AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 63:405-435 (1984)

Additional Fossil From Hopefield, : A Comparison With Other African Sites and a Reevaluation of its Taxonomic Status

PAUL C. DECHOW AND RONALD SINGER Department ofAnatomy and Cell Biology, The University of Michigan, Ann Arbor, Michigan 48109 (I? C.D.) and Department of Anatomy, University of Chicago, Illinois 60637 fR.S.1

KEY WORDS Fossil Theropithecus; Taxonomy; Hopefield, South Africa; Cranial and dental variation ABSTRACT Additional fossil Theropithecus remains, recovered from mid to late Pleistocene deposits near Hopefield, South Africa, include portions of the jaws of at least five individuals. Extensive comparisons with fossil Thero- pithecus from other African sites, including Makapan, Swartkrans, Kanjera, Olorgesailie, and Olduvai, reveal few morphological differences, especially when variation in modern baboons (Theropithecus gelada) and savan- nah baboons (Papio) is considered. The most pronounced differences between fossil forms are overall size and relative P3 length. However, these traits do not separate the fossil forms either chronologically or geographically. Other traits, such as depth of the fossa of the mandibular corpus, slope of the upper symphyseal shelf, and variation in the depth of the mandibular corpus, do not distinguish alleged primitive forms (Makapan and lower beds at Olduvai) from remains found at Hopefield, Swartkrans, Kanjera, Olorgesailie, Olduvai Bed IV,or the lower Ndutu Beds. Other traits, such as canine crown height and incisor size, are poorly documented for fossil Theropithecus. Thus, the available evidence suggests that Theropithecus darti and its successional species, I: oswaldi, can best be considered as a single fossil species, I: oswaldi, of which the remains from Hopefield are a late representative. Furthermore, lack of morphological differences dictates that Hopefield Theropithecus not be consid- ered a distinct subspecies. Variation within the Hopefield sample shows that only one taxa is found at this site. Hypothesized physical and climatic condi- tions at Hopefield during the Pleistocene suggest that I: oswaldi lived near vleis or fresh water lagoons. Comparisons with modern I: gelada suggest a graminivorous diet for the fossil form.

Fossil remains of Theropithecus have been ‘The term “fossa of the mandibular corpus” denotes a fossa located on cercopithecoid mandibles on the superficial aspect of found at a variety of Pleistocene sites the corpus inferior to P3 and Pq.This structure is usually re- throughout northern, eastern, and southern ferred to as the mandibular fossa (see Freedman, 1957 for ex- Africa (Freedman, 1957; Jolly, 1972; Szalay ample). However, the fossa mandibularis is defined in the Nomina Anatomica as an entity of the pars squamosa of the 0s and Delson, 1979), and several taxonomic temporale, indicating the articular surface for the condyle of the schemes have been proposed to account for mandible in the temporomandibular joint. In cercopithecoid monkeys, the structure of the bony parts of the temporomandi- their morphological diversity. The most gen- bular joint differs from that in humans. The mandibular fossa is eral scheme suggests the evolution of several not deeply excavated with only a thin wall of bone separating it from the middle cranial fossa. Rather, the mandibular fossa is cranial features throughout the Pleistocene, more of a platform that cannot be easily distinguished from including 1)reduction of the size of the fossa what would be the articular eminence in humans. The portion of the temporal bone supporting the fossa is thick. In any case, of the mandibular corpus’; 2) reduction of for consistency and correctness in the anatomical literature, it male P3 length and canine height; 3) flatten- is suggested that the structure in cercopithecoid that is referred to by Freedman (1957) and others as the mandibular fossa should hereafter be referred to as the fossa of the mandi- bular corpus, and mandibular fossa be reserved to denote the Received November 1, 1982; revised December 7, 1983; ac- recessed portion of the temporal articular surface of the jaw cepted December 22, 1983. joint.

(i:1984 ALAN R. LISS, INC 406 P.C. DECHOW AND R. SINGER ing of the upper symphyseal shelf; 4) devel- 1, 21, an incomplete left mandibular corpus opment of equal depth of the posterior and (16649) (Fig. 31, a right P3 (16650C), and a anterior mandibular corpus contrasting with series of gnathic fragments probably derived the proposed primitive condition where the from a single individual, which include a left mandibular corpus deepens anteriorly, 5) I2 (166801, a portion of a left mandibular cor- greater specialization of cheek teeth; and 6) pus (16680A) (Fig. 3), a right M3 with a piece reduction of incisor size (Jolly, 1972; Szalay of mandible attached (16680B)(Fig. 3), a right and Delson, 1979). M2 (16680C), a right P4 (16680D), and a can- Fossil Theropithecus from the Middle to ine root fragment (possibly upper left) Upper Pleistocene site ‘Elandsfontein” near (16680F). These fossils are currently in the Hopefield, South Africa, has been thought to laboratory of one of us (R.S.) in the Depart- represent an advanced form (Freedman, ment of Anatomy at the University of Chi- 1957; Jolly, 1972; Szalay and Delson, 1979). cago, but will soon be returned to the South Additional undescribed remains aid in reas- African Museum, Cape Town, where the col- sessing Hopefield Theropithecus in particu- lection is permanently housed. lar and, in general, the morphology and One specimen (16650C) was recovered by J. evolution of fossil members of the genus as a and H.J. Deacon on January 21, 1964 on the whole. The goals of this paper are: 1) to de- surface near a trench excavation in a ferru- scribe additional fossil Theropithecus from ginous plain about 730 m north of the site of Hopefield, South Africa; 2) to make compari- recovery of the specimens described by Singer sons with described fossil Theropithecus; 3) (1962). Six other fragments (16650A,B, to compare modern baboons to assess varia- D,E,F,G) found there are now considered not bility in the fossils; 4) to reevaluate the tax- to represent Theropithecus. The other speci- onomic position of Hopefield Theropithecus; mens described here were recovered on the and 5) to speculate on its natural history. surface in January, 1964 by one of us (RS) The extensive fossiliferous site on the farm and some students at two separate areas, “Elandsfontein” near Hopefield in the south- about 275 m apart and about 1.8 km north of western part of the Cape Provence has Main Site (see Fig. 1 in Singer, 1962). The yielded, mainly by surface collecting, several fossil horizons are discussed by Singer and thousand fossils of approximately fifty spe- Wymer (1968)and comments on the dispersal cies of including Homo (see Dren- of the fossils are given by Singer and Heltne nan, 1954; Drennan and Singer, 1955; Ewer (1966) and Inskeep and Hendey (1966). and Singer, 1956; Hendey, 1974; Hooijer and Cranial features were measured on skulls Singer, 1960, 1961; Keen and Singer, 1956; (n = 696) of extant wild baboons (genera Singer, 1954, 1957; Singer and Bone, 1960; Mandrillus, Papio, and Theropithecus, to es- Singer annd Inskeep, 1961; Singer and Keen, timate variability. These features and their 1955). Preliminary archeological data have significance are described at appropriate lo- been recorded (Singer and Crawford, 1957; cations throughout this paper. The baboon Singer and Wymer, 1968) but an extensive crania are located in museums throughout monograph detailing the description of the North America and Europe. (For a more com- site, its stratigraphy, the various archeologi- plete description of specimens and measure- cal excavations, and an analysis of the fauna ment techniques, see Dechow, 1980.) Sta- is in preparation. The fossil baboon remains tistics on modern baboon measurements are are of particular interest as they represent not described fully in this paper if data for the southernmost extent of the range of this one or two modern groups is suMicient for genus. analyzing variation. MATERIALS AND METHODS DESCRIPTION Singer’s (1962) descriptions of Hopefield Measurements similar to those discussed Theropithecus include a partially recon- by Freedman (1957) were taken on all speci- structed calvaria and other possibly associ- mens wherever possible (see Table 1for man- ated skull fragments, an incomplete right dibular dental measurements and subse- mandibular corpus, several isolated teeth, quent text for other measurements). and a proximal radius. Additional remains Specimen 1667 (Fig. 11, a fragmentary ju- discussed in the present study are two frag- venile mandible, is reconstructed from two mentary mandibles (16647 and 16648) (Figs. hemimandibles (16647A and 16647B) broken Fig. 1. Views of female mandible, 16647, showing oc- (lower left) and right mandibular corpus, 16647B (lower clusal surface (upper left), inferior surface (upper right), right). and buccal aspects of left mandibular corpus, 16647A P 0 00

Fig. 2. Views of male mandible, 16648, showing occlu- buccal aspects of left mandibular corpus, 16648A (lower sal surface (upper left), inferior surface (upper right), and left) and right mandibular corpus, 16648B (lower right). HOPEFIELD FOSSIL THEROPITHECUS 409 at the symphysis. The P3 root and root socket morphology indicate that this specimen is from a male. The eroded and broken external symphysis reveals the roots of the canines. A small piece of the alveolus that surrounded the incisor roots remains with the tip of the right I1 root lodged therein. The internal symphysis is complete superior to the mandibular torus. Inferior to the torus, the bone is eroded obli- terating much of the area of the suprahyoid muscle attachment and the canal for the in- ferior lingual artery. The superior symphy- seal shelf extends distally to the level of the mesial roots oi P4 while the inferior symphy- seal shelf extends distally to the mesial roots of MI. The superior shelf is poorly developed as expected in a young specimen. Three mental foramena are found inferior to the premolars bilaterally, while the left hemimandible (16647A) has a portion (see Fig. 1) of ascending ramus present. The sur- face cortical bone is eroded away from much of the buccal surface but is intact on the lingual surface. The fossa of the mandibular corpus has only minimal development. Due to the erosion of cortical bone, width and height measurements can only be approxi- mated as follows: maximum width at the level of the mesial margin of M3 (right)-21.4 Fig. 3. Occlusal views of right M3, 16680B (left), and mm, (left)-21.7 mm; height at the level of left hemimandibles, 16649 and 16680A (center and right). the mesial margin of M3 (right)-32.0 mm, (left)-31.4 mm; maximum width at the level of the mesial margin of M1 (right)--17.3 mm, (sidetl6.4 mm; maximum height at the level of the mesial margin of M1 (right)-37.6 mm, (left)-38.4 mm. The external symphysis is intact anteriorly The dentition is fragmentary. The only but is broken away inferior to the proximal complete teeth are the left and right M~s, inferior symphyseal shelf. The right canine which are not fully erupted and exhibit wear and the cortical bone anterolateral to its root only on their mesial cusps. Their morphology are missing. The incisors are absent al- is similar to that described by Freedman though the roots remain. The alveolus that (1957, p. 210) for lower molars from Swart- bordered the medial face of the right 12 is krans. The right M2 has present the buccal discernable in the empty root socket of the wall of the crown and roots. Portions of the right canine; the alveolus that bordered the roots and the distal part of the mesial wall lateral root face is missing. An estimate of are also present for the left M2, MI, Pq, Ps, the incisor root width at the alveolar junction and canine and the right MI, P4, Ps, and is 18 mm. The superior symphyseal shelf is canine. The length of the cheek tooth row long, with a gradual slope extending posteri- from the distal margin of M3 to the mesial orly to the distal cusps of Pq. The inferior margin of P4 are 67 mm (right side) and 69 symphyseal shelf extends to the distal cusps mm (left side). of M1. The pit between the inferior and su- Specimen 16648 (Fig. 2) is fragmentary perior symphyseal shelves contains three for- adult mandible found in two parts (A,B) and amina; two are probably secondarily enlarged rejoined at the fracture line through the right due to postmortem deterioration. canine socket. The specimen is male as is The cortical bone is largely complete on the evident from P3 and canine morphology. buccal and lingual surfaces of the mandibu- 410 P.C. DECHOW AND R. SINGER lar corpora. On the left side, the cortical bone is deteriorated over the roots of the canine and P3. The remaining bone is cracked and pitted. On the right side, the bone overlying the root sockets of the canine and P3 is miss- ing. Multiple mental foramina (2-left; 3- right) are present. A large pit, which is prob- ably the result of postmortem deterioration rather than chronic abscess formation, lies near the mesial root tip of the left P3. Little development of the fossa of the mandibular corpus is apparent. Both hemimandibles are broken posterior to M3 although small por- tions of the ascending rami are present on both sides. A groove passes obliquely from within outward, forward, and downward from the buccal alveolar margin behind M3 to near the mesial cusp of M3. Singer (1962, p. 49) concludes from studies of modern savannah baboon anatomy that this "groove was prob- ably occupied partly by a thickened buccina- tor muscle but mainly by a pad of fat acting as a bursa between temporalis and buccina- tor." On the left side, the buccal wall of bone is broken away posteriorly revealing a man- dibular canal sweeping downward into the corpus. Height and width measurements of the mandible are as follows: maximum width at the level of the mesial margin of M3 (right)-22.0 mm, (left)-21.8 mm; maximum width at the level of the mesial margin of MI (right)-20.3 mm, (left)--19.3 mm; height at the level of the mesial margin of M3 (right)-- 44.3 mm, (left)-43.5 mm; height at the level of the mesial margin of MI (right)-43.1 mm, (left)-43.3 mm. Most of the dentition are damaged and some teeth are missing. The left corpus has the canine through M3 present. On M3, the enamel is missing distally and the tooth is broken on the buccal aspect of the protoconid and the mesial aspect of the metaconid. On M2, the enamel is missing lingually while on MI, it is missing mesially. P4 has some breakage on its lingual aspect. P3 is exten- sively damaged with only the distal cusp in- tact; the honing surface is broken away. The canine is in good condition although enamel is missing from most of its surface. The right corpus has P3 through M3 present. M3 has some breakage on the protoconid and meta- conid. On Mz, enamel is missing on the buc- cal face of the hypoconid while on MI, the lingual face of the metaconid is broken. P4 is damaged on its lingual surface. P3 has only its distal root present. The root sockets of the right mesial root of P3 and the right canine HOPEFIELD FOSSIL THEROPITHECUS 411 are exposed buccally. The incisors are miss- Specimens 16680, 16680A (Fig. 3), 16680B ing except for remnants of the roots of the (Fig. 31, 16680C, 166800, and 16680F are 11s. The wear on the cheek teeth reveals den- probably from a single individual as is indi- tine connecting all cusps on each tooth. cated by the similar size and analogous The morphology of the dentition is similar amounts of wear of contralateral cheek teeth. to that described by Freedman (1957) for Mandibular bone in these specimens is not Theropithecus from Swartkrans and Maka- extensive. The long sloping sectorial cusp on pan. The length of the cheek tooth row from P3 of 16680A indicates a male individual. the distal margin of M3 to the mesial margin Specimen 16680 is a left 12. The root is of P4 is 68.4 mm (right) and 66.2 mm (left). embedded in a piece of alveolar bone and, Specimen 16649 (Fig. 3) is an adult left except for a small portion on the lateral as- hemimandible reconstructed from seven pect of the root, cannot be seen. The tooth is fragments. P3 morphology indicates this considerably worn and its long axis leans specimen is female. mesially relative to the occlusal surface of Anteriorly, the corpus is irregularly frac- the crown. The wear is reminiscent of older tured at the symphysis. However, the man- specimens of Papio or Mandrillus. Freedman dibular torus and the genial region can be (1957, p. 208) reports 12son a female cranium partially discerned in cross-section. The sym- from Swartkrans that, like the Hopefield physis opens into the root chamber of the specimens, are small and lean “mesially as canine as much of its internal structure is in Papio ursinus.” By contrast, modern Ther- not present. The incisors and the incisal al- opithecus has small closely packed incisors veolus are broken away. The superior sym- that do not wear to this extent and in which, physeal shelf extends distally to the distal the 12sdo not lean mesially (Dechow, unpub- border of P4 and slopes downward at a steeper lished data). angle relative to the occlusal plane than in Specimen 16680A consists of the alveolar specimen 16648. region of a left corpus with the left M3 Posteriorly, the mandibular corpus is trun- through P4 intact. The corpus is fractured cated posterior to M3 although some ascend- directly posterior to M3. Anteriorly, a space ing ramus is present. Two mental foramina for the distal root of P3 is evident. The left P3 are present on the buccal surface of the cor- (also labeled 16680A) is detached from the pus inferior to the P4 roots. The cortical bone mandible. On the right side, the alveolar surface is intact over most of the surface of bone is present only on the lingual aspect of the specimen. The alveolar bone that covers M3 (16680B). the buccal roots of P3 through M2 is missing. The dentition is well-preserved, especially The damage is much less lingually. Height on the left side, but is considerably worn with and width measurements of the mandible wide dentine exposure on the occlusal sur- are as follows: maximum width at the level faces. The sectorial surface of the left P3 is of the mesial margin of M3-22.4 mm; height destroyed mesially. The right M2 (16680C) at the level of the mesial margin of M3-35.0 has most of its lingual aspect missing. The mm; heizht at the level of the mesial margin anterior or posterior breadth of this tooth of M1-35.3 mm. The breadth measurement could not be measured. The right P4 is suffi- at the mesial margin of P4 was estimated at ciently damaged that neither length nor 18 mm. breadth could be measured. Specimen 16680F The dentition consists of M3 through the is the root of a male baboon canine, possibly canine. M3 has enamel broken away on all a left upper canine, that is probably part of aspects but is most damaged lingually. M2 the same individual as the other fragments also evinces some damage lingually. M1 has because of its superficial resemblance, sex, extensive lingual damage; the metaconid and and proximity to the other specimens at the the entoconid are not present. P4 and the time of discovery. honing blade of P3 are missing enamel me- siolingually. The canine is fractured below RESULTS AND DISCUSSION the level of the crown. The teeth are more Morphological Comparisons with Remains worn than in specimen 16648 so that the fiom other Sites occlusal surfaces form a dentine pool sur- Fossil Theropithecus has been found rounded by a ridge of enamel. throughout Africa (Fig. 4) at Makapan Specimen 16650C is the crown of a right (Freedman, 1957, 1960, 1976; Maier, 1970, P3. The sex is female. 1972), Swartkrans (Freedman, 1957; Freed- 412 P.C. DECHOW AND R. SINGER

Ternifine

i-,Hadar - Orno East Turkana Lothagam njera

7Swartkrans Hopefield

Fig. 4. Distribution of African Plio-Pleistocene sites where fossil Theropithecus have been found. Hopefield represents the southernmost extent of the range. man and Brain, 19771, and Hopefield (Singer, specimens have been recovered from the 1962) in southern Africa; Kanjera (Andrews, Usno and Shungura Formations in the Omo 1916; Hopwood, 1936; Jolly, 1972; Leakey, Valley of which two dozen are relatively com- 19431, Omo Valley (Arambourg, 1947; Butzer, plete crania and mandibles (Eck, 1977). Sev- 1971; Eck, 1976, 1977), Lake Turkana eral photographs and a brief description show (Leakey, 1970, 19761, Lothagam Hill (Patter- that several of these specimens differ from son et al., 19701, Olorgesailie (Jolly, 1972; other Theropithecus in having “larger, flar- Leakey and Leakey, 1973); Olduvai (Hop- ing zygomtic bones” and “sharp well defined wood, 1934; Jolly, 1972; Leakey, 1965; Leakey maxillary ridges and deep maxillary fossae.” and Leakey, 1973; Leakey and Whitworth, Eck assigns the name Theropithecus brumpti 1958), Kaiso (Hopwood, 1939), Hadar (Szalay to these specimens after the specific name and Delson, 1979; Taieb et al., 19761, Melka given to some dental fragments from the Omo Kunture (Geraads, 1979), Chesowanja (Car- by Arambourg (1947). As comparable zygo- ney et al., 19711, and Bod0 D’ar (Kalb et al., matic or maxillary fragments have not been 1980, and other Awash Valley localities (Kalb found at Hopefield, it is not possible to com- et al., 1982a,b) in eastern Africa; and Terni- pare the features of T brumpti with the fine, (Arambourg, 1962; Delson, 1974; Hopefield specimens. Eck states that “the Szalay and Delson, 1979), Ain Jourdel, Al- mandibles . . . are not as distinct.” However, geria (Delson, 1975; Simons and Delson, 1978; I: brumpti usually have well defined fossae Szalay and Delson, 1979) and Thomas of the mandibular corpora while the Hope- Quarry, (Geraads, 1980) in northern field specimens have only minimally devel- Africa. The dating of the material from these oped fossae. The several jaw and dental localities ranges throughout the Plio-Pleisto- fragments that are described from the Omo cene and is reviewed by Jolly (19721, Maier by Arambroug (1947) are not distinguishable (1972), and Szalay and Delson (1979). from the type Theropithecus oswaldi frag- Morphological and/or metrical descriptions ments found at Kanjera (Jolly, 1972). Eck of the fossils are available from many of the and Howell (1982) show that one of Aram- sites listed above. Eck (1976) states that 1343 bourg’s specimens differs from the others and HOPEFIELD FOSSIL THEROPZTHECUS 413 thus is designated as the lectotype of T from the remaining sites in South and East brumpti. The length and width of the molar Africa. Table 2 presents statistics for the teeth from the Omo (Arambourg, 1947) fall mandibular dental measurements. Data are toward the lower end of the range of similar derived from multiple sources, as follows: measurements of the Hopefield dentition. Hopefield-Singer (1962 and this study); Mak- Leakey (1976) reports that more than 300 apan-Freedman (1957, 1960); Maier (1970, cranial and postcranial fragments of There 1972); Swartkrans-Freedman (1957); Kan- pithecus were found in the Koobi Fora and jera-Jolly (1972); Olorgesailie and Olduvai- Kubi Algi Formations at East Turkana. Fos- Jolly (1972); Leakey and Leakey, (1973). Fig- sil Theropithecus sp. from Hadar are men- ure 5 plots ranges of combined male and fe- tioned in faunal lists by Taieb et al. (19761, male tooth length and mesial breadth. Figure and more extensive descriptions are in prep- 6 plots tooth length means for each sex. The aration (Delson, personal communication). A sexing of the fossils was based on differences variety of Theropithecus has been recovered in the upper canines and P3s wherever pos- from localities in the Middle Awash, Afar, sible. However, some sexing of Makapan and (Kalb et al., 1980, 1982a,b). Speci- Swartkrans remains by Freedman (1957, mens are a variety of cranial and postcranial 1960) is based on size alone. material and include several well preserved Makapan: The 27 Theropithecus fossils from crania. Makapan consist predominantly of mandi- Several sites from East and North Africa bular fragments (Freedman, 1976) but also reveal minimal Theropithecus material. In include one nearly complete female skull East Africa, a single lower molar from Loth- (Maier, 1970, 1972). agam Hill (Lothagam 3) (Patterson et al., Freedman (1957, 1960), Jolly (1972), Maier 1970) is described by Simons and Delson (1970), Simons and Delson (1978), and Szalay (1978, p. 106) as having “a morphology rather and Delson (1979) propose primitive morpho- typical of early Theropithecus.” From Kaiso, logical features that distinguish Makapan a maxillary fragment with well worn Mzs Theropithecus from fossils found at other lo- and M3s is known (Hopwood, 1939). A small calities, particularly those from East Africa. number of gnathic fragments from Laetolil Those features that are relevant to the mor- are attributed to Theropithecus by Dietrich phology of the Hopefield specimens include (1942) and Leakey and Whitworth (1958) al- 1) the presence of fossae of the mandibular though Freedman (1957, 1960) and Jolly corpora; 2) molar structure that is closer to (1972) suggest that they are probably Papio the typical cercopithecine pattern than that or Parapapio since the ranges of tooth mea- found on fossils from Kanjera, 3) relatively surements are less than any known fossil long P3s; 4) high-crowned male upper can- Theropithecus. More recently, Leakey et al. ines; 5) a more abruptly downward-sloping (1976) mention that fossil Theropithecus, superior symphyseal shelf; 6) greater mandi- which are found in deposits in the southern bular corpus depth relative to length; 7) man- Serengeti Plains, are not from the Laetolil dibular corpora that deepen in their vertical Beds (Szalay and Delson, 1979, pp. 346-7). dimensons mesially; and 8) relatively broad Two sites in Algeria with scanty fossil incisors (Dechow, 1981). Each of these fea- Theropithecus are Ain Jourdel and Ternifine. tures is discussed here in turn. A lower molar from Ain Jourdel, described Well-developed fossae of the mandibular as Cynocephalus atlanticus by Thomas (1884) corpora are not present on any specimen from is assigned to Theropithecus by Delson (19751, Hopefield. Conversely, one adult male speci- Simons and Delson (1978), and Szalay and men (M.626) from Makapan has “very large Delson (1979). Remains from Ternifine have and deep” fossae while those of another adult been mentioned (Arambourg, 1962; Delson, male (M.201) are “almost totally absent” 1974; Szalay and Delson, 1979) but not (Freedman, 1957, p. 204). Freedman (1960, p. described. 43) refers to a specimen (M.621) as having An incomplete mandible, and several iso- “very deep” fossae. This specimen is proba- lated teeth of Theropithecus have been re- bly the same as that discussed in his 1957 covered from Thomas quarries near study as M.626, as nowhere in his descrip- Casablanca, Morocco (Geraads, 1980). Mea- tions of the Makapan fossils (Freedman, 1957, surements (Table 2) and brief descriptions of 1960) is a specimen described under the cat- these remains suggest similarity in size and alog number M.621. Maier (1970) notes that morphology with the Hopefield fossils. several Makapan adult specimens, including More extensive descriptions and measure- M.201, M.621 (M.626?), and M.3074, have “a ments are available for fossil Theropithecus kind of” fossa of the mandibular corpus but TABLE 2. Mandibular dental dimensions of fossil Theropithecus (in mmi Sex Males Females indeterminate

N Mean S Range N Mean S Range N Range P3 breadth Hopefield 1 7.5 1 8.0 Makapan 4 7.1 .15 7.0- 7.3 Swartkrans 2 7.2 6.6- 7.8 2 5.8 5.6- 6.0 Olduvai I 1 5.8 Olduvai I1 1 7.1 Olduvai IV 1 9.4 la Ndutu Beds 1 8.5 a Kanjera 2 7.1 6.8- 7.3 4 6.4 .32 5.9- 6.8 Olorgesailie 5 8.1 .50 7.5- 8.6 6 6.7 .41 6.2- 7.4 P3 length Hopefield 1 19.9 1 12.9 Makapan 4 22.5 3.38 17.5-25.0 1 10.0 Swartkrans 1 25.1 2 11.0 10.8-11.3 Olduvai I 1 22.0 1 13.0 Olduvai I1 2 19.0 18.0-20.0 2 13.0 12.5-13.4 Olduvai N 1 17.7 Ndutu Beds 1 12.0 Kanjera 1 20.3 4 12.4 1.44 11.4-13.8 Olorgesailie 14 17.9 1.6 16.0-21.0 16 12.2 1.00 10.0-13.5 Thomas Quarry 1 14 + P4 breadth Hopefield 2 9.0 8.9- 9.0 2 10.0 9.9-10.0 Makapan 7 8.3 .43 7.7- 9.0 1 7.1 Swartkrans 3 9.0 .78 8.5-10.0 2 8.1 7.8- 8.4 Olduvai I 1 7.4 Olduvai I1 1 8.5 Olduvai IV 1 11.2 Ndutu Beds 1 10.5 Kanjera 2 7.9 7.8- 8.0 Olorgesailie 2 9.5 8.8-10.2 1 9.6 10 8.6- 9.7 Thomas Quarry 1 9.0 P, length Hopefield 3 10.8 .26 10.6-11.1 10.7 10.2-11.1 Makapan 7 9.5 .65 8.4- 1.40 8.2 8.2- 8.2 Swartkrans 3 11.1 .76 10.6-12.0 9.5 9.4- 9.5 Olduvai I 9.5 10.6 Olduvai I1 11.3 11.0-11.5 10.3 10.0-10.5 Olduvai IV 12.8 Ndutu Beds 11.5 Kanjera 2 9.0 8.7- 9.2 3 8.7- 9.4 Olorgesailie 2 11.0 10.0-12.0 1 10.0 44 10.0-13.4 Thomas Quarry 1 11.0 MI mesial breadth Hopefield 2 10.3 9.9-10.6 9.7 Makapan 3 10.0 50 9.5-10.5 Swartkrans 2 10.7 9.6- 11.8 10.1 .35 9.8-10.5 x Olduvai I 1 9.0 8n Olduvai I1 11.4 11.0-11.8 1 12.0 Olduvai IV r8 Ndutu Beds 1 11.3 U Kanjera 3 9.2 34 8.8- 9.9 5 8.8- 9.9 1 11.5 12 10.5-12.6 2 Olorgesailie rJl MI distal breadth 3r Hopefield 3 11.0 .32 10.8-11.4 1 9.9 Makapan 4 9.7 .58 9.0-10.4 1 9.0 h2 10.0-11.4 a Swartkrans 2 11.4 10.4-12.3 3 10.5 .76 0 Olduvai I 1 9.8 Olduvai I1 2 11.1 10.7-11.4 2 Olduvai IV 1 12.0 l3 1 11.1 Ndutu Beds c,c: Kanjera 3 9.3 .45 9.0- 9.9 5 8.6- 9.9 0, Olorgesailie 1 10.5 MI length Hopefield 3 12.9 .46 12.4-13.3 2 13.5 .49 13.1-13.8 Makapan 5 11.7 59 11.0-12.6 2 11.0 9.6-12.4 Swartkrans 3 14.0 1.53 13.1-15.8 3 12.0 .62 11.3-12.5 Olduvai I 1 13.0 2 10.3-13.0 Olduvai I1 2 13.8 13.5-14.0 4 13.0 1.58 11.0-14.5 Olduvai IV 1 16.4 Ndutu Beds 1 13.6 Kanjera 3 11.2 1.24 10.1-12.9 Olorgesailie 1 14.4 37 13.9-17.8 (Table 2 continued on next page) rp CL UI TABLE 2. Mandibular dental dimensions of fossil Theropithecus (in mm) (continued) Sex Males Females indeterminate N Mean S Range N Mean S Range N Range M2mesial breadth Hopefield 3 14.1 1.00 13.1-15.1 Makapan 4 12.3 .24 12.0-12.5 6 11.2-12.5 Swartkrans 3 12.9 1.07 12.2-14.1 6 12.2-14.1 Olduvai I 1 11.8 Olduvai I1 4 12.6-13.7 Olduvai IV 1 16.2 2 15.7-16.2 Kanjera 5 11.5-12.5 Olorgesailie 1 16.0 8 12.8-16.0 Thomas Quarry 1 14.0 Mz distal breadth Hopefield 2 15.2 15.0-15.3 Makapan 4 11.8 54 11.1-12.3 6 11.0-12.3 Swartkrans 3 12.6 1.03 12.0-13.8 6 11.7-13.8 Olduvai I 1 11.3 Olduvai I1 4 12.4-13.1 Olduvai IV 1 15.1 2 13.6-15.1 Kanjera 5 11.1-11.5 Olorgesailie 1 15.0 8 12.4-15.0 Mz length Hopefield 5 18.0 1.06 16.5-19.0 1 17.6 Makapan 6 15.8 1.41 13.9-18.2 3 14.0 1.86 12.7-16.1 Swartkrans 3 18.2 1.79 17.1-20.3 3 15.3 .42 14.8-15.6 Olduvai I 1 17.0 2 17.0-21.1 Olduvai I1 2 19.0 19.0-19.0 4 17.5 .87 16.5-18.5 8 16.5-19.1 Olduvai IV 1 21.1 Ndutu Beds 1 17.0 Kanjera 3 14.9 .77 13.8-15.5 5 13.8-15.5 Olorgesailie 1 22.5 1 17.2 41 17.2-22.5 Thomas Quarry 1 18.5 M3 mesial breadth Hopefield 3 17.1 .78 16.6-18.0 3 15.4 .75 14.5-15.8 Makapan 4 13.3 .13 13.1-13.4 2 12.3 12.1-12.4 Swartkrans 3 14.8 1.65 13.2-16.5 3 13.4 .35 13.1-13.8 Olduvai I 1 14.7 2 13.5-14.7 Olduvai I1 1 14.4 Ndutu Beds 1 16.6 Kanjera 1 12.1 6 11.7-13.5 Olorgesailie 1 15.9 8 15.1-17.2 Thomas Quarry 1 16.0 M3 distal breadth Hopefield 5 15.0 1.08 13.7-16.5 2 15.1 15.0-15.2 Makapan 3 11.7 .38 11.4-12.1 2 11.3 10.8-11.7 Swartkrans 2 14.3 13.3-15.2 3 12.5 .46 12.0-12.9 Olduvai I 1 12.6 2 12.3-12.6 Olduvai I1 1 13.0 Ndutu Beds 1 14.0 Kanjera 1 11.3 6 11.3-12.0 Olorgesailie 1 14.5 8 13.2-15.6 M3 hypoconulid breadth Hopefield 5 12.1 .85 11.3-13.3 2 11.3 11.2-11.3 Makapan 2 8.1 7.3- 8.8 1 7.6 Swartkrans 3 10.0 1.33 8.5-11.1 M3 length Hopefield 4 25.8 1.37 23.8-26.6 3 24.5 .83 23.8-25.4 Makapan 6 21.3 1.30 19.8-23.5 2 18.6 18.2-18.9 Swartkrans 2 25.9 25.2-26.5 3 21.5 1.32 20.1-22.7 Olduvai I 1 21.9 3 20.2-21.9 Olduvai I1 2 24.0 23.0-25.0 2 23.3 22.5-24.1 Ndutu Beds 1 23.8 Kanjera 1 20.0 6 19.8-23.2 Olorgesailie 1 24.7 23 23.7-29.0 Thomas Quarrv 1 25.0 418 P.C. DECHOW AND R. SINGER

0 21 - 29- - - - 19 - 21 n - - 0 25 - -

23 - -

21 - S -

E 19- E .-c- Cll- -C - 15 - -

13 - F - S Fig. 5. Ranges of mandibular tooth length (left) and 11 - breadth (right) for mixed sex samples of fossil Theropi- thecus. Data is plotted from Table 2. 0. Olorgesailie; F, - Olduvai Bed IV;N, Lower Ndutu Beds; S, Swartkrans; H, Hopefield; T, Olduvai Upper Bed 11; Q, Thomas 9- Quarry; L, Olduvai Bed I and Lower Bed 11; K, Kanjera; M, Makapan.

he does not mention the pronounced differ- lateral portion of the lower border of the sym- ences between M.621 (M.626?) and M.3074 physis. A graph of these data (Fig. 8) gives noted by Freedman. In addition, Maier finds the following results: 1) There was consider- that one immature male specimen (M.3071) able variation within several of the different has no development of the fossae. baboon groups. For instance, fossa depth in To determine how much variability might male varied from just greater than exist in fossa of the mandibular corpus devel- zero mm to greater than 11 mm. 2) All groups opment among fossil Theropithecus, a proto- of female baboons and some male baboons col to measure the depth of the fossa was exhibited values of zero in their range, re- used on mandibles of modern baboons. Two vealing individuals with little or no develop- measurements were made as illustrated in ment of the fossa. 3) There were some Figure 7: 1)the maximum width of the man- disparities in fossa development between dible inferior to the fossae of the mandibular some of the extant baboon groups. For in- corpora in a coronal plane that was perpen- stance, there was not a great amount of over- dicular to the occlusal plane and contained lap in the ranges of male kinda baboons and the most posterior margin of the inferior male chacma baboons, indicating that fossa symphyseal shelf and 2) the distance be- depth can be used to distinguish some mod- tween the most medial points in the depths ern groups. 4) A difference in fossa depth of the bilateral fossae of the mandibular cor- between sexes revealed that most females pora. The second measurement was sub- had less fossa development than males. tracted from the first and the difference was Variation in fossa depth could not distin- divided by two, resulting in a measurement guish Hopefield and Makapan Theropithecus of the depth of the fossae relative to the most when modern baboon variation was consid- HOPEFIELD FOSSIL THEROPITHECUS 419

.-:Ic 16

Fig. 6. Means of tooth length for mandibular denti- tion. Males are on the left; females are on the right. Key is the same as in Figure 5. ered (Fig. 9). Two specimens from Hopefield Jolly (1972, p. 69) notes that lower molar (16647 and 1668) were sufficiently complete structure in Makapan Theropithecus more to allow the depth of their fossae to be mea- closely resembles a typical cercopithecine sured as in the modern sample, giving fig- condition than that of Kanjera Theropithe- ures of 1.1 mm and 3.2 mm, respectively, and cus. Lack of quantification of the relevant indicating shallow fossa development. As features of the molars, makes comparison noted, only one Makapan specimen exhibited with the Hopefield dentition difficult. The pronounced fossa development (Freedman, Hopefield molar pattern is qualitatively sim- 1957; Maier, 1970). This range of variation ilar to a typical Theropithecus pattern as de- in fossa development among Makapan Ther- scribed by Freedman (1957) and Jolly (1972). opithecus was not unusual compared to most Jolly (1972, p. 69) suggests that Makapan extant male and some female baboon groups. Theropithecus differs from East African However, understanding the distribution of forms in that “the sectorial face of the male this trait in the fossils was limited by small P3 is considerably more elongated relative to sample sizes (see Table 2). A single specimen its breadth and to general dental size” and with well-developed fossae reveals little that this elongated P3 is part of a higher about the prevalence of this trait among the crowned upper canine and longer sectorial Makapan Theropithecus population. Like- premolar complex in male Makapan There wise, variation in fossa development in pithecus. The utility of P3 length relative to Hopefield Theropithecus was likely to be breadth and overall dental size in separating greater than that documented in the few fossil Theropithecus groups was analyzed by available specimens. constructing indices of 1)P3 breadth divided 420 P.C. DECHOW AND R. SINGER

ard deviation units, indicating real differ- ences in P3 shape among the fossils. As Jolly (1972) suggested, there is a difference be- tween Makapan and most East African Ther- opithecus. Makapan has a lower index (.32), indicating a narrower and longer tooth while Olorgesailie (.45), Olduvai IV (.53), and Ndutu Beds (.71) have high indices, indicat- ing wider and shorter teeth. Conversely, Kanjera has an index (.35) that is similar to Makapan’s. The index for Hopefield (.38) is intermediate between the Swartkrans, Mak- apan, and Kanjera groups, on the one hand, and the groups from Olorgesailie, Olduvai Bed IV,and Ndutu Beds, on the other. The M2 length/P3 length index results in similar differences between fossil baboons as in the preceding index (Table 3, and Fig. 11). If the variance (s = .05) of the anubis group n is used again as an estimate of variance in fossil groups, the indices have a range of eleven standard deviation units. The East African groups of Olorgesailie, Olduvai IV, and Ndutu Beds have higher values, indicat- ing short P3s relative to molar size, while Makapan, Swartkrans, and one East African group, Olduvai I, have lower values. Hope- field and Olduvai I1 have indices that are intermediate. Jolly speculates that differences in male fossil P3 length indicate differences in upper canine crown height. The Theropithecus fos- sil record is inadequate to demonstrate such differences. Remains from Makapan are re- Fig. 7. Measurement of the depth of the fossa of the stricted to a single isolated upper canine mandibular corpus. The figure illustrates a cross-section (M.2974) (Freedman, 1960, p. 38). One un- of the mandible in the region of the fossa (at P3 or P4), “A” is the maximum width of the mandible inferior to worn specimen from Kanjera (F3668) and the fossa in a coronal plane that is perpendicular to the several from Olorgesailie (no catalog num- occlusal plane and contains the most posterior margin of bers given) are not as high-crowned as those the inferior symphyseal shelf. “B” is the distance be- from Makapan (Jolly, 1972). Canines of ex- tween the most medial points in the depths of the bilat- eral fossae. Fossa depth is indicated by the arrows and tant Papio with minimally worn dentitions is calculated by subtracting “B” from “A” and dividing reveal considerable variation. For example, the difference by 2. in 51 wild male anubis baboons with no den- tine exposure on the entoconid of the M~s, canine height ranges from 22.9 to 49.6 mm (mean = 38.1 mm, s = 5.4 mm). Similar statistics are found for other extant baboon by length and 2) M2 length divided by P3 groups. Clearly, larger sample sizes and a length (Table 3). For comparison, similar in- quantitative approach are necessary to show dices were constructed for modern anubis and canine height differences between fossil gelada baboons. Theropithecus groups. The P3 breadtmength indices (Table 3, Fig. The assumption that the sectorial face of 10)range from .26 (Swartkrans) to .53 (Oldu- the P3 is indicative of canine crown height vai IV). If the variance from the olive baboon seems intuitively obvious, but is difficult to sample (s = .03) is taken as an estimate of demonstrate. For instance, in modern Papio, the variance for the fossil baboon groups, the both canine height and P3 length are posi- total range of fossil means equals nine stand- tively correlated with each other and facial '.*1 1 r - 0.75

0 5 7 I E" E 0 .-C 0.25 5P Q) I' n U 0 U u ' -0.3 - 025-

YEdW42 CHAChA 60 GWNdA 10 MANDklU 15 BABOON GROUP

Fig. 8. Variation in fossa of the mandibular corpus indicates the mean. Bars on the ends of the vertical depth in extant baboons (genera Mandrillus, Pupio, cross-hatchingare one standard deviation from the mean. Theropithecus). Male, left; female, right. Sample sizes Bars on the ends of the clear zone indicate the range. follow each baboon group name. The center crossbar 422 P.C. DECHOW AND R. SINGER

site n development

Makapansgat 4 Swart krans several Hopefield 3 Kanjera 3 Olorgesailie 4 Olduvai I 2 Olduvai II 3 Olduvai IV 1 NdutuBeds 1

Fig. 9. Variation in fossa of the mandibular corpus ment of fossa development for each site is further de- depth in fossil Theropithecus. The qualitative assess- scribed in the test.

TABLE 3. Male P3 indices

- N Mean 5 Range P3 breadtMength index Hopefield 1 .38 Makapan 4 .32 .06 .28- .42 Swartkrans 1 .26 Olduvai IV 1 .53 Ndutu Beds 1 .71 Kanjera' .35 Olorgesailie2 13 .43 .04 .38- .48 olive3 baboons 138 .28 .03 .28- .43 gelada3 baboons 19 .36 .02 .32- .39 Mz length/P3 length index Hopefield 1 .95 Makapan 4 .70 .14 .58- .90 Swartkrans 1 .68 Olduvai I 1 .77 Olduvai I1 2 1.01 .08 .95-1.06 Olduvai IV 1 1.19 Ndutu Beds 1 1.43 Olorgesailiel 1.26 olive3 baboons 139 .58 .05 .41- .76 eelada3 I baboons 19 .67 .04 .60- .72 'Index calculated from means; data for individual are not available. 'Figures taken from Leakey and Leakey (1973). 3P3 length in modern sample is not total tooth length as in the fossil sample but is the length of the sectorial surface of the tooth measured along the long axis of this surface. HOPEFIELD FOSSIL THEROPITHECUS 423

site n in Makapansgat 4 Swartkrans 1 Hopef ield 1

Kanjera 3f Olorgesai Iie 13 Olduvai IV 1 Ndutu Beds 1 olive baboons 138 gelada baboons 19

3f index of means

Fig. 10. Ranges of P3 breadthilength index for fossil data for individual animals are unavailable. P3 length Theropithecus and extant baboons. Indices are calcu- for extant olive baboons (Papio anubis) and gelada ba- lated from individual tooth measurements. Olorgesailie boons (Theropithecus gelada) is not the total length as in measurements are taken from Leakey and Leakey (1973). the fossil sample but is the length of the sectorial surface The Kanjera index is calculated from means because of the tooth measured along the long axis of this surface.

site Makapansgat Swart krans Hopef ield Olorgesailie I Olduvai I Olduvai II Olduvai IV Ndutu Beds

olive baboons

s! index of means

Fig. 11. Ranges of male Mz lengthP3 length index for olive baboons (P. anubis) and gelada baboons (Zgelada) fossil Theropithecus and extant baboons. Indices are cal- is not the total tooth length as in the fossil sample but is culated from individual tooth measurements. The Olor- the length of the sectorial surface of the tooth measured gesailie index is calculated from means because data for along the long axis of this surface. individual animals are unavailable. Pg length for extant 424 P.C. DECHOW AND R. SINGER length (Dechow, 1980). Thus, correlation be- (Fig. 121, and 2) the distances between pos- tween canine height and P3 length may be terior extents of the symphyseal shelves and related to changes in facial size. Arguments the P4 relative to the occlusal plane. Results that a correlation in the length of the secto- show that the angle of the symphyseal shelf rial surfaces of the canine-premolar complex in extant Theropithecus varies by a large are of functional necessity await further amount (Fig. 12) from 15.1” to 39.9” (mean study. = 26.2“, SD = 5.7”). Comparisons with data The slope of the superior symphyseal shelf from Makapan fossils would be interesting. does not readily distinguish Makapan and The position of the posterior extent of the Hopefield Theropithecus. Freedman (1960, p. superior symphyseal shelf varies from 7.5 43) notes that in M.621 (M.626?), “the sym- mm posterior to 7.5 mm anterior to the apex physeal region slopes down very steeply be- of the buccal cusp of P4 (mean 1.8 mm ante- tween the premolars and behind the rior, S.D. = 3.3 mm). Qualitatively, the pos- incisors.” Jolly (1972, p. 68), citing Freedman terior extent of the superior symphyseal shelf (1957, 1960), also remarks that in Makapan in extant adult male Theropithecw ranges Theropithecus, “the internal surface of the from distal P3 to mesial MI but usually lies symphysis, instead of being flat, slopes down- near mesial P4. The position of the posterior wards rather abruptly between the premo- extent of the inferior symphyseal shelf varies lars.” Neither author notes any specimens from 1.0 mm anterior to 13.0 mm posterior other than M.626 as having this trait. On to the apex of the buccal cusp of P4 (mean = the contrary, Freedman (1957, p. 204) states 6.2 mm posterior, S.D. = 3.6 mm). Qualita- that while M.626 appears to differ consider- tively, the inferior shelf extends posteriorly ably from M.201, actually this difference is from mesial P4 to distal MI but is usually “of no great magnitude, . . . because in M.626 located near distal P4 or mesial MI. Juvenile the avleolar part of the symphysis is broken baboons have less-developed symphyseal off and the mandibular fossae are consider- shelves than adults, thus increasing the total ably deeper.” Maier (1970, p. 85) discusses range of variability. the differences between two specimens The internal surface of the symphyseal (M.3071 and M.3074) in the development of area is present in two Hopefield mandibles the symphyseal area, including the superior (16647 and 16648). The differences between shelf. He correctly points out that the under- them are similar to those between an imma- development of this area in M.3071 is a re- ture and a mature specimen from Makapan sult of immaturity but he does not mention (Maier, 1970). The immature specimen, that the internal symphyseal area of either 16647, has an underdeveloped upper sym- specimen is unusual. In general, the internal physeal shelf that does not project as far pos- symphyseal area of Makapan Theropithecus, teriorly as that of 16648, the adult specimen. with the possible exception of M.626, does One hemimandible from Hopefield, 16649, not differ from Theropithecus from Hopefield resembles 16647 in the available features of or other localities. the internal surface of the symphysis. No studies of fossil Theropithecus have at- The sparse data on corpus depth relative to tempted to quantify symphyseal features that mandibular length in Theropithecus from possibly represent differences between Makapan, Hopefield, and other localities groups. To estimate what symphyseal varia- limit any possible conclusions (Fig. 13). Jolly bility might be like in the fossils, measure- (1972, p. 68) produces a ratio of the depth of ments were taken on 19 adult male the corpus below the median buccal cleft of Theropithecus gelada crania (Fig. 12). Data M2 divided by mandibular molar row length were collected using a diagraph to measure for female specimens from Makapan (.95), the position (via Cartesian coordinates) of 1) Olduvai Bed I (.71), Kanjera (.69), and Olor- the posterior extent of the superior symphy- gesailie (.63). One female specimen from seal shelf, 2) the posterior extent of the infe- Hopefield (16649) has a ratio of .62, similar rior symphyseal shelf, 3) infradentale, 4) the to the low ratio from Olorgesailie and most tip of the buccal cusp of the P4s and 5) several different from Makapan. The meaning of points approximating the orientation of the these differences is unclear; a sample of 14 occlusal plane. From these data, measure- adult male anubis baboons have a range for ments were derived including 1) an approxi- this index nearly as large as that among the mation of the slope of the superior sym- fossil forms (Fig. 13). Among Makapan males, physeal shelf relative to the occlusal plane ratios of .69 for M.201 and .64 for M.626 were HOPEFIELD FOSSIL THEROPITHECUS 425

Fig. 12. Range of variation for superior symphyseal a line that intersects the posterior extent of the superior slope angle in Theropithecus gelada. The top figure illus- symphyseal shelf (A) and infradentale (B). The middle trates that the superior symphyseal slope angle (C)was figures show the range of variation for a sample of 19 computed by measuring the angle between the intersec- male gelada baboons (mean = 26”;s = 6”). tion of the midsagittal plane and the occlusal plane and

calculated from Freedman’s (1957, p. 206) are parallel in most fossil Theropithecus. data. The Hopefield male mandible, 16648 M.626 is an exception as “the inferior border has a ratio of .79. Contrary to the female and the occlusal plane can be seen to diverge condition, the ratio among males is larger in anteriorly quite strongly.” Jolly’s description the Hopefield than Makapan specimens. This is verified by mandibular height data (Freed- variability calls into question the relevance man, 1957, p. 206). According to Freedman of this index. (p. 2051, M.201 is similar to M.626 in the The anterior deepening of the mandible is anterior deepening of the mandibular corpus, also not a good criterion to separate Maka- but data (p. 206) show that M.201 has a sim- pan and Hopefield Theropithecus. Jolly (1972, ilar depth below the distal molar (33 mm) p. 68) discusses that the occlusal plane and and premolars (34 mm) (Freedman, 1957). the lower border of the mandibular corpus Other male and female specimens examined 426 P.C. DECHOW AND R. SINGER kcaity In summary, size is the clearest difference between Hopefield and Makapan fossils. The MdrgMgeat dd 9 relative dimensions of the P~salso separate Hcpetw 9 d Makapan from other Theropithecus, al- though not particularly from the Hopefield Kmjera 9 group. Other proposed differences such as the okrgeaailie 9 molar cusp morphology, upper male canine Olduvai I 9 crown height, relative mandibular corpus Ndutu Beds d‘ depth, and incisor breadth require further data to be evaluated. Other suggested differ- olive baboons I d 1 ln=14 ences in 1) fossa of the mandibular corpus size and depth, 2) upper symphyseal shelf slope, and 3) depth of the anterior relative to the posterior mandibular corpus, cannot be Fig. 13. Mandibular corpus deptWmolar row length shown to be real given the limited fossil sam- index in fossil Theropithecus. Sex of fossil specimens is noted by the appropriate sign. Range of sample of extant ple sizes and the morphological variation in olive baboons (I? anubis) is added for comparison. Some the fossil and modern baboon groups. For values (see text) are taken from Jolly (1972:68). each of these traits, a single specimen, M.626, varies from the morphology of other speci- mens from Makapan, Hopefield, and other localities. The taxonomic position of this by Freedman (1957,1960) are not sufficiently specimen to other Makapan Theropithecus complete to assess this feature. Maier (1970) should be reexamined. discusses three mandibles, of which one, Swartkrans: Theropithecus remains from M.3073, has mandibular corpora that de- Swartkrans, which consist of 20 maxillary crease in depth anteriorly. This feature is not and mandibular fragments including a fe- discussed for an immature male mandible male skull, SK561 (originally crushed but (M.3071)or an adult male mandible (M.30741, now reconstructed by Ronald Clark and Eric but a plate (Maier, 1970, his Fig. 20) shows Delson) are from a minimum of 17 individu- that M.3071 has a nearly parallel occlusal als and derive from a common geographical plane and lower border of the left corpus. The member (Member 1) (Freedman, 1957). adult mandible is not figured. The available Two forms of fossil Theropithecus may be data indicate that this trait is variable in present at Swartkrans as indicated by the Makapan Theropithecus. The occlusal planes large male P4 of SK569 (Freedman, 1957) of Hopefield Theropithecus are nearly paral- and differences in muzzle height and maxil- lel to the lower borders of the mandibular lary fossa depth (Jolly, 1972). At present, the corpora (see data for 16648 and 16649). sample sizes of the Swartkrans fossils are too Data are insufficient to judge if incisal small to make taxonomic distinctions based breadth is greater at Makapan than at Hope- on tooth dimensions (Freedman, 1957). field and other sites. The Hopefield upper Differences in muzzle dimensions are sug- incisor (16680) is very worn and only an esti- gested between two fossils, SK561 and mate of incisor root socket width, which is SK563. According to Freedman (1960, p. 43), not comparable to dimensions given by Maier SK561, a badly crushed female skull, has no (1970) for Makapan fossils, can be made on maxillary fossae, while SK563, a fragmen- the best preserved mandible (16648). Some tary female maxilla, has a muzzle that is data on incisal breadth in Olorgesailie and “rather higher” than some East African fos- Olduvai Bed I1 fossils (Leakey and Leakey, sil Theropithecus and maxillary fossae that 1973)indicate smaller teeth than in the Mak- are “deep.” Surprisingly, Freedman in his apan remains despite their smaller overall original (1957, p. 208) description of the max- size (Fig. 14). illary fossa of these specimens states that The most consistent differences between “there is only a slight excavation in SK563 Makapan and Hopefield Theropithecus are in and none at all in SK561.” This later descrip- the size of the teeth and jaws (Table 2, Figs. tion is supported by appropriate figures 5,6). On the average, dental and gnathic size (Freedman, 1957, Plate XLII). Jolly (1972) is greater in the Hopefield specimens despite suggests that the alleged difference in max- overlap of the ranges for many mea- illary fossa size between SK561 and SK563 surements. leads to a question of “whether more than HOPEFIELD FOSSIL THEROPITHECUS 427

locality n range that of Kanjera, though not as extreme as in the Makapan male (Jolly, 1972, p. 70).” This Makapansgat 3 impression is not wholly substantiated by data (Table 3, Fig. lo), which indicates that Olorgesailie - the male P3 is longer relative to its width in the Swartkrans specimen than in specimens OMuvai II from other localities. The Hopefield male P3 gelada baboons is not extreme in this feature among the 32 fossil forms. .6 .8 to 1.’2 1.b The ranges for Hopefield and Swartkrans width in cm mandibular tooth size overlap (Fig. 5). Like- wise, the means of the male tooth dimensions Fig. 14. Range of mandibular incisal width in fossil are similar (Table 2, Fig. 61, but the means Theropithecus. Measurement is the combined width of for Swartkrans female tooth length are con- the 11 and 12. The Olorgesailie range is based on the added ranges of the individual teeth and is taken from sistently smaller than those from Hopefield Leakey and Leakey (1973). The range of variation for a (two-tailed T test for P4: t = 2.65, P < .15; sample of 32 gelada baboons (T gelada) is added for MI: t = 2.72, P < .1; Ma: t = 4.60, P < .025; comparison. M3: t = 3.36, P < .05) indicating a greater degree of sexual dimorphism at Swartkrans than at Hopefield in tooth size and possibly other dimensions, such as skull size. one form of Simopithecus occurs at Swart- Kanjera: The Kanjera Theropithecus sam- krans” because “this feature is not generally ple consists of 21 cranial and mandibular so variable within populations of living Cer- pieces and 69 postcranial fragments (An- copithecoidea.” Jolly’s supposition was ana- drews, 1916; Hopwood, 1936; Leakey, 1943; lyzed by documenting maxillary fossa depth Leakey and Whitworth, 1958; Jolly, 1972). in groups of extant baboons. This depth was Remains comparable to Hopefield consist of measured by subtracting the minimum dis- an almost complete female mandible tance across the muzzle between the apices (M115391, a female juvenile mandible of the paracones of the M~sand dividing this (F33981, three corporal fragments each with difference by two. The variation in baboon several teeth (M18770, M11541, M19011), a groups (same groups as in Fig. 8) ranged male symphyseal fragment (unregistered), from moderate to large. For instance, in 19 and a male lower canine (M18729) (Jolly, male gelada baboons, maxillary fossa depth 1972). ranged from 4.65 mm to 9.45 mm. while in The above material indicates no substan- 42 female anubis baboons, maxillary fossa tial qualitative differences from the Hope- depth ranged from less than zero to 10.6 mm. field specimens. The fossa of the mandibular Thus, some female anubis baboons had fos- corpus (Fig. 9) ranges from absent (F3398) to sae as developed as the deepest fossae of male “only the slightest trace” (M11539) to “shal- gelada baboons while others had no develop- low” (M11541)(Jolly, 1972) on specimens that ment. Given this range of variation in extant are respectively female, juvenile, and un- baboons, variation between SK561 and known. Appropriate remains of adult males, SK563 is not adequate for taxonomic dis- which usually have the greatest fossa devel- tinctions. opment, are not present. Fossil Theropithecus from Swartkrans and Differences in mandibular morphology Hopefield have similar morphology. The among Kanjera specimens can be attributed Swartkrans male and female mandibles have to age (Jolly, 1972, p. 18-19). The juvenile “only a very shallow” fossa of the mandibu- corpus (F3398) is more lightly built than the lar corpus (Freedman, 1957, p. 209) similar adult female (M11539). The internal aspect to the Hopefield specimens (Fig. 9). One spec- of the juvenile symphysis is “less backwardly imen, SK402, a female mandible, has a cor- extended relative to the dentition than in the pus that does not deepen anteriorly but is of adult individual.” constant height (see Freedman, 1957, Table The chief difference between Kanjera and 16b), as in the Hopefield specimens. The Hopefield specimens is size. Other features cheek teeth from Swartkrans are unremark- such as P3 breadtMength index (Table 3, able, resembling those from Kanjera al- Fig. 10) and relative corpus depth (Fig. 13) though the male P3 “is relatively longer than (see Makapan discussion) are similar in 428 P.C. DECHOW AND R. SINGER Hopefield and Kanjera specimens. The Hope- KNM-OG 0003 (Jolly, 1972, p. 44). The struc- field dental dimensions are larger than Kan- ture of the symphysis (Jolly, 1972) is also jera’s with no overlap in the ranges except similar to the Hopefield remains. The V- for MI dimensions. Due to the incomplete- shaped outline of KNM-OG 0004 (Jolly, 1972, ness of the specimens from Kanjera, none Plate 19) is similar to the shape of the adult can be positively identified as males, accord- male mandible (16648) from Hopefield. ing to Jolly’s (1972) criterion for sexing, mor- Tooth size is similar in Hopefield and Olor- phology of the canine-sectorial premolar gesailie fossil Theropithecus (Figs. 5, 6), al- complex. However, some of the specimens though the Olorgesailie ranges are larger listed in Table 2 under “Total Sample” (see indicating a few individuals with absolutely also Fig. 5) are probably male. The means of larger measurements for most dimensions. the Hopefield female mandibular teeth Olduvai: Fossil Theropithecus have been lengths are all greater than any Kanjera recovered from various sites in Beds I measurement. through IV and the lower Ndutu Beds of Olorgesailie: Nine mandibular and cranial Olduvai Gorge in . Mandibular and fragments, over 100 postcranial fragments dental fragments comparable to Hopefield (Jolly, 1972), and 722 isolated teeth (Leakey remains number 5 from Bed I and Lower Bed and Leakey, 1973) of fossil Theropithecus are I1 (M14937; M14938; OLD/63,050; OLD/ reported from Olorgesailie. Shipman and col- 63,283; 067/6640), 7 from Upper Bed I1 (BK leagues (1981) argue that the pattern of 11; 1953/117; M14953; 580,57; OLD/63,3366; breakage and representation of these Thero- 067,2771; 067,56031, 1definite (OLD/69,5186) pithecus remains suggest that these animals and 1 questionable (OLD/69,S.194)from Bed were butchered or perhaps hunted by hom- 111, 1 from Bed IV (M14680), and 1 from the inids. Fossils comparable to Hopefield re- lower Ndutu Beds (OLD/1472,57) (Leakey mains are a symphysis and right mandibular and Whitworth, 1958; Jolly, 1972; Leakey corpus of an adult male (KNM-OG 0004) and and Leakey, 1973; Hay, 1976). Remains from mandibular corpora of a young adult female Bed I11 are too poorly preserved to allow sa- (KNM =OG 0002), a young adult male (KNM- lient comparisons (Leakey and Leakey, 1973) OG 0005) and two juvenile males (KNM-OG and are not considered further. 10003 and KNM-OG 0781). Bed Z and Lower Bed ZZ.. Jolly (1972) and Jolly (1972, pp. 45-46) lists several features Leakey and Leakey (1973) suggest several that may distinguish Olorgesailie from other traits of the three best preserved Bed mower fossil Theropithecus, namely: 1) the develop- Bed I1 fossils to distinguish them from the ment of extra vertical grooves on the molars fossils of Upper Bed 11, Bed IV, and other and premolars; 2) the relative shortness of East African sites. Leakey and Leakey (1973, the male P3 compared to Kanjera Theropithe- p. 118) list traits of several fragments (OLD/ cus; and 3) lower-crowned male canines rela- 63,3050-right mandibular corpus fragment; tive to Kanjera. Data (Table 3, Fig. 10) OLD/63,283--left mandibular corpus frag- demonstrate the relative shortness of P3 in ment; and OLD/63,3064-upper canine), that Olorgesailie Theropithecus. Canine height at probably constitute a single individual in- Olorgesailie cannot be evaluated because cluding 1) very large canines relative to pos- data are unavailable although Jolly (1972) terior dentition; 2) long sectorial cusps on P3; and Leakey and Leakey (1973) note relevant 3) shallow mandibular corpus deepening an- specimens. (For further discussion, see sec- teriorly; 4) lower crowned teeth; and 5) tion of this paper on Makapan). smaller size. Jolly (1972, p. 63) notes that an Data on the number of vertical grooves on adult female right mandibular corpus the cheek teeth of Olorgesailie Theropithecus (M14938) from site DKI, like one described are unavailable, but should be accessible, by Leakey and Leakey (19731, has a mandi- given the large number of teeth available bular corpus that deepens anteriorly and a among the Olorgesailie remains. One hy- more steeply sloping anterior symphyseal pothesis that should be tested is that the shelf than female specimens from Olorge- larger number of vertical grooves on the sailie, Kanjera, or Olduvai Upper Bed 11. cheek teeth of Olorgesailie Theropithecus is Both mandibular fragments (M14938 and related to the larger size of this form. OLD/63,3050)have a fossa of the mandibular In summary, Olorgesailie and Hopefield corpus. Theropithecus differ little. The fossa of the Some of the above features are better than mandibular corpus (Fig. 9) varies from “no others for establishing differences between trace” on KNM-OG 0004 to “shallow” on remains from Olduvai Bed mower Bed I1 HOPEFIELD FOSSIL THEROPITHECUS 429 and other sites. For instance, the presence ens appreciably anteriorly reaching its great- of lower crowned cheek teeth is doubtful. est depth below the mesial cusp of the MI.” Leakey and Leakey (1973, p. 104) claim this However, this deepening is not as pro- for OLD/63,3050 and they (1973, p. 104) also nounced as that exhibited by M.626 from suggest that M14937 has dental morphology Makapan (see Jolly, 1972, Plate lb; Freed- that “is not inconsistent with other female man, 1957, p. 206). Likewise, OLD/63,3050 specimens from Bed I.” However, Jolly (1972, has some deepening of the mandible ante- p. 63) states, regarding the fossil dentitions riorly (Leakey and Leakey, 1973, Plate 1) from Bed mower Bed I1 (including M14937), while the Hopefield mandibular corpora do that “the structure of the molars and premo- not. lars shows no differences from other popula- The presence of the fossa of the mandibular tions which could not be attributed to corpus is a small difference of questionable individual variation.” Jolly also finds that significance between Olduvai Bed mower Bed mower Bed I1 teeth are smaller than Bed I1 and Hopefield Theropithecus (Fig. 9). those from Upper Bed I1 and Bed IV, suggest- The female fragment (OLD/63,3050)has only ing that the difference from other sites is a “slight depression” representing the fossa size-related. In any case, data on cheek tooth (Leakey and Leakey, 1973, p. 103) while the height are unavailable, making settlement male fragment (M14938) has “a distinct, of this issue impossible. However, it is illus- though not deep” fossa (Jolly, 1972, p. 63). trative that cheek tooth height varies greatly The Hopefield remains do not have any ap- in modern baboons. Hypoconid height from preciable development of fossae. However, the enamel-dentin juncture to the tip of the considering the large amount of variation in hypoconid and tooth length were measured fossa depth among extant baboons (Fig. 71, on pristine M2s of extant baboons. Thirty this small difference is not significant. male anubis baboons ranged in crown height Available symphyseal morphology is simi- (hypoconid height) from 8.2 mm to 12.6 mm lar between Hopefield and Olduvai Bed I/ (mean = 10.1, S.D. = 1.0) and in relative Upper Bed I1 Theropithecus. One specimen crown height (hypoconid height divided by from Olduvai (M14938) has a flat inferior tooth length) from 6.6 to 9.2 (mean = 7.4, symphyseal surface, a superior symphyseal S.D. = .6). Thirteen male gelada baboons shelf that “extends posteriorly to the level of ranged from 8.9 mm to 10.9 mm (mean = the anterior part of the P4”, and an inferior 10.2 mm, S.D. = .5 mm) in crown height and shelf that extends “to the level of the ante- from 6.6 to 8.9 (mean = 7.8, S.D. = .6) in rior cusps of the MI” (Jolly, 1972, p. 63). This relative crown height. Other extant baboon description agrees closely with the morphol- groups exhibit similar variation. Compara- ogy of 16649, the adult female specimen from ble amounts of variation might be expected Hopefield. M14938 differs from other East among the fossils. African Theropithecus in that “the anterior The male P3 (OLD/63,3050) (Leakey and part of the symphyseal shelf is rather more Leakey, 1973) resembles fossils from Swart- steeply sloping” (Jolly, 1972), although no krans and Makapan in being long relative to clear differences from the Hopefield speci- M2 length (see Table 3, Fig. 10). The fossil men are apparent (see Jolly, 1972, Plate 16). contrasts with the shorter P3 of the Hope- The size difference between Hopefield and field, Olorgesailie, and Olduvai Upper Bed I1 Olduvai Bed mower Bed I1 fossils are illus- and Bed IV remains. Likewise, a relatively trated by the larger Hopefield tooth dimen- high-crowned upper canine might be found sions (see Fig. 5). in Bed mower Bed I1 Theropithecus. How- In summary, Hopefield and Olduvai Bed I/ ever, data are not available for a single iso- Lower Bed I1 fossil Theropithecus differ in 1) lated upper canine (OLD/63,3064-probably size as reflected in cheek tooth dimensions from the same individual as OLD/63,3050). and 2) relative P3 length. Two other differ- Modern baboons reveal considerable varia- ences of the Olduvai specimens, development tion in canine crown height (see earlier of the fossa of the mandibular corpus and an discussion). anteriorly deepening mandibular corpus, are Differences between Olduvai Bed mower small and their significance is unclear. Bed I1 and Hopefield Theropithecus in the Upper Bed IZ.. The Theropithecus from 01- anterior deepening of the mandibular corpus duvai Upper Bed I1 do not differ from Hope- are small. Jolly (1972, p. 63) describes the field in any significant features. The adult female mandibular fragment (M14938) dentition of mandibular fragments, BKII as having a mandibular corpus that “deep- (juv. female), 1953/117, and M14953 (female), 430 P.C. DECHOW AND R. SINGER

“agree with those of Kanjera and Olorge- and figures in this paper, OLD/1472,57 is sailie in general structure” (Jolly, 1972 p. considered a male, so as to conform with the 59). BKII also lacks a fossa of the mandibular most recent points of view on the sex of this corpus. A composite description of an Upper specimen (Jolly, 1972; Leakey and Leakey, Bed I1 mandible based on two male speci- 1973; Szalay and Delson, 1979). mens 067/5603; and OLD/63,3366 (Leakey Leakey and Leakey (1973) suggest that and Leakey 1973, p. 107) is as follows: 1) OLD/1472,57 is unusual in having 1) rela- “The mandibular corpus is. . . slightly tively wide molar teeth and 2) an almost deeper below the premolars than below the vertical ascending ramus. An index of M2 M3.” 2) The fossae of the mandibular corpora breadth divided by length shows that this “are represented by slight depressions.” 3) specimen does have relatively wide Mas. The “On the inferior aspect,. . . the symphysis index for OLD/1472,57 (.92) is larger than extends just posterior to the level of the Pq. the largest values found among available On the superior aspect, . . . the symphysis ex- male Theropithecus at Hopefield (.85), Mak- tends just posterior to the level of the P3.” apan (.88), Swartkrans (.72), and Olduvai Bed Mandibular height is 43 mm anterior to M3 IV (.77). However, the situation is not so clear and 46 mm anterior to M1 for 067/5603 for indices constructed with MI or M3 dimen- (Leakey and Leakey, 1973, p. 106). sions. For instance, a Makapan specimen The Hopefield mandibles are similar to Up- (M3081)has a breadtMength index for M1 of per Bed I1 remains in most morphological .90, which exceeds the value of .83 for OLD/ features including tooth form and symphy- 1472,57. Larger sample sizes are needed to seal morphology. Small discrepancies in the resolve this problem. fossa of the mandibular corpus (Fig. 9) and The second difference, the orientation of the relative depth of the anterior mandibular the ascending ramus in OLD/1472,57, has corpus are not significant. been discussed by Jolly (1972, p. 65), who Size similarity between Hopefield and 01- states that the steep vertical ramus is a re- duvai Upper Bed I1 Theropithecus is sug- sult of postmortem distortion of the left side gested by the considerable overlap of the of the mandible rather than the real anatom- ranges of dental measurements (Figs. 5, 6). ical relationship. The right side has an ori- Bed IV and lower Ndutu Beds.. The There entation of the ramus similar to Kanjera pithecus mandibles from Olduvai Bed IV and specimens. lower Nduto Beds (M14680; OLD/1472,57)are Theropithecus is slightly smaller at Hope- similar to the remains from Upper Bed I1 field than Olduvai Bed IV and lower Ndutu and Hopefield. Jolly’s (1972, p. 65) descrip- Beds for most dental measurements, al- tion of P3 in these fossils as “exceptionally though there is some overlap with the larg- short and broad, with a very short sectorial est Hopefield specimen (see Table 2, Fig. 5). face” is supported by the high P3 breadth/ length index (Table 3, Fig. 10). The fossils do Taxonomy not have fossae of the mandibular corpora The Hopefield Theropithecus mandibular (Fig. 9) and the lower Ndutu Beds specimen fragments and teeth discussed in this paper has a symphysis similar to specimens from further help to elucidate 1) the taxonomic Kanjera and Olorgesailie (Jolly, 1972). The position of the Hopefield form, and 2) the Bed IV mandible (M14680) exhibits no other taxonomic diversity of fossil Theropithecus at unusual features (Jolly, 1972; Leakey and the Hopefield site itself. Leakey, 1973). Singer (1962) places all Hopefield fossil ba- OLD/1472,57, the type specimen of SimcF boons in the genus Simopithecus. Jolly (1972) pithecus jonathoni, has elicited some contro- sinks the genus Simopithecus into Theropi- versy (Leakey and Whitworth, 1958; Leakey, thecus, subgenus Simopithecus. This latter 1965). This specimen is probably male based convention is followed by other workers (Del- on canine cross-sectional areas, which are son, 1975; Eck, 1977; Szalay and Delson, intermediate between expected male and fe- 1979) and is used here despite objections by male values (Jolly, 1972) and based on the Maier (1972) and Freedman (1976). large canine root size (Leakey and Leakey, The specific status of Hopefield Theropithe- 1973). Conversely, the sectorial blade on P3 cus has been alternately claimed to be S. is quite short, indicating a female. Sex deter- oswaldi (Singer, 1962), T (S.) oswaldi (Jolly, mination is confounded by the extreme wear 1972; Szalay and Delson, 19791, and S. darti of the dentition. For purposes of the tables (Freedman, 1976). The species name T os- HOPEFIELD FOSSIL THEROPITHECUS 431 waldi is used by Jolly (1972) to denote fossil arate the fossil Theropithecus groups, al- Theropithecus remains from Middle and Up- though these traits do not order the groups per Pleistocene sites throughout Africa. Re- on either chronological or geographical mains from Olduvai Bed I and Lower Bed 11, grounds. For instance, specimens from Mak- Swartkrans, and Makapan are placed in T apan, Swartkrans, Hopefield, and Kanjera (S.) darti. Likewise, Szalay and Delson (1979) have similar proportions for male PQs(Table refer Hopefield remains to T oswaldi along 3 and Fig. 10) despite differences in proveni- with remains from most fossil Theropithecus ence. Thus, Theropithecus mandibular mor- sites including Swartkrans and the Lower phology supports the view that all forms Beds at Olduvai. Szalay and Delson refer the considered as T oswaldi or T darti should be Makapan specimens and currently undes- placed in a single fossil species T oswaldi as cribed remains from Hadar and the lower suggested by Singer (1962). Szalay and Del- member of the Koobi Fora formation at East son (1979, p. 379) also suggest that with fur- Turkana to Theropithecus darti. Freedman ther material ‘ta single species might be the (1976) places the Hopefield remains in S. best way to recognize this situation darti along with Theropithecus from Maka- taxonomically. ” pan and Swartkrans but groups the East Af- Singer’s (1962)designation of the Hopefield rican remains in S. oswaldi. material as the subspecies S. 0. hopefielden- Most of the morphological features on sis is maintained by Freedman (1976) and which the above taxonomic assessments are Szalay and Delson (1979). Conversely, Jolly based are reviewed in this paper. Freedman’s (1972)places the Hopefield specimens in T 0. views are not considered as they are based mariae because of similarity in size and other primarily on geographical rather than mor- features to Olorgesailie remains. Data pre- phological criteria. Although different in the sented in this paper indicate that the Hope- taxonomic assessment of a few groups (e.g., field remains differ little from other sites, Swartkrans and the Lower Beds at Olduvai), especially remains from Olorgesailie, Swart- Jolly (1972) and Szalay and Delson (1979) krans, and the Upper Beds at Olduvai, which base their taxonomic conclusions on similar are similar to the Hopefield remains in size. morphological criteria. They suggest that T Thus, the only criteria for maintaining sub- oswaldi is a successional species to T darti specific distinctions between these groups are with a number of advanced morphological geographic separation or taxonomic conven- features. Such features relevant to the Hope- ience, neither of which are sufficient: Subspe- field remains include 1) reduced fossae of the cific distinctions should be based on mandibular corpora; 2) reduced P3 length and morphological criteria (Mayr, 1970). If geo- canine height; 3) flattened upper symphyseal graphic separation is the basis for taxonomic shelf; 4) mandibular corpora of constant separation, a sample can be referred to as depth anteriorly and posteriorly; 5) more spe- that from a particular locality rather than as cialized cheek teeth; and 6) smaller incisors. a formal subspecies. For instance, the Hope- Extensive discussion in this paper demon- field remains should be designated “T os- strate that most of these traits do not reliably waldi from Hopefield” rather than by the separate the alleged primitive forms (Maka- formal subspecific nomen, “T oswaldi hope- pan and Olduvai Bed I and Lower Bed 11) fieldensis”. We conclude that the subspecific from the advanced forms (Kanjera, Olorge- name for the Hopefield Theropithecus re- sailie, Swartkrans, Olduvai Upper Bed 11, mains be dropped until distinct morphology Bed IV and lower Ndutu Beds, and Hope- can distinguish these specimens from other field) when variation in the fossil groups and groups. Likewise, the use of subspecific nom- in extant baboon groups is considered. This ina for all fossil Theropithecus groups should is especially true for such traits as size of the be reconsidered. Comparative mandibular fossa of the mandibular corpus, slope of the data presented in this paper do not make a upper symphyseal shelf, and variation in compelling case for any subspecific classifi- depth of the mandibular corpus. Other traits, cation in the Theropithecus oswaldi species. such as canine crown height, cheek tooth Questions about the number of Theropithe- morphology, and incisor size, are not well cus taxa at Hopefield are raised by Jolly documented among the fossils. One of these (1972, p. 70), who states that “the total range traits, canine crown height, shows consider- of dental size represented by the sample is able variation in modern baboon groups. considerable . . . It is questionable whether Overall size and relative P3 length best sep- such a range can be attributed solely to sex- 432 P.C. DECHOW AND R. SINGER ual dimorphism and intrapopulational vari- varia size does not suggest multiple taxa at ability, and the possibility arises that more Hopefield. than one form may be represented, a possi- bility which can only be tested in the light of Ecology further material.” Jolly (1972, his Table 4) A survey of the fauna of African Pleisto- presents data from Singer (1962) on Hope- cene localities (Jolly, 1972)reveals that Ther- field dental dimensions of which only M1 opithecus is found primarily at “waterside measurements have more than a single ob- sites.” Jolly (p. 102) concludes: “it seems rea- servation. Jolly gives ranges for M1 dimen- sonable to infer that Theropithecus popula- sions that are large. For instance, anterior tions living in the lowlands of tropical breadth ranges from 9.9 mm to 14.0 mm (n Africa . . . frequented preferentially the allu- = 2). Conversely, Singer (1962, his Table VII) vial flats surrounding shallow lakes and gives only a single measurement for M1 an- vleis. Such areas would . . . support a rich and terior breadth, 14.0 mm. The smaller mea- dense ground-flora, especially grasses, but, surement given by Jolly is identical to the being liable to season flooding, are unlikely measurement of the Makapan females given to have been wooded or forested.” This scen- in the column adjacent to the Hopefield spec- ario corresponds with the hypothesized phys- imen datum in Table IV of Singer (1962). ical conditions at Hopefield during the Likewise, for M1 posterior breadth, Jolly mis- periods of deposition when the site consisted copies Singer’s (1962) figures, 12.0-12.5 mm, of a series of vleis, or freshwater lagoons, as 9.5-12.5 mm. The lower 9.5 mm figure is with natural drainage blocked or slowed by identical to a figure given by Singer (taken offshore dunes (Singer and Wymer, 1968). from Freedman, 1957) for Makapan females. Some parallels exist between the environ- Thus, the range of variation for Hopefield ment of fossil and modern Theropithecus dental measurements given by Jolly (1972) is leading to inferences about the diet of the a miscopying of Singer’s data and is not too fossil forms (Jolly, 1972). Modern T gelada large to be accounted for within a single live at high altitudes in the montane grass- taxon. Data presented in this paper (Table 2, lands and alpine communities of the Ethio- Fig. 5) also show that the range of Hopefield pian highlands (Hall, 1966; Starck and Frick, dental measurements is not exceptional com- 1958). Studies from several localities reveal pared to ranges of dental measurements for I: gelada to be almost exclusively gramini- other fossil groups. vorous, eating grass seeds, dry and fresh Jolly (1972) and Maier (1972) also suggest grass blades and stems, roots and small that the Theropithecus calvaria (8400a,b,c,e) bulbs, and a few other plant products (Crook from Hopefield described by Singer (1962) is and Aldrich-Blake, 1968; Dunbar, 1977; Dun- small relative to the size of the dentition and bar and Dunbar, 1974; Iwamoto, 1975, 1978, mandibular remains from other Hopefield 1979; Slatkin, 1975). Similar dietary items specimens. However, data given by Singer would have constituted food products avail- (1962) for glabella-inion length or minimum able in open grasslands at Hopefield and frontal breadth indicate that this calvaria is probably were an important part of the diet similar in size to both a male, F3668, and of Hopefield Theropithecus. female, M14936, specimen from Kanjera Mandibular and dental morphology of (Jolly, 1972, his Table 3) and a female, Hopefield Theropithecus also suggest a pos- SK.561, from Swartkrans (Freedman, 1957, sible graminivorous diet. The cheek teeth of his Table 16a) while it is larger than two extant and fossil Theropithecus, as discussed Makapan females, M.3073 and MP.222, in detail by Jolly (1970, 1972), share general (Maier, 1970, his Table 11; Freedman, 1976, features such as high crowns, complex ridg- his Table 2) and smaller than the possibly ing, and columnar shape with other grami- female Olduvai Bed I1 specimen, BKII 1957, nivorous mammals including bovids, equids, (Jolly, 1972, his Table 3). On the whole, this elephantids, and microtin rodents. small sample of fossil calvaria does not indi- The incisor wear pattern of fossil Theropi- cate an unusual size for the Hopefield speci- thecus suggests usage similar to that of mod- men relative to dental measurements from ern savannah baboons or drills and other Hopefield specimens, especially if the mandrills. The left I’ from Hopefield (16680) Hopefield calvaria is female (as suggested by and a specimen from Swartkrans (Freedman, Singer, 1962) or juvenile. Therefore, the cal- 1957, p. 208) show much wear and lean me- HOPEFIELD FOSSIL THEROPITHECUS 433 sially, as in older Papio and Mandrillus, and mie Comparee and the Laboratoire de Zoolo- are dissimilar from the straight, closely gie of the Museum National D’Histoire packed incisors of modern Theropithecus. Re- Naturelle, Paris; Senckenbergische Anato- ports of incisor use in modern savannah ba- mie, Frankfurt am Main; Natur-Museum boons include biting pieces from larger Senckenberg, Frankfurt am Main; Konink- objects (Hamilton et al., 1978; Rose, 19771, linjk Museum voor Midden Afrika, Ter- tearing meat from carcasses (Hard- vuren, Belgium; and the Anthropology ing, 1973, 1975; Rose, 19771, pulling up rhi- Department of New York University. zomes (Dunbar and Dunbar, 1974) and sedges The Hopefield fossils were collected over (Rhine and Westlund, 19781, prying limpets several years under the direction of one of us from rocks (Hall, 1961), and removing inedi- (R.S.). Numerous students from the Univer- ble layers in tamarind preparation (Rhine sity of Cape Town participated as well as and Westlund, 1978). By contrast, Dunbar professional field assistants including Peter and Dunbar (1974) report that loosen Saunders and Jeremy Adams, to all of whom dirt around a root and remove it manually. our appreciation is expressed. Likewise, geladas collect seeds by “stripping Research was carried out under several standing stems between the thumb and in- grants: NIH Fellowship DE05271 (to P. De- dex finger” although they also collect seeds chow), and NIH GM-10113, NSF GS-961, and by pulling the grass stems through the teeth grants from the Wenner-Gren Foundation for one at a time (Dunbar, 1977, p. 258). The Anthropological Research, the Boise Fund of increased dental wear of the limited sample Oxford University, the Lichtenstern Fund, of fossil incisors suggests that the anterior and the Abbott Fund of the University of dentition of the fossil forms was used for a Chicago (to R. Singer). wider variety of tasks than in modern Photographic assistance was provided by geladas. Ms. Shirley Aumiller, University of Chicago, The deep mandibular corpus of extant and Mr. Les Siemens, Ms. Clara Franklin, and fossil Theropithecus may reflect an adapta- Medical Photography of the University of tion to prevent fatigue failure of mandibular Michigan. Some illustrations were drawn by bone due to repeated bending moments gen- Ms. Nancy Bates. erated on the balancing side corpus during mastication (Hylander, 1979, p. 230). Such LITERATURE CITED bending moments presumably would be more Andrews, CW (1916) Notes on a new baboon (Sirnopithe frequent in graminivorous animals due to cus oscualdi, gen. et sp. n.) from the (?) Pliocene of British East Africa. Annu. Mag. Nat. Hist. 18:(8th the relatively greater amount of mastication series):410-4 19. necessary to break up grasses and seeds than Arambourg, C (1947) Mission Scientifique de l’bmo other food items such as fruits. Likewise, the 1932-1933. Tome I, Geologie-Anthropologie. Museum symphysis of Theropithecus is well but- National D’Histoire Naturelle, Fascicule 111, Contri- tressed, which would better enable it to bution a L’Etude Geologique et Paleontologique du Bassin du Lac Rudolphie et de la Basse Vallee de counter repeated shearing stresses such as L’Omo. those that have been found to be generated Arambourg, C (1962) Les faunes mammalogiques du at the symphysis during mastication in ma- Pleistocene circummediterraneen. Quaternaria 6:97- caques (Dechow and Carlson, 1983). 109. Butzer, KW (1971)The Lower Omo Basin: Geology, fauna ACKNOWLEDGMENTS and hominids of plio-Pleistocene formations. Naturwis- senschaften 58:7-16. The specimens of extant primates used in Carney, J, Hill, A, Miller, J, and Walker, A (1971) Late this study are housed in the American Mu- australopithecine from Baringo District, . Na- seum of Natural History, New York; the Brit- ture 230:509-514. Crook, JH, and Aldrich-Blake, P (1968) Ecological and ish Museum of Natural History, London; The behavioural contrasts between sympatric ground Cleveland Museum of Natural History; the dwelling primates in Ethiopia. Folia Primatol. 8:192- Field Museum of Natural History, Chicago; 227. the Florida State Museum, Gainesville, Flor- Dechow, PC (1980) Functional Morphology of the Cran- ida; the Leiden Museum of Natural History, ofacial Skeleton of Baboons. Ph.D. dissertation, Uni- versity of Chicago, Chicago. The Netherlands; the Museum of Compara- Dechow, PC (1981) Evaluation of primitive morphologi- tive Zoology, Cambridge, Massachusetts; the cal features of Makapansgat Theropithecus. Am. J. US. National Museum of Natural History, Phys. Anthropol. 54:213-214(Abstract). Washington, D.C.; the Laboratoire d’Anato- Dechow, PC, and Carlson, DS (1983) In uiuo symphyseal 434 P.C. DECHOW AND R. SINGER

bone strain in the macaque mandible. Anat. Rec. Hendey, QB (1974) The Late Cenozoic carnivore of the 205:44A-45A(Abstract). southeastern Cape Province. Ann. S. Afr. Mus. 63:l- Delson, E (1974)Preliminary review of cercopithecid dis- 369. tribution in the Circum Mediterranean region. Mem. Hopwood, AT (1934) New fossil mammals from Olduvai, Bur. Rech. Geol. Min. (France) 78:131-135. Tanganyika Territory. Ann. Mag. Nat. Hist. Lond. Delson, E (1975) Evolutionary history of the cercopithe- 14(10th series):546-550. cidae. In Szalay, F (ed): Approaches to Paleo- Hopwood, AT (1936) New and little-known fossil mam- biology. Contrib. Primatol. 5t167-217. mals from the Pleistocene of Kenya Colony and Tan- Dietrich, WO (1942) Altestquartare Saugetiere aus der ganyika Territory. Ann. Mag. Nat. Hist. 17(10th Sudlichen Serengeti, Deutsch-Ostafrika. Palaeonto- series):636-641. graphica 93t43-133. Hopwood, AT (1939) Appendix B, The mammalian fos- Drennan, MR (1954) Saldanha man and his associations. sils. In O'Brien, TP fed): The Prehistory of the Uganda Am. Anthropol. 562379-884. Protectorate. Cambridge: University Press, pp. 308- Drennan, MR, and Singer, R (1955) A mandibular frag- 316. ment, probably of the Saldanha skull. Nature 175364. Hooijer, DA, and Singer, R (1960) Fossil rhinoceroses Dunbar, RIM (1977) Feeding ecology of gelada baboons: from Hopefield, South Africa. Zool. Med. Museum Lei- A preliminary report. In Clutton-Brock, TH (ed): Pri- den 37(8):113-128. mate Ecology. New York: Academic Press, pp. 251- Hooijer, DA, and Singer, R (1961) The fossil hippopota- 273. mus from Hopefield, South Africa. Zool. Med. Mus. Dunbar, RIM, and Dunbar, EP (1974) Ecological rela- Leiden 37(10):157-165. tions and niche separation between sympatric terres- Hylander, WL (1979) Functional significance of primate trial primates in Ethiopia. Folia Primatol. 21:36-60. mandibular form. J. Morphol. 160:223-240. Eck, GG (1976)Cercopithecoidea from Omo group depos- Inskeep, RR, and Hendey, QB (1966) An interesting as- its. In Coppens, Y, Howell, FC, Isaac, GL, and Leakey, sociation of bones from the Elandsfontein fossil site. REF (eds.) Earliest Man and Environments in the Lake Actas v Congr. Panagr. Prehist. Estudio Cuaternario Rudolf Basin. Chicago: University of Chicago Press, 2(6):109-124. pp. 332-344. Iwamoto, T (1975) Food resource and feed activity, stud- Eck, GG (1977) Diversity and frequency distribution of ies of the gelada society (111). Contemporary Primatol- Omo group cercopithecoidea. J. Hum. Evol. 6:55-63. ogy, 5th Int. Congr. Primatol. Basel: Karger, pp. 475- Eck, GG, and Howell, FC (1982) Un primate des forma- 480. tions plio-pleistocenes d'Afrique orientale: Theropithe- Iwamoto, T (1978) Food availability as a limiting factor cus brumpti (Arambourg), Primates, Cercopithecidae. on population density of the Japanese monkey and C.R. Acad. Sci. [D] (Paris)2950 1U:397-400. gelada baboon. Chivers and Herbert (eds): Recent Ad- Ewer, RF, and Singer, R (1956) Fossil carnivora from vances in Primatology, Vol. 1. London: Academic Press, Hopefield. Ann. S. Afr. Mus. 42t335-347. pp. 287-303. Freedman, L (1957) The fossil cercopithecoidea of South Iwamoto, T (1979) Feeding ecology. In Kawai, M (ed): Africa. Ann. Transvaal Mus. 23t121-262. Ecological and sociological studies of gelada baboons. Freedman, L (1960) Some new cercopithecoid specimens Contrib. Primatol. 16t280-330. from Makapansgat, South Africa. Palaeontol. Afr. 7:7- Jolly, CJ (1970) The large African monkeys as an adap- 45. tive array. In Napier, JR, and Napier, PH (eds): Old Freedman, L (1976) South African fossil cercopithe- World Monkeys: Evolution, Systematics, and Behav- coides: a re-assessment including a description of new ior. New York Academic Press, pp. 139-174. material from Makapansgat, Sterkfontein and Taung. Jolly, CJ (1972) The classification and natural history of J. Hum. Evol. 5t297-315. Theropithecus (Simopithecus, (Andrews, 19161, ba- Freedman, L, and Brain, CK (1977) A re-examination of boons of the African PIio-Pleistocene. Bull. Br. Mus. the cercopithecoid fossils from Swartkrans (Mam- Nat. Hist. (Geol.)22:l. malia: Cercopithecidae), Ann. Transvaal Mus. 30:211- Kalb, JE, Jolly, CJ, Mebrate, A, Tebedge, S, Smart, C, 218. Oswald, EB, Cramer, D, Whitehead, P, Wood, CB, Con- Geraads, D (1979) La faune des gisements de Melka roy, GC, Adefris, T, Sperling, L, and Kana, B (1982a) Kunture (Ethiopie): Artiodactyles, Primates. Abbay Fossil mammals and artefacts from the Middle Awash (CNRS, Paris) IOt21-50. Valley, Ethiopia. Nature 298t25-29. Geraads, D (1980) La faune des sites a Home erectus des Kalb, JE, Jolly, CJ, Tebedge, S, Mebrate, A, Smart, C, carrieres Thomas (Casablanca, Maroc). Quaternaria Oswald, EB, Whitehead, P, Wood, CB, Adefris, T, and 22:65-95. Rawn-Schatzinger, V (1982b) Vertebrate faunas from Hall, KRL (1961) Feeding habits of the chacma baboon. the Awash Group, Middle Awash Valley, Afar, Ethio- Adv. Sci. 17t559-567. pia. J. Vertebr. Paleontol. 2t237-258. Hall, KRL (1966) Distribution and adaptations of ba- Kalb, JE, Wood, CB, Smart, C, Oswald, EB, Mabrete, A, boons. Zool. SOC.Lond. Symp. 17t49-73. Tebedge, S, and Whitehead, P (1980) Preliminary ge- Hamilton, WJ, Buskirk, RE, and Buskirk, WH (1978) ology and palaeontology of the Bod0 D'Ar hominid site, Omnivory and utilization of food resources by chacma Afar, Ethiopia. Palaeogeogr. Palaeoclimatol. Palaeoe- baboons, Pupio ursinus. Am. Nat. 112:911-924. col. 3Ot107-120. Harding, RSO (1973) Predation by a troop of olive ba- Keen, EN, and Singer, R (1956) Further fossil suidae boons (Pupio anubis). Am. J. Phys. Anthropol. 38:587- from Hopefield. Ann. S. Afr. Mus. 42:350-360. 592. Leakey, LSB (1943) Notes on Simopithecus oswaldi An- Harding, RSO (1975) Meat-eating and hunting in ba- drews from the type site. J. E. Afr. Nat. Hist. SOC. boons. In Tuttle, RH (ed): Socioecology and Psychology 17t39-44. of Primates. Paris: Mouton, pp. 245-257. Leakey, LSB (1965) Olduvai Gorge, 1951-1961: Fauna Hay, RL (1976)Geology of the Olduvai Gorge. University and Background. Cambridge: Cambridge University of California Press, Berkeley. Press. HOPEFIELD FOSSIL THEROPITHECUS 435

Leakey, LSB, and Whitworth, T (1958) Notes on the Parapithecidae. In Maglio, VJ, and Cooke, HBS, (eds): genus Simopithecus, with a description of a new spe- Evolution of African Mammals. Cambridge, MA: Har- cies from Olduvai. Coryndon Memorial Museum Occa- vard University Press. sional Papers, 6. Singer, R (1954) The Saldanha skull from Hopefield, Leakey, MD, Hay, RL, Curtis, GH, Drake, RE, Jackes, South Africa. Am. J. Phys. Anthropol. 12345-362. MK, and White, TD (1976) Fossil hominids from the Singer, R (1957) Investigations at the Hopefield Site. In Laetolil Beds. Nature 262:460-466. Clark, JD (ed): Proc. Third Pan-Afr. Congr. Prehist. Leakey, MG (1976) Cercopithecoidea of the East Rudolf 1955. pp. 175-182. succession. In Coppens, Y, Howell, FD, Isaac, GL, and Singer, R (1962) Simopithecus from Hopefield, South Af- Leakey, REF (eds): Earliest Man and Environments in rica. Bibl. Primatol. 1:43-70. the Lake Rudolf Basin. Chicago: University of Chicago Singer, R, and Bonk, EL (1960)Modern giraffes and fossil Press, pp. 345-350. girafids of Africa. Ann. S. Afr. Mus. 45:375-548. Leakey, MG, and Leakey, REF (1973) Further evidence Singer, R, and Crawford, JR (1957) The significance of of Simopithecus (Mammalia, Primates) from Olduvai the archaeological discoveries at Hopefield, South Af- and Olorgesailie. In Leakey, LSB, Savage, RJG, and rica. J. R. Anthropol. Inst. 88:lI-19. Cornydon, SC (eds): Fossil Vertebrates of Africa 3. New Singer, R, and Heltne, PG (1966) Further notes on a bone York Academic Press, pp, 121-138. assemblage from Hopefield, South Africa. Actas v Leakey, REF (1970) New hominid remains and early Congr. Panafr. Prehist. Estudio Cuaternario 2(6):261- artifacts from Northern Kenya. Nature 226:223-224. 264. Maier, W (1970) New fossil cercopithecoidea from the Singer, R, and Inskeep, RR (1961) A complete fossil equid Lower Pleistocene cave deposits of the Makapansgat skull from Hopefield, C.P. S. Afr. Archaeol. Bull. 17:23. limeworks, South Africa. Palaeont. Afr. 13:69-107. Singer, R, and Keen, EN (1955) Fossil suiforms from Maier, W (1972)The first complete skull of Simopzthecus Hopefield. Ann. S. Afr. Mus. 42:169-179. darti from Makapansgat, South Africa and its system- Singer, R, and Wymer, J (1968) Archaeological investi- atic position. J. Hum. Evol. 1:395-405. gations at the Saldanha skull site in South Africa. S. Mayr, E (1970) Populations, Species, and Evolution. Afr. Archaeol. Bull. 25:63-74. Cambridge, MA: Harvard University Press. Slatkin, M (1975) A report on the feeding behavior of Patterson, B, Behrensmeyer, AK, and Sill, WD (1970) two East African baboon species. Contemporary Pri- Geology and fauna of a new Pliocene locality in North- matology, 5th Int. Congr. Primatol. Basel: Karger, pp. western Kenya. Nature 226:918-921. 418-422. Rhine, RJ, and Westlund, BJ (1978) The nature of a Stark, D, and Frick, H (1958) Beobachtungen an athiop- primary feeding habit in different age-sex classes of ischen Primaten. Zool. Jb. 86:41-70, 100-119. yellow baboons (Pupio cynocephalus). Folia Primatol. Szalay, FS, and Delson, E (1979) Evolutionary History of 30:64-79. the Primates. New York: Academic Press. Rose, MD (1977) Positional behaviour of olive baboons Taieb, M, Johanson, DC, Coppens, Y, and Aronson, JL (Papzo anubis) and its relationship to maintenance and (1976) Geological and palaeontological background of social activities. Primates 18:59-116. Hadar hominid site, Afar, Ethiopia. Nature 260:289- Shipman, P, Bosler, W, and Davis, KL (1981)Butchering 293. of giant geladas at an Acheulian site. Curr. Anthropol. Thomas, P (1884) Quelques Formations d’Eau Douce de 22:257-268. 1’Algerie. Mem. SOC.Geol. France, Ser. 3, Vol. 111, Mem. Simons, EL, and Delson, E (1978) Cercopithecidae and 2.