Hyaenodonts and Carnivorans from the Early Oligocene to Early Miocene of Xianshuihe Formation, Lanzhou Basin, Gansu Province, China

Home , Chalicothere, Creodonta, Hsanda Gol Formation, Hyaenodon, Hyaenodontidae, Hyainailouros

Palaeontologia Electronica http://palaeo-electronica.org

HYAENODONTS AND CARNIVORANS FROM THE EARLY OLIGOCENE TO EARLY MIOCENE OF XIANSHUIHE FORMATION, LANZHOU BASIN, GANSU PROVINCE, CHINA

Xiaoming Wang, Zhanxiang Qiu, and Banyue Wang

ABSTRACT

Fieldwork in the 1990s produced a few records of carnivorous mammals (creodonts and carnivorans) in the early Oligocene through early Miocene of Lanzhou Basin, Gansu Province, China. Although only five taxa are known so far, most represented by fragmentary material, the new carnivore assemblage is unique and shows little resemblance to faunas elsewhere in eastern Asia. The early Oligocene record is represented by a single premolar of a Hyaenodon, referable to H. pervagus. In the early Miocene, a new species of Hyaenodon, H. weilini sp. nov., represented by several cheek teeth, is the last record of this genus in east Asia. A horizontal ramus of an amphicyonid, here identified as Ictiocyon cf. I. socialis, is the first record of this taxon in Asia, and a very small musteloid lower carnassial, although difficult to identify to genus, is clearly a new record because nothing of this small size has been known in Asia. The overall faunal composition seems to suggest affinity with northern Eurasia rather than southern Asia.

Xiaoming Wang. Department of Vertebrate Paleontology, Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, California 90007, United States [email protected] Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P.O. Box 643, Beijing 100044, China. Zhanxiang Qiu. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P.O. Box 643, Beijing 100044, China. [email protected] Banyue Wang. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P.O. Box 643, Beijing 100044, China. [email protected]

KEY WORDS: Creodonta; Carnivora; Oligocene; Miocene; Gansu; China

PE Article Number: 8.1.6 Copyright: Society of Vertebrate Paleontology May 2005 Submission: 1 July 2004. Acceptance: 4 April 2005

Wang, Xiaoming, Qiu, Zhanxiang, and Wang, Banyue, 2005. Hyaenodonts and Carnivorans from the Early Oligocene to Early Miocene of Xianshuihe Formation, Lanzhou Basin, Gansu Province, China, Palaeontologia Electronica Vol. 8, Issue 1; 6A: 14p, 478KB; http://palaeo-electronica.org/paleo/2005_1/wang6/issue1_05.htm WANG, QIU, & WANG: PALAEOGENE HYAENODONTS AND CARNIVORANS FROM GANSU

INTRODUCTION records during the early Miocene are rather scarce in Asia, and this is especially true for carnivorous Lanzhou Basin in central Gansu Province, mammals (creodonts and carnivorans). Our newly northern China, is relatively unknown in vertebrate acquired Lanzhou carnivore collections, although paleontology but has attracted considerable atten- still far too sketchy to permit a full picture of the tion during the 1990s because of its potential to fill community, appear to represent a unique assem- a critical gap in fossil record in the early Miocene blage, including either first records in China or last and because of its location along the northeastern record of a lineage. Various groups of fossils verte- rim of the Tibetan Plateau. Located just north of the brates and invertebrates from the Lanzhou Basin city of Lanzhou (Figure 1), the Lanzhou Basin have been described (Qiu and Xie 1997; Qiu et al. received terrestrial sediments during a substantial 1998; Qiu and Wang 1999; Xie 1999; Qiu 2000; B. part of the early through late Cenozoic, although Wang and Qiu 2000a, 2000b; Qiu 2001a, 2001b; vertebrate fossils are mainly found in the early Oli- Wang et al. 2001). This report is part of this effort gocene through middle Miocene part of the sec- and presents a systematic description of these car- tion. A multinational, multidisciplinary team led by nivorous mammals. the Institute of Vertebrate Paleontology and Pale- Abbreviations: IVPP, Institute of Vertebrate oanthropology investigated the vertebrate paleon- Paleontology and Paleoanthropology, Chinese tology and magnetostratigraphy of the Lanzhou Academy of Sciences, Beijing; PIN, Institute of Basin for several field seasons (Qiu et al. 1997; Paleontology, Russian Academy of Sciences, Mos- Flynn et al. 1999; Qiu et al. 2001). Vertebrate cow; PSS, Paleontology and Stratigraphy Section of Geological Institute, Mongolian Academy of Sci- ences, Ulaanbaatar.

SYSTEMATIC PALEONTOLOGY

Order CREODONTA Cope, 1875 Family HYAENODONTIDAE Leidy, 1869 Genus HYAENODON Laizer and Parieu, 1838 Hyaenodon weilini new species Hyaenodon sp.: Qiu et al. 1997, p. 186; Qiu et al. 2001, p. 378. Holotype: IVPP V12186, isolated left P4 and M2, right P3, P4, and M2, and root of left C (Figure 2). Type Locality: IVPP V12186 was acquired from a villager in Zhangjiaping, by Qiu Zhanxiang, Yan Defa, and Xie Junyi on 19 April, 1987, about 10 km north of Lanzhou along the highway to the Lan- zhou Airport (Figure 1). Loc. #2 of Zhangjiaping, probably from one of several sand quarries within the first white sandstones in the Middle Member of the Xianshuihe Formation, Zhangjiaping l.f., correlated to magnetic Chron C6n (about 19–20 Ma) in early Miocene (see Qiu et al. 1997; Qiu et al. 2001). Although the holotype of Hyaenodon weilini was acquired from a farmer living near a “white sands” quarry (see below), our own independent collecting has yielded records (referred specimens) of this species in the “white sands,” increasing our Figure 1. Map of the Lanzhou Basin and fossil carni- confidence that the holotype is from the “white vore localities cited in this paper. Map drawn by Will sands” as well. Downs.

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Figure 2. Hyaenodon weilini new species, IVPP V12186, holotype. Right P3 (A, lingual, F, occlusal, I, labial views), partial P4 (B, lingual, E, occlusal, H, labial views), and M2 (C, lingual, D, occlusal, G, labial views).

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Referred Specimens: IVPP V12187, isolated left siastically participated in the Lanzhou Basin field- P4 and anterior half of M1, probably from IVPP loc. work. 8801 in Duitinggou area, Middle Member of the Description: Isolated teeth in the holotype IVPP Xianshuihe Formation; IVPP V12188, isolated left V12186 are regarded as belonging to the same P3, from IVPP loc. 9512, near the village of Hua- individual because of their consistency of colora- ngyangtou, basal white sandstone in a sand tion and approximately same stage of wear. How- quarry, Middle Member of the Xianshuihe Forma- ever, the possibility exists that they belong to more tion; and IVPP V12189, isolated left m1, from IVPP than one individual because there are moderate loc. 9010, Yangtonggou, basal white sandstone, size differences between the left and right sides Middle Member of the Xianshuihe Formation (Fig- (Table 1). ure 3). The P3 is double rooted, and its posterior root Associated Fauna and Age: We here attempt to is substantially larger than the anterior one, sup- demonstrate this species to be the last known porting a lingual swelling of the main cusp. The Hyaenodon in Eurasia, and thus it is a matter of main cusp is slightly recumbent and followed some importance to establish the age of the Middle behind by a low posterior accessory cusp. There Member of the Xianshuihe Formation. Vertebrate are faint ridges on the anterior and posterior faces fossils in the Zhangjiaping local fauna are mostly of the main cusp. collected from sediments in and around several The P4 is about the same size as the P3 (in light colored coarse sandstones and fine gravels anteroposterior length) and is triple rooted. The lin- that are concentrated at the lower part of the Mid- gual root forms the base of a swelled lingual cingu- dle Member of the Xianshuihe Formation (Qiu et al. lum. This lingual swelling is only slightly more 1997; Qiu et al. 2001). Locally known as the “white pronounced than that on the P3, and there is no sands,” in contrast to the “yellow sands” at the bot- discrete protocone despite the additional root. The tom of the Lower Member of the Xianshuihe For- P4 main cusp and posterior accessory cusp are mation, the channel sandstones are useful as more recumbent than in the P3. In addition, the P4 prominent stratigraphic marker beds in geologic has an incipient anterior accessory cusp that is not mapping, although the sandstones tend to be thin- present on the P3 (more pronounced in IVPP ner and less stable laterally toward the upper part V12187). of the Middle Member. The Zhangjiaping l.f., first The two upper molars of the holotype are here proposed by Qiu (1990) and further elaborated on regarded as M2s because of their considerably by Qiu et al. (1997; 2001), includes such early larger (anteroposterior length) size than the P4. A Miocene elements as the primitive ochotonid Sino- prominent M2 is a characteristic of the subfamily lagomys pachygnathus and a large-tusked Asiatic Hyaenodontinae, and the M1 is usually about the rhino Aprotodon lanzhouensis (Qiu and Xie 1997). same size or only slightly larger than the P4. The In particular, the Zhangjiaping l.f. appears to docu- M2 is highly hypercarnivorous with its long (antero- ment the first Chinese appearance of proboscide- posteriorly) and thin (transversely) shearing blade ans (see Qiu et al. 2001 for full faunal list). and reduced protocone. Although there are three Constrained by the so-called Proboscidean Datum shallow grooves on the labial surface of the M2 Event (Tassy 1990), Qiu et al. (2001) correlated the (more distinctly displayed on the left M2), none “white sands” beds in the Duitinggou section with seems to represent a notch between the paracone magnetic Chrons C6n (in part) through C5Cr, and metacone, because these grooves extend all approximately 17–20 Ma. the way to the base of the crown. It is likely that the Diagnosis: The Lanzhou creodont is distinguished paracone and metacone are fully fused into a sin- from the contemporaneous Hyainailouros in having gle cusp. Instead, the grooves appear to be part of more reduced protocones and metastyle notches the tooth ornamentation since finer wrinkles are in M1-2 with thin shearing blades. Hyaenodon interspersed between the grooves. Wear on the weilini is substantially larger than all known species metastyle has eliminated any trace of a metastyle of Hyaenodon except H. gigas. It differs from the notch (“carnassial notch”). The M2 protocone is latter in its relatively smaller and lower crowned P4 extremely reduced (much of its crown was worn with more distinct anterior accessory cusp and lin- off); its existence is only suggested by a small root, gual cingulum, and its distinct anterior ridge on the which is closely compressed to the larger, labial paracone of M2. root below the paracone, and by a shallow notch immediately behind the protocone, which produces Etymology: In fond memory of Will Downs, whose a V-shaped enamel edge after wearing. This notch adopted Chinese name is Dong Weilin, a Chinese is visible on the left M2. The anterior border of the approximation of “Downs William,” and who enthu- protocone is behind the anterior ridge of the para-

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Figure 3. Hyaenodon weilini new species. Left P3, IVPP V12188 (A, lingual, E, occlusal, I, labial views); left P4, IVPP V12187 (B, lingual, F, occlusal, J, labial views); partial left M1, IVPP V12187 (C, lingual, G, occlusal, K, labial views); and right m1, IVPP V12189 (D, lingual, H, occlusal, L, labial views). Large scale (20 mm) is for A, B, C, E, F, G, I, J, K, and small scale (10 mm) is for D, H, and L.

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Table 1. Measurements (in mm) of Hyaenodon weilini of hypercarnivory far exceeds that seen in Hyainai- from Lanzhou Basin. Measurements for H. gigas are esti- louros in terms of elongation of shearing blade, mated from a combination of Dashzeveg’s measure- reduction of metastyle notch (“carnassial notch”), ments and his figure 12 (1985), because he apparently and reduction of protocone on the M2. The Lan- adopted an unconventional system of measuring the zhou form is thus more readily referable to Hyaen- dimensions of the roots at the points of contact with the odon. maxilla. Numerous species from Africa, Europe, Asia, Lanzhou Basin Hyaenodon H. gigas and North America have been referred to Hyaeno- IVPP IVPP IVPP PSS don (37 by Lange-Badré 1979; 42 by Polly 1993). V121 V1218 Most of them, however, are from the Eocene to Oli- V12186 87 8 27–10 gocene and are small to medium-sized predators. left right By early Miocene time, only a few relics are left. P3 length 27.1 20.6 The last North American Hyaenodon (such as H. P3 width 16.0 13.1 brevirostris) is found in the early Arikareean (late P4 length 24.5 25.6 21.3 38.0 Oligocene) of California and the northern Great P4 width 18.0 14.5 24.0 Plains (Mellett 1977; Gunnell 1998; Tedford et al. M2 length 45.7 50.3 54.0 2004). None of the North American Hyaenodon M2 width 18.8 18.3 22.0 achieved the giant size of the Lanzhou taxon. In Europe, the last Hyaenodon are represented by such late Oligocene (Chattian) species as H. millo- cone, and there is a weak indentation between the quensis, H. bavaricus, and H. leptorhynchus. They protocone and paracone. A sharp ridge is present are small in size, their m1 being in the range of 7-8 on the anterior surface of the paracone. mm (see summary in Dehm 1935) in contrast to A heavily worn m1 (IVPP V12189), measuring the 18.5 mm of the Lanzhou Hyaenodon. Three 18.5 mm in length and 8.8 mm in width, reveals lit- species of Hyaenodon (Isohyaenodon) described tle more than the presence of a large protoconid- by Savage (1965) from the Miocene of Africa, H. paraconid blade and a small talonid with a single andrewsi, H. matthewi, and H. pilgrimi, were based trenchant hypoconid. on fragmentary lower jaws (and a single referred Discussion: The Lanzhou Hyaenodon represents M1 of H. pilgrimi). Even the largest of the three the last survivor of this ancient lineage in northern species, H. andrewsi (8.9 mm in length), is consid- and central Asia. Of the Miocene forms (see Zoo- erably smaller than the Lanzhou Hyaenodon. geographic Remarks below), only Hyainailouros In Asia, Hyaenodon is present in the Paleo- and Hyaenodon achieved the giant size and high gene of Mongolia, China, and Kazakhstan (e.g., degree of hypercarnivory (Helbing 1925; Koenig- Matthew and Granger 1924; Teilhard de Chardin swald 1947; Ginsburg 1999b) seen in the Lanzhou 1926; Young 1937; Huang 1982; Dashzeveg 1985; specimens. Recent phylogenetic analyses sug- Russell and Zhai 1987; Lange-Badré and gest that these two genera may represent terminal Dashzeveg 1989; Huang 1993; Kordikova 1994; members of two distinct clades within the family Lavrov 1999). Of these, the Mongolian records are Hyaenodontidae (Polly 1993, 1996), and many of the most complete, both in diversity and strati- their hypercarnivorous characters (such as the loss graphic representation. As summarized by Lange- of metaconids on lower molars) are independently Badré and Dashzeveg (1989, figure 3), a pattern of acquired within the two clades. declining diversity can be observed from about 3–4 Five nominal species of Hyainailouros were species in the late Eocene to 1–2 species in the recognized by Ginsburg (1980): H. sulzeri, H. bug- Oligocene. tiensis, H. fourtaui, H. nyanzae, and H. napakensis. Currently, seven species of Hyaenodon are All whose upper cheek teeth are known (including recognized in the late Paleogene of Asia: H. perva- unpublished materials referable to H. bugtiensis gus Matthew and Granger 1924 from the Loh local- from Chinji Formation of Pakistan, Barry, personal ity, early Oligocene Hsanda Gol Formation, H. commun., 2004) still primitively retain a large (rela- eminus Matthew and Granger 1925 from the late tive to those in Hyaenodon), lingually positioned Eocene Ergilin Dzo Formation, H. yuanchensis protocone on the M1-2, and the shearing blade of Young 1937 from middle Eocene Heti Formation of the M1-2 is still relatively thick (mediolaterally) with Yuanqu Basin, H. mongoliensis (Dashzeveg 1964) a deep metastyle notch. Such primitive morphology from Khoer Dzan and Bayan Tsav localities of the of the M1-2 in Hyainailouros is in sharp contrast to Ergilin-Dzo Formation, H. incertus Dashzeveg the far more hypercarnivorous “carnassials” of 1985 and H. (=Neohyaenodon in Lavrov, 1999) Hyaenodon. In the Lanzhou materials, the degree gigas Dashzeveg 1985 from Khoer Dzan locality,

6 WANG, QIU, & WANG: PALAEOGENE HYAENODONTS AND CARNIVORANS FROM GANSU and H. chunkhtensis Dashzeveg 1985 from ymous should be explored when additional materi- Chunkht locality of the Hsanda Gol Formation (see als become available. Russell and Zhai 1987 for a summary of these The size difference between the P3s in IVPP localities). V12186 (25.6 x 18.0 mm) and V12187 (21.1 x 14.3 Only Hyaenodon gigas and H. mongoliensis mm) is substantial (more than 20%), but is well approach the size of the Lanzhou Hyaenodon. H. within the documented variation (16 to23 mm for mongoliensis is based on lower jaw and teeth only, P3s, or more than 40%) in Hyaenodon horridus, and thus cannot be directly compared with the Lan- the largest species in North America (Mellett zhou materials. Given that H. gigas and H. mon- 1977). At the present our sample size is too small goliensis co-occur in the Khoer Dzan locality of the to evaluate intraspecific variations and we treat this Ergilin-Dzo Formation, and even allowing that size difference as variation within species. these two giant Hyaenodon species are distinct, it Overall, the above outlined features seem to indi- is likely that they are closely related (either sister cate a somewhat more primitive stage of evolution species or anagenetically successive forms). If so, in Hyaenodon weilini, and considering the long hia- the following substantial differences of H. gigas tus (more than 10 m.y.) between H. weilini, on the from H. weilini also likely to apply to H. mongolien- one hand, and H. gigas and H. mongoliensis, on sis. the other, it seems unlikely that the Lanzhou Based on Dashzeveg’s (1985, figure 12) illus- Hyaenodon is conspecific with the Ergilin Dzo tration, the P4 of Hyaenodon weilini differs from H. forms. Instead, it represents the last survivor of this gigas in the following features: somewhat smaller genus in Eurasia, one that developed gigantism M2 (Table 1), substantially smaller P4 (i.e., rela- independently from its earlier Asian relatives. tively small P4 compared to M2), and P4 with more distinct anterior accessory cusp and a lingual cin- Hyaenodon pervagus gulum. Perhaps the most prominent difference Matthew and Granger, 1924 between these two species is the considerably higher crowned P4 in H. gigas (see especially Material: IVPP V13573, an isolated left p4, from Dashzeveg 1985, figure 12b). Considering the fact IVPP loc. 9016, 100 m west of the village of Duit- that PSS 27-10, holotype of H. gigas, has suffered inggou from basal yellow conglomeratic sand- far more wear on the tip of the main cusp of the P4, stones, Lower Member of the Xianshuihe the crown height of PSS 27-10 may be twice as tall Formation, Nanpoping local fauna, in magnetic as that of IVPP V12187. The P4 in PSS 27-10 Chron C11r (about 30.3–30 Ma) in late early Oli- shows substantial apical wear, in contrast to the gocene (Qiu et al. 2001). shearing wear on the M1–2, indicating its primary Comments: IVPP V13573 (Figure 4) has a tall, function as a bone-crushing tooth. The M2 has slightly recumbent main cusp, a thin anterior ridge gone through extensive wear on PSS 27-10 and along its anterior face, and a posterior ridge reach- shows signs of lingually bent shearing blades typi- ing down to the posterior accessory cusp. The pos- cal for many late adult individuals of Hyaenodon. terior accessory cusp is well developed. A very PSS 27-10 appears to lack a distinct anterior ridge weak lingual cingulum is present on the anterior on the anterior face of the paracone, which is and posterior half of the tooth. present in IVPP V12186. This ridge is present in Measuring 17.4 x 7.2 mm, IVPP V13573 is nearly earlier and more primitive species from North identical in size to the holotype of Hyaenodon perv- America (such as in some individuals of H. vetus, agus Matthew and Granger 1924 (17.3 x 8.4 mm) H. montanus, and H. horridus, see Mellett 1977, from the Hsanda Gol Formation, although the latter figures 6, 7, 10), and its absence in H. gigas may falls in the upper range of the species (Lange- be another derived character. Badré and Dashzeveg 1989, table 2). The size and A new genus and species, Macropterodon shape of IVPP V13573 easily distinguish it from zelenovi Lavrov 1999, was named on a lower jaw other Hsanda Gol species (p4 of H. chunkhtensis fragment, PIN 3110/630, also from the Khoer Dzan measuring 7.0 x 3.0 mm, p4 of H. eminus measur- locality in the Ergilin Dzo Formation. This taxon is ing 11.0 x 5.5 mm, and H. incertus having a robust mainly diagnosed on the basis of a large, high- and broad p4 measuring 17 x 11 mm). crowned p4 that is relatively larger than the m1. Although lacking comparable materials of Hyaeno- Order CARNIVORA Bowdich, 1821 don gigas and Macropterodon zelenovi, we cannot Infraorder ARCTOIDEA Flower, 1869 help but note the similar giant size and robustness, Family AMPHICYONIDAE Haeckel, 1866 as well as a similarly massive P4 in both species. Genus ICTIOCYON Crusafont-Pairó et al., 1955 The possibility of that these two species are synon-

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Figure 4. Hyaenodon pervagus Matthew and Granger 1924, IVPP V13573, left p4 (A, occlusal, B, lingual, C, labial views).

Ictiocyon cf. I. socialis (Schlosser 1904) Middle Member of the Xianshuihe Formation, ?Ictiocyon sp.: Qiu et al. 1997, p. 186. Zhangjiaping l.f., early Miocene (see further discussion in Associated Fauna and Age under Hyaeno- Ictiocyon cf. I. socialis (Schlosser 1904): Qiu et al. don weilini). 2001, p. 378. Description: This large fox-sized carnivoran has a Materials: IVPP V12185, partial right horizontal robust horizontal ramus (Figure 5), which is rather ramus with anterior half of p4 and alveoli of c1-m3, deep relative to its length. The jaw depth is 22.8 collected from IVPP locality 9308, N 36° 13' 52.1" mm below the talonid of m1 (on the lingual side). E 103° 36' 23.9", south of the village of Qujia- The anteroventral corner of the masseteric fossa is chuan, on a small road cut in the first white sands, preserved and located rather high, about 10 mm

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Figure 5. Ictiocyon cf. I. socialis (Schlosser, 1904), IVPP V12185, right horizontal ramus with broken p4 (A, occlusal, and B, labial views).

above the ventral border of the ramus. There are ened premolar toothrow and correspondingly two mental foramina: one below the anterior root of broad and closely spaced premolars. the p2 and the other below the posterior root of the Ginsburg (1992) recognized two distinct lin- p3. The premolar toothrow is short, and the p3-m1 eages of small, short-snouted amphicyonids in the are apparently in close contact or even imbricate early to middle Miocene of Europe: an early slightly. There is a short diastema between the p2 Miocene Ictiocyon and a mostly middle Miocene and p3. The p1 and m3 are single rooted, whereas Pseudarctos, in contrast to an earlier hypothesis of the p2-m2 are all double rooted. The anterior half a single anagenetic lineage of Pseudarctos that of the p4 indicates a short but rather high-crowned decreases in size through time (Kuss 1965). The tooth, its anterior ridge of the main cusp being Lanzhou specimen readily falls in the size range of rather erect as compared to the more recumbent both Pseudarctos and Ictiocyon, and has similarly anterior ridges in many amphicyonids. Its anterior short and closely spaced premolars, derived char- cingulum swells slightly to form a low, cingulum acters shared by both genera. In addition, V12185 cusp. Alveoli of the corresponding teeth indicate a has a rather long m2 relative to its m1, a derived robust lower canine, a broad m1-2, an elongated feature that is well-developed in I. socialis (Gins- m2, and a reduced m3. burg 1992, figure 4, plate II), and still primitively Measurements of IVPP V12185 (all in alveolar retains a p1, which was lost in Pseudarctos. There- length and in mm): p1 = 2.9, p2 = 7.9, p3 = 7.3, p4 fore, the Lanzhou specimen is here referred to Icti- = 9.8, m1 = 16.8, m2 = 8.7, m3 = 3.8, and p1-m3 = ocyon based on its possession of a large m2 and 62.3. its lack of a Pseudarctos synapomorphy of the loss Comparison: From what little is preserved, IVPP of p1. Caution, however, must be exercised in an V12185 possesses amphicyonid characters such identification based on so little material. as a high position (relative to the ventral border) of A short rostrum and imbricated premolars also the masseteric fossa and a large m2. The Lanzhou characterize the European Oligocene Brachycyon. specimen is slightly more derived than European However, Brachycyon is much larger and has a and North American Oligocene small- to medium- much more robust lower jaw than the Lanzhou sized amphicyonids (such as Pseudocyonopsis, specimen. In addition, the horizontal ramus of Cynelos, Daphoenus, and Temnocyon) in its short- Brachycyon tends to expand ventrally near both its anterior and posterior ends (Ginsburg 1966) in contrast to a rather straight ventral border in the

9 WANG, QIU, & WANG: PALAEOGENE HYAENODONTS AND CARNIVORANS FROM GANSU

Lanzhou specimen. Finally, the m2 of Brachycyon nivoran from the Lanzhou Basin, smaller than any is not enlarged as in the Lanzhou specimen. known early Miocene carnivoran in Asia. The In Europe, the monotypic Ictiocyon socialis is metaconid is well developed, slightly offset (located known from several early Miocene localities (Gins- slightly posterior to) from the protoconid in occlusal burg 1992; Viranta 1996; Ginsburg 1999a), Winter- view, and of approximately the same height as the shof (MN3), Artenay (MN4a), Solnhofen fissures paraconid. The talonid appears to be narrow, but (MN4), and El Canyet (MN4). Pseudarctos bavari- this is partly due to damage to the labial portion of cus, on the other hand, occurs later in MN4b the talonid. The talonid is dominated by a centrally through MN9, and a series of three subspecies of located hypoconid (only the lingual half is pre- P. bavaricus were recognized by Ginsburg to rep- served), and the entoconid is poorly differentiated. resent a morphocline of increasing size through The possibility that this tooth is a deciduous p4 time. The present recognition of a Chinese occur- cannot be ruled out. rence of Ictiocyon extends its geographic range to With the poor preservation, IVPP V12190 can- East Asia and suggests an early Miocene age of not be easily identified. The relatively low-crowned the first white sands in the Lanzhou strata. trigonid and well-developed metaconid suggest a caniform carnivoran (in contrast to higher crowned Amphicyonidae gen. et sp. indet. feliforms). Among early Miocene caniforms, certain Material: IVPP V13574, posterior half of left p4, European basal musteloids, such as Plesictis (Wol- acquired from local villagers, specimen probably san 1993; Ginsburg 1999a), are closest in size and from near IVPP loc. 8801 in Duitinggou area, in overall morphology, although a definite match basal white sandstones, Middle Member of the awaits discovery of additional specimens. Xianshuihe Formation, Zhangjiaping l.f., early Miocene (see further discussion in Associated BIOGEOGRAPHY Fauna and Age under Hyaenodon weilini). Qiu (1997) listed several large mammals, Comments: Although of large size, this tooth is mostly large herbivores, which are shared by early primitive in its retention of a well- developed poste- Miocene faunas in Lanzhou and in Bugti, Pakistan: rior cingulum and posterior accessory cusp, fea- a gomphothere proboscidean, the schizotheriine tures that tend to occur in less derived species of chalicothere Phyllotillon, giant paraceratherine rhi- amphicyonids (most derived amphicyonids tend to nos, the endemic Asian rhino Aprotodon, and the reduce and simplify their premolars through time). large archaic artiodactyl Paraentelodon. Such fau- On the other hand, its broadened heel (11.0 mm nal exchange is indicative of a lack of barriers, at wide) reminds us of robust forms such as Gobicyon least for large mammals, between the two regions (Colbert 1939), which is known only in the middle in the early Miocene. This is in contrast to biogeo- Miocene of China (a jaw from Serbia referred to graphic differentiation observed in the middle and Gobicyon by Pavlovic and Thenius [1959] was late Miocene of mainland Asia, commonly attrib- recently transferred to Haplocyonoides by Gins- uted to the uplift of the Tibetan Plateau (Qiu and Li, burg [1999a]). With the scanty material available, it in press). is not possible to further explore the identity of this The carnivores from Lanzhou, on the other form. hand, appear to be mostly Palearctic elements and no southern Asian affinity can be detected. The Musteloidea indet Lanzhou Hyaenodon is the only Miocene survivor of the genus outside Africa. Hyaenodon is a highly ?Plesictis sp.: Qiu et al. 1997, p. 186. hypercarnivorous (almost exclusively meat eating) Plesictis cf. P. vireti Dehm, 1950: Qiu et al. 2001, p. and cursorial predator (Morlo 1999). This highly 378. diverse genus is one of the most wide-ranging, Material: IVPP V12190, isolated right m1, from highly mobile predators, occupying the entire IVPP locality 9309, N 36° 13' 44.1" E 103° 36' northern hemisphere. As archaic predators, cre- 18.6", Daochazigou, near a sand and gravel quarry odonts are mostly dominant in the Paleogene. By south of Qujiachuan, in the third white sands in the Miocene time, hyaenodonts were largely replaced Middle Member of the Xianshuihe Formation, by carnivorans in Eurasia and North America, and Zhangjiaping l.f., early Miocene (see further discus- were survived by only a few relicts in Africa, sion in Associated Fauna and Age under Hyaeno- Europe, and southern Asia. A single species, Hyai- don weilini). nailouros, is left in the early Miocene of Europe (Ginsburg 1999b). In the early and middle Miocene Comments: This isolated carnassial (Figure 6), of eastern and northern Africa, these archaic forms 4.6 mm long and 2.1 mm wide, is the smallest car-

10 WANG, QIU, & WANG: PALAEOGENE HYAENODONTS AND CARNIVORANS FROM GANSU

Figure 6. Musteloidea indet, IVPP V21290, right m1 (A, labial, B, lingual, and C, occlusal views).

still thrived in relative isolation and include modest DEDICATION AND ACKNOWLEDGMENTS generic diversity: Teradon, Anasinopa, Metasi- Our love for Will Downs cannot be easily nopa, Dissopsalis, Metapterodon, Leakitherium, expressed in a few words. Will made a profound Hyaenodon and Hyainailouros (Savage 1965; impact in Chinese vertebrate paleontology at a Ginsburg 1980; Barry 1988; Morales et al. 1998). time of maximum stress as the Chinese scientific In India and Pakistan, Dissopsalis, ?Metapterodon, communities struggled to find their footing amid and Hyainailouros are Miocene survivors, showing rapid changes of research environment and sci- geographic relationships to both Africa and Europe ence policy during the early days of economic (Pilgrim 1908, 1914; Colbert 1933; Barry 1980, reforms of the country. Besides being one of the 1988), but not to mainland Asia. The immediate few western scientists who could read technical ancestry of Hyaenodon weilini is unclear, for lack of Chinese paleontological literature, Will inspired us a comparable form elsewhere. It seems likely that with his single-minded dedication to field paleontol- this Chinese survivor was derived from northern ogy, his love of adventure, his care for Chinese cul- Eurasia stocks, instead of southern Asia. ture, and his tireless promotion of Chinese Other taxa from Lanzhou, such as Ictiocyon, vertebrate paleontology. Those of us who were may also indicate European affinity, although mate- privileged to enjoy many field seasons with Will rials are too limited to draw firm conclusions. A Downs will forever marvel at his great sense of more definite assessment has to wait for improve- humor and unique blend of optimism and carefree ment over the currently limited number of taxa attitude. available from the Lanzhou Basin.

11 WANG, QIU, & WANG: PALAEOGENE HYAENODONTS AND CARNIVORANS FROM GANSU

We thank numerous persons who have made Dehm, R. 1935. Über tertiäre Spaltenfüllungen im Fränk- valuable contributions in collecting the specimens ischen und Schwäbischen Jura. Abhandlungen der described herein and in establishing the strati- Bayerischen Akademie der Wissenschaften, Mathe- graphic framework: Will Downs, L. Flynn, E. Lind- matisch-naturwissenschaftliche Klasse, N. F., 29:1- say, B. Engesser, D. Oppliger, C. Mödden, P. 86. Dehm, R. 1950. Die Raubtiere aus dem Mittel-Miocän Heller, N. Opdyke, Xie Junyi, Xie Guangpu, Yue (Burgidalium) von Wintershof-West bei Eichstätt in Leping, Wu Ruijin, Zhang Liren, Chen Shanqin, Bayern. Abhandlungen der Bayerischen Akademie Feng Wenqing, and Gao Wei. We are grateful to R. der Wissenschaften, Mathematisch-naturwissen- Tedford who has been a consistent sponsor and schaftliche Klasse, N. F. 58: 1-141. advisor on the Lanzhou project and serves as an Flower, W.H. 1869. On the value of the characters of the excellent sounding board for both stratigraphic and base of the cranium in the classification of the order systematic issues. Discussions with P.D. Polly, J.C. Carnivora, and on the systematic position of Bassaris Barry, and A.V. Lavrov helped to clarify hyaenodont and other disputed forms. Proceedings of the Zoolog- systematics. Furthermore, Barry kindly allowed us ical Society of London:4-37. to examine unpublished Hyainailouros materials Flynn, L.J., Downs, W.R., Opdyke, N.O., Huang, K., from Pakistan. We appreciate the detailed reviews Lindsay, E.H., Ye, J., Xie, G. and Wang, X. 1999. Recent advances in the small mammal biostratigra- by J. Baskin and Barry, which greatly improved phy and magnetostratigraphy of Lanzhou Basin, p. both the language and the substance of this paper. 105-118. In Fang, X.-m. and Nettleton, D. (eds.), Field and laboratory research was supported by International Symposium and Field Workshop on grants from the Chinese National Natural Science Paleosols and Climatic Change. Science in China Foundation to Wang (40128004) and Qiu Press, Lanzhou, China. (49872011). International travel was supported by Ginsburg, L. 1966. Les amphicyons des Phosphorites du National Geographic Society (6771-00; 6004-97; Quercy. Annales de Paléontologie, 52:23-64. 5527-95) and James Carter Fund, American Ginsburg, L. 1980. Hyainailourus sulzeri, mammifère Museum of Natural History. créodonte du Miocène d'Europe. Annales de Paléon- tologie (Vertébrés), 66:19-55. REFERENCES Ginsburg, L. 1992. Les genres Pseudarctos et Ictiocyon, Amphicyonidae (Carnivora, Mammalia) du Miocène Barry, J.C. 1980. Occurrence of a hyaenodontine cre- européen. Bulletin du Muséum national d'Histoire odont (Mammalia) in the late Miocene of Pakistan. naturelle, Paris, 14(3-4):301-317. Journal of Paleontology, 54(5):1128-1131. 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