characterised by more ancient Neogene animals such as the gomphotheriid proboscidean (relative of elephants) Sinomastodon, the chalicothere Hesperotherium, the pig Hippopotamodon, the mouse-deer Dorcabune, and the deer Cervavitus. The middle stage is indicated by the appearance of the panda Ailuropoda wulingshanensis, the dhole Cuon antiquus, and the tapir Tapirus sinensis. The late stage features more typical Middle Pleistocene animals such as the panda Ailuropoda baconi and the stegodontid proboscidean Stegodon. Other classic animals typically include orangutans, macaques, rhinos, the extinct pigs Sus xiaozhu and S. peii, muntjac, Cervus (a deer), gaur (a cow), the goat-antelope Megalovis, and more rarely the large saber-toothed cat Megantereon. In 2009, American palaeoanthropologist Russel Ciochon hypothesised an undescribed, chimp-sized ape he identified from a few teeth coexisted with Gigantopithecus, which in 2019 was identified as the closely related Meganthropus. Longgudong Cave may have represented a transitional zone between the Palaearctic and Oriental realms, featuring, alongside the typical Gigantopithecus fauna, more boreal animals such as hedgehogs, hyenas, horses, the cow Leptobos, and pikas. Gigantopithecus appears to have gone extinct about 300,000 years ago, possibly due to the southward retreat of forest and prime habitat throughout the Middle Pleistocene caused by increasing seasonality, intensifying winter and summer monsoon strength, and regional climatic cooling and/or wettening. Savanna would remain the dominant habitat of Southeast Asia until the Late Pleistocene. It has been speculated that immigrating H. erectus also contributed to its extinction. Human activity in southern China is known as early as 800,000 years ago, but does not become prevalent until after the extinction of Gigantopithecus, so it is unclear if pressures such as competition over resources or overhunting were factors. In 2009, Ciochon suggested Gigantopithecus was the dominant primate inhabiting the tropical forests south of the Qinling Mountains, whereas H. erectus remained in the savannas straddling it. Cryptozoology Gigantopithecus has been used in cryptozoology circles as the identity of the Tibetan yeti or American bigfoot, humanlike monsters in local folklore. This began in 1960 with zoologist Wladimir Tschernezky, briefly describing in the journal Nature a 1951 photograph of alleged yeti tracks taken by Himalayan mountaineers Michael Ward and Eric Shipton. Tschernezky concluded that the yeti walked like a human and was similar to Gigantopithecus. Subsequently, the yeti attracted short-lived scientific attention, with several more authors publishing in Nature and Science, but this also incited a popular monster hunting following for both the yeti and the similar American