Cranial shape and intrageneric diversity in the genus Cercopithecoides Monya Anderson 1 , Stephen R. Frost 1 , Christopher C. Gilbert 2,3 , and Eric Delson 3,4,5 1. Department of Anthropology, University of Oregon 2. Department of Anthropology, Hunter College City University New York 3. New York Consortium in Evolutionary Primatology (NYCEP) 4. Department of Anthropology, Lehman College, City University New York 5. Division of Paleontology, American Museum of Natural History Acknowledgements We thank Lee Berger, Bernhard Zipfel, and Christine Steininger at the University of the Witswatersrand and Stephany Potze at the Ditsong Museum of Natural History (Pretoria) for access to specimens. We also thank the Wenner-Gren Foundation, Hunter College, PSC-CUNY, NYCEP, and the University of Oregon for their generous support of this project. Sources Delson E. 1984. Cercopithecid biochronology of the African Plio-Pleistocene: correlation among eastern and southern hominid-bearing localities. Courier Forschungsinstitut Senckenberg 69: 199-218. Freedman L. 1957. Cercopithecoides. In Annals of the Transvaal Museum. University Press, Cambridge, UK: 225-238. Freedman L. 1961. Some New Fossil Cercopithecoid Specimens from Makapansgat, South Africa. Palaeontol Afr 7:7-44. Frost SR, Delson E. 2002. Fossil Cercopithecidae from the Hadar Formation and surrounding areas of the Afar Depression, Ethiopia. J Hum Evol 43:687-748. Frost SR, Marcus LF, Bookstein FL, Reddy DP, and Delson E. 2003a. Cranial Allometry, Phylogeography, and Systematics of Large-Bodied Papionins (Primates: Cercopithecinae) Inferred From Geometric Morphometric Analysis of Landmark Data. The Anatomical Record Part A 275A:1048-1072. Frost SR, Plummer T, Bishop LC, Ditchfield P, Ferraro J, Hicks J. 2003b. Partial Cranium of Cercopithecoides kimeui Leakey, 1982 from Rawi Gully, SW Kenya. Am J Phys Anthropol 122:191-199. Jablonski NG. 2002. Fossil Old World monkeys: The late Neogene radiation. In The Primate Fossil Record. Ed. Hartwig WC. Cambridge University Press, UK: 255-299. Leakey M. 1982. Extinct Large Colobines from the Plio-Pleistocene of Africa. Am J Phys Anthropol 58:153-172. Material and Methods • 45 3-D landmarks (Frost et al., 2003a) taken on 293 extant and fossil colobine crania. • 15 Cercopithecoides cranial specimens including C. haasgati, C. kimeui, C. williamsi, and 2 potential C. "coronatus" specimens (Table 1) • Principal components analysis (PCA) and Procrustes distances (PD) to compare shape differences within and among taxa to assess the variation in the target sample. Both PCA and PD were evaluated on 3 different landmark configurations (LC) to include as many Cercopithecoides and C. "coronatus“ specimens as possible (Table 2). • 3 cranial linear metrics (interorbital breadth, biorbital breadth, and brow ridge thickness) were also used to assess variation within and among the fossil samples and extant colobine taxa. Background The fossil colobine genus Cercopithecoides is temporally, geographically, and morphologically diverse and is represented at multiple site throughout East and South Africa (Freedman 1957, 1961). There are currently six species recognized from Late Miocene to Pleistocene deposits, with a possible seventh form present at Kromdraai B and Swartkrans in South Africa (Jablonski, 2002; Frost et al., 2003b). This seventh form is distinct from other South African fossil Cercopithecoides by its relatively large size and has been singled out as a possible separate taxon by Delson (1984) and Freedman (1957), who gave the first of these specimens the species name "coronatus” although its generic affiliation has varied. This study focuses on the cranial morphology of C. “coronatus” to both evaluate its affinities with other recognized Cercopithecoides species and assess whether these observed differences are sufficient to warrant separate taxonomic status. TAXON SPECIMEN # SITE C. “coronatus” KB 122(KA 195) Kromdraai B, South Africa C. “coronatus” KB 5241 Kromdraai B, South Africa C. williamsi ER 6000 Upper Burgi, Koobi Fora, Kenya C. kimeui AL 603-1a Upper Kada Hadar, Ethiopia C. kimeui ER 398 Upper Burgi, Koobi Fora, Kenya C. kimeui ER 991 Upper Burgi, Koobi Fora, Kenya C. kimeui Old 068/6514 Olduvai Upper Bed II, Tanzania C. williamsi BF 43 Bolt’s Farm Pit 23, South Africa C. williamsi ER 4420 Upper Burgi, Koobi Fora, Kenya C. williamsi MP3a Makapan Mbr. 3, South Africa C. williamsi SWP 495 Sterkfontein 4, South Africa C. williamsi MP 113 Makapan Mbr. 3, South Africa C. williamsi M3055 Makapan Mbr. 4, South Africa C. haasgati HGD 1166 Haasgat, South Africa TABLE 1 Cercopithecoides specimens included in analyses. C. “coronatus” specimens are in bold FIGURE 1 L-R: C. kimeui holotype O69/6514 calvaria , “C. coronatus” KB 122, and C. kimeui ♀ ER 398 MIDLINE BILATERAL (RIGHT/LEFT) 1. Inion A, C 8./19. Prosthion2 B 2. Bregma A 9./20. Premax-max superior B 3. Glabella A, B 10./21. Zygo-max inferior B, C 4. Nasion A 11./22. Zygo-max superior B 5. Rhinion 12./23. Dacryon B 6. Nasospinale B 13./24. Mid-torus inferior A, B 7. Prosthion B 14./25. Mid-torus superior A, B 30. Opisthion C 15./26. Frontomalare orbitale A, B 31. Basion C 16./27. Frontomalare temporale A, B 32. Staphylion B 17./28. Porion A, B, C 33. Incisivion B 18./29. Zygo-temp superior 34./40. Postglenoid A, C 35./41. Zygo-temp inf 36./42. Distal M3 B, C 37./43. M1–2 contact B, C 38./44. Mesial P3 B, C 39./45. Premax-max inf B, C TABLE 2 Cranial landmark coordinates used . Superscripts indicate points kept to include the following pecimens in PCA and Procrustes distance Analyses: A KB 122, B KB 5241, C ER 6000 (modified from Frost et al., 2003a ). FIGURE 2 C. cf. williamsi “large” specimen KB 5241. This specimen is a suggested “C. coronatus” female FIGURE 3 Top to bottom: Plot of PC1 and PC2 run on Landmark configurations A, B, and C. The color key in configuration A applies to all 3 plots FIGURE 4 Box plots of univariate analyses comparing Cercopithecoides taxa to other fossil forms. Results/Conclusions A PCA conducted on LC A, in order to include the neurocranium of KB 122 (Figure 1), separates C. “coronatus” from other extant African and fossil taxa and plots it closest to C. kimeui (Figure 3). In the PCA on LC B , to include the KB 5241 face (Figure 2), the Cercopithecoides specimens cluster while overlapping with extant Nasalis and Simias (especially C. “coronatus” KB 5241 with Simias; Figure 3). A similar pattern is seen in the PCA on LC C (to include ER 6000), although this configuration includes no c. “coronatus” specimens. Looking at univariate analyses, the box and whisker plots of Cercopithecoides samples reveal that in interorbital breadth, biorbital breadth, and brow thickness, C. “coronatus” falls in the range of both C. kimeui and C. williamsi, with C. haasgati smaller than other Cercopithecoides taxa in all measures except biorbital breadth (Figure 4). The Cercopithecoides taxa also overlap with Rhinocolobus turkanensis in both interorbital breadth and biorbital breadth. A comparison of Procrustes distance ranges on individuals (Figure 5) reveals that Cercopithecoides shows less cranial shape variation within and among samples than is seen for species of extant groups. It is important to note here that only one C. “coronatus” specimen was included in this analysis (KB 5241) and only C. williamsi had specimens complete enough for the within and among analyses. Our analysis further documents the presence of a large species of Cercopithecoides in South Africa similar in cranial size and shape to East African C. kimeui. Further analyses are necessary to determine whether C." coronatus" can be recognized as a distinct species or whether C. kimeui Leakey, 1982 should be recognized as a junior synonym of C. "coronatus". FIGURE 5 Results of a Procrustes distance analysis on individual specimens. The analysis was run on landmark configuration B. PC 2 PC 1 PC 1 PC 2 Procrustes Distances Within Cercopithecoides Among Cercopithecoides Within Extant African Taxa Among Extant African Taxa Within Extant Asian Taxa Among Extant Asian Taxa Rhinocolobus turkanensis P. mutiwa Paracolobus chemeroni Mesopithecus pentelici C. haasgati C. williamsi Cercopithecoides “coronatus” C. kimeui Interorbital Breadth (mm) Biorbital Breadth (mm) Brow Ridge Thickness (mm)