Abstract:
Karst caves in Guangxi contain a large number of Quaternary vertebrate fossils; however, research on taxonomy and biostratigraphy remains insufficient. Therefore, more detailed reports on fossil assemblages are essential. Between 2014 and 2016, the excavation of two caves (Cave A and Cave B) in Maoshan, Lipu, northern Guangxi, yielded over 200 vertebrate fossils, of which 151 were identified in taxonomy. These animal fossils originated from two distinct sedimentary formations: calcareous nodules and sandy clay. For the fossils in the calcareous nodules, the uranium-series age of four mammal teeth was determined to be 211 to 158.8 ka BP. For the fossils in the sandy clay, the carbon-14 age of a deer tooth was established as 8590±30 BP, with a calibration of 9563 to 9521 cal BP; the uranium series age of five additional animal teeth was determined to be 7 to 4.7 ka BP. When the sedimental characteristics, as well as the carbon-14 and uranium-series dating results, are taken into the consideration, the Maoshan fossil remains can be classified into two groups: the Middle Pleistocene fauna and the Early Holocene fauna.
Morphological analyses have shown that the Middle Pleistocene fauna of Maoshan includes nine taxa: Hystrix brachyura, Panthera tigris, Ailuropoda melanoleuca baconi, Arctonyx collaris, Rhinocerotidae gen. et sp. indet., Sus scrofa, Muntiacus sp., Cervus nippon, and Rusa unicolor. While there are no significant morphological differences between these fossils and their modern-day counterparts, the sizes of Malayan porcupines (Hystrix brachyura), tigers (Panthera tigris), and greater hog badgers (Arctonyx collaris) are significantly larger than those of their Holocene counterparts. This suggests that the forest habitat at that time was more developed than during the Holocene.
The Maoshan Early Holocene fauna is comprised of 20 species, including Viperidae gen. et sp. indet., Cuora sp., Rhizomys sp., Hystrix brachyura, Macaca sp., Hylobatidae gen. et sp. indet., Panthera tigris, Paguma larvata, Cuon alpinus, Nyctereutes procyonoides, Ailuropoda melanoleuca, Arctonyx collaris, Arctonyx albogularis, Rhinoceros sondaicus, Sus scrofa, Muntiacus reevesi, Muntiacus gigas, Cervus nippon, Rusa unicolor, and Bubalus sp. The fauna is dominated by cerviae, including a large number of primates and small carnivores, as well as a small population of rhinoceroses and buffaloes. This composition reflects an ecological environment dominated by forests and a significant extent of wetlands. Thus we can speculate that the climate at that time was relatively warm and humid.
The Maoshan Early Holocene fauna consists almost entirely of extant species. Several Holocene faunas containing extinct members of the “Ailuropoda-Stegodon fauna” have been reported throughout southern China; however, their taxonomic identification or stratigraphic age remain uncertain. Available evidence suggests that the modern fauna of southern China originated in the Early Holocene and did not include any extinct species from the “Ailuropoda-Stegodon fauna”.
However, the Maoshan Early Holocene fauna contains a significant number of regionally extinct species, including giant pandas (Ailuropoda melanoleuca), greater hog badgers (Arctonyx collaris), Javan rhinos (Rhinoceros sondaicus), giant muntjacs (Muntiacus gigas), and wild buffalo (Bubalus sp.). These species underwent a gradual extinction from Guangxi after the Middle Holocene or were replaced by smaller related species. It reflects the profound ecological transformation caused by human activities, such as agricultural development and population growth.