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HOW GIGANTOPITHECUS WAS DISCOVERED

In 1935, German paleontologist Ralph von Koenigswald came across an unusually large molar while looking through fossil teeth in a Hong Kong pharmacy. He realized that the tooth belonged to a new primate species, which he named Gigantopithecus blacki. Over the next four years, Von Koenigswald searched many more pharmacies, finding just three more Giganto teeth. The pharmacists told him that the teeth had probably come from a region called Guangxi. Based on the dirt clinging to the teeth and the fact that their roots had apparently been gnawed away by porcupines, he inferred that they probably came from cave deposits. Since the Giganto teeth were mixed in with middle-Pleistocene elephant and panda fossils, von Koenigswald estimated their age at 125,000 to 700,000 years.

These days, scientists looking for Giganto dig in the caves and limestone towers of Southeast Asia.

Von Koenigswald's researches were interrupted when he was taken prisoner by the Japanese in World War II. His collection of Giganto teeth (at the time, the only existing evidence of the giant ape) were buried in a milk bottle in a friend's backyard for safekeeping until the war was over.

Chinese apothecaries have been using powdered fossils in medicine for thousands of years. They buy the fossils (which they call dragon bones) from farmers who find them in caves. Many potential fossil sites in China have already been picked clean by peasants looking for dragon bones; this is one of the reasons UI researcher Russ Ciochon chose to look for Giganto remains in nearby Vietnam instead of China.

FOSSIL SITES

THE GIGANTO DIET

Early in his Gigantopithecus investigations, Ciochon noticed similarities between the giant ape and the bamboo-eating giant panda. Both animals have thick mandibles, pitted teeth, and unusually high occurences of tooth decay. Ciochon knew that large herbivores tend to favor one type of plant, so he hypothesized that Giganto fed mainly on the plentiful bamboo of Southeast Asia.

There seemed to be no way to investigate Giganto's diet directly until Anthropology graduate student Robert Thompson mentioned phytoliths to Ciochon. Phytoliths are microscopic bits of silica formed by certain plants between their cells. Different kinds of plants form different phytolith shapes. Thompson knew that scanning electron microscopes had been used to check stone tools for phytoliths, and he suggested applying the technique to fossil Giganto teeth.

	The SEM analysis revealed that some Giganto teeth do have phytoliths embedded in the enamel. Two types of phytoliths- needlelike grass phytoliths and hat-shaped fruit phytoliths- were found in the teeth. Several types of grass (including bamboo) have needlelike phytoliths, so the presence of these phytoliths is consistent with Ciochon's theory
SEM of fruit phytolith

THEORIES ABOUT THE GIANT APE'S EXTINCTION

Gigantopithecus appeared in the fossil record about 6.3 million years ago and thrived in Southeast Asia for five and half million years. Early humans, Homo erectus, spread into Giganto's territory about 800,000 years ago. Within half a million years of the arrival of these early humans, Giganto had gone extinct. Several factors probably contributed to Giganto's extinction:Bamboo forests are subject to mysterious die-offs every twenty to sixty years. Competition with giant pandas and the arrival of humans, who may also have eaten bamboo and used it to make tools, may have made it very difficult for Giganto to survive the die-offs.

CONSTRUCTION OF THE GIGANTO MODEL

The Giganto recreation was designed by University of Iowa paleoanthropologist Russell Ciochon and primate reconstructor Bill Munns. It is based on fossil jawbones and teeth collected from China and Vietnam.

Ciochon and Munns used their knowledge of the skull proportions of great apes to estimate the size and shape of Giganto's head. The body is patterned after two other huge terrestrial primates, the gorilla and the extinct baboon Theropithecus oswaldi. The orangutan was not used because they are arboreal, and Giganto is too large to be arboreal; the other two are ground-dwelling and therefore have an entirely different set of skeletal proportions. The golden fur color is borrowed from Giganto's close Asian relative, the orangutan.

The ten-foot size estimate is based on approximate head-to-skeleton ratios in primates. In humans that ratio is approximately 1:7; in Lucy, an early human, it was 1:8. Ciochon and Munns tried 1:7 and thought the result looked too small. They settled on 1:6.5. Though shocked by resulting huge size, the researchers believe their estimate is conservative.

Relative arm and leg size is based on the ratio of forelimbs to hindlimbs, also known as the intermembral index. In humans the ratio is approximatelty 70%; in orangs 134%. Munns split the difference between the gorilla and Theropithecus, yielding 108%.

More about Giganto on Dr. Ciochon's web site, including a 1991 article from Natural History magazine.

http://www.uiowa.edu/~bioanth/giganto.html