Paleobiological Implications of the Ardipithecus ramidus Dentition

The University Museum, the University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan.
Science (Impact Factor: 33.61). 10/2009; 326(5949):69-99. DOI: 10.1126/science.1175824
Source: PubMed

ABSTRACT

The Middle Awash Ardipithecus ramidus sample comprises over 145 teeth, including associated maxillary and mandibular sets. These help reveal the earliest stages
of human evolution. Ar. ramidus lacks the postcanine megadontia of Australopithecus. Its molars have thinner enamel and are functionally less durable than those of Australopithecus but lack the derived Pan pattern of thin occlusal enamel associated with ripe-fruit frugivory. The Ar. ramidus dental morphology and wear pattern are consistent with a partially terrestrial, omnivorous/frugivorous niche. Analyses show
that the ARA-VP-6/500 skeleton is female and that Ar. ramidus was nearly monomorphic in canine size and shape. The canine/lower third premolar complex indicates a reduction of canine
size and honing capacity early in hominid evolution, possibly driven by selection targeted on the male upper canine.

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    • "Tooth identifications follow the same convention as the text. Measurement protocols followed Suwa et al. (2009, see their SOM). 480 L.J. HLUSKO ET AL. "

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    • "Two possible classes of food sometimes suggested to be central to early hominid diets, as noted, are animal resources and low-fiber underground storage organs (Hatley and Kappelman 1980; Milton 1987; Wrangham et al. 1999; Conklin-Brittain et al. 2002; Laden and Wrangham 2005; Yeakel et al. 2007; Dominy et al. 2008). Arguing by analogy and structural similarity to living species, both can be considered likely foods in Ardipithecus (Suwa et al. 2009) and especially Australopithecus, whose postcanine teeth strongly converge on those of bears and pigs, taxa which consume both of these gross food categories and are wellknown for their exceptionally generalist foraging strategy (Hatley and Kappelman 1980 and see below). The changes that likely occurred in gut morphology/physiology throughout human evolution, from at least as ancient a form as Australopithecus , are also consistent with, although not necessarily indicative of, exploitation of similar resources (Milton 1987; Conklin-Brittain et al. 2002; Mann 2007; Haile-Selassie et al. 2010). "
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