Marshall University Marshall Digital Scholar Biological Sciences Faculty Research Biological Sciences Spring 3-2007 The volutE ion of Zinjanthropus boisei Paul J. Constantino Biological Sciences, [email protected] Bernard A. Wood George Washington University Follow this and additional works at: http://mds.marshall.edu/bio_sciences_faculty Part of the Biological and Physical Anthropology Commons, Biology Commons, Paleobiology Commons, and the Paleontology Commons Recommended Citation Constantino, Paul J. and Wood, Bernard A., "The vE olution of Zinjanthropus boisei" (2007). Biological Sciences Faculty Research. 38. http://mds.marshall.edu/bio_sciences_faculty/38 This Article is brought to you for free and open access by the Biological Sciences at Marshall Digital Scholar. It has been accepted for inclusion in Biological Sciences Faculty Research by an authorized administrator of Marshall Digital Scholar. For more information, please contact [email protected], [email protected]. Evolutionary Anthropology 16:49–62 (2007) ARTICLES The Evolution of Zinjanthropus boisei PAUL CONSTANTINO AND BERNARD WOOD Many people assume that OH 5, the type specimen of Paranthropus boisei, HISTORY OF DISCOVERY collected in 1959, was the first evidence of that taxon to be found, but OH 3, The first evidence of a megadont recovered in 1955, predated the discovery of OH 5 by four years. Thus, Para- hominin (that is, a hominin with very nthropus boisei recently celebrated the equivalent of its fiftieth birthday. This large postcanine tooth crowns relative review marks that milestone by examining the way our understanding of this to its estimated body size) from East taxon has changed during its fifty, or so, year history. Africa was found at Olduvai Gorge in 1955 (Fig. 1).6,7 Labeled OH 3, for Several hominin taxa have been hominin taxon that began life as Zin- ‘‘Olduvai Hominid 3,’’ it was a speci- established longer or have a larger fos- janthropus boisei, is unusual for several men consisting of two teeth, a decidu- sil record, but Paranthropus boisei, the reasons. First, much of its skull mor- ous canine and a large deciduous phology is apparently derived1–3 and molar crown (Fig. 2). The huge size of the teeth made them unique among Paul Constantino is a doctoral candidate highly distinctive (Table 1). Second, in hominid paleobiology at the George most of its hypodigm comes from sites East African hominins known at the Washington University in Washington, with good stratigraphic and chrono- time. The taxonomy of OH 3 therefore DC. His interest in Paranthropus led to remained uncertain until the 1959 re- his dissertation study on how fracture-re- logical control and can be dated with sistant foods influence masticatory mor- relative precision.4,5 Third, the fossil covery of a well-preserved subadult phology and function in primates and record of Paranthropus boisei is cranium with similar teeth (OH 5) bears. In addition to his laboratory- almost exclusively cranial, consisting that was assigned to Zinjanthropus based morphology work, Paul studies 8 the dietary ecology of baboons in south- mostly of jaws and teeth. This means boisei (Fig. 3). ern Africa and giant pandas in central No mandibles to match the OH 5 China. Hominid Paleobiology Doctoral there are reasonably sized, relatively Program, Department of Anthropology, well-dated samples for some morpho- cranium have been found at Olduvai The George Washington University, 2110 logical regions like the mandible and Gorge, but the recovery in 1964 of a G Street NW, Washington, DC 20052. well-preserved, robust-bodied, adult Phone: 202-994-7894, Fax: 202-994- the mandibular dentition. Researchers 6097, E-mail: [email protected] can thus trace the evolution of metri- mandible with megadont postcanine cal and nonmetrical variables across tooth crowns (Peninj 1) from a site on Bernard Wood is University Professor of Human Origins at the George Washing- hundreds of thousands of years. the western shore of Tanzania’s Lake ton University. His main research inter- Finally, all these factors, together with Natron seemed to provide evidence of ests have been the alpha taxonomy and the fifty, or so, years that have elapsed the type of mandible that would be systematics of the hominin fossil record, 9 and he has always had a particular inter- since its discovery, mean that it is pos- compatible with OH 5. Three years est in Paranthropus boisei. His current sible to use Paranthropus boisei as an later, another hominin mandible with preoccupation is how to make detailed postcanine megadontia was recovered data about the hominin fossil record example of how our understanding of more widely available for the purposes a hominin taxon changes over time. from the Omo Shungura Formation 10 of education and research. For example, to what extent has the in southern Ethiopia (Omo 18.18). Center for the Advanced Study of Human Paleobiology, Department of Anthropol- increase in the size of the sample Since 1967, many additional mandi- ogy, The George Washington University, changed our perception of the taxon? bles and isolated teeth similar to these 2110 G Street NW, Washington, DC Have important sample parameters megadont fossils have been collected 20052, USA, and Human Origins Pro- 11–14 gram, National Museum of Natural His- changed significantly as the hypodigm from these same sediments. tory, Smithsonian Institution, Washington, has increased in size? To what extent Beginning in 1968, a series of P. boi- DC 20560, USA. E-mail: bernardawood@ gmail.com can we disentangle the influence of an sei fossils was uncovered near what enlarged fossil record from the bene- was then known as East Rudolf (now fits that have accrued from advances called Koobi Fora) in northern Kenya. Key words: Paranthropus; Australopithecus; Oldu- in analytical methods? Thus, this This series included the recovery in vai Gorge; Koobi Fora; cranial morphology review not only summarizes what we 1969 of a well-preserved but edentu- know of the evolutionary history of lous adult cranium (KNM-ER 406) VC 2007 Wiley-Liss, Inc. Paranthropus boisei, but also traces and the recovery in 1970 of an adult DOI 10.1002/evan.20130 Published online in Wiley InterScience the evolution of our understanding of hemicranium preserving the majority (www.interscience.wiley.com). its evolutionary history. of the vault, the right side of the face, 50 Constantino and Wood ARTICLES Koobi Fora in the late 1960s and early 1970s resulted in the rate of discovery of P. boisei fossils reaching its peak in the second decade (1966–1975) of the taxon’s history (Fig. 6). After that time, cranial remains belonging to P. boisei continued to be recovered from Koobi Fora and began to be found at West Turkana.1,4,16–18 Two notewor- thy P. boisei-like specimens from West Turkana, a mandible (KNM-WT 16005) and a cranium (KNM-WT 17000), were recovered in sediments dating to ca. 2.5 Ma.16,19 Along with Omo 18.18 and others, these speci- mens have been suggested as possible representatives of a second megadont taxon in East Africa, Paranthropus aethiopicus, which was geologically older than P. boisei. They therefore have particular relevance to the debate about the origin and subse- quent evolution of megadont archaic hominins. Additional evidence of P. boisei has come from sites elsewhere in East Africa, most notably in 1993, when a well-preserved skull of P. boi- sei (KGA 10-525) was recovered in Ethiopia at Konso (formerly called Konso Gardula).20 This skull was not only the geologically youngest known specimen of P. boisei, at 1.4 Ma, but also increased the geographical range of the taxon. Moreover, this was the first time that cranial and mandibular evidence from the same individual had been found in proximity, affirm- ing the presumed associations between the ‘‘robust’’ crania and large jaws made by previous researchers. Also, in 1999, a P. boisei-like maxilla was recovered from Malema, Malawi, thus substantially expanding the Figure 1. Map of P. boisei sites in East Africa highlighting the change in its known geo- southern extent of P. boisei’s range by graphic range over the past five decades. The only new site discovered between 1975 more than 1,000 km.21 and 1985 was West Turkana; no new sites were discovered between 1985 and 1995. The last decade has seen a significant increase in the range of P. boisei due mainly to the discovery of Malema in Malawi, but also Konso in Ethiopia. Adapted from Delson and coworkers.99 FOSSIL EVIDENCE Cranial More than 111 craniodental speci- and part of the right side of the cranial mation at Chesowanja, Kenya also mens are now attributed to P. boisei base (KNM-ER 732) (Fig. 4). Several provided evidence of P. boisei, most sensu stricto; an additional 56 are mandibular specimens have also been notably in the form of a cranium assigned to P. aethiopicus. Only the found at Koobi Fora and elsewhere, discovered in 1970 that preserved most complete and well-preserved of so that numerically it is the best- the right side of the face and the ante- these are reviewed here. sampled region of the P. boisei skele- rior part of the cranial base (KNM- Similarities between the type speci- ton (Fig. 5).1 About the same time that CH 1).15 men (OH 5, Fig. 3) and the large, many of the Koobi Fora fossils were The intensive prospecting in the crested cranium from Koobi Fora being discovered, the Chemoigut For- Omo Shungura Formation and at (KNM-ER 406, Fig. 4) were noted at ARTICLES The Evolution of Zinjanthropus boisei 51 TABLE 1. Some Characteristic and Distinctive Features of Paranthropus boisei Most researchers now agree with this sensu stricto assessment, interpreting these crania as smaller-bodied, presumably female Cranium 1,26,27 – Orthognathic facial profile representatives of P.