Supporting Information

Silcox et al. 10.1073/pnas.0812140106 SI Text cercus lowii having much smaller optic foramina than diurnal Activity Pattern in Ignacius graybullianus. In living primates with Tupaia glis (5). Bloch and Silcox (5) argued that the very small crania less than 75 mm long, there is a consistent relationship optic foramen size in the plesiadapiform Carpolestes simpsoni between orbit size relative to cranial length and activity period, suggested that it was nocturnal despite its small orbit size. with diurnal forms having smaller orbits than nocturnal ones A measurement of the optic foramen for I. graybullianus has (1–4). This relationship does not hold outside of Primates, with never been published. Although it has been suggested (8) that this foramen may be preserved in UM 65569, our examination of regression lines for ln orbit diameter vs. ln cranial length for photographs of this specimen taken by D. Boyer suggests that it nocturnal and diurnal noneuprimate mammals falling nearly on is too damaged to unambiguously identify the foramina that it top of one another (5) (Fig. S2). Because plesiadapiforms are preserves. The optic foramen is not preserved on the surface of stem primates (6), it is unclear whether or not they exhibit the USNM 421608 (8). However, on the endocast for USNM 421608, same scaling relationships as living members of the order, so roots of the optic nerves can be seen—these represent the casts while I. graybullianus and all other plesiadapiforms that have of the first portion of the optic canal, which should also serve as been measured have relatively small orbits (1, 5) (see Fig. S2), a proxy for the size of the optic nerve. Therefore, the diameters it is not clear that this represents compelling evidence of a of these roots were measured in Amira 3.1.1 (Table 1) and used diurnal activity period. Another measure that scales to some in lieu of the optic foramen to calculate values of optic foramen extent with activity period in living primates is the size of the index (1.82) and optic foramen quotient (–37.65) (2). These optic foramen (2, 7). Diurnal haplorhines in particular have large values fall within the range of diurnal haplorhines (Fig. S3) and optic foramina. A similar relationship holds for a small sample approach the values for Tupaia glis (5), which suggests that I. of other euarchontans, with nocturnal dermopterans and Ptilo- graybullianus was diurnal.

1. Kay RF, Cartmill M (1977) Cranial morphology and adaptations of Palaechthon nacimi- 9. Stephan H, Bauchot R, Andy OJ (1970) in The Primate Brain, eds Noback CR, Montagna enti and other Paromomyidae (Plesiadapoidea, ?Primates), with a description of a new W (Appleton-Century-Crofts, New York), pp 289–297. genus and species. J Hum Evol 6:19–53. 10. Stephan H, Frahm H, Baron G (1981) New and revised data on volumes of brain 2. Kay RF, Kirk EC (2000) Osteological evidence for the evolution of activity pattern and structures in insectivores and primates. Folia Primatol 35:1–29. visual acuity in Primates. Am J Phys Anthrop 113:235–262. 11. Gurche JA (1982) in Primate Brain Evolution: methods and concepts, eds Armstrong E, 3. Heesy CP, Ross CF (2001) Evolution of activity patterns and chromatic vision in primates: Falk D (Plenum, New York), pp 227–246. morphometrics, genetics and cladistics. J Hum Evol 40:111–149. 12. Kielan-Jaworowska Z (1984) Evolution of the therian mammals in the Late Cretaceous of 4. Ni X, Wang Y, Hu Y, Li C (2004) A euprimate skull from the early Eocene of China. Nature Asia. Part VI. Endocranial casts of eutherian mammals. Acta Palaeontol Pol 46:157–171. 427:65–68. 13. Novacek MJ (1982) The brain of Leptictis dakotensis, an Oligocene leptictid (Eutheria: 5. Bloch JI, Silcox MT (2006) Cranial anatomy of Paleocene plesiadapiform Carpolestes Mammalia) from North America. J Paleontol 56:1177–1186. simpsoni (Mammalia, Primates) using ultra high-resolution X-ray computed tomogra- 14. Pirlot P, Kamiya T (1982) Relative size of brain and brain components in three gliding phy, and the relationships of ‘‘plesiadapiforms’’ to Euprimates. J Hum Evol 50:1–35. placentals (Dermoptera; Rodentia). Can J Zool 60:565–572. 6. Bloch JI, Silcox MT, Boyer DM, Sargis EJ (2007) New Paleocene skeletons and the 15. Martin RD (1990) Primate Origins and Evolution (Princeton University Press, Princeton). relationship of ‘‘plesiadapiforms’’ to crown-clade primates. Proc Natl Acad Sci 16. Stephan H (1972) in The Functional and Evolutionary Biology of Primates, ed Tuttle R 104:1159–1164. (Aldine-Atherton, New York), pp 155–174. 7. Kirk EC, Kay RF (2004) in Anthropoid Origins: New Visions, eds Ross CF, Kay RF (Kluwer, 17. Cartmill M (1970). The orbits of arboreal mammals: a reassessment of the arboreal Boston), pp 539–602. theory of primate evolution. PhD dissertation (University of Chicago). 8. Kay RF, Thewissen JGM, Yoder AD (1992) Cranial anatomy of Ignacius graybullianus 18. Kirk EC (2006) Visual influences on primate encephalization. J Hum Evol 51:76–90. and the affinities of the Plesiadapiformes. Am J Phys Anthrop 89:477–498.

Silcox et al. www.pnas.org/cgi/content/short/0812140106 1of10 Fig. S1. Bivariate plots of ln olfactory bulb volume vs. (A) ln intracranial volume and (B) ln body mass for an array of living and fossil mammals. Range of values presented for Ignacius in (B) reflects varying body mass estimates, including confidence intervals (see Table 2). Data from multiple sources (9–15) and the current study (see Table S1). Designation of taxa as ‘‘basal’’ vs. ‘‘progressive’’ insectivores follows Stephan (16), who indicated that the basal forms had relatively primitive cerebral patterns, while the progressive forms ‘‘reveal distinct marks of higher development.’’ Note that while Ignacius falls within the range of variation of euprimates for the volume of the olfactory bulbs relative to body mass, they have relatively larger bulbs relative to brain mass than in any euprimate.

Silcox et al. www.pnas.org/cgi/content/short/0812140106 2of10 Fig. S2. Bivariate plot of ln orbital diameter vs. ln cranial length. Data from multiple sources (2, 4, 5, 17) and the current study. Note that I. graybullianus has a relatively small orbital diameter for its cranial length compared to most modern mammals sampled.

Silcox et al. www.pnas.org/cgi/content/short/0812140106 3of10 Fig. S3. Box plots for optic foramen index (OFI) and optic foramen quotient (OFQ) for I. graybullianus, Carpolestes simpsoni, and select extant euarchontans. OFI and OFQ were calculated following Kay and Kirk (2). The measurement of the stem of the optic nerve from the endocast of I. graybullianus (Table 1) was used as a proxy for optic foramen size. Note that I. graybullianus ’ values for OFI and OFQ are much higher than those calculated for C. simpsoni, falling within the range for diurnal haplorhines, and approaching the values for diurnal Tupaia glis.

Silcox et al. www.pnas.org/cgi/content/short/0812140106 4of10 Fig. S4. Bivariate plot of relative endocranial volume vs. relative optic foramen area, redrawn from Kirk (18), with the addition of data for I. graybullianus. Vertical lines connect multiple estimates of endocranial volumes for the same specimens. Values were calculated as residuals from the following equations, 3/2 3 3 derived from a sample of extant primates (7): Log10(OFA ) ϭ 0.652(Log10PI )-2.698, Log10ECV ϭ 0.942(Log10PI )-3.907 in which OFA ϭ olfactory foramen area, PI ϭ prosthion-inion cranial length, and ECV ϭ endocranial volume.

Silcox et al. www.pnas.org/cgi/content/short/0812140106 5of10 Table S1. Data for Fig. S1 Body mass (g) Total brain volume (net; mm3) Olfactory bulb volume (mm3)

Sorex minutus 5.3 103 8.7 Sorex araneus 10.3 188 14.2 Crocidura russula 11 178 16.4 Crocidura occident 28 408 37.8 Suncus murinus 35 354 34.4 Echinops telfairi 87.5 569 65.7 Hemicentetes semisp. 110 757 93.8 Setifer setosus 243 1,404 210 Tenrec ecaudatus 832 2,336 293 Erinaceus europaeus 860 2,969 350 Aethechinus algirus 700 3,174 297 Solenodon paradoxus 900 4,262 478 Nesogale talazaci 50.4 741 74.6 Limnogale mergulus 92 1,046 43.2 Potamogale velox 660 3,822 87 Neomys fodiens 15.2 299 15.9 Talpa europaea 76 953 60 Galemys pyrenaicos 57.5 1,230 39.2 Desmana moschata 440 3,620 142 Chorotalpa stuhimanni 39.8 693 60.8 Elephantulus fuscipes 57 1,233 63.9 Rhynchocyon stuhimanni 490 5,680 427 Tupaia glis 150 2,959 128 Tupaia minor (2) 70 2,430 94.3 Urogale everetti 275 3,997 186 Microcebus murinus 54 1,663 40.3 Cheirogaleus medius 177 2,941 99.3 Cheirogaleus major 450 6,323 155 Lepilemur ruficaud. 915 7,167 131 Hapalemur simus 1,300 8,868 79.4 Eulemur fulvus 1,400 22,053 229 Varecia variegatus 3,000 29,713 374 Avahi laniger 860 9,075 80.6 Propithecus verr. 3,480 25,080 168 Indri indri 6,250 36,159 142 Daubentonia madagasc. 2,800 42,611 693 Loris gracilis 322 6,269 88.1 Nycticebus cougang 800 11,755 164 Perodicticus potto 1,150 13,212 312 Galago demidovii 81 3,203 84.4 Galago senegalensis 186 4,512 81.8 Galago crassicaudatus 850 9,602 180 Tarsius syrichta 87.5 3,416 18.1 Callithrix jacchus 260 7,248 28.4 Saguinus oedipus 405 10,576 24.6 Saguinus tamarin 340 9,459 16.8 Aotus trivirgatus 850 15,229 60.3 Callicebus moloch 650 14,434 16.8 Pithecia monacha 1,500 32,836 38.2 Alouatta seniculus 6,400 47,749 45.2 Cebus ap. 2,600 68,672 49.6 Cehus albifrons 3,000 75,592 37.2 Saimiri sciureus 680 20,691 25.4 Ateles geoff royi 8,000 101,034 92.6 Lagothrix logotricha 5,200 94,939 83 Macaca mulatta 6,000 87,896 84.3 Cereocebus albigena 7,900 97,603 121 Cercopithecus talapoin 1,000 36,830 22.3 Cercopithecus ascanius 3,600 61,610 96.5 Cereopithecus mitis 6,500 71,505 118 Colobus badius 7,000 73,818 51.3 Pan troglodytes 46,000 396,255 267 Gorilla gorilla 125,000 437,433 294 Homo sapiens 65,000 1,251,847 114

Silcox et al. www.pnas.org/cgi/content/short/0812140106 6of10 Body mass (g) Total brain volume (net; mm3) Olfactory bulb volume (mm3)

Cynocephalus (3) 810 5,781 131 Iomys (3) 119 2,095 44 Glaucomys (3) 50 899 24 Adapis parisiensis (4, 5) 2,350 8,800 267 Notharctus tenebrosus (4, 5) 1,990 10,400 237 Necrolemur antiquus (4, 5) 233 3,800 33 Tetonius homunculus (4, 5) 74 1,500 51 Leptictis dakotensis (6) 700 6,000 1,000 Kennalestes gobiensis (7) 39 299 30 Asioryctes nemegetensis (7) 43.2 454 47 Zalambdalestes lechei (7) 82.69 930 86 Ignacius graybullianus [dental estimate (8)] 375 2,141.288 118.31 Ignacius graybullianus [insectivore equation (9)] 231 2,141.288 118.31 Ignacius graybullianus [generic primate (4)] 286 2,141.288 118.31 Ignacius graybullianus [horizontal primate PGLS 253 2,141.288 118.31 (10)]

Data from Stephan and colleagues (1) unless otherwise noted.

1. Stephan H, Bauchot R, Andy OJ (1970) in The Primate Brain, eds Noback CR, Montagna W (Appleton-Century-Crofts, New York), pp 289–297. 2. Stephan H, Frahm H, Baron G (1981) New and revised data on volumes of brain structures in insectivores and primates. Folia Primatol 35:1–29. 3. Pirlot P, Kamiya T (1982) Relative size of brain and brain components in three gliding placentals (Dermoptera; Rodentia). Can J Zool 60:565–572. 4. Martin RD (1990) Primate Origins and Evolution (Princeton University Press, Princeton). 5. Gurche JA (1982) in Primate Brain Evolution: methods and concepts, eds Armstrong E, Falk D (Plenum, New York), pp 227–246. 6. Novacek MJ (1982) The brain of Leptictis dakotensis, an Oligocene leptictid (Eutheria: Mammalia) from North America. J Paleontol 56:1177–1186. 7. Kielan-Jaworowska Z (1984) Evolution of the therian mammals in the Late Cretaceous of Asia. Part VI. Endocranial casts of eutherian mammals. Acta Palaeontol Pol 46:157–171. 8. Gingerich PD, Smith BH, Rosenberg KR (1982) Allometric scaling in the dentition of primates and prediction of body weight from tooth size in fossils. Am J Phys Anthrop 58:81–100 9. Thewissen JGM, Gingerich PD (1989) Skull and endocranial cast of Eoryctes melanus, a new palaeoryctid (Mammalia: Insectivora) from the early Eocene of western North America. J Vert Paleo 9:459–470. 10. Silcox MT, et al. (2009) Semicircular canal system in early primates. J Hum Evol 56:315–327.

Silcox et al. www.pnas.org/cgi/content/short/0812140106 7of10 Table S2. Body mass, endocranial volumes and encephalization quotient estimates Body mass (g) Endocranial volume (cc) EQ [Jerison (14)] EQ [Eisenberg (15)]

Allenopithecus nigroviridis 4,655 59.07 1.72 2.07 Alouatta palliata 6,250 56.05 1.34 1.58 Alouatta seniculus 5,950 54.84 1.35 1.61 Aotus azarai 1,205 20.67 1.49 1.97 Aotus trivirgatus 775 17.65 1.71 2.34 Arctocebus aureus 210 5.51 1.28 1.92 Arctocebus calabarensis 309 7.02 1.26 1.83 Ateles fusciceps 9,025 116.9 2.18 2.51 Ateles geoffroyi 7,535 109.2 2.30 2.68 Avahi laniger 1,175 9.75 0.71 0.95 Brachyteles arachnoides 8,840 119.4 2.26 2.61 Cacajao melanocephalus 2,935 68.73 2.72 3.39 Callicebus torquatus 1,245 19.49 1.37 1.82 Callimico goeldii 484 11.57 1.53 2.17 Callithrix argentata 345 8.14 1.35 1.96 Callithrix jacchus 321 7.77 1.35 1.97 Cebuella pygmaea 116 4.37 1.51 2.36 Cebus albifrons 2,735 63.36 2.63 3.30 Cebus capucinus 3,110 75.86 2.89 3.59 Cercocebus galeritus 7,435 114.1 2.42 2.83 Cercocebus torquatus 7,485 107.2 2.27 2.65 Cercopithecus cephus 3,585 66.26 2.29 2.82 Cercopithecus mitis 6,090 72.39 1.76 2.08 Cercopithecus petaurista 3,650 58.57 2.00 2.46 Cheirogaleus major 400 5.83 0.88 1.26 Cheirogaleus medius 283 3.24 0.61 0.90 Chiropotes satanas 2,740 56.79 2.35 2.95 Chlorocebus aethiops 3,620 69.77 2.40 2.95 Colobus guereza 8,895 82.95 1.56 1.80 Colobus polykomos 9,100 78.86 1.46 1.69 Daubentonia madagascariensis 2,555 44.87 1.95 2.46 Erythrocebus patas 9,450 94.38 1.71 1.96 Eulemur coronatus 1,655 20.31 1.18 1.53 Eulemur fulvus 2,215 24.75 1.18 1.51 Eulemur macaco 2,440 24.8 1.11 1.40 Eulemur mongoz 1,620 20.82 1.23 1.60 Eulemur rubriventer 1,960 26.33 1.37 1.75 Euoticus elegantulus 274 5.85 1.13 1.67 Galago alleni 273 5.85 1.14 1.68 Galago matschiei 210 4.73 1.10 1.64 Galago moholi 180 3.83 0.98 1.49 Galago senegalensis 213 4.65 1.07 1.60 Galagoides demidoff 62 2.72 1.43 2.33 Galagoides zanzibaricus 143 3.52 1.06 1.63 Gorilla gorilla 121,000 491.3 1.61 1.55 Hapalemur griseus 945 13.77 1.16 1.57 Hapalemur simus 1,725 29.83 1.69 2.18 Hylobates klossii 5,795 88.84 2.23 2.65 Hylobates lar 5,620 101.5 2.60 3.10 Hylobates syndactylus 11,300 128.4 2.06 2.34 Indri indri 6,335 36.58 0.86 1.02 Lagothrix lagotricha 7,150 100.9 2.20 2.58 Lemur catta 2,210 23.79 1.14 1.45 Leontopithecus chrysomelas 578 11.98 1.41 1.97 Leontopithecus rosalia 609 13.04 1.48 2.06 Lepilemur leucopus 606 6.85 0.78 1.09 Lepilemur mustelinus 777 9.56 0.92 1.26 Lophocebus albigena 7,135 95.71 2.09 2.45 Lophocebus aterrimus 6,800 104.7 2.36 2.78 Loris tardigradus 193 5.69 1.40 2.11 Macaca fascicularis 4,475 68.7 2.05 2.48 Macaca nemestrina 8,850 109.1 2.06 2.38 Mandrillus sphinx 22,250 162.1 1.65 1.79 Microcebus murinus 61 1.66 0.88 1.44

Silcox et al. www.pnas.org/cgi/content/short/0812140106 8of10 Body mass (g) Endocranial volume (cc) EQ [Jerison (14)] EQ [Eisenberg (15)]

Microcebus rufus 43 1.63 1.09 1.83 Miopithecus talapoin 1,250 41.34 2.90 3.84 Mirza coquereli 315 5.81 1.03 1.50 Nasalis larvatus 15,110 96.05 1.27 1.41 Nycticebus coucang 653 10.27 1.11 1.54 Nycticebus pygmaeus 307 7.23 1.30 1.90 Otolemur crassicaudatus 1,150 10.82 0.80 1.07 Otolemur garnettii 764 10.87 1.06 1.45 Pan troglodytes 38,200 400.9 2.84 2.96 Papio anubis 19,200 171.1 1.92 2.10 Papio cynocephalus 17,050 186.6 2.27 2.51 Perodicticus potto 1,230 12.68 0.90 1.19 Phaner furcifer 460 6.47 0.89 1.26 Pithecia pithecia 1,760 34.97 1.95 2.52 Pongo pygmaeus 57,150 384.1 2.08 2.11 Presbytis comata 6,700 72.79 1.66 1.95 Presbytis frontata 5,620 81.02 2.08 2.47 Presbytis geei 10,150 97.89 1.69 1.93 Presbytis melalophos 6,530 66.22 1.53 1.81 Procolobus badius 8,285 70.69 1.40 1.62 Propithecus diadema 6,100 40.06 0.97 1.15 Propithecus verreauxi 3,990 26.8 0.86 1.05 Pygathrix nemaeus 9,720 88.2 1.57 1.80 Pygathrix roxellana 14,750 114.4 1.54 1.71 Saguinus fuscicollis 351 7.83 1.29 1.86 Saguinus leucopus 492 9.33 1.22 1.73 Saguinus midas 545 9.65 1.18 1.66 Saimiri oerstedii 789 25.96 2.48 3.39 Saimiri sciureus 721 27.5 2.79 3.84 Semnopithecus entellus 11,450 103.7 1.65 1.87 Simias concolor 7,975 59.09 1.20 1.39 Tarsius bancanus 123 3.24 1.07 1.67 Tarsius spectrum 117 3 1.03 1.61 Tarsius syrichta 126 3.46 1.13 1.76 Theropithecus gelada 15,350 131.8 1.72 1.91 Trachypithecus cristatus 6,185 64.88 1.56 1.85 Varecia variegata 3,490 32.25 1.14 1.40 Meniscotherium (2) 8,013.5 12 0.24 0.28 Coryphodon (2) 135,433 73 0.22 0.21 Phenacodus (2) 52,833 35 0.20 0.20 Arctocyon (2) 35,285.5 37 0.28 0.29 Leptolamba (2) 198,813 84 0.20 0.18 Arctocyonides (2) 4,667 12 0.35 0.42 Pantolambda (2) 14,343 24.5 0.33 0.37 Titanoides (2) 170,116.5 80 0.21 0.20 Kennalestes gobiensis (3) 39 0.299 0.21 0.36 Asioryctes nemegetensis (3) 43.2 0.5 0.33 0.56 Zalambdalestes lechei (3) 82.69 1.02 0.44 0.71 Ptilodus montanus (2) 200 1.09 0.26 0.39 Pleuraspidotherium (2) 3,300 6 0.22 0.27 Hyopsodus (2) 630 3.2 0.36 0.49 Barylambda (2) 620,000 102 0.11 0.10 Tetheopsis (2) 2,500,000 350 0.15 0.12 Thinocyon (2) 800 5.7 0.54 0.74 Cynohaenodon (2) 3,000 8.3 0.32 0.40 Pterodon (2) 42,000 62 0.41 0.43 Adapis parisiensis (4) 2,350 8.8 0.40 0.51 Leptadapis magnus (4) 9,500 21.7 0.39 0.45 Pronycticebus gaudryi (4) 1,220 4.8 0.34 0.45 Notharctus tenebrosus (4) 1,990 10.4 0.53 0.68 Smilodectes gracilis (4) 1,960 9.5 0.49 0.63 Necrolemur antiquus (4) 233 3.8 0.82 1.22 Tetonius homunculus (4) 74 1.5 0.70 1.13 Rooneyia viejaensis (4) 782 7.4 0.71 0.97 Aegyptopithecus zeuxis (4) 6,710 34.4 0.78 0.92

Silcox et al. www.pnas.org/cgi/content/short/0812140106 9of10 Body mass (g) Endocranial volume (cc) EQ [Jerison (14)] EQ [Eisenberg (15)]

Parapithecus grangerib (4, 5) 961.39 11.4 0.95 1.29 Catopithecusb (4, 6) 281.86 3.1 0.59 0.87 Proconsul africanus (4) 10,500 167 2.81 3.21 Mioeuoticus sp. (4) 1,280 7.8 0.54 0.71 Oreopithecus(7, 8) 17,541 200 2.39 2.63 Chilecebus(9) 583 7.46 0.87 1.22 Plesiadapis cookei (10) 2,200 5 0.24 0.31 Ignacius graybullianus [dental estimate (11)] 375 2.14 0.34 0.48 Ignacius cranial [insectivore equation (12)] 231 2.14 0.47 0.69 Ignacius cranial [horizontal primate PGLS 253.47 2.14 0.44 0.65 equationn (13)] Ignacius cranial [generic primate equation (4)] 286.45 2.14 0.40 0.59 Ignacius body mass upper bounda 460 2.14 0.29 0.42 Ignacius body mass lower bounda 140 2.14 0.65 1.01

Modern primate endocranial volumes from Kirk (1); fossil data from multiple sources as indicated. aSee Table 2. bRef. (4) for body mass estimate from cranial length, primate equation.

1. Kirk EC (2006) Visual influences on primate encephalization. J Hum Evol 51:76–90. 2. Radinsky LB (1978) Evolution of brain size in carnivores and ungulates. Am Nat 112: 815–831. 3. Kielan-Jaworowska Z (1984) Evolution of the therian mammals in the Late Cretaceous of Asia. Part VI. Endocranial casts of eutherian mammals. Acta Palaeontol Pol 46:157–171. 4. Martin, RD (1990) Primate Origins and Evolution (Princeton University Press, Princeton). 5. Bush EC, Simons EL, Dubowitz DJ, Allman JM (2004) in Anthropoid Origins: New Visions, eds Ross CF, Kay RF (Kluwer, Boston), pp 603–614. 6. Simons EL, Rasmussen DT (1996) The skull of Catopithecus browni, an early Tertiary catarrhine. Am J phys Anthrop 100:261–292. 7. Szalay FS, Berzi A (1973) Cranial Anatomy of Oreopithecus. Science 180:183–185. 8. Conroy GC (1987) Problems of body-weight estimation in fossil primates. Int J Primatol 8:115–137. (Only used for a body mass of Oreopithecus.) 9. Sears KE, Finarelli JA, Flynn JJ, Wyss AR (2008) Estimating body mass in New World ‘‘monkeys’’ (Platyrrhini, Primates), with a consideration of the Miocene platyrrhine, Chilecebus carrascoensis. Am Mus Novit 3617:1–29. 10. Gingerich PD, Gunnell, GF (2005) Brain of Plesiadapis cookei (Mammalia, Proprimates): surface morphology and encephalization compared to those of Primates and Dermoptera. Contributions from the Museum of Paleontology, University of Michigan 31:185–195. 11. Gingerich PD, Smith BH, Rosenberg KR (1982) Allometric scaling in the dentition of primates and prediction of body weight from tooth size in fossils. Am J phys Anthrop 58:81–100 12. Thewissen JGM, Gingerich PD (1989) Skull and endocranial cast of Eoryctes melanus, a new palaeoryctid (Mammalia: Insectivora) from the early Eocene of western North America. J Vert Paleo 9:459–470. 13. Silcox MT, et al. (2009) Semicircular canal system in early primates. J Hum Evol 56: 315–327. 14. Jerison HJ (1973) Evolution of the Brain and Intelligence, (Academic Press, New York). 15. Eisenberg JF (1981) The Mammalian Radiations: an Analysis of Trends in Evolution, Adaptation, and Behavior, (University of Chicago Press, Chicago).

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