https://en.wikipedia.org/wiki/Gigantopithecus
Gigantopithecus is considered to have been a herbivore. Carbon-13 isotope analysis suggests consumption of C3 plants, such as fruits, leaves, and other forest plants.[21] 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.[2]
The molar-like premolars, large molars, and long rooted cheeked teeth could point to chewing, crushing, and grinding of bulky and fibrous materials.[22][23] Thick enamel would suggest a diet of abrasive items, such as dirt particles on food gathered near or on the ground (like bamboo shoots).[19]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.[24]Gigantopithecus does not appear to have consumed the commonplace savanna grasses (C4 plants).[21] Nonetheless, in 1990, a few opal phytoliths adhering to four teeth from GigantopithecusCave 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.[23]
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.[7][25][26]
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.[27] This hypothesis is no longer considered viable because its dental anatomy is consistent with herbivory.[21] 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.[28] This garnered support from some subsequent researchers, but thicker enamel and hypsodonty in Gigantopithecus could suggest different functionality for these teeth.[19]
It would seem tooth morphology and preferred foods was not consistent across the species as a whole. Based on the fossil record in Asia.