Opal phytoliths found on the teeth of the extinct ape Gigantopithecus blacki: implications for paleodietary studies.

Abstract

Identification of opal phytoliths bonded to the enamel surface of the teeth of Gigantopithecus blacki indicates that this extinct ape had a varied diet of grasses and fruits. By using the scanning electron microscope at magnifications of 2000-6000x specific opal phytoliths were observed and photographed on the fossilized teeth of an extinct species. Since opal phytoliths represent the inorganic remains of once-living plant cells, their documentation on the teeth of Gigantopithecus introduces a promising technique for the determination of diet in extinct mammalian species which should find numerous applications in the field of paleoanthropology as well as vertebrate paleontology.Since the discovery of extinct species, the determination of diet from fossilized teeth has remained a contentious issue. Early paleontologists often drew dietary conclusions from dental cusp patterns, crown height, and overall shape after detailed comparisons with the teeth of living species. Recent studies have focused on more empirical methodologies such as measurement of enamel thickness (1-3), examination of enamel wear striae (4, 5), and the relationship of cusp size, shape, and angulation to biomechanical stresses encountered during mastication (6). All of these techniques share one central theme: the dietary preferences of extinct species are inferred by comparison and analogy with extant species.An alternative technique based on the identification of opal phytoliths found bonded to the enamel surfaces of the teeth of extinct species allows for identification of the actual plant remains eaten by an animal prior to its death. Thus the vegetative dietary preferences of an extinct species no longer have to be inferred but can be demonstrated directly through the identification of phytoliths, the inorganic remains of plant cells, on the teeth of extinct species.Opal phytoliths are created when hydrated silica dissolved in ground water is absorbed through the roots of a plant and carried throughout its vascular system. This silica may be precipitated in the lumina, cell walls, and intercellular spaces of any plant organ, although aerial structures, including leaves, fruits, and inflorescence bracts, tend to accumulate solid silica more frequently than do subterranean organs (7,8). Recent studies have shown that plant families have a strong tendency either to accumulate or not to accumulate silica, and, contrary to traditional expectations, frequency of phytolith production is very high in dicotyledons and Pteridophytes as well as in monocotyledons (7). A marked constancy in both phytolith production and morphology has been demonstrated for many classes of phytoliths, indicating considerable genetic control over these attributes. Furthermore, it has also been shown that numerous woody and herbaceous plant species produce phytoliths identifiable to the familial and generic levels (7-11).Phytoliths have been shown to have numerous applications in archaeology and paleoecology (7,(9)(10)(11)(12). Baker et al. (13) showed in 1959 t...

Dental wash: a problematic method for extracting microfossils from teeth

“…In addition, microfossil studies on lithic instruments (Piperno and Holst, 1998;Piperno et al, 2000;Barton et al, 1998) reported much lower concentrations of starch than we found in the human teeth. Besides that, the number of phytoliths found in both our teeth samples was lower than that observed in samples from individuals of the late Roman period (Fox et al, 1996), in teeth of an extinct ape (Ciochon et al, 1990) and in herbivore teeth (Middleton and Rovner, 1994). The concentrations of phytoliths in our samples were also very small when compared to that of the starch grains of these same teeth.…”

“…A concentration of 3% HCl in Gigantopitecus blacki teeth did not prevent microwear analyses, in the contrary, the acid was used to clean the teeth prior to this kind of analysis (Ciochon et al, 1990). However, a specific study showed that after 30 min exposure of a neolithic human tooth to a solution of 2.5% hydrochloric acid, no alteration was noticed but, after 2 h exposure the enamel was affected and ''almost all the microwear features were removed'' (King et al, 1999).…”

“…This method is based on the pollen wash technique developed for artifacts (Pearsall, 2003a,b), but instead, uses human teeth with faint marks of dental calculus. A similar procedure is used to remove residual material from the surface of teeth before scanning electron microscope analysis (Ciochon et al, 1990). However, in this case, not the residues, but instead, the cleaned tooth is analyzed.…”

Enamel carbon isotope evidence of diet and habitat of Gigantopithecus blacki and associated mammalian megafauna in the Early Pleistocene of South China

“…Identification of opal phytoliths bonded to the enamel surface of G. blacki indicates this giant ape had a varied diet of grasses and fruits [29]. Compared with the dental microwear of living anthropoids, G. blacki was intermediate between folivorous forms and hard-object specialists, and was most similar to the predominantly frugivorous Pan troglodytes species [30].…”

Extinction of Siwalik fossil apes: a review based on a new fossil tooth and on palaeoecological and palaeoclimatological evidence

“…Indopithecus (= Gigantopithecus) is thought to have survived until 7.8 and ~7.3 Ma in Pakistan and India, respectively. Opal phytoliths in molar enamel of Gigantopithecus teeth from China probably indicates a varied diet of grasses (possibly bamboo) and fruits (Ciochon et al, 1990). The new Indopithecus tooth with a large caries indicates that a habitat drier than that preferred by Sivapithecus existed at the Late Miocene in India.…”