Tungurictis peignei, Wang & Tseng & Ye & Meng & Bi, 2020

Wang, Xiaoming, Tseng, Z. Jack, Wu, Wen-yu, Ye, Jie, Meng, Jin & Bi, Shundong, 2020, A new species of Tungurictis Colbert, 1939 (Carnivora, Hyaenidae) from the middle Miocene of Junggar Basin, northwestern China and the early divergence of basal hyaenids in East Asia, Geodiversitas 42 (3), pp. 29-45 : 32-39

Tungurictis peignei n. sp.

( Figs 4-6 ; Tables 1 , 2 )

Protictitherium intermedium – Wang et al. 1998: 221, figs 3A, B.

HOLOTYPE. — IVPP V 25222 , isolated upper third incisor, isolated right upper canine, right maxillary fragment with P1 and P3-4 (broken), left maxillary fragment with P1, P3-4, partial right dentary with p1 alveolus and p2-m2 ( Figs 4 ; 5A, C, D ), all apparently of the same individual; the locality was discovered by Jin Meng on July 5, 2009 and the specimen was obtained by screen washing.

TYPE LOCALITY. — IVPP XJ 200910 locality, 46°33.993’N, 87°46.965’E, Duolebulejin area, south bank of the Ulungu River,

Thickness

Magnetic GMPTS

Declination Inclination Polarity ( CK 95) Age

–90 90 270 –90 0 90

second sandstone layer from top of the Suosuoquan Formation, Junggar Basin, Xinjiang Uygur Autonomous Region ( Fig. 2A ).

DIAGNOSIS. — The most primitive known species of Tungurictis , T. peignei , n. sp. is smaller than T. spocki and has a more distinct lingual bulge on P3, a more distinct notch on M1 parastyle, and an m1 hypoconulid enclosing the talonid basin. Tungurictis peignei ,

n. sp. is similar in size to Protictitherium intermedium but has less well developed m1-2 hypoconulid.

ETYMOLOGY. — In memoriam of Stéphane Peigné for his contribution to the understanding of fossil carnivorans.

REFERRED SPECIMENS. — IVPP V 25223 , isolated right P2 (posterior part only; not figured), P3, and M1, from XJ 200815 intermedium

( Fig. 2B ), 46°24.281’N, 87°25.991’E, at 45 km mark of West Main Irrigation Channel (Xi-gan-qu), southwest of Dingshan Salt Lake (Dingshanyanchi), upper siltstones of Halamagai Formation, 13.3 m below the boundary of Halamagai-Dingshanyanchi formations; some of the carnivoran materials were obtained by screen washing ( Fig. 6 ). — IVPP V 11493 , left dentary with c-p1 roots, p2-m1, from Tieersihabahe, lower part of Halamagai Formation ( Wang et al. 1998: fig. 3A) ( Fig. 5B, E, F ). — IVPP V 11494 , left dentary fragment with p3 alveolus and p4-m1, from Tieersihabahe, Halamagai Formation, collected on August 14 ( Wang et al. 1998: fig. 3B). — IVPP V 11495 , right dentary fragment with c-p4 alveoli, from Tieersihabahe, Halamagai Formation. — IVPP V 11496 , right dentary fragment with p1-m1 (all broken), from Tieersihabahe, Halamagai Formation. — IVPP V 25224 , left dentary fragment with m1, and p4 and m2 alveoli, from Tieersihabahe, Halamagai Formation. — IVPP V 25225 , right dentary fragment with p3-4 and m1 alveolus, from Tieersihabahe, Halamagai Formation. — IVPP uncatalogued, left dentary fragment with p3-4 and p2 and m1 alveoli, from Tieersihabahe, second sandstone layer of Halamagai Formation.

GEOLOGIC SETTING, FAUNA, AND AGE. — Extensive exposures of middle to late Cenozoic sediments in northern Junggar Basin and its western extension in Kazakhstan produce a rich record of fossil vertebrates ( Fig. 1 ). Explorations of the Junggar Basin by Chinese geologists began in the 1950s. Although Chow (1957, 1958) was first to report fragmentary mammal fossils from several Cenozoic localities in Xinjiang, all collected by local geological survey and petroleum teams, dedicated explorations by vertebrate paleontologists did not begin until 1982 and 1984, when a joint IVPP and Xinjiang Bureau of Petroleum team worked in the Ulungu River region. A basic stratigraphic framework of the Suosuoquan Formation and Halamagai Formation, plus associated vertebrate fossils, was first established by Tong et al. (1990). Since then various efforts have focused on the regional stratigraphy and chronology ( Wu et al. 1998; Ye et al. 2000; Ye et al. 2001a, b; Ye et al. 2003; Meng et al. 2006; Meng et al. 2008; Ye et al. 2012; Meng et al. 2013), paleoenvironment and paleoclimate ( Sun et al. 2010), small mammal taxonomy (Bi 1999; Bi et al. 1999; Wu et al. 2004, 2006; Bi et al. 2009; Wu et al. 2009; Maridet et al. 2011; Bi et al. 2013), and descriptions of large mammals ( Ye 1989; Wu et al. 2003; Ye et al. 2005).

REMARKS

Carnivorans from the Junggar Basin are generally rare. From collections made during the early expeditions, Qi (1989) reported two fossil carnivorans, Amphicyon ulungurensis Qi, 1989 and Ictitherium cf. I. gaudryi (de Beaumont & Mein, 1972), from three localities (IVPP loc 82501, 82503, 82513, plus a reworked locality 82505) in the Halamagai beds. The next major expeditions that saw a large increase in carnivoran diversity were led by another IVPP team in 1995 and 1996, and were summarized by Wu et al. (1998). Carnivoran collections made in the 1990s from the Halamagai Formation were described by Wang et al. (1998). These include Nimravus ṙ sp., Pseudaelurus cuspidatus Wang, Ye, Meng, Wu, Liu & Bi, 1998, Protictitherium intermedium Schmidt-Kittler, 1976 ( Tungurictis herein), Protictitherium small species, Thalassictis chinjiensis (Pilgrim, 1932), Gobicyon ṙ sp., Oligobunis ṙ sp., Alopecocyon goeriachensis (Toula, 1884), and Simocyon Wagner, 1858 small form. Although Wang et al. ’s (1998) report represents a substantial increase of carnivoran diversity, fragmentary jaws and isolated teeth were the main basis of most taxa. Not surprisingly, many of the above identifications are tentative, or even speculative, and await confirmation (or rejection) by better materials. Continued collecting from the Halamagai Formation since the 1990-2000s has yielded five species of bear dogs, recently described by Jiangzuo et al. (2018), but isolated teeth and jaw fragments are still mostly what are known at the moment.

A newly described specimen herein, IVPP V 25223 , is from IVPP XJ 200815 locality ( Fig. 2B ) in the Dingshanyanchi area ( Meng et al. 2008; Wu et al. 2009). Ye et al. (2012) described the Duolebulejin section and produced a magnetostratigraphy. Unfortunately, much of the Halamagai Formation are sandstones, coarse-grained sediments unsuitable for magnetic studies. Only two short segments of fine-grained sediments at the top and bottom of the Halamagai Formation yielded useful magnetic results ( Ye et al. 2012: fig. 3), consisting of just a few short magnetic chrons in a busy part of the magnetic time scale, not enough to offer much constraint in correlation. Nevertheless, as constrained by fossil mammals within, such as Anchitherium gobiense Colbert, 1939 ( Ye et al. 2005), Ye et al. (2012) placed the Halamagai Formation roughly in C5Cn.3n through somewhere in C5A, or about 16-14 Ma.

In contrast to the fluviatile sandstones of the middle Miocene Halamagai Formation, the underlying Suosuoquan Formation is mainly a fine-grained red bed of late Oligocene to early Miocene age ( Ye et al. 2003; Meng et al. 2013). So far, no carnivoran has been reported in the Suosuoquan Formation. Specimen IVPP V 25222 described in this paper is from IVPP XJ 200910 locality ( Fig. 2A ) in the Duolebulejin area at the top of the Suosuoquan Formation. This is known as the “Top of Suosuoquan Fauna” ( Ye et al. 2001a, b). Constrained by small mammal faunas, Meng et al. (2013: pl. 3.1) magnetically correlated the lower half (up to the S-III assemblage) of the Suosuoquan Formation to C6Cn.3n-C6An.1n, spanning 23.30 Ma of GTS2012 ( Vandenberghe et al. 2012) to 20.04 Ma of ATNTS2012 ( Hilgen et al. 2012) ( Fig. 3 ). The top part of the Suosuoquan Formation can be as young as 16.8 Ma ( Ye et al. 2012). IVPP V 25222 falls within the reversed chron C5Cr ( Fig. 3 ) with a duration of 16.72-17.24 Ma of ATNTS2012. This specimen thus represents the oldest record of Tungurictis in East Asia.

DESCRIPTION

The maxilla fragments and right dentary of IVPP V 25222 have associated upper and lower teeth. These form the main

basis of description, supplemented by additional specimens to evaluate variation. Dental measurements are provided in Tables 1 and 2 .

Maxilla and upper teeth

We interpret the isolated teeth of IVPP V 25222 , collected by screen washing from a single site, as belonging to a single individual because they all have the same stage of wear (a young adult) and there are no duplicate teeth from the same side. The left and right maxillae do not preserve much beyond where the cheek teeth are rooted. The floor of the left infraorbital foramen is preserved, and it appears that the anterior opening of this foramen is approximately at the anterior edge of P4.

An isolated upper incisor ( Fig. 4A ) is here identified as a right I3 because of its relatively rounded root, as opposed to the more mesiodistally compressed roots of I1-2, as seen on Tungurictis spocki (IVPP V 13784 ) ( Wang 2004: fig. 1). The crown surface is simple and single-cusped, but with a mesial and distal crest converging toward the tip of the main cusp. The maximum mesiodistal length at the base of the crown is 2.13 mm.

A well-preserved right upper canine ( Fig. 4B ) preserves the entire crown, but much of its root is missing. The cross section at the base of the crown is oval, with a mesiodistal length of 4.72 mm, linguobuccal width of 3.69 mm, and crown height of 13.45 mm. The surface of the crown is smooth, lacking crenulations or grooves. A thin but distinct posterior and anterolingual ridge runs along the entire length of the tooth.

An isolated left P1 ( Fig. 4C, D ) is double-rooted, as in Tungurictis spocki. It measures 5.50 mm in mesiodistal length and 2.33 mm in linguobuccal width. A single main cusp leans forward with a distinct ridge both anterior and posterior to the cusp. An incipient posterior cingular cusp is present and the posterior cingulum is confined to the posterior end of the tooth.

The left and right P3s ( Fig. 4C, D ; Table 1 ) are wellpreserved. As in P1, the main cusp of P3 is flanked by an anterolingual ridge and a posterior ridge. At the anterior end of the anterolingual ridge is a small cingular cusp, and similarly, the posterior ridge is also terminated by a posterior cingular cusp. Immediately anterior to the posterior cingular cusp is an incipient posterior accessory cusp, more distinct on the left side, at the base of the posterior ridge. There is no buccal cingulum. On the lingual side, there is a distinct bulge just posterior to the main cusp and a cusp-like lingual cingulum. This bulge did not result in a lingual root above the lingual cingulum, as confirmed by an isolated P 3 in IVPP V 25223 ( Fig. 6B, C ) (on Tungurictis spocki, a lingual bulge also does not result in a third root).

The left P4 ( Fig. 4C, D ; Table 1 ) is essentially unworn except the very tip of the paracone. This tooth is slender with a long shearing blade. The paracone is the most dominant cusp not only in crown height but also in cusp size. An anterior ridge on the paracone leads up to a small but distinct parastyle separated from the paracone by a notch. There is no buccal cingulum, but a narrow but distinct lingual cingulum. The protocone protrudes forward, its anterior edge being anterior to that of the parastyle. The protocone is slightly taller than the parastyle and is formed by the rising anterior and lingual cingula, i.e., a distinct ridge leads from the protocone tip and continues with the anterior and lingual cingula. There is also a sharp ridge connecting the protocone to the paracone, a condition also seen in Tungurictis spocki. The metastyle blade is of similar height to the protocone and there is a deep carnassial notch separating it from the paracone.

An isolated right M1 is present in IVPP V 25223 ( Fig. 6A, C ; Table 1 ) It is unworn. The paracone dominates as the tallest cusp and has a distinct lingual crista extending toward the protocone. A parastyle protrudes buccally, forming a prominent lateral bulge. The metacone is about half the size of the paracone and is located in a posterior and lingual position relative to the paracone. The protocone is located at the lingual border and features distinct pre- and postprotocristae. A very indistinct swelling along the buccal end of the postprotocrista indicates the presence of a metaconule. A paraconule is not present. There is no cingulum surrounding any part of the tooth.

M2 is not preserved.

Dentary and Lower Teeth

Several fragmentary dentaries are available, but IVPP V 25222 ( Fig. 5A, C, D ) and V 11493 ( Fig. 5B, E, F ) are the best preserved with the most lower teeth. The unworn nature of these teeth permits a clear view of cusp morphology. The following descriptions are mainly based on these two specimens, with additional comments on variations in other specimens where warranted.

Overall construction of the horizontal ramus of the dentary is modestly robust and it gently tapers anteriorly, forming a curved lower border. The deepest point of the lower jaw is at the m1. Both IVPP V 25222 and V 11493 preserve two mental foramina. The anterior foramen is located below the anterior root of the p2 and is more than twice as large as the posterior one. The smaller posterior mental foramen is below the anterior root of the p 3 in V 11493 and between the roots of the p 3 in V 25222 .

The p1 is only present as a single root in IVPP V 25222 and V 11493 . The p2 is double-rooted. It has a single main cusp with a small ( V 11493 ) or indistinct ( V 25222 ) posterior cingulum. Distinct anterior and posterior ridges flank the main cusp and there is very vague bulge to suggest an incipient posterior accessory cusp. There is no cingulum on either side of the tooth. The p3 is similar to p2 with the exception of a more distinct posterior accessory cusp, a better-developed posterior cingulum, and an incipient anterior accessory cusp. On IVPP V 25225 , the p3 accessory cusps are more prominent than seen in other specimens. The p4 has a distinct anterior accessory cusp, a very strong posterior accessory cusp, and a widened posterior cingulum.

The m1 has a much wider trigonid than talonid. The protoconid is the largest and tallest cusp. The paraconid is the second largest and tallest cusp. The posterolingual aspect of the paraconid has a gentle ridge flanking the lingual side and enclosing a slightly concave groove. The metaconid is slightly lower than the paraconid and jutting toward the lingual side. The hypoconid is approximately equal in size to the entoconid in occlusal view, but it is only slightly taller than the latter. A sharp ridge flanks the anterior face of the hypoconid enclosing the labial side of the talonid basin. This ridge connects to a posterior ridge on the posterior face of the protoconid, but is separated from the latter by a thin notch. Posterolingual to the hypoconid is a posterior ridge running down the apex of the hypoconid. This posterior ridge forms an obtuse angle with the anterior ridge of the hypoconid. The entoconid, by contrast, is more cusp-like and pointing somewhat lingually, such that the tip of the entoconid protrudes outside the lingual border of the talonid in occlusal view in IVPP V 11493 ( Fig. 5B, E, F ). Slightly taller-crowned than the hypoconid, the entoconid flanks the lingual side of the talonid but does not fully enclose the talonid basin. Instead, there is a V-shaped notch anterior to the entoconid such that the basin is open lingually. This notch runs deep to sharply divide the base of the metaconid from that of the entoconid in lingual view. This condition is more pronounced in IVPP V 25222 than in V 11493 . The anterior face of the entoconid is mostly rounded, with a vague ridge on its anterolingual surface, but posteriorly the entoconid has a sharp ridge oriented in the posterolabial direction. This posterior ridge continues to the hypoconulid in IVPP V 25222 but is separated from the hypoconulid in IVPP V 11493 . Posterolingual to the hypoconid, the hypoconulid forms a thin, ridge-like structure enclosing the posterior aspect of the talonid basin. The hypoconulid is either an independent cusp ( V 11493 ) or a ridge continuous with the entoconid ( V 25222 ).

The m2 is only preserved in IVPP V 25222 . The m2 crown forms an elongated basin rimed by its trigonid and talonid cusps. The paraconid is absent. The protoconid forms a ridge-like structure along the buccal rim. The ridges fall away from the tip of the protoconid and are oriented longitudinally. Located at the anterolingual corner of the tooth, i.e., more anterior than the protoconid, the metaconid is taller but not much larger than the protoconid. On its buccal side, there is a vague ridge toward the base of the metaconid. Like the protoconid, the hypoconid is a ridge-like structure and is essentially continuous with the protoconid but separated by a notch. As in the m1, the entoconid is taller-crowned than the hypoconid but is much larger in occlusal view. The entoconid is also more posteriorly located at the posterolingual corner of the tooth. This more posteriorly located entoconid, combined with the more anteriorly located metaconid, permits a wider separation between these cusps, resulting in a broad valley on the lingual side that opens into the talonid. On the posterior face of the entoconid, a transversely oriented ridge encloses the posterior aspect of the talonid basin. At the base of this ridge, a slight bulge seems to indicate the presence of a hypoconulid.

Figures

FIG. 4. — Tungurictis peignei, n. sp., IVPP V 25222, holotype, isolated right I3, mesial view (A), right upper canine, buccal view (B), left P1, and left maxilla with P3-4 (C, stereo photos of occlusal view; D, buccal view). Scale bar: 10 mm.

FIG. 5. — Tungurictis peignei, n. sp., IVPP V 25222, holotype, right dentary with p2-m2 (A, stereo photos, occlusal view,C, lingual, and D, buccal views) and IVPP V 11493, left dentary with p2-m1 (B, stereo photos, occlusal view; E, lingual view; F, buccal views). Scale bars: 10 mm.

FIG. 6. — Tungurictis peignei, n. sp., IVPP V 25223, isolated right P3 and M1: A, posterior view of M1; B, buccal view of P3; C, stereo photos of occlusal view of P3 and M1. Scale bar: 5 mm.

FIG. 2. — Two Junggar Basin localities that produce Tungurictis Colbert,1939:A, Duolebulejin section showing contact of sandstones of Halamagai Formation and red mudstones of Suosuoquan Formation; the Duolebulejin locality is the only section where Suosuoquan and Halamagai formations are in continuous deposition with a superpositional relationship (Ye et al. 2012). XJ 200910 locality is from the second sandstone lens within Suosuoquan Formation. B, XJ 200815 locality in Dingshanyanchi section, upper siltstones of Halamagai Formation. Photos by Wenyu Wu.

FIG. 1. — Map of Tungurictis Colbert, 1939 localities in Junggar Basin of northern Xinjiang.

FIG. 3. — Bio- and magnetostratigraphy of basal hyaenids from Junggar Basin.