Mohui Cave Research Articles

Environmental fluctuation impacted the evolution of Early Pleistocene non-human primates: Biomarker and geochemical evidence from Mohui Cave (Bubing, Guangxi, southern China)

Quaternary climate variability, profoundly impacting the evolution and distribution of plants and animals across the globe, has been reconstructed by many sediment archives. Here, we track past changes of temperature, rainfall and plant type by using the n-alkane and glycerol dialkyl glycerol tetraethers (GDGTs), as well as weathering and pedogenesis by mineralogical and geochemical proxies from a 250 cm deep soil sediment profile from the Early Pleistocene deposits in Mohui Cave, southern China. Indices for weathering intensity such as mineral composition (quartz, feldspar and calcite), major element proxies (Ti/Na, Al/Na, Al/Mg, Ti/Mg, CIW, PIA, CPA, CIA), trace element proxies (Ba/Sr and Rb/Sr), and biomarker proxies (OEP, LSR and CPI) show similar secular trends, revealing a three-stage historical accumulation. The high long-chain n-alkane ratios (C31/C29 and (C31+C33)/(C27+C29)) indicate that the vegetation in the region had increases in percentage of woody plants and decreases in herbs during periods of relatively lower temperature and less precipitation, which evidenced from GDGTs, consistent with a weak weathering process influenced by summer monsoon strength. Further, we compared the distribution of these plant types with the taxonomic variation in the vertebrate paleontological fossils excavated from the same profile in Mohui Cave. The distribution of Lufengpithecus appears in only one interval but Gigantopithecus blacki appears throughout the profile, despite an environment that experienced transitional stages from grassland to woodland in relatively cooler and drier conditions. We infer that in face of these climatic changes Lufengpithecus may have preferred to emigrate from the region, while Gigantopithecus blacki may have stayed given that it was limited to staying in its core area.

Magnetostratigraphy of Plio–Pleistocene fossiliferous cave sediments in the Bubing Basin, southern China

Abstract Our understanding of the chronological sequence of Pleistocene land mammal faunas (including hominids) preserved in caves and fissures in the karstic terrain of subtropical southern China has been greatly impeded by the discontinuous nature of the strata yielding the fossils. A contributory issue is the lack of suitable elements for numerical dating, especially for the Early Pleistocene cave sediments. Here we present new magnetostratigraphic dating results for five cave sedimentary sequences in the Bubing Basin, Guangxi Zhuang Autonomous Region, which contain the typical Pleistocene Gigantopithecus fauna and Ailuropoda–Stegodon fauna of southern China. The five karstic caves are situated at elevations ranging from 252 m to 191 m above sea level. The integrated dating results reveal that the five cave sedimentary sequences span an age range from the late Gauss normal Chron to the early Brunhes normal Chron. The faunas are assigned to >2.6 Ma (Mohui–houshan Cave), 1.95–1.78 Ma (Mohui Cave), 0.99–0.78 Ma (Baolai Cave) and ∼0.7 Ma (Upper Wuyun and Ganxian Caves). Furthermore, by combining our new magnetostratigraphy work with previously published magnetostratigraphic, U–series and electron spin resonance dating results, a chronological sequence of the Plio–Pleistocene mammalian faunas from cave sites in southern China has been established. The chronological sequence contributes to an improved understanding of the evolutionary processes of Plio–Pleistocene land mammals, as well as of early humans in subtropical southern China.

The stable isotope record in cervid tooth enamel from Tantang Cave, Guangxi: Implications for the Quaternary East Asian monsoon

Abstract Studies have shown that stable isotope [oxygen (O) and carbon (C)] composition of mammal tooth enamel can provide information on a region's paleoclimate and paleoecology. Stable isotope analysis has been used to investigate the impact of the Qinghai–Tibetan Plateau uplift on the development and strength of the Asian monsoon. However, due to sparse data from southern China, a region dominated by the East Asian monsoon, O and C isotope analysis of mammal tooth enamel has been unable to fully inform on the impact of the monsoon environment in the region. Here, we present the results of the analysis of stable isotopes on a set of cervid tooth enamel from late Middle Pleistocene Tantang Cave in Bubing Basin, Guangxi, southern China and compare them with comparable isotope data from nearby early Early Pleistocene Mohui and middle Early Pleistocene Sanhe Caves. The results of the oxygen isotope analysis indicates that Tantang Cave (−8.70‰ to −6.39‰) is similar to Mohui Cave (−8.71‰ to −6.34‰), with both sites being more negative than Sanhe Cave (−4.77‰ to −1.20‰). We suggest the East Asian summer monsoon was stronger during the Tantang and Mohui mammal occupations and weaker during the lifetime of the Sanhe mammals. This result is indirectly corroborated by vertebrate paleontological evidence. Murid rodents, implying an open grassland and somewhat drier climate, are found in great numbers in Sanhe. The carbon isotope results from Tantang (−17.70‰ to −10.26‰), Mohui (−15.27‰ to −12.51‰), and Sanhe (−16.63‰ to −14.71‰) overlap extensively suggesting these various faunas primarily lived in a closed forest environment. The implications of these findings from stable isotope studies from Tantang are discussed in their broader context.

Paleoenvironmental background of the Early Pleistocene Gigantopithecus fauna in Bubing Basin, south China

Thanks to the presence of the enigmatic Gigantopithecus fossils, vertebrate paleontologists have spent much time analyzing the Pleistocene faunas of southern China. Although research has been conducted in the region for more than one half century, the vast majority of this research has focused on the direct analysis of the associated vertebrate fossils, particularly for taxonomic identification purposes. In order to develop a firmer understanding of the paleoenvironment in which these various taxa lived there is still a relative paucity of data derived from other lines of evidence besides taxonomic identifications. Here, we contribute to these paleoenvironmental reconstructions of southern China by presenting the results of clay mineral composition and geochemical analyses of the deposits from the Early Pleistocene Mohui Cave (Bubing Basin, Guangxi). In general, the Mohui Cave clay mineral samples are dominated by kaolinite, which indicates a warm and humid climate. The relatively high content of smectite in Unit II implies a relatively long dry season within the overall context of the warm and humid environment. Based on the Chemical Index of Alteration (CIA), the estimated land surface temperature during the Early Pleistocene (27 °C) was much higher than today (21.9 °C). Our results are consistent with previous environmental reconstructions based on vertebrate paleontological and isotopic studies of the Gigantopithecus fauna in southern China that the environment during the Early Pleistocene was warmer and more humid than today.

The Early Pleistocene Gigantopithecus-Sinomastodon fauna from Juyuan karst cave in Boyue Mountain, Guangxi, South China

As one of the most important Quaternary mammalian faunas in southern China, the Gigantopithecus-Sinomastodon fauna has received much attention. The large-primate fossil teeth newly collected from Juyuan karst cave in Boyue Mountain, Guangxi Zhuang Autonomous Region of southern China, can be identified as Gigantopithecus blacki. The morphology and size of these G. blacki teeth differ from those of the middle Pleistocene Gigantopithecus teeth which hold evidently larger dental dimensions and more complex crenulations from Hejiang Cave also in Guangxi and Tham Khuyen Cave in Vietnam. However, the G. blacki teeth from Juyuan Cave are relatively similar to those from Early Pleistocene Mohui Cave and Liucheng Gigantopithecus Cave both in Guangxi, which suggests that the three cave sites have similar age. The Juyuan fauna associated with Gigantopithecus blacki, consisting of 45 mammalian species (such as Sinomastodon yangziensis, Ailuropoda wulingshanensis, Stegodon huananensis, and Rhinoceros fusuiensis), is a typical Early Pleistocene Gigantopithecus-Sinomastodon fauna of southern China. The Juyuan fauna is mostly similar to Mohui fauna, also implying their contemporaneity. Paleomagnetic analyses demonstrate that the fossil-bearing sediments in Juyuan Cave are dominated by normal polarity. Combining the faunal analysis and magnetostratigraphic evidence, the Juyuan sediments can be best correlated with the Olduvai normal subchron, giving an estimated age of 1.8 Ma.

New Early Pleistocene Perissodactyl remains associated with Gigantopithecus from Yangliang Cave, Guangxi of southern China

Herein the new Perissodactyl fossils associated with Giantopithecus blacki recovered from Yanliang Cave, Guangxi of southern China were described as Hesperotherium sinense, Tapirus sanyuanensis and Rhinoceros fusuiensis, which are all the common elements of the typical Early Pleistocene Gigantopithecus–Sinomastodon fauna in southern China. Especially, we analyse and compare to the metacarpus and metatarsus among extinct Rhinoceros fusuiensis and extant Asian rhinos based on quantitative indexes of measurements. The results show that the sizes between genera Rhinocers and Dicerorhinus are different. Specifically, the sizes of metacarpus and metatarsus of Rhinoceros fusuiensis are smaller than those of the living Rhinoceros (Rhinoceros unicornis and Rhinoceros sondaicus), but greater than those of Dicerorhinus sumatrensis. So, the measurements of metacarpus and metatarsus can be considered to provide available evidence in identifying rhino fossils. The assemblage of Perissodactyl remains from Yanliang Cave is most similar to those of Longgupo Cave, Chongqing and Mohui Cave, Guangxi, indicating its age as the early Early Pleistocene (∼2.0 Ma). These Perissodactyl fossils also implied a tropical bushy and forested environment with the humid and warm climate favourable for habitation of high-evolved primates such as Giantopithecus blacki.

Coupled ESR and U-series dating of early Pleistocene Gigantopithecus faunas at Mohui and Sanhe Caves, Guangxi, southern China

Several caves of the Guangxi Zhuang Autonomous Region, southern China, have delivered Gigantopithecus blacki remains, an extinct Pleistocene giant ape, in association with abundant mammalian faunas. To determine their geological ages, fossil teeth from Mohui and Sanhe Caves were dated using the coupled ESR/U-series method. The teeth from Mohui Cave gave age estimates of 1.69 ± 0.22 Ma and 1.29 ± 0.11 Ma. The Sanhe Cave samples had age estimates ranging from 910 ± 200 ka to 600 ± 150 ka with error weighted mean ages of 890 ± 130 ka and 720 ± 90 ka for the layers 5 and 4, respectively. Our results and previous paleomagnestism data place the Gigantopithecus fauna at Mohui Cave between Olduvai and Jaramillo subchrons and suggest that it was coeval with Chuifeng, Longgupo and Liucheng assemblages. The Sanhe fauna is younger, of late early Pleistocene age, and can be dated to the period between Jaramillo subchron and B/M boundary.

Early Pleistocene large-mammal fauna associated with Gigantopithecus at Mohui Cave, Bubing Basin, South China

The Mohui fauna, associated with Gigantopithecus blacki, has been recovered from the Pleistocene karst cave deposit in Bubing Basin, Guangxi, South China. The large-mammalian assemblage derives from 28 species, 15 of which have no historic descendants. Occurrence of some ancient species implies that this fauna is early Early Pleistocene, such as Hystrix magna, Sinomastodon yangziensis, Stegodon huananensis, Ailuropoda microta, Pachycrocuta licenti, Tapirus sanyuanensis, Hespertherium sp., and Dorcabune liuchengense. Comparisons to already-dated early Pleistocene faunas in South China, combined with preliminary paleomagnetic, electron spin resonance (ESR) and U-series analysis of this cave, indicate mammalian fauna age around 1.7 Ma. Comparisons to five faunal assemblages in the same basin show species-level differences in Ailuropoda, Stegodon, Hystrix, Tapirus, and Sus, implying the large-mammal fauna has passed through a slow process of evolution during the Quaternary in East Asia.

New remains of Rhinoceros (Rhinocerotidae, Perissodactyla, Mammalia) associated with Gigantopithecus blacki from the Early Pleistocene Yanliang Cave, Fusui, South China

Abundant dental fossils of Rhinoceros, associated with Gigantopithecus blacki from the early Early Pleistocene Yanliang Cave deposits in Fusui County, Guangxi Zhuang Autonomous Region of southern China, are described as Rhinoceros fusuiensis sp. nov. (Rhinocerotidae, Perissodactyla, Mammalia). The new species is morphologically more similar to the extant species Rhinoceros sondaicus (Javan rhinoceros) than to other species of the genus, but differs from R. sondaicus in bearing a slightly smaller size, a complete protoloph on P2 after heavily worn, a better developed crochet which is close to the protoloph, and a more curved ectoloph. Rhinoceros fusuiensis sp. nov. is considered as the potential ancestor of the living R. sondaicus and the common element of the Early Pleistocene Gigantopithecus-Sinomastodon fauna in southern China. The Rhinoceros remains from other Early Pleistocene sites (e.g., Longgupo Cave and Mohui Cave in southern China and Irrawaddy sediments in Myanmar) are also assigned into the new species. The discovery of R. fusuiensis sp. nov. provides important information on Quaternary biostratigraphy in southern China, as well as implicating southern China as a significant evolutionary and zoogeographic center for Rhinoceros during the Early Pleistocene.

Sequence of mammalian fossils, including hominoid teeth, from the Bubing Basin caves, South China

A Plio-Pleistocene to Holocene faunal sequence has been recovered from four carefully excavated caves in the Bubing Basin, adjacent to the larger Bose Basin of South China. The caves vary in elevation; we suggest that the higher caves were formed and filled with sediments prior to the lower caves. The highest deposits, which are from Mohui Cave, contain hominoid teeth and other fossilized remains of mammalian taxa most similar to late Pliocene and early Pleistocene faunas. Wuyun Cave (∼50 m lower in elevation than Mohui) contains a late middle Pleistocene fauna, which is supported by U-series age constraints from 350 to 200 ka. Lower Pubu Cave (∼23 m below Wuyun) is assigned to the late Pleistocene, while the Cunkong Cave (the lowest, ∼2 m lower elevation than Lower Pubu) preserves a Holocene fauna. The four faunal assemblages indicate species-level changes in Ailuropoda, Stegodon, and Sus, the appearance of Elephas, the local disappearance of Stegodon, and the migration of Equus hemionus to South China. These initial results of our work call into question the continued value of the Stegodon/ Ailuropoda Fauna, a category long used to characterize the Pleistocene faunas of South China. Excavation of karstic caves of varying elevation within the basins of South China holds promise for defining local sequences of mammalian fossils that can be used to investigate faunal variations related to climate change, biogeographic events, and evolutionary change over the past two million years. Stable isotopic analysis of a small sample of mammalian teeth from Bubing Basin caves is consistent with 100% C 3 vegetation in the Bubing/Bose region, with certain δ 13C values consistent with a canopied woodland or forest. A preliminary assessment of the hominoid teeth indicates the presence of diverse molar and premolar morphologies including dental remains of Gigantopithecus blacki and a sample with similarities to the teeth reported from Longgupo.

Early Pleistocene hominid teeth recovered in Mohui cave in Bubing Basin, Guangxi, South China

Two hominid teeth recovered in Mohui cave are morphologically distinguished from Australopithecus in Africa, but close to Homo erectus in China. These teeth are therefore provisionally assigned to Homo erectus. The associated mammalian fauna include Gigantopithecus blacki, Nestotitherium sp., Sus xiaozhu, Sus peii and Ailuropoda microta, which are typical early Pleistocene taxa in South China. The general characteristics of the Mohui faunal assemblage are similar to the Longgupo site, which is dated to 2 Ma, implying a contemporaneity for the two sites. To date, compared with the discoveries in Africa, far fewer early Pleistocene hominid fossils have been recovered in Asia, and there are intensive controversies concerning their stratigraphic provenience and typological and temporal positions. The hominid fossils from Mohui cave, with their reliable biostratigraphic positions and distinct typological features, provide important evidence regarding the issue of early human origins and evolution.

Early Pleistocene hominid teeth recovered in Mohui cave in Bubing Basin, Guangxi, South China

Early Pleistocene hominid teeth recovered in Mohui cave in Bubing Basin, Guangxi, South China