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Chinese Science Bulletin 2006 Vol. 51 No. 6 704—712 hominoid , L. lufengensis, were discovered in the DOI: 10.1007/s11434-006-0704-5 1970’s from the Shihuiba lignite bearing layers in the Lufeng[3,4]. More hominoid fossils were discovered from the Xiaohe, Zhupeng and Leilao in the Yuanmou , age and [5－7] Basin since 1986 , but their taxonomic status had environment status of the been very controversial, e.g. Ramapithecus hudienen- sis[5], habilis zhupengensis[6], Homo orientalis[7], Yuanmou hominoids Sinopithecus hudienensis[8], Lufengpithecus yuanmouen- [9] [10] 1 1 2 sis , yunnanensis yuanmouensis , and QI Guoqin , DONG Wei , ZHENG Liang , [11] 1 2 3 Lufengpithecus keiyuanensis . Their age status had ZHAO Lingxia , GAO Feng , YUE Leping [5] [6] & ZHANG Yunxiang3 also been controversial, e.g. 4－3 Ma , 2 Ma , 6－5 Ma[12], and 6.0－3.4 Ma[13], and all previous chrono- 1. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese logical conclusions were that the Yuanmou hominoids Academy of Sciences, Beijing 100044, China; 2. Cultural Relics and Archaeology Institute, Kunming 650118, were younger than those of the Lufeng. In order to bet- China; ter understand the taxonomic and age status of the 3. Key Laboratory for Continental Dynamics of the Ministry of Educa- Yuanmou hominoids, we carried out two large-scaled tion of China, Geology Department, Northwest University, Xi’an 710069, China excavations from 1998 to 2000 at Xiaohe, Zhupeng and Correspondence should be addressed to Qi Guoqin (Email: qiguoqin@ Leilao areas in the Yuanmou Basin (Fig. 1) within the ivpp.ac.cn) framework of “State Key Project of the 9th Five-Year Abstract The taxonomy, age and environment Plan－－Origin of Early Human and Environmental status of the Yuanmou hominoids had been contro- Background” and we collected 9 maxillary and man- versial since their discovery. We launched new ex- dibular fragments, 298 isolated teeth, as well as large cavations and investigations in the Yuanmou Basin quantity of mammalian fossils. We carried out, in addi- and analyzed both old and newly collected data. We tion, taphonomic and environmental investigations. conclude that all hominoids from the Yuanmou Basin and the so-called Pliocene hominids can be attributed into a single , and its valid nomination is Lufengpithecus hudienensis. It is different from Lufengpithecus lufengensis and Lufengpithecus kei- yuanensis. Based on the faunal comparison and pa- leomagnetic correlation, the strata yielding the Yuanmou hominoids are older than those of Lufeng hominoids and younger than those of the Kaiyuan hominoids. The age of the Yuanmou hominoids is Late . The environments of the Yuanmou hominoids were subtropical, hilly, with some dense forestry and partial transitional bushes and seasonal climate.

Keywords: Lufengpithecus hudienensis, Yuanmou Basin, Late Mio- cene, mammalian fauna, paleoenvironment. When, where and from which hominoid the human originated has been one of the key subjects in the study of human natural history. It is therefore very important to learn the chronological, geographical and taxonomic distribution of all hominoids. Yunnan Province is rich in hominoids. Lufengpithecus keiyuanensis was the first Fig. 1. Geographical location of excavated hominoid localities in the hominoid fossils discovered in the province in the 1950’s Yuanmou Basin. L: Leilao; X: Xiaohe; Y: Yuanmou Man Site; Z: Zhu- [1,2] from the Xiaolongtan lignite mine in Kaiyuan . New peng.

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1 Systematic paleontology New materials Two maxillary fragments (PDYA2, Mammalia Linnaeus, 1758 PDYA228) from Locs. 9802 and 9803 at Xiaohe; a Linnaeus, 1758 right mandibular fragment (PDYA1) from Loc. 9803 at Hominoidea Gray, 1825 Xiaohe; a left mandibular fragment (PDYA120) from Gray, 1825 9903 at Leilao; a right mandibular fragment (PDYA229.1) and a left mandibular fragment (PDYA229.2) of the same Lufengpithecus Wu, 1987 Lufengpithecus hudienensis (Zhang et al., 1987) individual from Loc. 9801 at Xiaohe; a right mandibular Ramapithecus hudienensis Zhang, Lin, Jiang et al., 1987[5] fragment (PDYA122) from Xiaoahe; a right mandibular Homo habilis zhupengensis Jiang, Sun et Liang, 1987[6] fragment (PDYA121) from Loc. 9903 at Leilao; left Homo orientalis Zhang, Lin, Jiang et al., 1987[7] mandibular fragment (PDYA167) from Leilao. 298 iso- [8] Sinopithecus hudienensis (Zhang, Lin, Jiang et al., 1987) lated teeth from Zhupeng-Xiaohe and Leilao areas. [9] Lufengpithecus yuanmouensis Zheng et Zhang, 1997 Distribution Xiaohe Formation in Zhupeng- Sivapithecus yunnanensis yuanmouensis Zhou, 1998[10] Lufengpithecus keiyuanensis Woo, 1957[11] Xiaohe and Leilao areas of the Yuanmou Basin, Yunnan 3 3 Province, Late Miocene. Holotype A left maxillary fragment with P -M Description The mandibular morphology is repre- (YV916), conserved at the Yunnan Cultural Relics and sented by PDYA228 (Fig. 2(a), (b)), facial bone is bro- Archaeology Institute. ken above M1-M2 and maxillary sinus is exposed which Revised diagnoses The juvenile facial cranium has is narrow and high, and extends anteriorly behind P4. large inter-orbital width and glabella area is not con- The canine fossa is present 15mm above P4, and it is cave, and frontal sinus is present. Dental arcade is “V” not deep, implying that the canine root is not strong. shaped. The posterior margin of mandibular inferior Both P3 and P4 are well preserved, their buccolingual transversal torus extends upward. The dimensional diameter is larger than mesiodistal one, the buccal me- proportion of anterior teeth to the cheek teeth is larger 3 siodistal diameter is larger than lingual one on PP , and it than that of the Lufeng hominoids. The vertical crests 4 is contrary on P . on the lingual side of maxillary lateral incisors are more Mandibular morphology is represented by PDYA120 developed than those of the Kaiyuan hominoids but the (Fig. 2 (e)). In lateral view, the anterior margin of man- cingula are less developed than those of the latter, and dibular ramus covers posterior half of M and the buc- their labial side is more transversally curved than in the 3 cal muscle sulcus is shallow and narrow. In medial view, Kaiyuan hominoids. Lingual cingulum on the maxillary superior transversal torus thickens from below alveoli canines does not extend to the labial side, and vertical margin but weakens towards the inferior margin of the groove between main crest and mesial crest is deeper mandibular corpus, making a shallow fossa at one third than in the Kaiyuan hominoids. The labial surface of the mandibular lateral incisors turns curvedly towards height of mandibular corpus; the inferior transversal the distal side and the distal surface appears very nar- torus develops along the inferior margin of the man- row, and unlike that in the Lufeng hominoids, the labial dibular corpus, another shallow fossa is formed be- surface turns sharply towards the distal side. The tween two torus but it weakens posteriorly and nearly mesiodistal diameter of crown is short and the disappears at M3. PDYA121 (Fig. 2 (c)) represents a buccolingual one is wide, and cusps are more obtuse small-sized hominoid. Its buccal muscle sulcus is very and concentrated than in the Lufeng hominoids. The narrow, quite different from the wide sulcus in the last molar is shorter. The two cusps of maxillary third Lufeng hominoids. The molar size in its dentition are smaller than in the Kaiyuan hominoids. shows that M1

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Fig. 2. Maxillary and mandibular fragments of Lufengpithecus hudienensis. Right maxillary fragment (PDYV228), buccal view (a) and occlusal view (b); right mandibular fragment (PDYV121), lingual view (c); right mandibular fragment (PDYV122), lingual view (d); left mandibular fragment (PDYV120), buccal view (e); a reconstructed mandibular image by superposing occlusal image of PDYV122 over that of the anterior part of PDYV121 and reassembling them with that of PDYV120.

The newly unearthed isolated teeth and those on the The dental morphology of the Yuanmou hominoids above-mentioned jaws have the same morphology as is even closer to that of the Kaiyuan hominoids[1,2], es- [9] those described by Zheng and colleague . Their meas- pecially the P3 is unicusped in both hominoids. Never- urements are summarized in Table 1. theless, the lingual main oblique crest base is not Comparison and discussion Indeed, the dental swelled and mesiobuccal cingulid is developed in the morphology of hominoids from the Yuanmou Basin is Kaiyuan hominoids but the crest base is swelled and the very close to that from Lufeng[3,4,14], but the differences cingulid is absent in the Yuanmou hominoids; the ver- still exist. For example, the dimensional proportion of tical crests on the lingual side of maxillary lateral inci- anterior teeth to the cheek teeth and incisor area are sors are more developed in the Yuanmou hominoids larger in the Yuanmou hominoids than in the Lufeng than those in the Kaiyuan hominoids but the cingula are hominoids; the symphysis is wider in the Yuanmou less developed than those of the latter, their labial side hominoids than in the Lufeng hominoids. The labial is more transversally curved than in the Kaiyuan surface of the mandibular lateral incisors turns curvedly hominoids; lingual cingulum on the maxillary canines towards the distal side and the distal surface appears does not extend to the labial side, vertical groove be- very narrow in the Yuanmou hominoids, but in the tween main crest and mesial crest is deeper in the Lufeng hominoids the labial surface turns sharply to- Yuanmou hominoids than in the Kaiyuan hominoids; wards the distal side; molar cusps are more obtuse and the two cusps of maxillary third premolar are smaller in concentrated, occlusal enamel crenulations are fewer in the Yuanmou hominoids than in the Kaiyuan hominoids; the Yuanmou hominoids than in the Lufeng hominoids. M1 is not very small and the dimensional difference The most significant difference is that the mandibular between M2 and M3 is not very obvious in the Kaiyuan third premolar of the Yuanmou hominoids is unicusped hominoids. and the contour of the crown is triangular or sectorial, Compared with the late Miocene hominoids from the the anterior fossa is very small and posterior fossa is Khorat, Thailand[15], the cheek dentitions of two sides narrow, but this mandibular third premolar of the are parallel to each other and the mandibular dental Lufeng hominoids is bicusped, metaconid is evidently arcade is “U” shaped, the M3 and P3 are very large in present, i.e. the P3 of the Yuanmou hominoids still pre- the dentition in the Khorat hominoids, but the cheek served the middle Miocene hominoid character. dentitions of two sides are oblique to each other, the

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Table 1 Statistics of measurements of isolated teeth of Lufengpithecus hudienensis Dentition Dimension Number Min (mm) Max (mm) Average(mm) StD I1 Mesiodistal 13 7.5 11.8 9.78 1.263 Labiolingual 13 7.5 10.3 8.91 0.843 Height 13 8.9 15.4 12.14 1.994 I2 Mesiodistal 8 4.9 6.9 5.66 0.648 Labiolingual 8 5.3 7.5 6.35 0.865 Height 8 6.5 10.4 8.66 1.701 C1 Mesiodistal 15 7.2 13.5 9.75 1.955 Labiolingual 15 7.1 16.3 10.77 3.357 Height 15 9.2 26 15.17 6.179 P3 Mesiodistal 11 6.7 8.6 7.35 0.561 Buccolingual 12 8.4 12.1 10.02 0.921 Height 12 6 11.3 8.49 1.470 P4 Mesiodistal 22 6.1 11.3 7.39 1.077 Buccolingual 22 9.2 12.5 10.98 1.042 Height 22 5 8.8 7.49 0.970 M1 Mesiodistal 21 8.6 10.9 9.84 0.660 Buccolingual 20 8.4 12.8 10.60 1.136 Height 21 4.2 6.8 5.57 0.734 M2 Mesiodistal 31 9.3 14 11.04 1.222 Buccolingual 31 10.5 14.4 12.35 1.161 Height 31 4.8 7.8 6.16 0.855 M3 Mesiodistal 16 8.4 11.5 9.98 1.063 Buccolingual 16 9.5 13.4 11.34 1.347 Height 16 4 6.8 5.49 0.825

I1 Mesiodistal 11 4.8 6.4 5.55 0.585 Labiolingual 11 4 8.4 6.97 1.159 Height 10 9 14 11.39 1.716

I2 Mesiodistal 5 5 6 5.46 0.397 Labiolingual 5 6.1 8.6 7.10 1.077 Height 5 6.1 8.6 7.10 1.077

C1 Mesiodistal 12 7.6 13 9.93 1.974 Labiolingual 12 5.2 12.3 7.32 2.192 Height 11 8.9 34 15.55 7.237

P3 Mesiodistal 10 7.9 12.8 11.18 1.458 Buccolingual 10 5.6 13.8 8.08 2.289 Height 10 6 13.4 10.40 2.001

P4 Mesiodistal 18 7 10.1 8.31 1.113 Buccolingual 18 6.8 10 8.59 1.087 Height 16 5.6 8.7 7.13 0.943

M1 Mesiodistal 23 9 11.8 10.40 0.797 Buccolingual 23 7.3 10.6 9.21 0.728 Height 23 4 7.9 5.77 0.798

M2 Mesiodistal 26 10.4 14.6 11.83 0.957 Buccolingual 26 9.2 13 10.89 0.934 Height 26 4.8 8.5 6.33 0.785

M3 Mesiodistal 20 10.6 14 12.30 1.047 Buccolingual 20 9.4 12.4 10.95 0.933 Height 20 5 7.3 6.27 0.671

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ARTICLES dental arcade is “V” shaped (Fig. 2 (f)), the sizes of M3 After assigning the Yuanmou hominoids to Lufeng- and M2 are close to each other. The difference between pithecus, we try to discuss the phylogenetic position of

the Yuanmou hominoids and the Khorat hominoids is the Lufengpithecus. The results of three- dimensional very obvious. morphometric analyses of hominoid lower molars show The difference between the Siwalik hominoids[16] that Lufengpithecus is closest to the extant great [19]. and Yuanmou hominoids is even evident. The mesio- Among the numerous similar characters between distal diameter of the maxillary central incisors is very Lufengpithecus and Sivapithecus[14], the synapomor- large but labiolingual one of those is small, lingual sur- phies are triangular lower face (outward stretching ca- face of the incisors has no tubercles and vertical crests nines), and developed canine fossa and enamel crenula- but many tiny folds, the mesiodistal diameter of the tions on occlusal surface of molars. The similar skull mandibular molars is longer and buccal cingulid is evi- characters between Lufengpithecus and hominins are dent on mandibular molars in the Siwalik hominoids mainly plesiomorphies. But whether such characters as and very different from the Yuanmou hominoids. lachrymal fossa and infra-orbital foramen, a pair of incisor foramens, relatively long formation period (av- 2 Taxonomic and systematic positions of the erage 3.9 years) of mandibular incisors and 3B enamel Yuanmou hominoids prism pattern[20] etc. are synapomorphies of Lufeng- There were various generic attributions for the pithecus and hominins or not is still to be confirmed. Yuanmou hominoids. Besides excluding Homo, pro- On the other hand, Lufengpithecus has some unique [5] [8] posed genera are Ramapithecus , Sinopithecus , autopomorphies such as sunken glabella area, and ex- [10,17] [9] Sivapithecus , and Lufengpithecus . Compared treme of canines. with other contemporary hominoids, especially with Based on the above analyses, if we place Lufeng- Dryopithecus and Sivapithecus (= Ramapithecus), the pithecus in , we must interpret the synapo- Yuanmou hominoids are closest to Lufengpithecus morphies (frontal sinus, lachrymal fossa, infra-orbital [18,19] based on dental morphology . But as to the cranial foreman, enamel prism 3B pattern, long formation pe- and mandibular evidences, it is not yet sufficient. riod of incisors, etc.) between Lufengpithecus and Lufengpithecus has many differences from the other as parallel or convergent evolution result; on contemporary hominoids and its generic independence the contrary, if we place Lufengpithecus in Homininae, is indisputable. Both the Lufeng hominoid adult skull we must interpret the synapomorphies (triangular lower and the Yuanmou hominoid juvenile skull have charac- face, canine fossa, developed molar enamel crenulations, ters as broad glabella region, mounted orbit rims, ante- etc.) between Lufengpithecus and Ponginae as parallel or riorly placed zygomatic base, etc. But the glabella re- convergent evolution result. Lufengpithecus has neither gion in the Yuanmou juvenile skull is not sunken as that main apomorphies of Ponginae (narrow glabella dis- in the Lufeng adult skull. It is not yet known if it is tance, oval orbits, etc.), nor main apomorphies of ontogenetic variation. In short, based on the current Homininae (developed supra-orbital ridge, reduced data, it is better to assign the Yuanmou hominoids to sexual dimorphism, etc.), but it has its own unique Lufengpithecus. autopomorphies (sunken glabella region, thick maxillary As to the specific attribution, the Yuanmou homi- central incisors and extreme sexual dimorphism, etc.). It noids were considered as the same species as the Kai- is the most reasonable and parsimonious way to place yuan hominoids[11], or as an independent species dif- Lufengpithecus at the base of Hominidae as a special- ferent from all known hominoids[9]. As mentioned ized branch. above, we think the Yuanmou hominoids are different from the Kaiyuan hominoids and should be considered 3 Age and environment of the Yuanmou hominoids as an independent species. According to the Law of Priority, Lufengpithecus hudienensis is the only valid 3.1 Mammalian fauna associated with the Yuanmou specific assignment among all available ones[5－11] and hominoids and their age only valid type specimen is the left maxillary fragment A large quantity of mammalian fossils associated with P3-M3 (YV916) conserved at the Yunnan Cultural with the hominoids were also collected during the Relics and Archaeology Institute. large-scaled excavations in the Yuanmou Basin. Based

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ARTICLES on the comprehensive study on these new materials and brevis, Paracervulus attenuatus, Muntiacus nanus, Mun- those collected in the previous excavations[21], the tiacus leilaoensis, Muntiacinae gen. et sp. indet. mammalian fauna associated with the Yuanmou The fauna associated with the Yuanmou hominoids is hominoids can be classified into following species: evidently more advance than that associated with the Prodendrogale yunnanica, Ptilocercinae gen. et sp. Kaiyuan hominoids[22,23], which is demonstrated par- indet., Hylomys aff. Suillus, Yunoscaptor scalprum, ticularly by the composition of proboscideans. The Heterosorex wangi, Anourosorex oblongus, Sorex sp. 1, Tetralophodon from the Yuanmou has 6－7 lophed Sorex sp. 2, Soricinae gen. et sp. indet., Insectivora fam. third molars, being more advance than that with 5 and gen. et sp. indet., Chiroptera fam. gen. et sp. indet., Ves- half lophs from the Kaiyuan; elephantids are present in pertilionidae gen. et sp. indet., Hipposideridae gen. et sp. the Yuanmou hominoid fauna but absent from the Kai- indet., Sciurotamias wangi, Sciurotamias leilaoensis, yuan hominoid fauna. It demonstrates that the Kaiyuan Sciurotamias sp., Tamiopus atavus, Callosciurus sp., hominoid fauna is more primitive than the Yuanmou Dremomys primitivus, Dremomys sp., Ratufa yuan- hominoid fauna and the former is chronologically older mouensis, Sciurinae gen. et sp. indet., Miopetaurista than the latter. However, the micromammalian fauna asiatica, Hylopetodon dianense, Pliopetaurista speciosa, associated with the Yuanmou hominoids[24] is more Pliopetaurista sp., Yunopterus jiangi, “Monosaulax” sp., primitive than that associated with the Lufeng homi- Platacanthomys dianensis, Typhlomys primitivus, Ty- noids[25－27]. Our comparison on large results phlomys hipparianum, Leptodontomys sp. Eomyidae gen. in the same conclusion. It suggests that the Yuanmou et sp. indet., Branchyrhizomys blacki, Branchyrhizomys hominoid fauna is chronologically older than the tetracharax, Branchyrhizomys sp. nov., Tachyoryctinae Lufeng hominoid fauna. gen. et sp. indet., Kowalskia hanae, Cricetidae gen. et The high-resolution paleomagnetic sampling was sp. indet., Linomys yunnanensis, Leilaomys zhudingi, carried out at the Xiaohe and Leilao sections[28], the Muridae gen. et sp. indet., Atherurus sp., Hystrix sp., samples were taken at every 10cm interval so as to Pedetidae gen. et sp. indet., Leporidae gen. et sp. indet., reduce the possibility of omitting the short polarity Indraloris progressus, Sinoadapis parvus, Yuanmoup- events. The paleomagnetic measuring shows that the ithecus xiaoyuan, Amphicyon palaeoindicus, Vishnucyon Yuanmou hominoid bearing layers can be dated as 8.2 cf. Chinjiensis, Ursavus sp., Indarctos yangi, Indarctos cf. [28] －7.2 Ma , much earlier than the previous paleo- Yangi, Pseudarctos bavaricus bavaricus, Ailurarctos magnetic dating of 6.0－3.4 Ma[13]. The paleomagnetic yuanmouensis, Eomellivora wimani, Trochotherium dating at the Zhupeng by another team also proves the yuanmouensis, Melinae gen. et sp. indet., Sivaonyx [29] bathygnathus, Lutra sp., Mustelidae gen. et sp. indet. 1, hominoid bearing layers older than 7 Ma . This dif- Mustelidae gen. et sp. indet. 2, Vishnuictis cf. ference is because the previous paleomagnetic dating is Salmontanus, Viverridae gen. et sp. indet. 1, Viverridae not based on high-resolution sampling, the samples gen. et sp. indet. 2, Ictitherium viverrinum, Ictitherium were taken at 50－200 cm intervals that some polarity hyaenoides, Thalassictis wongi, Adcrocuta eximia, events were very likely omitted on the one hand, and Hyaenidae gen. et sp. indet. 1, Hyaenidae gen. et sp. indet. our dating is carried out with new and advanced super- 2, Machairodus cf. maximiliani, Machairodus sp., conductive equipment that the measurements are much Metailurus parvulus, Felis sp. 1, Felis sp. 2, Felis sp. 3, more precise on the other hand. We also carried out Felis sp. 4, Felidae gen. et sp. indet., Carnivora fam. high-resolution sampling at Sections A and D at Lufeng. gen. et sp. indet., Tetralophodon xiaohensis, Mammut The paleomagnetic age of the Lufeng hominoid layers zhupengensis, Stegotetrabelodon primitium, Stegolo- is dated as 6.9－5.8 Ma (Fig. 3, unpublished data). It phodon sp., Cormohipparion cf. chiai, Subchilotherium also shows that the Yuanmou hominoids are older than intermedium, Rhinoceros cf. vidali, Rhinoceratidae gen. the Lufeng hominoids. Based on evolutionary et sp. indet., Macrotherium yuanmouensis, Tapirus sp., characters of fauna and paleomagnetic data analysis, Yunnanochoerus sp., Chleuastochoerus sp., Hippopo- we conclude therefore that the Yuanmou hominoids are tamodon hyotherioides, Molarochoerus yuanmouensis, younger than the Kaiyuan hominoids but older than the Dorcabune cf. Progressus, Dorcatherium sp., Yunnanoth- Lufeng hominoids, and their age is 8.2－7.2 Ma, or erium sp., Moschus sp., Euprox robustus, Paracervulus Late Miocene. www.scichina.com www.springerlink.com 709

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Fig. 3. Paleomagnetic correlation of the sections A and D in Lufeng (unpublished data) with the Xiaohe section[28]. 1. Clay; 2. sandy clay; 3. clayey sand; 4. sand; 5. sand with gravel; 6. layer; 7. carbonic clay; 8. lignite; 9. reversed polarity; 10. normal polarity.

3.2 Environmental implications of the mammalian of total, insectivores amount to 8 species or 7.5% of fauna total, carnivores amount to 32 species or 30.1% of The mammalian fauna associated with the Yuanmou total, proboscideans amount to 4 species or 3.8% of hominoids from the Xiaohe and Leilao includes 106 total, perissodactyls amount to 6 species or 5.7% of species or 107 species if including hominoids. The total, artiodactyls amount to 14 species or 13.2% of number of species is much more than extant subtropical total, and the other taxa amount to 6 species or 5.7% of evergreen forest (45－52 species), tropical Asian ever- total. We can see from the composition that the Yuan- mou hominoid fauna is dominated by carnivores, ro- green broadleaf forest (44－60 species), high mountain dents and artiodactyls. This composition is somewhat forest (42－60 species), tropical African savanna (40 similar to that of the Middle Miocene Pasalar homi- － species), semi-arid shrubbery zone (54 73 species), noid fauna in Turkey. The latter is composed of 58 defoliate land (51－75 species), defoliate forest (62― mammalian species[31], among which rodents amount 63 species), semi-defoliate forest (59－67 species), to 13 species or 22.4% of total, insectivores amount to evergreen forest (72－76 species), and alpine forest (62 4 species or 6.8% of total, primates amount to 2 spe- －67 species), and the number of species reflects in cies or 3.4% of total, artiodactyls amount to 12 species some aspects the non-monotone of natural landscape[31]. or 20.3% of total, carnivores amount to 16 species or Among 107 species, primates amount to 4 species or 28.5% of total, the other taxa amount to 11 species or 3.8 % of total, rodents amount to 33 species or 31.1% 18.9% of total, and the Pasalar hominoid fauna is also

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ARTICLES dominated by carnivores, rodents and artiodactyls. distribute south of Yunnan Province. The fauna associ- Such composition can still be seen in many different ated with the Yuanmou hominoids is not in full accor- actual habitats of mammalian fauna (e.g. mammalian dance with the faunal composition of modern Oriental

faunas in subtropical semi- deciduous forest, tropical Region although it has such appearance. The large Tu- deciduous forest and tropical semi-evergreen forest). It paiidae, numerous tropical squirrels and flying squirrels, indicates in some aspects the information about the rich typhlomys, primates, viverrids, proboscideans and habitation of the Yuanmou hominoids. tragulids coexisting in the Yuanmou Basin seem indi- The statistics show that 50% of the micromammals cating that the climate in the time of the Yuanmou associated with the Yuanmou hominoids are strict forest hominoids was more humid and warmer than today, habitat selectors, 18.4% are forest and relatively humid and the ecological environment was close to that of woodland margin habitat selectors, and shrubbery and modern Southeast Asia. It is worthwhile to notice that open grassland habitat selectors only take 5.3%. The all cervids in the Yuanmou hominid fauna are micromammals associated with the Yuanmou homi- brachyodont, the common but sub-hypsodont Se- [32] noids indicate a habitat very close to that of the Lufeng lenoportax in the Lufeng hominoid fauna is absent hominoids, the compositional proportion of different from the Yuanmou hominoid fauna. It indicates that the habitat selection by both faunas shows no significant Yuanmou cervids fed on rather tender leaves, likely difference (X 2 = 0.4037, P = 0.9952), and both fauna juicy young leaves of dicotyledon. Such vegetation can habitats are mainly forests, but with some scattered only thrive in the warm and humid environment. [33] shrubberies and grasslands, as well as some watery de- All cervids have developed burr , impling that the pressions[24]. climate in their habitat is seasonally changing. The The above analyses show that all ten orders of seasonal replacement of antlers results in the developed mammals in the fauna go down to present. Among them burr. Based on the study of extant cervids, the replace- Scandentia is a unique order of the Oriental Region, and ment of antlers is controlled by the seasonal cycle of endocrine of the cervids. And this cycle is mainly in- that Proboscidea and Primates almost only distribute in [34,35] the Oriental Region. The other seven orders have their fluenced by annual difference of sunlight . The extant descendants besides extinct families such as Eo- Yuanmou Basin is located within 25°－26° N latitudes, myidae, Sivaladapidae, Gomphotheridae, Mummutidae, very close to the tropic of Cancer. The annual differ- Amphicyonidae and Chalicotheriidae. Extant Talpidae, ence of the sunlight irradiating the earth’s surface is Soricidae, Vespertilionidae, Sciuridae, Muridae, Lepori- much less than that in the northern and northwestern dae, Ursidae, Mustelidae, Equidae, Suidae, Moschidae China in much higher latitudes. Because the annual and Cervidae distribute widely in both northern and difference of sunlight irradiating the earth’s surface in southern China, and Erinaceidae, Hipposideridae, Plata- the Yuanmou Basin is small, and the seasonal climatic change in the basin during the Yuanmou hominoids’ canthomyidae, Viverridae, Hyaenidae, Elephantidae, epoch should be influenced by some other factors. Due Rhinoceratidae and Tragulidae are unique or main fami- to the coverage of clouds, sunlight will be greatly re- lies distributing in Old World tropical and subtropical duced on the earth’s surface during cloudy seasons. The regions. Ailuropoidae distribute in relatively high lati- distribution of the clouds is evidently influenced by the tudes, but they have not surpassed the boundary between movement of humid air. It could be inferred that the subtropical regions and sub-alpine taiga or conifer- annual difference of sunlight irradiating the earth’s sur- broadleaf forest regions. Moschidae widely distribute in face in the Yuanmou Basin during that time was mainly both northern and southern China, but due to geographic influenced by the monsoon across the basin, and sec- and ecological replacement, they tend to concentrate in ondly by the altitude. eastern Himalayas and southern Hengduan Mountains. We conclude based on the above-mentioned analyses Castoridae are unique pro-water rodents of modern that the habitats of the Yuanmou hominoids and associ- Holarctic Region. Modern Cricetidae also distribute in ated fauna are mainly composed of mountainous forests, the Holarctic Region. All extant families in the Yuan- including some dense forests and transitional shrubber- mou hominoid fauna appear in Yunnan Province except ies, as well as some open flat valleys and rivers. Castoridae, Cricetidae, Ailuropoidae, Hyaenidae, Rhi- noceratidae and Tapiridae, and the last three families Acknowledgements We thank all members of Yunnan team www.scichina.com www.springerlink.com 711

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