Gigantopithecus
Gigantopithecus is an extinct genus of ape from the Early to Middle Pleistocene of southern China, represented by one species, Gigantopithecus blacki. Potential identifications have also been made in Thailand, Vietnam, and Indonesia. The first remains of "Gigantopithecus", two third molar teeth, were identified in a drugstore by anthropologist Ralph von Koenigswald in 1935, who subsequently described the ape. In 1956, the first mandible and more than 1,000 teeth were found in Liucheng, and numerous more remains have since been found in at least 16 sites. Only teeth and four mandibles are known currently, and other skeletal elements were  likely consumed by porcupines before they could fossilise. "Gigantopithecus" was once argued to be a hominin, a member of the human line, but it is now thought to be closely allied with orangutans, classified in the subfamily Ponginae. "Gigantopithecus" has traditionally been restored as a massive, gorilla-like ape, potentially when alive, but the paucity of remains make total size estimates highly speculative. The species may have been sexually dimorphic, with males much bigger than females. The incisors are reduced and the canines appear to have functioned like cheek teeth (premolars and molars). The premolars are high-crowned, and the  fourth premolar is very molar-like. The molars are the largest of any known ape, and have a relatively flat surface. "Gigantopithecus" had the thickest enamel by absolute measure of any ape, up to 6 mm (a quarter of an inch) in some areas, though this is only fairly thick when tooth size is taken into account. "Gigantopithecus" appears to have been a generalist herbivore of C forest plants, with the jaw adapted to grinding, crushing, and cutting through tough, fibrous plants, and the thick enamel functioning to resist foods with abrasive particles such as stems, roots, and tubers with  dirt. Some teeth bear traces of fig family fruits, which may have been important dietary components. It primarily lived in subtropical to tropical forest, and went extinct about 300,000 years ago likely because of the retreat of preferred habitat due to climate change, and potentially archaic human activity. "Gigantopithecus" has become popular in cryptozoology circles as the identity of the Tibetan yeti or the American bigfoot, humanlike creatures in local folklore. Taxonomy. Research history. "Gigantopithecus blacki" was named by anthropologist Ralph von Koenigswald in 1935 based on two third lower molar teeth, which, he noted, were of enormous size (the  first was ""Ein gewaltig grosser (...) Molar"", the second was described as ""der enorme Grösse besitzt""), measuring . The specific name "blacki" is in honour of Canadian palaeoanthropologist Davidson Black, who had studied human evolution in China and had died the previous year. Von Koenigswald, working for the Dutch East Indies Mineralogical Survey on Java, had found the teeth in a drugstore in Hong Kong where they were being sold as "dragon bones" to be used in traditional Chinese medicine. By 1939, after purchasing more teeth, he determined they had originated somewhere in Guangdong or Guangxi. He could not formally describe the  type specimen until 1952 due to his internment by Japanese forces during World War II. The originally discovered teeth are part of the collection of the University of Utrecht. In 1955, a survey team that was led by Chinese palaeontologist Pei Wenzhong was tasked by the Chinese Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) with finding the original "Gigantopithecus" locality. They collected 47 teeth among shipments of "dragon bones" in Guangdong and Guangxi. In 1956, the team discovered the first "in situ" remains, a third molar and premolar, in a cave (subsequently named ""Gigantopithecus" Cave") in Niusui Mountain, Guangxi. Also  in 1956, Liucheng farmer Xiuhuai Qin discovered more teeth and the first mandible on his field. From 1957 to 1963, the IVPP survey team carried out excavations in this area and recovered two more mandibles and more than 1,000 teeth. Confirmed "Gigantopithecus" remains have since been found in 16 different sites across southern China. The northernmost sites are Longgupo and Longgudong, just south of the Yangtze River, and southernmost on Hainan Island in the South China Sea. An isolated canine from Thẩm Khuyên Cave, Vietnam, and a fourth premolar from Pha Bong, Thailand, could possibly be assigned to "Gigantopithecus", though  these could also represent the extinct orangutan "Pongo weidenreichi". Two mandibular fragments each preserving the last two molars from Semono in Central Java, Indonesia, described in 2016 could represent "Gigantopithecus". The oldest remains date to 2 million years ago from Baikong Cave, and the youngest 380,000–310,000 years ago from Hei Cave. In 2014, a fourth confirmed mandible was discovered in Yanliang, Central China. Indicated by extensive rodent gnawing marks, teeth primarily accumulated in caves likely due to porcupine activity. Porcupines gnaw on bones to obtain nutrients necessary for quill growth, and can haul large bones into their underground dens and  consume them entirely, except the hard, enamel-capped crowns of teeth. This may explain why teeth are typically found in great quantity, and why remains other than teeth are so rare. Classification. In 1935, von Koenigswald considered "Gigantopithecus" to be closely allied with the Late Miocene "Sivapithecus" from India. In 1939, South African palaeontologist Robert Broom hypothesised that it was closely allied with "Australopithecus" and the last common ancestor of humans and other apes. In 1946, Jewish German anthropologist Franz Weidenreich described "Gigantopithecus" as a human ancestor as ""Gigantanthropus"", believing that the human lineage went through a gigantic phase. He  stated that the teeth are more similar to those of modern humans and "Homo erectus" (at the time ""Pithecanthropus"" for early Javan specimens), and envisioned a lineage from "Gigantopithecus", to the Javan ape "Meganthropus" (then considered a human ancestor), to ""Pithecanthropus"", to ""Javanthropus"", and finally Aboriginal Australians. This was part of his multiregional hypothesis, that all modern races and ethnicities evolved independently from a local archaic human species, rather than sharing a more recent and fully modern common ancestor. In 1952, von Koenigswald agreed that "Gigantopithecus" was a hominin, but believed it was an offshoot rather than a human ancestor . Much debate followed whether "Gigantopithecus" was a hominin or not for the next three decades until the Out of Africa hypothesis overturned the Out of Asia and multiregional hypotheses, firmly placing humanity's origins in Africa. "Gigantopithecus" is now classified in the subfamily Ponginae, closely allied with "Sivapithecus" and "Indopithecus". This would make its closest living relatives the orangutans. However, there are few similar traits (synapomorphies) linking "Gigantopithecus" and orangutans due to fragmentary remains, with the main morphological argument being its close affinities to "Sivapithecus", which is better established as a pongine based on skull features. In 2017, Chinese palaeoanthropologist  Yingqi Zhang and American anthropologist Terry Harrison suggested that "Gigantopithecus" is most closely allied to the Chinese "Lufengpithecus", which went extinct 4 million years prior to "Gigantopithecus". In 2019, peptide sequencing of dentine and enamel proteins of a "Gigantopithecus" molar from Chuifeng Cave indicates that "Gigantopithecus" was indeed closely allied with orangutans, and, assuming the current mutation rate in orangutans has remained constant, shared a common ancestor about 12–10 million years ago in the Middle to Late Miocene. Their last common ancestor would have been a part of the Miocene radiation of apes. The same study calculated a divergence time  between the Ponginae and African great apes about 26–17.7 million years ago. Cladogram according to Zhang and Harrison, 2017: In 1969, an 8.6 million year old mandible from the Sivalik Hills in northern India was classified as ""G. bilaspurensis"" by palaeontologists Elwyn L. Simons and , who believed it was an the ancestor of "G. blacki". This bore resemblance to a molar discovered in 1915 in the Pakistani Pothohar Plateau then classified as ""Dryopithecus giganteus"". Von Koenigswald reclassified ""D. giganteus"" in 1950 into its own genus, "Indopithecus", but this was changed again in 1979 to ""G. giganteus"" by American anthropologists Frederick  Szalay and Eric Delson until "Indopithecus" was resurrected in 2003 by Australian anthropologist David W. Cameron. ""G. bilaspurensis"" is now considered a synonym of "Indopithecus giganteus", leaving "Gigantopithecus" monotypic (with only one species), "G. blacki". Description. Size. Total size estimates are highly speculative because only tooth and jaw elements are known, and molar size and total body weight do not always correlate, such as in the case of post-canine megadontia hominins with a small-bodied primate exhibiting comparatively massive molars and thick enamel. In 1946, Weidenreich hypothesised that "Gigantopithecus" was twice the size of male gorillas. In 1957, Pei  estimated a total height of about . In 1970, Simons and American palaeontologist Peter Ettel approximated a height of almost and a weight of up to , which is about 42% heavier than the average male gorilla. In 1979, American anthropologist Alfred E. Johnson Jr. used the dimensions of gorillas to estimate a femur length of and humerus length of for "Gigantopithecus", about 20–25% longer than those of gorillas. In 2017, Chinese palaeoanthropologist Yingqi Zhang and American anthropologist Terry Harrison suggested a body mass of , though conceded this was likely an overestimate and it is impossible to obtain a reliable body mass  estimate without more complete remains. The average maximum length of the upper canines for presumed males and females are and , respectively, and Mandible III (presumed male) is 40% larger than Mandible I (presumed female). These imply sexual dimorphism, with males being larger than females. Such a high degree of dimorphism is only surpassed by gorillas among modern apes in canine size, and is surpassed by none for mandibular disparity. Teeth and jaws. "Gigantopithecus" had a dental formula of , with two incisors, one canine, two premolars, and three molars in each half of the jaw for both jaws. The canines, due  to a lack of honing facets (which keep them sharp) and their overall stoutness, have been suggested to have functioned like premolars and molars (cheek teeth). Like other apes with enlarged molars, the incisors of "Gigantopithecus" are reduced. Wearing on the tongue-side of the incisors (the lingual face), which can extend as far down as the tooth root, suggests an underbite. Overall mandibular anatomy and tooth wearing suggests a side-to-side movement of the jaw while chewing (lateral excursion). The incisors and canines have extremely long tooth roots, at least double the length of the tooth crown (the  visible part of the tooth). These teeth were closely packed together. In the upper jaw, the third premolar averages in surface area, the fourth premolar , the first and/or second molars (which are difficult to distinguish) , and the third molar . In the lower jaw, the third premolar averages , the fourth premolar , the first/second molars , and the third molar . The molars are the biggest of any known ape. Teeth appear to have increased in size over time. The premolars are high-crowned, and the lower have two tooth roots, whereas the upper have three. The lower molars are low-crowned, long  and narrow, and waist at the midline—which is more pronounced in the lower molars—with low-lying and bulbous cusps and rounded-off crests. The tooth enamel on the molars is in absolute measure the thickest of any known ape, averaging in three different molars, and over on the tongue-side (lingual) cusps of an upper molar. This has attracted comparisons with the extinct "Paranthropus" hominins, which had extremely large molars and thick enamel for their size. However, in relation to the tooth's size, enamel thickness for "Gigantopithecus" overlaps with that of several other living and extinct apes . Like orangutans and potentially all pongines (though unlike African apes) the "Gigantopithecus" molar had a large and flat (tabular) grinding surface, with an even enamel surface, and short dentine horns (the areas of the dentine layer which project upwards into the top enamel layer). The molars are the most hypsodont (where the enamel extends beyond the gums) of any ape. Palaeobiology. Diet. "Gigantopithecus" is considered to have been a herbivore. Carbon-13 isotope analysis suggests consumption of C plants, such as fruits, leaves, and other forest plants. The robust mandible of "Gigantopithecus" indicates it was capable of resisting high strains while  chewing through tough or hard foods. However, the same mandibular anatomy is typically seen in modern apes which primarily eat soft leaves (folivores) or seeds (granivores). "Gigantopithecus" teeth have a markedly lower rate of pitting (caused by eating small, hard objects) than orangutans, more similar to the rate seen in chimpanzees, which could indicate a similarly generalist diet. The molar-like premolars, large molars, and long rooted cheeked teeth could point to chewing, crushing, and grinding of bulky and fibrous materials. Thick enamel would suggest a diet of abrasive items, such as dirt particles on food gathered near or on  the ground (like bamboo shoots). Similarly, oxygen isotope analysis suggests "Gigantopithecus" consumed more low-lying plants such as stems, roots, and grasses than orangutans. Dental calculus indicates the consumption of tubers. "Gigantopithecus" does not appear to have consumed the commonplace savanna grasses (C4 plants). Nonetheless, in 1990, a few opal phytoliths adhering to four teeth from "Gigantopithecus" Cave were identified to have originated from grasses; though, the majority of phytoliths resemble the hairs of fig family fruits, which include figs, mulberry, breadfruit and banyan. This suggests that fruit was a significant dietary component for at least this population of "Gigantopithecus . The 400–320,000 year old Middle Pleistocene teeth from Hejiang Cave in southeastern China (near the time of extinction) show some differences from Early Pleistocene material from other sites, which could potentially indicate that the Hejiang Gigantopithecus" were a specialised form adapting to a changing environment with different food resources. The Hejiang teeth display a less level (more crenulated) outer enamel surface due to the presence of secondary crests emanating from the paracone and protocone on the side of the molar closer to the midline (medially), as well as sharper major crests. That is, the teeth are not as flat. In  1957, based on hoofed animal remains in a cave located in a seemingly inaccessible mountain, Pei had believed that "Gigantopithecus" was a cave-dwelling predator and carried these animals in. This hypothesis is no longer considered viable because its dental anatomy is consistent with herbivory. In 1975, American palaeoanthropologist Tim D. White drew similarities between the jaws and dentition of "Gigantopithecus" and those of the giant panda, and suggested they both occupied the same niche as bamboo specialists. This garnered support from some subsequent researchers, but thicker enamel and hypsodonty in "Gigantopithecus" could suggest different functionality for these teeth. Growth . A "Gigantopithecus" permanent third molar, based on an approximate 600–800 days required for the enamel on the cusps to form (which is quite long), was estimated to have taken four years to form, which is within the range (albeit, far upper range) of what is exhibited in humans and chimpanzees. Like many other fossil apes, the rate of enamel formation near the enamel-dentine junction (dentine is the nerve-filled layer beneath the enamel) was estimated to begin at about four μm per day; this is seen in only baby teeth for modern apes. Protein sequencing of "Gigantopithecus" enamel identified  alpha-2-HS-glycoprotein (AHSG), which, in modern apes, is important in bone and dentine mineralisation. Because it was found in enamel, and not dentine, AHSG may have been an additional component in "Gigantopithecus" which facilitated biomineralisation of enamel during prolonged amelogenesis (enamel growth). Pathology. "Gigantopithecus" molars have a high cavity rate of 11%, which could mean fruit was commonly included in its diet. The molars from "Gigantopithecus" Cave frequently exhibit pitting enamel hypoplasia, where the enamel improperly forms with pits and grooves. This can be caused by malnutrition during growth years, which could point to periodic food shortages, though it  can also be induced by other factors. Specimen PA1601-1 from Yanliang Cave shows evidence of tooth loss of the right second molar before the eruption of the neighboring third molar (which grew slantedly), which suggests this individual was able to survive for a long time despite impaired chewing abilities. Society. The high levels of sexual dimorphism could indicate relatively intense male–male competition, though considering the upper canines only projected slightly farther than the cheek teeth, canine display was probably not very important in agonistic behaviour, unlike modern non-human apes. Palaeoecology. "Gigantopithecus" remains are generally found in what  were subtropical evergreen broadleaf forest in South China, except in Hainan which featured a tropical rainforest. Carbon and oxygen isotope analysis of Early Pleistocene enamel suggests "Gigantopithecus" inhabited dense, humid, closed-canopy forest. Queque Cave featured a mixed deciduous and evergreen forest dominated by birch, oak, and chinkapin, as well as several low-lying herbs and ferns. The ""Gigantopithecus" fauna", one of the most important mammalian faunal groups of the Early Pleistocene of southern China, includes tropical or subtropical forest species. This group has been subdivided into three stages spanning 2.6–1.8 million years ago, 1.8–1.2 million years ago, and 1.2–0.8  million years ago. The early stage is characterised by more ancient Neogene animals such as the elephant "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 elephant "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". 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 and monsoon strength, and a cooling trend. 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 bigfoot which has persisted into the present day . The only scientist who continued trying to prove such monsters exist was anthropologist Grover Krantz, who continued pushing for a connection between "Gigantopithecus" and bigfoot from 1970 to his death in 2002. Among the binomial names he came up with for bigfoot included "Gigantopithecus canadensis". Krantz did not meet support from either mainstream science or amateurs who said he readily accepted clearly false evidence.