The anterior border of the orbit is located between the level of M1 and M2, and its anteriormost point is distinctly higher than the infraorbital foramen. The area anterior to the orbit is slightly concave. The postorbital process of the frontal is slightly lower than the cranial roof. The anterior root of the zygomatic arch is robust and high. The ventral border of the zygomatic arch forms a distinct process at the anterior part, and the suture between the maxilla and jugal begins at the apex of this process, running anterodorsally and stopping at the anteriormost point of the orbit. The orbital region is not well preserved. The posterior opening of the infraorbital canal lies at the front of the orbit. Dorsal to that opening, the lacrimal fossa is not clearly demarcated, due to poor preservation. A large fossa for the confluent caudal palatine foramen and sphenopalatine foramen is located posteroventral to the posterior opening of the infraorbital canal, located at the level of the posterior end of M2 and relatively high above the toothrow. The inferior orbital crest is well developed and wide. It begins at the boundary between the lacrimal fossa and the posterior opening of the infraorbital canal and ends at the orbital fissure. The middle part of this crest is wide and is distinguished from the inferior temporal fossa (lateral wall of the medial pterygoid fossa) by a wide and shallow groove. The superior orbital crest is not distinct. The positions of the ethmoid foramen and optic foramen are not clear. The orbital fissure and foramen rotundum are close to each other but are separated by a thin bony partition. There is no alisphenoid canal. The anterior border of the braincase (dorsal border of the superior orbital crest) is nearly perpendicular to the orbital region, and bears several ridges for attachment of the temporal muscle. The suture between the frontal and parietal bones on its dorsal side is located at the level of the anterior part of the braincase. Its dorsal tip joins the point where the temporal ridges unite into the sagittal crest. The suture between the parietal and the squamosal part of the temporal bone cannot be seen, but a horizontal ridge is present in the expected location of this suture based on comparisons to other taxa. The postglenoid fossa faces anteriorly, and is situated distinctly higher than the toothrow. The mastoid process is broken. The ventral contour between the postglenoid process and the mastoid process is strongly concave dorsally. The sagittal crest is moderately developed. At the surface of the posterodorsal part of the braincase, a large foramen (probably for a vein) is present.

VENTRAL VIEW: The rostrum is slightly elongate compared with that of other species of Huracan , slightly constricted posterior to the canine, and widest at the level of the M1. The palate is slightly vaulted. The palatine fissure is elongate, surrounded by the premaxilla, and its posterior border reaches the posterior part of the upper canine. The posterior process of the premaxilla reaches the level of the P1 along the midline. The suture between the maxilla and palatine curves and tapers anteriorly, and its anterior border reaches the level of the P4 paracone. On the left side, the major and minor posterior palatine foramina are united by a small fissure. The major posterior palatine foramen is located at the level of the P4 paracone. On the right side, the major posterior palatine foramen is situated slightly more anteriorly, between the level of the P4 and M1. Behind M2, the maxilla forms a small spine at the suture of the maxilla and palatine. Medial to this spine, a distinct lateral palatine notch is present. The anteroventral border of the medial pterygoid fossa (bony choana) lies at the level of the M2 talon, and includes a distinct medial spine near the center of this border. The posterior border of the zygomatic arch is located at the M2 metacone. Judging from the preserved part, the zygomatic arch is not very wide. The ventral borders of the medial pterygoid fossa are parallel, whereas the lateral walls of this fossa are distinctly convex laterally. Anteriorly, the ventral border of the medial pterygoid fossa forms a distinct process at the level of the M2 metaconule. Posteriorly, at the suture between the palatine and the basisphenoid, the lateral wall of the pterygoid fossa forms a spine. Both the anterior and posterior glenoid processes are well developed medially. The distance between the posterior borders of the M2 and the glenoid fossa is ~ 113 mm, exceeding the P4–M2 length (101.18/100.00 mm on the left and right sides, respectively). The basicranium is not well preserved. The oval foramen is located medial to the glenoid fossa, and faces anteriorly. A bony crest is present lateral to the oval foramen. The postglenoid foramen is located at the posteromedial border of the postglenoid process. The basioccipital and basisphenoid bones are completely fused on the ventral side, so that no distinct boundary between them can be discerned. The paired attachment fossae (anteriorly) for the M. rectus capitis ventralis major (or M. longus capitis) and those for the M. rectus capitis ventralis minor, situated posterior to the former, are not distinguishable. The auditory bullae are largely broken, preserving only the anteromedial part. Details of the foramina surrounding the bulla cannot be seen. The mastoid and paroccipital processes also are broken. The hypoglossal foramen is located close to the bulla, but is still separated from the posterior lacerate foramen by a wide bony bridge. The occipital condyle is broken. The condyle neck is 76.62 mm, and the condyle would be ~ 90–95 mm wide.

OCCIPITAL VIEW: The occipital surface is poorly preserved, with most borders broken. On the left side, the lambdoidal crest and the lateral border of the mastoid form an obtuse angle. The occipital condyles are widely separated. The foramen magnum is ovoid, being wider than high. The external occipital crest is well developed in its dorsal part. Latero-dorsal to the occipital condyle, there is a concave area above the paroccipital process.

DENTITION: The dentition is completely preserved. The incisor row protrudes anteriorly, forming a convex arch. Upper incisor sizes increase from I1 to I3. I2 is slightly larger than I1, whereas I3 is distinctly larger than I2. I1 and I2 are very similar in morphology, with one large main cusp and two posterior accessory cusps. The posteromedial accessory cusp is enlarged and occupies 3/4 (I1) and 2/3 (I2) of the area of the posterior part of the tooth. The posterolateral accessory cusp is small in size (more distinct in I1). I3 is large, robust, and caniniform. I3 has a long and distinct lateral ridge and a much shorter medial ridge. At the medial base of I3, a cingulumlike ridge is present along the tooth edge, subdivided into two parallel ridges in the middle with the lateral one less distinct.

All three anterior upper premolars are present, and all are small and buttonlike. All the anterior premolars show similar morphology, with one main cusp, anterior and posterior ridges, and a well-developed lingual cingulum. The posterior ridge of the P2 turns lingually at its posterior part, whereas the anterior ridges on the other two anterior premolars do not. P3 is slightly longer than P1 and P2. Both P2 and P3 are double-rooted, whereas P1 is single rooted.

P4 is large, robust, and triangular in shape. A distinct buccal concavity is present at the paracone apex. The P4 inner lobe is moderate in size, and its anterior border forms an acute angle with the lingual border of the parastyle. A buccal cingulum is only weakly developed on the buccal side of the parastyle and the anterobuccal side of the metacone. Three buccal cusps are present: parastyle, paracone, and metacone. The parastyle is large, slightly lingually shifted, and with weak buccal and lingual ridges at the anterior tip. The metacone is slightly shorter than the paracone. The hypocone dominates the inner lobe, and is weakly subdivided into two cusps, with the anterior one being slightly smaller. A tiny cusp is present at the anterobuccal corner of the tooth, representing a rudimentary protocone. A well-developed lingual cingulum flanks the side of the metacone. M1 is square in shape, with a relatively straight border, no anterior concavity, and an extremely weak buccal concavity. Three cusps are present on the buccal side of M1. The M1 metacone is smaller than the paracone, due to the large area occupied by a huge metastyle, which is approximately 2/3 the length of the metacone. A small bulge is present at the anteriormost point of the paracone, but it does not form a distinct cusp. Lingually, any cusps present are too worn to distinguish and identify. The lingual cingulum merges with the lingual slope of the protocone-metacone. M2 is similar in length to M1, but is trapezoidal rather than square in shape. The buccal concavity between the paracone and the metacone is distinct on M2. The M2 talon is relatively short. M2 generally is less worn than M1. The M2 paracone is larger than the metacone. A ridge on the posterior border of the metacone elevates slightly to form a tiny metastyle. The lingual ridge of the paracone is indistinct, whereas that of the metacone is strong. The protocone is a long ridge without distinct subdivision, whereas the metaconule is a shorter and conical cusp. A small ridge is present between the M2 metacone and the edge of the protocone and metacone cusps.

Figures

FIG. 17. Holotype skull of Huracan qiui, sp. nov., HMV 2005, from Wangjiashan, China.