AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 69:441-464 (1986)

Miocene Fossil Cercopithecoids From Kenya BRENDA R. BENEFIT AND MARTIN PICKFORD Department of Anthropology, New York Uniuersity, New York, New York 10003; and National Museums ofKenya, Nairobi, Kenya (B. R.B.); Johannes Gutenberg Uniuersitat, Department of Palaeontology, Institut f i r Geowissenschaften, FB 2,0-6500 Mainz 1, West Germany (M.W

KEY WORDS Ngeringerowa, Victoriupithecus, Mandible, Dentition

Colobine, Fossil, Miocene, Microcolobus,

ABSTRACT Fossil cercopithecoid material from Ngeringerowa, Ngorora, and Nakali, dated at between 8.5 and 10.5 m.y., is described. The specimens are the only cercopithecoid remains dated between 15 and 6 m.y. from sub- Saharan Africa. The mandible of a small colobine from Ngeringerowa (similar in size to Colobus uerus) is assigned to a new genus and species, Microcolobus tugenensis. Unlike other colobine genera, the symphysis of Microcolobus lacks an inferior transverse torus. A colobine lower MI or 2 from Nakali is longer and narrower than molars of M. tugenensis, indicating that it may belong to a distinct taxon. A P4 from Ngorora cannot be assigned confidently to subfamily, due to its unique metaconid morphology. The relationship between the new genus and other Miocene monkeys is considered.

The discoveries of an almost complete man- dible from Ngeringerowa and a lower molar from Nakali, Kenya, both dated at between 8.5 and 10.5 m.y., provide the oldest known evidence of fossil Colobinae from Africa. Since Ngeringerowa and Nakali are proba- bly older than Pikermi (the type site of Me- sopithecus (Gaundry, 1862)) and Marceau (where remains of ?Colobus flundrini have been recovered (Delson, 197511, it is likely that the Kenyan specimens are the oldest known colobines. Apart from a lower fourth premolar from Ngorora, which cannot be as- signed unequivocally to either Colobinae or Cercopithecinae, they are the only monkeys known between 15 and 7 m.y., with the pos- sible exception of a lower third molar of ?Mu- cuca (Delson, 1975) or ?cf.Macucu cq. Mesopithecus (Hooijer, 1963) from Ongoliba, which may be of Middle or Late Miocene age. Although the new material is scanty, the mandible from Ngeringerowa is complete enough to provide sufficient diagnostic char- acters for its generic and specific assignment. Comparison of the Ngeringerowa specimen with Mesopithecus and other fossil colobines demonstrates that it is not only smaller, but is also sufficiently distinct in mandibular morphology to warrant its placement into a separate genus. Material from Ngeringe- rowa and Nakali have been mentioned

briefly by Simons and Delson (1978), Szalay and Delson (19791, and Leakey (19821, but have not yet been described. This paper pro- vides descriptions of these Late Miocene Af- rican colobines and information concerning their geological context. Comparisons of the new material with other fossil and extant colobines are made.

MATERIALS AND METHODS

The specimens discussed here are com- pared to African and Eurasian fossil Colobi- nae housed at the National Museums of Kenya, Nairobi; Laboratoire de Paleontolo- gie, Museum National d'Histoire Naturelle, Paris; and the Bayerische Staatssamlung fur Palaeontologie, Munich. All Mesopithecus specimens examined were collected at Pi- kermi. The specimens are also compared to extant monkeys housed at the American Mu- seum of Natural History, New York, the Sen- kenbergische Museum, Frankfurt, and the Museum of Vertebrate Zoology, Berkeley. The majority of extant monkeys sampled are medium-sized species. Modern dental speci- mens were measured if dentine exposed on

Received November 26,1984; revision accepted September 12, 1985.

0 1986 ALAN R. LISS, INC.

442 B.R. BENEFIT AND M. PICKFORD

the protoconid and hypoconid was distinct, rather than joined, as occurs in more ad- vanced stages of wear. Breadths and lengths of isolated teeth were measured with a ver- nier caliper accurate to 0.05 mm. Angles be- tween cusps, which are referred to in the descriptions, were measured from camera lu- cida drawings of each tooth. Angles between metaconid and entoconid are taken from the lingual perspective, and between protonocid and hypoconid from the buccal perspective. Angles formed by the protolophid and hypo- lophid are taken from the posterior view. All other measurements and lengths of teeth in jaws were taken with the aid of a calibrated reticle mounted to a Wild stereoscopic micro- scope. The list of measurements are as foiiows:

L

B

MB

DB

CH

NR

NC

MSL

The maximum mesiodistal length of the crown taken from the buccal side (molars, premo- lars) or labial side (incisors, canines).

Maximum labial-lingual width of the crown (incisors, canines, and premolars).

Maximum buccolingual width of the crown between the mesial pair of cusps (molars).

Maximum buccolingual width of the crown between the distal pair of cusps (molars).

Maximum height of the meta- conid from its tip to the cervix directly below (molars).

Maximum height of the crown from the base of the lingual notch to the cervix directly below (molars).

Maximum height of the meta- conid from the base of the lingual notch to the tip of the cusp, mea- sured perpendicular to the occlu- sal margin (molars).

Maximum distance between the metalophid at its lowest point and the mesial margin (molars).

Indices are calculated to eliminate some of the size bias resulting from the comparison of medium- to smaller-sized teeth, and to elu- cidate important relationships between structures of the crown. They are computed as follows:

NC/NR NC/NR x 100

NCMB NC/MB x 100 NCL N C L x 1 0 0 NRMB NRMB x 100 NR/L NR/L x 100 NWCH NWCH x 100 L/MB L M B x 1 0 0 MSLL MSLL x 100

The mandibles of a wide variety of extant and fossil colobine species were surveyed, but only two individuals of each sex were mea- sured, with the exception of Colobus uerus and Rhinopithecus roxellanae, for which the sample size is smaller. Because of the small sample size per species, standard deviations are not included in Table 2. Such measures of variation await further study. All mea- surements, with the exception of the angle of the planum alveolare, were measured with a caliper. The angle between the planum al- veolare and the alveolar surface of the corpus was measured from drawings made of the symphysis and corpus. Due to difficulties en- countered drawing the symphysis of com- plete mandibles, the measurement is con- sidered an approximation. The remaining measurements are as follows:

LM

LI-M

CDMl

CDM2

CDM3

Maximum length of the molar row between the distal aspect of the M3 and the mesial aspect of MI, measured from the buccal side. Maximum length of the dental ar- cade, measured perpendicular to a line connecting the distal as- pects of the M3s on both sides, from the midpoint of that line to the labial aspect of the first incisors. Maximum height of the corpus, measured perpendicular to the al- veolar plane on the buccal side, from the alveolar surface be- tween the roots of MI to the infe- rior border of the corpus directly below. Maximum height of the corpus, measured perpendicular to the al- veolar plane on the buccal side, from the alveolar surface be- tween the roots of Mz to the infe- rior border of the corpus directly below. Maximum height of the corpus, measured perpendicular to the al- veolar plane on the buccal side,

MIOCENE FOSSIL CERCOPITHECOIDS 443

from the alveolar surface be- tween the roots of M3 to the infe- rior border of the corpus directly below.

The following indices are computed in or- der to evaluate the depth of the corpus rela- tive to the length of the jaw, and the evenness of its height:

I2 CDM2LM x 100 I2 CDM2LI-M x 100 I3 CDMUCDM3 x 100

Results of the mandibular measurements and indices are presented in Table 2, and of the dental analysis in Tables 3-5.

GEOLOGICAL CONTEXT

Ngeringerowa lies to the west of Lake Bar- ingo in Kenya (Fig. 1). The strata a t Ngerin- gerowa are more than 135 m thick (Fig. 2). The Tiim Phonolites, which were deeply weathered prior to being covered by the Ngeringerowa beds, have been radioisotopi- cally dated a t ca. 12 m.y. (Chapman and Brook et al., 1978). The Ewalel Phonolite, which caps the sequence at Ngeringerowa, has been dated at about 8.25 m.y. (Chapman and Brook, 1978).

A Fig. 1. A. Locality map of 1, Ngorora;Z, Ngeringe-

rowa; 3, Nakali. B. Geological sketch map of Ngeringe- rowa. 1-8; sites l / l O O l t o 1/1008. A-B; Location of type section; division between upper and lower

Bishop and Pickford (1975) and Pickford (1978) originally correlated the strata at Ngeringerowa with Members D and E of the Ngorora Formation based on lithologic simi- larities between the two areas and their po- sition between the Tiim and Ewalel phono- lites. The presence of Hipparion cf. primigen- ium and Nyanzachoerus sp. at Ngeringe- rowa, the former of which is present only in Member E of the Ngorora type area, indi- cates that the Ngeringerowa fauna is younger than Members A-D of the Ngorora Foramation in the type area of Kabersero (Bishop et al., 1971). A local name is here assigned to the Ngeringerowa strata to avoid further confusion of the two heterochronous units.

Faunal evidence indicates that Ngeringe- rowa is somewhere between 8.5 and 10.5 m.y. The particular stratum from which the colo- bine jaw came (Fig. 2) yielded a small sample of vertebrate fossils belonging to 17 taxa (Ta- ble 1) of which 12 are large mammals. Of the 26 taxa known from Fort Ternan (ca. 14 m.y., Faunal Set IV of Pickford, 1981; Figure 3) five occw at Ngeringerowa, three of which are common at the generic level. The faunal resemblance between Ngorora (ca. 11 m.y., Faunal Set V) and Ngeringerowa is some-

beds; A fault with throw in metres; f i strike and dip of strata in degrees;’.lephermeral stream; 4/ permanent stream; --- track.

Fossil

Small

120

Fossil fish

100 wood

90

80

turtles

70

111004 111007

60

Mammals 111005 - _ -

OJ Metres

Poorly exposed silty & pumice tu f f

Well-bedded gritty green tuff

Phonol ite conglomerate 20cm yellow silt

Green tuffs forming prominent cliff

Interbedded silt and conglomerate

Green sandy tuf f

Phonolite conglomerate Green silty tuff - forms cliff Grey silt with pumice

Green shaley tuff forming prominent cliff 1 lcm persistent white-pink limestone band - - - - - - Grey to pink silt : mudballs near top Grey cross-bedded sandstone with grit and pumice lenses Grey, pink and white shaley silts with brown tossilif erous li mestone Grit Gre silt Brigit green shale Grey to pink silts with hardpan horizon

Red to green bouldery silt (?mudflow)

i

m a m

a

Grey silts with pebble-filled channel w

w Red cross-bedded sandy grit: forms cliff

Grey pumiceous silts with red shale horizon

- ---Beach deposit rich in gastropods 8 pumice

Red cross-bedded silts 8, sands with shale cap Grey silts wi th red coprolites Grey shales with compressed pumices: forms dipslope Red cross-bedded sand with grit lenses Red to grey cross-bedded silt and sand Angular phonolite conglomerate Grey ripple-marked shale Hard grey cross-bedded grit

Base not exposed

TYPE SECTION NGERINGEROWA BEDS

Fig. 2. Type section of Ngeringerowa beds showing fossiliferous localities. 111005--Micr@ colobus tugenensis type locality.

TAB

LE

1.

Larg

e

mam

mal

faun

as

from

Ngo

rora

,

Nak

ali,

and

Nge

ring

erow

a

Ngo

rora

A-D

Ngo

rora

Upp

er

E

Nak

ali

Nge

ring

erow

a

-

-

-

Hom

inoi

dea

larg

e

sp. X

Hom

inoi

dea

smal

l

sp. X

Cer

copi

thec

oide

a

inde

t.

X

Col

obin

ae

sp.

-

-

Mic

roco

lobu

s

tuge

nens

is

-

-

-

Agn

othe

rium

sp. X

Eom

elliv

ora

sp. X

Siua

onyx

sp. X

Perc

rocu

ta

tobi

eni

X

Can

idae

smal

l

sp. X

Ory

cter

opus

chem

eldo

i

X

Cho

erol

opho

don

ngor

ora

X X ?

Tetr

alop

hodo

n

sp. X

Dei

noth

eriu

m

sp.

cf.

boza

si

X

- X X

Par

aplio

hyrm

sp.

. X X

Hip

pari

on

prim

igen

ium

- X X X

Chi

loth

erid

iun

patte

rson

i

X

Ace

rath

eriu

m

or

Dic

eror

hinu

s

X

Brac

hypo

ther

ium

cf.

lew

isi

X

Ken

yath

eriu

m

bish

opi

-

- X

-

?Con

ohyu

s

sp. X

Nya

nzac

hoer

us

sp.

-

Loph

olis

trw

don

kido

gosa

na

X

Tay

assu

idae

X

Ken

yapo

tam

us

cory

ndon

i

X X

-

Ken

yapo

tam

us

sp.

-

- X

-

Dor

cath

eriu

m

cf.

pigo

tti

X

- X

Pal

amtr

agus

prim

aevu

s

X X ? X

?Sam

othe

rium

sp. X

Clim

acoc

eras

gent

ryi

X

Prot

rago

ceru

s

labi

dotu

s

X

Sivo

reas

erem

ita

X

?Hippotraginae/?Reduncini

-

Hom

oiod

orca

s

tuge

nium

X

?A

ntid

orca

s

X

-

Pseu

dotr

agus

?

gent

ryi

X X

Pach

ytra

gus

aff.

solig

naci

X

-

-

-

-

-

-

- X

X

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

- X

X

-

-

-

-

-

-

X

-

-

-

-

-

-

-

-

-

-

X

- X

X

- X

-

-

-

-

-

-

-

-

-

-

X,

pres

ence

;

-,

abse

nce.

446 B.R. BENEFIT AND M. PICKFORD

Fig, 3. Biostratigraphy of Middle and Late Miocene sites of East Africa.

what stronger with seven of the 28 taxa from Ngorora occurring at Ngeringerowa, six of which are shared at the generic level and one at the subfamily level. Of the 22 taxa known from Lukeino (ca. 6.5 m.y., Faunal Set VIU five of the genera occur at Ngerin- gerowa, and two higher taxa are also shared. The Ngeringerowa fauna can therefore be placed between Faunal Sets V and VII, some- where between 6.5 and 10.5 m.y. Martin Pickford (M.P.) ascribes to the view that the age of the Ngeringerowa beds is closer to 10.5 m.y. based on the presence of the bovid Siue reas eremita, a primitive species of Nyanza- choerus, and Hipparion primigenium, rather than H. turkanense or H. sitifense, which oc- cur at Lukeino and Lothagam (Hooijer, 1975).

Ngeringerowa is probably closest in age to early Vallesian deposits of Europe and is likely to be appreciably older than Pikermi, which has yielded Mesopithecus. The limited and largely endemic fauna at Ngeringerowa renders comparison with Eurasian faunas difficult. Equivalence with the lower parts of the Nagri unit of the Siwaliks of Pakistan, the Hipparion s.h interval zone of Barry et al. (1982) (9.5-7.4 m.y.), is suggested by the presence of Hipparion primigenium and Si- voreas eremita. Ngeringerowa probably pre- dates colobine-bearing deposits at Maragheh and Moloyan (Heinz et al., 1981) as well as the upper part of the Selenoportax lydekkeri Siwalik interval zone of Barry et al. (1982) (7.4-5.3 m.y.), which has yielded the colobine Presbytis sivalensis.

Much of the Ngeringerowa sequence is flu- vio-lacustrine in origin. Most of the mammal remains are weathering out of reddened clays and silts representative of floodplain or lake margin sedimentation. The presence of shales as well as of fish and turtle remains is indic- ative of aquatic episodes in the depositional history of the area, but the development of several paleosol profiles attests to subaerial exposure from time to time. The bed in which the colobine mandible was found in situ con- sists of a silty, pumice-lapilli-rich horizon abundant with remains of the freshwater gastropod Melanoides tuberculata. The bed also has a marked similarity to mollusc-rich beach deposits accumulating today on the margins of Lakes Baringo and Victoria.

The lower molar from Nakali was discov- ered by Meave Leakey in 1978. On biostrati- graphic grounds Pickford (1981) placed these beds at between 8.5 and 9 m.y. The Ngorora premolar was found in channel grits a t local- ity 211, Ngorora type area, in 1972 by M.P. These beds are estimated to be 11 m.y. (Pick- ford, 1981).

SYSTEMATIC DESCRIPTION

Superfamily Cercopithecoidea Gray, 1821 Family Cercopithecidae Gray, 1821 Subfamily Colobinae Jerdon, 1867 Genus Microcolobus gen. nov. Type species Microcolobus tugenensis sp.

nov.

GENERIC DIAGNOSIS

Microcolobus is slightly smaller than Cole bus uerus and Presbytis obscurus. Unlike all other colobine genera, the symphysis lacks

MIOCENE FOSSIL CERCOPITHECOIDS 447

an inferior transverse torus below the gen- ioglossal fossa and above the area of inser- tion of the digastric muscles. Instead the bone slopes smoothly below the genioglossal fossa, inferodistally, to the inferior border of the symphasis. Unlike Mesopithecus, Nasalis, and Rhinopithecus, the buccal aspects of the mandibular corpus is only slightly inflated laterally, with no exaggeration in the degree of inflation inferiorly, below the M3 (Fig. 4). The corpus deepens posteriorly as in all colo- bines. The planum alveolare resembles Col- obus in being somewhat long and steeply sloping. No median symphyseal foramen is present. Unlike many colobine genera the P g s possess a well-developed heel distally (Fig. 5).Unlike Mesopithecus, no P3 mesiolin- gual sulcus occurs in Microcolobus. The P4 metaconid and protoconid are of almost equal

0 0.5 I 2 ern - Fig. 4. Mandible of Microcolobus tugenensis, KNM-

BN 1740, anterior and right lateral views.

BUCCAL

LINGUAL

Q 0.5 I 2 cm

Fig. 5. Occlusal, lingual, and buccal views of Micre colobus tugenensis dentition, KNM-BN 1740.

height, as in most African fossil colobines, but unlike Colobus. Molars are characterized by tall and anteriorly directed cusps, and deep lingual notches, typical of Colobinae. MI and Mz cusp height above the base of the lingual notch is lower than in many colo- bines. Unlike Mesopithecus the median buc- cal cleft is well defined and flat at its base, lacking a cingulumlike distal extension from its floor.

Microcolobus tugenensis sp. nov. Specific diagnosis: same as for the genus

Holotype KNM-BN 1740 is an almost complete man-

dible, broken behind the M3 on both sides, thereby lacking both rami and gonial angles. Only the right canine is missing from the

448 B.R. BENEFIT AND M. PICKFORD

full set of permanent lower dentition. The left canine, belonging to the same individual, was found outside its alveolus, in matrix sur- rounding the bone. Its position in the jaw is allocated by reference to its perfect fit in the canine alveolus. The mandible is warped on the left side due to the postmortem damage. The height of the canine and length of the P3 honing facet indicate that the specimen is probably female.

Horizon and locality Late Miocene, Locality 1/1005, Ngeringe-

rowa, Tugen Hills, Kenya.

Etymology Microcolobus denotes its small size. Tuge-

nensis is derived from the Tugen Hills where the specimen was found.

MORPHOLOGICAL DESCRIPTION Mandible

Description: The antero-labial surface of the corpus drops vertically below the incisors to a level approximately two-fifths of the total depth of the mandible. Below this level the bone continues inferiorly and distally at an angle 35" to the original vertical drop. The antero-inferior border is of subequal depth to the main body of the corpus. The surface of the bone between the incisors and the level where it angles distally has a roughened appearance in contrast to the bone inferior to it. The roughened surface follows the contour of the mandible where there is an abrupt change from the anterior to the lateral sides of the corpus, giving the impression that a line exists, extending from below the root of 12 to the inferior border of the corpus below MI. This line borders the anterior portion of the lateral prominence. The mental foramen is located on this line, inferior to the P4. The corpus is gently concave below the P4 to MI. Beneath the M2 and M3 the corpus is slightly inflated. On the right side a small portion of bone preserved behind the M3 demonstrates that the ramus ascended immediately behind the M3 hypoconulid and that below the same point the corpus begins to deepen.

Lineally, the planum alveolare of the symphysis extends distally and inferiorly a t an angle of 35" to the alveolar surface of the lateral corpus. At a position inferior to the middle of P3, the symphysis curves abruptly downward and mesially to form a large genioglossal fossa. Below this fossa there is a smooth transition in the profile of the bone,

inferodistally to the inferior border a t an angle of 45" to the lateral alveolar surface.

The buccal edge of the dental arcade is bowed gently outward, with the Mzs being furthest apart. From the buccal perspective, the alveolar surface beneath the postcanine teeth appears to be slightly concave, with the distal root of the MI and the mesial root of the Mz being at the lowest point. The occlusal surface of the buccal cusps parallels this concavity.

Comparison: The mandible of Microcolobus is slightly deeper below M3 than below MI (Table 2, Fig. 6). Measurements taken on a comparative sample of cercopithecoids housed at the National Museum of Kenya and the American Museum of Natural History demonstrate that this is a characteristic feature of colobines. In cercopithecines, with the exception of Cercocebus, corpus depth increases anteriorly. The ratio of serpus depth below M1 to its depth below M3 (Index I3 of Table 2) for Microcolobus is similar to those of Colobus, Rhinopithecus, Nasalis, and Meso- pithecus, rather than to those of Presbytis and Simias concolor, in which deepening below M3 is more pronounced.

Depth of the corpus below Ma, relative to the length of the molar row and to the tooth row (Indices 11 and 12 of Table 21, did not clearly separate Colobinae from Cercopithe- cinae. The corpus of the female specimen of Microcolobus is only moderately high to shallow and compares well with females of Colobus guereza kikuyuensis, C. badius powelli, C. badius badius, and Presbytis rubicunda.

No median symphyseal foramen is present. Among cercopithecoids this foramen is found in all cercopithecines, but among colobines only occurs in the taxa Cercopithecoides, Rhinocolobus, and Colobus uerus (Leakey, 1982). Absence of the foramen in Microcolobus clearly aligns the genus with Colobinae.

Microcolobus has no inferior transverse torus. In colobines this structure is normally located above a large area for the insertion of the anterior belly of M. digastricus at the inferior border of the symphysis and below the genioglossal fossa. The absence of such an inferior transverse torus was observed in one subspecies of Colobinae, Colobus guereza kikuyuensis, in addition to Microcolobus. Cer- copithecines, with the exception of Cer- cocebus, normally lack this feature. Ab- sence of the feature is unlikely to be size re- lated since it is found among both large and

MIOCENE FOSSIL CERCOPITHECOIDS

- - DISTAL 0 I 2 3 4 5 m m

DISTAL

LINGUAL BUCCAL

0 1 2 3 4 5 m m MESIAL - - -

MESIAL

LINGUAL BUCCAL

449

Fig. 6. Occlusal, lingual, and buccal views of colobine MI from Nakali, KNM-NA 305 (above), and P4 from Ngorora, KNM-BN 1251 (below).

TAB

LE

2.

Man

dibu

lar

ni

easu

rern

en

ts

Soec

ies

Mic

roco

lobu

s tu

genm

sis

Mes

opith

ecus

pe

ntel

ici

Col

obus

ve

rus

C.

guer

eza

kiku

yuen

sis

C.

guer

eza

uell

ensi

s

C.

pdyk

omos

sa

tanu

s

C.

poly

kom

os

ango

lmsi

s

C.

badi

us

powelli

C.

badi

us

thol

loni

C.

hadi

us

teph

rosc

eles

C.

badi

us

badius

C

badi

us

lang

i C.

kirk

ii

Rhi

nopi

ther

us

roxe

llann

e

Sex

~

F M

F

M

F

M

F M

F

M

M

F M

F

F F

F

M

F M

F

F

LM

LI-M

CD

M,

CD

M.,

CD

M,?

ST

17.7

23

.6

23.0

17

.4

17.5

24

.5

24.1

23

.7

23.6

21

.7

26.7

21

.1

23.6

23

.6

23.4

20

.5

24.1

22

.0

20.3

22

.4

20.4

28

.3

33.4

-

-

38.1

36

.7

48.7

47

.1

50.1

48

.3

45.1

53

.2

-

47.5

47

.0

46.1

40

.Y

45.1

45

.0

41.2

-

-

47.9

13.8

20

.5

18.5

14

.2

14.3

20

.3

19.1

21

.8

20.5

19

.2

22.4

18

.8

19.5

18

.1

15.2

17

.4

17.5

17

.2

13.8

24

.0

15.9

19

.6

13.2

20

.7

18.2

14

.4

14.5

21

.3

18.4

21

.2

19.4

18

.9

22.1

18

.5

18.8

17

.8

14.6

16

.9

17.6

17

.0

14.5

24

.3

15.7

18

.8

14.9

23

.1

22.8

15

.3

14.2

21

.3

19.4

21

.8

20.7

20

.4

23.8

21

.3

20.1

19

.5

15.5

17

.9

18.8

18

.7

16.4

23

.7

17.3

20

4

3 5 -

-

35

45

31

29

38

40

33

37

-

29

35

19

41

20

31

24

-

-

29

75

87

79

88

83

87

76

89

83

87

83

88

80

75

62

82

73

77

71

108

77

66

12

~~

39

-

-

43

40

44

40

42

40

42

42

-

40

3 8 3 2

41

39

88

3 5 -

-

39

-

1,

93

89

81

93

10

1

95

98

100

99

Y4

94

88

97

93

98

97

93

92

84

101

92

96

Nas

alis

la

ruat

us

Sirn

ias

conc

olor

P

resh

ytis

se

nex

l?

rubi

cuud

u

i?

fron

tatu

s

i?

john

ii

l?

rnel

alop

hus

P

cris

tafir

s

P

pote

nzia

nai

Cer

coce

hus

gale

ritu

s

C.

albi

genu

C

erco

pith

ecus

ae

thio

ps

Mac

aca

mau

ra

M.

nern

estr

ina

M.

fusc

icul

aris

fa

scic

ular

is

M.

fasc

icul

aris

rnor

dax

M

F M

F

M

F

M

F M

M

F

M

F

M

F

M

F

M

F

M

F M

F

M

F M

F

M

F

M

l7

24.8

25

.4

22.0

22

.1

21.1

20

.3

18.3

18

.2

17.7

21

.6

22.4

18

.2

18.6

20

.0

18.8

21

.0

20.9

22

.8

23.5

22

.6

22.4

18

.7

17.5

31

.7

25.7

27

.2

27.5

22

.5

21.0

25

.8

47.2

19.6

45.0

17.6

42.3

19

39.9

16.9

40.4

14.7

38.2

15.4

37.5

14.2

36.1

12.7

38.6

13.8

41.3

21.0

40.1

17.1

37.8

16.1

36.2

13.3

40.0

17.0

~.

37.6

15.9

42.6

17.5

41.6

15.9

54.2

22.0

48.7

19.9

52.3

24.2

45.3

22.3

40.0

15.7

36.6

16.9

56.2

21.8

51.3

17.4

61.4

21.6

54.0

21.3

47.7

16.1

41.8

13.9

51.8

20.5

18.4

19.6

17.3

18.3

20.1

21.8

18.1

21.9

16.1

17.4

16.9

17.2

15.3

16.7

13.6

15.0

14.7

16.1

20.6

22.5

18.1

20.5

17.4

18.5

15.3

16.9

17.4

19.9

16.4

18.7

17.2

18.5

16.2

18.3

21.4

20.6

19.4

18.8

24.0

24.4

21.9

22.4

14.4

14.6

16.6

16.9

20.3

18.9

17.3

16.8

18.8

17.4

19.3

18.5

15.2

14.6

13.8

12.6

29

40

40

40

25

25

18

15

15

20

15

26

15

13

15

10

15

16

27

19

34

25

25

23

25

10

9 13

13

15

22

74

68

91

8"

76

83

84

75

83

95

81

96

82

87

87

82

78

94

83

106

98

77

95

64

67

69

70

68

66

I7

72

39

38

48

45

40

44

41

38

38

50

45

46

42

44

44

40

39

39

40

46

48

36

45

36

34

31

36

3"

33

38

39

100

96

87

77

84

90

85

85

86

93

83

87

79

85

85

95

87

106

106

99

100

108

100

124

104

124

115

110

110

106

104

23.9

43.8

17.2

19.9

19.4

17.2

16.5

452 B.R. BENEFIT AND M. PICKFORD

small colobines. Microcolobus appears to be the only colobine genus characterized by the absence of the inferior transverse torus.

The length and angle of slope of the planum alveolare is variable within colobine species, but is important for differentiating between genera. The planum alveolare of Microcolobus is moderately long and somewhat steeply sloping (35" to the alveolar surface (Table 2, ST), a condition seen in Colobus (30-45"). Presbytis species have moderately long plana alveolare set at fairly shallow angles (less than 25" in eight species sampled). In contrast the plana alveolare of Nasalis, Rhinopithecus, Pygathrix, and Mesopithecus are either long and steeply sloping or very short and hor- izontal. Other intermediate conditions, such as the condition which occurs in Colobus, are never observed in these genera. The fossil col- obines Rhinocolobus and Paracolobus have long and fairly horizontal plana alveolare, while in Cercopitheocoides this feature re- sembles Nasalis in being short and hor- izontal.

The corpus of Microcolobus is only slightly inflated laterally, unlike Mesopithecus in which lateral inflation is pronounced. Among extant colobines Presbytis exhibits the least corporal inflation, while Nasalis and Rhinopithecus show the greatest amounts, particularly below M3 as in Mesopithecus. Corpora of many species and subspecies of Colobus exhibit greater lateral inflation than Microcolobus. In Colobus lateral bulging tends to be concentrated below MI and Mz, unlike the condition observed in Mesopi- thecus, Nasalis, and Rhinopithecus. Rhino- colobus and Paracolobus exhibit limited corporal inflation, while the corpus of Cerco- pithecoides shows the most extreme de- gree of inflation of any colobine.

Dentition Description: Labially the 11 is triangular in

outline, being widest at the top. The right I1 is preserved well enough to demonstrate the presence of a thin layer of enamel on its lingual surface. Labial enamel extends fur- ther rootward than the lingual. The occlusal surface of the right I1 is worn flat, with den- tine exposed in a rectangular area. A narrow area of dentine is also exposed on the lingual and distolingual margins of the crown. Lin- gually, enamel appears to be thicker on the distal margin than the mesial. Both raised margins converge toward the midline at the cervix, bordering a shallow sulcus.

The 12 is about the same size as the 11. Its labial surface is also triangular in outline. Lingually, its outline differs from that of 11, resembling a right triangle rather than an isosceles one. The mesial margin forms the longest side of the triangle. Mesial and distal margins meet at the base of the distal side of the crown rather than at the midline. The lingual sulcus is positioned distally rather than medially as it is in 11. It borders the distal shoulder of the crown where there is a decrease in height.

The canine has a single main cusp which is slightly convex mesially and concave dis- tally. In occlusal view the long axis of the canine alveolus parallels the long axis of the molar row and is positioned distal to the in- cisor row. Along the lingual side of the pro- toconid, below the apex of the cusp, the enamel margin is thickened and joins a cin- gulum bordering the lingual edge of the cer- vix. No distinct mesial sulcus is present. The distal heel of the tooth is well developed and is bordered distally by a thickened enamel margin.

The P3 is long and narrow. The tooth has a single main cusp, the protoconid, which oc- cupies the mesiobuccal portion of the tooth. The mesiobuccal flange, extending between the mesial and mediolingual crests of the protoconid and the mesial margin of the crown, appears to be flat rather than hol- lowed out by a sulcus. The distal heel of the crown is well developed. The distal crest of the protoconid meets the flat heel at a sharply defined angle of about 130". The buccal mar- gin of the distal heel is higher than the lin- gual margin, although the lingual margin is longer and its enamel is thicker. The thick- ened lingual margin grades into the medio- lingual crest of the protoconid. A tiny area of thickened enamel is located medially on the distal margin. A dimplelike distal buccal groove is present. A small bulge of enamel is present on the mesiobuccal edge of the crown just above the root.

The P4 is also long and narrow. The meta- conid is slightly higher but narrower than the protoconid, and is connected to it by a transverse loph. The anterior fovea is well developed, occupying the mesial fifth of the tooth. It is bordered by symmetrical lingual and buccal margins which meet mesially, lin- gual to the midline of the tooth. The talonid basin occupies the distal two-fifths of the oc- clusal surface. Its buccal side is lower than its lingual side, and enamel thickening oc-

MIOCENE FOSSIL CERCOPITHECOIDS 453

curs on the distolingual corner of the talonid. A weak distobuccal groove is present. The protoconid is slightly worn, to the stage where dentine is exposed along its post- protocristid.

All molars are straight-sided with limited lateral flare. Cusps are only moderately high. The lingual cusps appear to be anteriorly directed because the distal crests of the metaconid and of the entoconid are longer than their respective mesial crests, and meet the cervix of the crown at a shallower angle. The lingual cusps are higher than the buccal cusps and are less worn. The buccal cusps are worn on a plane horizontal to the occlusal surface of the crown. The angle between the lingual and buccal cusps is approximately 135". A small anterior fovea is situated me- sial to the lowest point of the metalophid. The fovea is deeper in the Mz than in the MI, and deeper in the M3 than in the Mz. A posterior fovea is present distal to the lowest point of the entolophid. It is also deeper in the posterior molars. The mesial and distal shelves are equally narrow in the mesiodis- tal dimension. In the buccolingual dimension the distal shelf is wider than the mesial shelf. The protocristid and the oblique cristid meet medially to form a low ridge bordering the talonid basin on its buccal side and the me- dian buccal cleft on its lingual side. The me- dial buccal cleft is taller from its base to the buccal ridge than is the portion of the crown between the flat base of the cleft and the root. Mesial and distal buccal grooves are present, but are shallow and do not extend far root- ward from the occlusal surface. These grooves are better developed in the posterior molars.

The MI is rectangular, being slightly longer than it is wide. The buccal cusps display fan- shaped dentine exposures. Dentine extends along the mesial shelf from the dentine ex- posed on the protoconid. Narrow triangular patches of dentine exposed on the lingual cusps run from the apex of each cusp, along the crests which form the lingual halves of the protolophid and hypolophid.

The Mz is larger than the MI and more equilateral in occlusal outline. The buccal cusps are worn in a similar pattern to those of the MI, but wear has not progressed to the stage at which a mesial extension of dentine is exposed. The lingual cusps are barely worn.

The M3 differs from the other molars in possessing a small hypoconulid positioned buccally on the distal part of the crown, and separated from the hypoconid by a distinct

groove. The mesial buccal groove is well de- veloped, bordering a V-shaped flattened area on its mesial side. The protoconid displays an oval, and the hypoconid a circular, patch of dentine.

Comparison: Dentally the female Microce lobus specimen from Ngeringerowa most closely resembles females of Mesopithecus pentelici although differences between the two genera include size, molar width se- quence, the absence in Microcolobus of a cin- gulumlike structure extending from the base of the buccal clefts of P4 to M3, more pro- nounced and flattened mesial and distal buc- cal grooves in Mesopithecus, shallow sulcus in the mesiolingual aspect of the P3 proto- conid absent in Microcolobus, and a less la- bially projecting canine in Microcolobus. The molar teeth of both Microcolobus and Mese pithecus resemble those of Colobus and Pres- bytis in having moderately high cusps angled slightly forward. In contrast Nasalis, Pygath- rix, and Rhinopithecus possess taller and more vertically oriented cusps. The mesial and distal shelves are equally well developed in Microcolobus and Mesopithecus. The tal- onid basin in these colobines is of moderate size and roughly square. Distal shelves are larger than mesial shelves in the African fossil colobines Cercopithecoides, Rhinocole bus, and Paracolobus. The talonid basins of Rhinocolobus and Paracobbus are elon- gated, while they are narrow and deep in Cercopitheco ides.

Molar indices calculated for several species of medium-sized colobines and cercopithe- cines, excluding the ratio of width to length, show clear distinctions between the two subfamilies (Table 4). With the exception of the ratio of mesial shelf length to the total length of the tooth (MSLL), index values for Microcolobus fall within the colobine range. MSLL falls within the cercopithecine range for MI, closer to the colobine range for Ma, and well within the colobine range for M3.

According to Delson (1975), it is possible to distinguish African from Asian colobines on the basis of molar width sequences. Al- though this may be true of extant colobines, it does not seem to apply to the fossil genera (Leakey, 1982). Mesopithecus follows the pat- tern of extant African colobines, the mesial width being less than the distal width in all molars except the M3, and the distal width of M2 being greater than the mesial width of M3. In Microcolobus the mesial width is greater than the distal width of the M1 and

TAB

LE

3.

Den

tal

mea

sure

men

ts'

Spec

ies

M1

Mic

roco

lobu

s

tuge

nens

is

KM

M-N

A

305

Mes

opith

ecus

pent

elic

i

Vic

tori

apith

ecus

Col

obus

veru

s

C.

badi

us

C.

poly

kom

os

C.

guer

eza

C.

ango

lens

is

Rhi

nopi

thec

us

rone

llana

e

Cer

coce

bus

albi

gena

C.

torq

uatu

s

C.

gale

ritu

s M

acac

a

nem

estr

ina

M.

sile

nus

M.

nigr

a

M.

radi

ata

M.

fasc

icul

aris

M.

mau

ra

Cer

copi

thec

us

aeth

iops

C.

ham

lyni

C.

tala

poin

C

olob

inae

C

erco

pith

ecin

ae

(exc

ept

Cer

copi

thec

us)

N

__

1

1

13

1

2 19

3

15

2 1

15

2 15

8

3 2

2 20

2

1

1

1

43

69

L MB

5.50

6.

40

6.80

f

0.35

6.30

-7.3

0 6.

35

5.30

f

0.04

5.30

-5.3

5 7.

05

f

0.50

6.30

-8.5

0 6.

70

f

0.08

6.60

-6.8

0 7.

35

f

0.98

6.5-

10.6

7.

60

f

0.85

7.00

-8.2

0 8.

00

6.75

f

0.18

6.40

-7.0

0 8.

05

f

0.57

7.60

-8.4

0 7.

40

f

0.47

6.90

-8.7

0 7.

65

f

0.58

6.90

-8.7

0 6.

85

f

0.21

6.60

-7.0

0 7.

15

f

0.32

6.95

-7.4

0 6.

55

f

0.07

6.50

-6.6

0 6.

80

f

0.71

5.60

-8.3

0 7.

10

5.40

6.

30

4.05

7.

10

f

0.80

5.30

-8.0

0 5.

60-8

.70

7.05

f

0.60

4.40

4.

80

5.50

-7.1

5 5.

25

3.85

f

0.0

5.05

f

0.47

4.50

-6.3

0 5.

90

k

0.62

5.40

-6.6

0 5.

65

f

0.47

5.10

-6.9

0 5.

65

f

0.83

5.10

-6.2

5 6.

4 5.

45

f

0.22

5.20

-5.9

0 6.

65

_+

0.74

6.10

-7.1

5 5.

80-7

.15

5.85

k

0.43

5.20

-6.4

0 4.

70-5

.70

6.00

f

0.32

5.75

-6.2

0 5.

15

f

0.32

4.90

-5.3

5 4.

30-6

.85

5.65

f

0.04

5.60

-5.6

5 4.

10

4.60

3.

10

5.30

f

0.65

3.85

-6.9

0 5.

60

f

0.65

4.30

-7.1

5 5.

95

f

0.43

6.40

k

0.38

5.25

_+

0.49

5.20

_+

0.62

DB

CH

4.30

4.

70

6.35

f

0.35

5.80

-7.1

5 5.

35

4.15

f

0.71

4.10

-4.2

0 5.

35

f

0.47

4.60

-6.8

0 5.

80

k

0.74

5.20

-6.6

0

5

20-6

.90

5.95

f

0.85

5.35

-6.5

5 6.

50

5.65

f

0.26

6.45

f

0.92

5.80

-7.1

0 6.

20

k

0.38

5.70

-6.9

0 6.

00

f

0.29

5.60

-6.3

0 5.

20

f

0.38

4.80

-5.6

0 6.

05

f

0.32

5.10

f

0.42

4.80

-5.4

0 5.

05

f

0.58

4.30

-6.7

0 5.

65

f

0.21

5.50

-5.8

0 4.

00

4.50

3.

10

5.55

f

0.65

4.10

-6.9

0 5.

65

k

0.63

4.30

-7.1

0 5.

85

f

0.51

5.30

-6.4

0 5.

80-6

.25

2.70

3.

50

4.30

f

0.30

3.75

-4.6

5 3.

90

3.40

f

0.07

3.35

-3.4

5 4.

25

f

0.30

3.70

-4.9

0 4.

30

f

0.16

4.10

-4.5

0 3.

90-5

.10

4.65

-5.0

0 4.

90

3.65

f

0.35

3.10

-4.4

0 4.

75 *

0.21

4.60

-4.9

0 4.

30

f

0.36

3.90

-5.3

0 4.

40

f

0.46

3.50

-4.9

0 4.

05

f

0.16

4.00

-4.3

0 4.

05

0.60

3.60

-4.4

5 3.

75

k

0.18

3.60

-3.8

5 2.

70-6

.00

4.00

&

0.04

4.00

-4.0

5 4.

45

f

0.35

4.85

f

0.25

3.65

f

0.67

3.20

3.

40

2.30

4.

30

&

0.39

3.95

i

0.63

3.35

-5.1

0 2.

70-6

.00

NC

1.20

1.

80

2.45

f

0.25

2.15

-2.8

5 1.

50

2.00

f

0.03

1.95

-2.0

2.

35

f

0.38

1.70

-3.1

0 1.

80

f

0.28

1.50

-2.1

0 2.

65

f

0.28

1.80

-2.7

0 2.

95

f

0.14

2.80

-3.0

5 2.

55

1.00

f

0.28

0.40

-1.6

0 1.

70

f

0.07

1.65

-1.7

5 1.

25

f

0.44

0.70

-2.2

0 1.

35

k

0.46

0.70

-2.1

0 1.

25

f

0.24

1.00

-1.4

0 1.

10

f

0.42

0.80

-1.4

0 1.

50

f

0.67

1.00

-1.9

5 1.

20

f

0.59

0.60

-3.2

0 1.

20

f

0.0

1.00

1.

25

0.70

2.

30

f

0.37

1.50

-3.1

0 1.

20

f

0.46

0.40

-3.2

0

NR

MSL

1.50

1.

80

1.85

k

0.35

1.45

-2.4

0 2.

35

1.40

f

0.03

1.40

-1.4

5 1.

95

k

0.26

1.50

-2.5

0 2.

50

5

0.23

2.20

-2.6

0 2.

20

f

0.34

1.70

-2.8

0 2.

90

f

0.14

2.80

-3.0

0 2.

30

2.65

f

0.20

2.30

-3.1

0 3.

07

f

0.28

2.90

-3.3

0 3.

05

f

0.31

2.60

-3.5

0 3.

05

f

0.30

2.60

-3.4

0 2.

85

f

0.20

2.60

-3.0

0 2.

80-3

.05

2.25

f

0.49

2.45

f

0.31

1.90

-2.6

5 2.

85

f

0.04

2.80

-2.8

5 2.

90

f

0.18

1.90

-2.6

0 2.

15

2.05

1.

55

2.10

f

0.35

1.40

-3.0

0 2.

75

k

0.37

1.90

-3.5

0

1.60

1.

60

f

0.20

1.17

-1.8

0 2.

00

1.40

f

0.0

1.65

0.19

1.40

-2.0

0 1.

75

f

0.14

1.60

-

1.90

1.60

&

0.18

1.30

-1.9

0 1.

50

f

0.0

2.00

2.

05

k

0.10

1.90

-2.3

0 2.

35

k

0.04

2.35

-2.4

0 2.

30

0.13

2.10

-2.5

0 2.

15

f

0.26

1.80

-2.6

0 1.

80-2

.10

2.15

f

0.0

1.75

k

0.13

1.65

-1.8

3 1.

95

f

0.24

2.05

f

0.18

1.90

-2.1

5 1.

65

1.80

1.

25

1.65

k

0.19

1.30

-2.0

0 2.

10

f

0.23

1.60

-2.6

5 -

1.90

f

0.16

Mz

Mic

roco

lobu

s

tuge

nens

is

Mes

opith

ecus

pent

elic

i

Vic

tori

apith

ecus

Col

obus

ueru

s

C.

badi

us

C.

poly

kom

os

C.

guer

eza

C.

ango

lens

is

Rhi

nopi

thec

us

roxe

llana

e

Cer

coce

bus

albi

gena

C.

torq

uatu

s

C.

gale

ritu

s M

acac

a

nem

estr

ina

M.

sile

nus

M.

nigr

a

M.

radi

ata

M.

fasc

icul

aris

M.

mau

ra

Cer

copi

thec

us

aeth

iops

C

negl

ectu

s

C.

tala

poin

C

olob

inae

C

erco

pi

thec

inae

(exc

ept

Cer

copi

thec

us)

1

15

7

2

26

1 18

1 2

22

2

7

11

1

3

2

27

3

1 1

1 50

77

5.60

7.50

f

0.48

7.10-8.00

7.90

f

0.30

7.55-8.50

5.60

f

0.11

5.50-5.65

7.40

f

0.45

6.55-8.35

6.60

7.65

?

0.29

7.35-8.35

7.41

9.30

f

0.0

7.30

f

0.34

6.60-8.00

9.00

f

0.14

8.90-9.10

8.15

f

0193

6.25-9.05

8.45

f

0.55

7.40-9.25

7.55

8.25

i

0.54

7.75-8.80

7.40

f

0.14

7.30-7.50

8.40

f

0.35

6.40-9.55

8.40

f

0.35

8.15-8.80

6.06

6.75

4.00

7.50

f

0.70

5.50-9.30

7.80

&

0.70

6.25-9.55

4.70

5.80-7.15

6.90

k

0.49

6.30-7.70

4.50

f

0.70

4.45-4.55

5.75

f

0.37

5.20-6.60

6.30

6.25

%

0.33

5.55-7.00

6.00

7.50

f

0.14

7.40-7.60

6.50

f

0.49

5.40-7.50

9.05

k

0.46

8.70-9.35

7.70

f

0.25

7.45-8.20

7.20

f

0.56

6.20-8.20

6.95

7.55

f

0.25

7.30-7.80

6.15

f

0.64

5.70-6.60

7.10

f

0.25

5.30-7.60

7.10

f

0.25

6.85-7.35

5.00

5.50

3.70

4.45-7.60

5.30-9.35

6.70

f

0.36

5.95

f

0.60

6.80

f

0.78

4.90

7.10

0.51

6.50-7.70

6.55

k

0.40

5.90-6.95

4.85

k

0.04

4.80-4.85

5.90

f

0.46

5.10-7.10

6.20

6.50

f

0.55

5.25-7.90

6.30

7.55

f

0.21

7.40-7.70

6.20

f

0.44

5.35-7.10

8.05

f

0.07

8.00-8.10

7.15

f

0.19

6.85-7.40

6.70

f

0.53

5.90-7.60

6.15

7.00

+ 0.13

6.85-7.io

5.95

k

0.67

5.45-6.40

6.80

f

0.19

4.85-7.30

6.80

f

0.19

6.60-6.95

4.75

5.20

3.55

6.15

k

0.70

4.80-7.90

6.40

f

0.69

4.85-8.10

3.50

4.85

f

0.51

3.65-5.60

4.05

f

0.35

3.55-4.45

3.70

f

0.07

3.65-3.75

4.70

f

0.32

4.05-5.20

4.45

4.95

i

0.45

4.20-5.60

5.40

5.90

f

0.14

4.20

f

0.24

5.60

f

0.04

5.55-5.60

4.95

f

0.58

5.35

f

0.55

4.40-6.00

4.40

4.85

f

0.61

4.30-5.50

4.50

f

0.03

4.50-4.54

5.25

f

0.51

5.25

f

0.51

4.95-5.80

3.95

3.75

2.90

4.80

k

0.50

3.65-6.00

4.60

f

0.60

5.80-6.00

3.85-4.60

3

.SO-5.60

3.60-4.50

3.60-6.00

1.70

2.65

k

0.42

1.90-3.60

1.35

f

0.40

0.50-1.65

2.30

k

0.28

2.10-2.50

2.85

f

0.34

2.25-3.45

2.55

2.70

+ 0.44

1.80

1.75-2.75

2.80

F 0.32

2.70

k

0.64

2.10-3.95

1.40

i

0.17

1.25-1.50

1.85

_t

0.30

1.35-2.45

1.90

2.25

+ 0.33

1.75-3.50

1.60-2.80

3.45

2.00

3.15

f

0.42

2.85-3.45

2.55-2.95

2.80

f

0.28

1.25

f

0.25

2.05

f

0.00

2.05-2.05

1.15

f

0.62

0.39-2.15

1.95

f

0.53

1

.lo-3.05

0.80

1.80

k

0.68

1.25-2.55

1.55

f

0.04

1.55-1.60

1.65

f

0.13

0.12-2.07

1.65

i-

0.13

1.50-1.75

1.55

1.55

1.05

2.80

k

0.40

1.75-3.50

1.45

f

0.49

0.12-3.05

0.85-1.80

3.00

k

0.27

2.30-3.35

3.50

f

0.0

3.70

k

0.31

3.35-4.20

3.35

f

0.43

2.80-4.05

3.60

3.05

+ 0.12

2.95-3.20

2.95

f

0.0

3.60

k

0.42

3.60

f

0.42

2.15-4.38

3.25-4.05

2.05

2.40

1.75

2.05

k

0.40

1.25-2.95

3.10

f

0.40

2.30-4.30

1.50

1.85

k

0.50

1.75-2.20

2.10

f

0.20

1.75-2.35

1.28

i

0.11

1.20-1.35

1.75

i

0.20

1.43-2.23

1.75

1.85

f

0.15

1.45-2.15

1.60

2.15-2.25

2.20

f

0.18

1.85-2.4

2.80-3.10

2.70

f

0.19

2.40-2.95

2.70

f

0.33

2.20-3.25

2.35

2.65

f

0.40

2.40-2.85

2.15

k

0.21

2.00-2.30

2.50

f

0.17

1.67-2.79

2.50

f

0.17

2.30-2.65

1.65

2.30

1.25

1.80

f

0.22

1.20-2.25

2.40

5 0.32

1.65-3.25

(con

tinue

d)

2.20

f

0.07

2.95

&

0.21

TAB

LE

3.

Den

tal

mea

sure

men

ts'

(Con

tinue

d)

~~

SDec

ies

N

M3

Mtc

~rc~

cok~

bus

tugi

wen

sis

Mes

opith

ecus

pen

tdic

i

Vic

tori

api

thec

us

Col

obus

ueru

s

C.

hadi

us

C.

poly

kom

os

C.

guer

eza

C.

ango

lens

is

Rhi

nopi

thec

us

roxe

llana

e C

rrtn

cebu

s

albi

gena

C.

gale

ritu

s M

acac

a

nem

estr

ina

M.

nigr

u

M.

radi

ata

M.

fasc

icul

aris

M.

rnau

ru

Cer

copi

thec

us

acth

iops

C.

negl

ectu

s C

olob

inae

C

erco

pi

thec

inae

(exc

ept

Cer

copi

thec

us)

~.

~

1

14

32

1

23

2 12

1

1

19

5 3

2 1

16

3 1

1

41

50

-~

L

6.50

8.

70-1

0.95

9.

15

f

0.81

7.90

-10.

80

6.95

8.

70

f

0.69

7.30

-9.6

5 8.

30

f

0.35

9.40

k

0.60

8.75

-10.

70

5.82

11

.35

7.95

k

0.67

6.75

-9.1

0 8.

45

f

0.72

7.50

-9.3

0 9.

70

f

0.78

8.80

-10.

15

10.1

0

f

0.0

9.30

9.

45

k

0.99

7.57

-11.

10

9.65

f

1.90

7.55

-11.

30

5.69

7.

55

8.85

1.01

5.80

-11.

35

8.85

f

1.40

6.75

-11.

30

9.30

f

0.56

8.05

-8.5

5

MB

DB

CH

NC

4.60

6.

60-7

.50

6.40

f

0.60

4.70

5.

85

f

0.53

4.25

-6.5

5 6.

80

f

0.27

4.90

-7.6

5 6.

20

f

0.46

5.85

-6.5

0 6.

25

f

0.48

5.35

-7.3

0 6.

75

7.75

6.

35

k

0.34

5.50

-6.9

0 7.

25

f

0.17

7.10

-7.5

0 7.

75

f

0.45

7.45

-8.2

5 7.

20

f

0.07

6.15

6.

35

f

0.76

4.70

-8.0

5 6.

70

It 0.78

5.90

-7.4

5 4.

75

5.70

6.

05

i

0.60

7.15

-7.2

5 4.

25-7

.75

6.55

_+

0.67

4.60

-8.2

5

~~

4.40

6.

55

k

0.33

6.15

-7.4

0 5.

60

f

0.46

4.90

-6.6

0 4.

55

5.70

f

0.47

4.75

-6.3

5 5.

95

f

0.28

5.75

-6.1

5 6.

30

f

0.45

5.50

-7.1

5 6.

80

7.15

5.

45

f

0.39

6.75

k 0.28

6.40

-7.1

0 6.

95

f

0.75

6.10

-7.4

5 6.

40

&

0.28

6.20

-6.6

0 5.

40

5.75

f

0.76

4.35

-7.4

0 6.

30

f

0.40

5.85

-6.6

0 4.

10

5.10

5.

90

i

0.60

4.55

-7.1

5 4.

50-6

.00

3.60

4.

70

i

0.46

4.30

-5.5

5 4.

15

f

0.54

2.55

-5.8

0 3.

75

4.70

k 0.33

4.00

-5.2

5 4.

25

It

0.04

4.20

-4.2

5 5.

00

f

0.46

4.26

-5.9

0 4.

54

6.45

4.

40

f

0.29

4.00

-5.1

0 4.

75

f

0.45

4.15

-5.4

0 5.

50

f

0.78

4.70

-6.2

5 4.

85

f

0.11

4.8

04

95

5.

00

4.50

+ 0.

34

3.75

-5.0

5 5.

25

f

0.74

4.60

-6.0

5 3.

95

3.60

4.

75

f

0.50

3.75

-6.4

5

5.85

f

0.70

4.60

i

0.48

4.35

-7.4

5

3.75

-6.2

5

1.90

2.

50

f

0.38

2.00

-3.2

5 1.

60 *

0.62

0.03

-3.9

0 2.

40

2.75

f

0.40

1.65

-3.3

5 2.

00

f

0.64

1.55

-2.4

5 2.

85

f

0.44

2.47

4.

46

1.45

f

0.32

2.35

-3.6

5 0.

85-2

.05

0.80

-1.6

0 1.

85-2

.20 1.

20

f

0.28

2.05

f

0.18

1.75

f

0.22

1.60

-1.9

0 2.

00

1.50

f

0.50

0.05

-2.0

0 1.

60

k

0.28

1.35

-1.9

0 1.

55

1.45

2.

00

i

0.35

1.55

-4.4

6 1.

20

f

0.35

0.05

-2.2

0

NR

-

~~

__

__

1.70

2.

20

i

0.50

1.65

-3.1

5 2.

60

i

0.54

1.05

-4.4

5 1.

35

1.95

f

0.44

1.05

-2.9

5 2.

25 *

0.68

1.75

-2.7

0 2.

15

f

0.26

1.65

-2.6

3 2.

07

1.99

2.

95 *

0.25

2.60

-3.3

5 3.

55

k 0.51

3.05

-4.1

5 3.

50

f

0.60

2.85

-4.0

5 3.

10

+ 0.

11

3.05

-3.2

0 3.

05

3.00

f

0.53

2.05

-4.6

0 3.

60

f

0.74

3.10

-4.4

0 2.

50

2.15

2.

00

i

0.40

1.05

-2.9

5

MSL

1.

50

2.00

k

0.25

1.55

-2.2

5 1.

95

&

0.28

1.44

-2.5

0 2.

20

1.70

f

0.15

1.35

-2.0

0 1.

80

f

0.07

1.75

-

1.85

1.85

f

1.94

1.60

-2.3

0 2.

23

2.39

2.

10

f

0.15

2.40

f

0.28

2.05

-2.8

0 2.

85

k

0.21

2.60

f

0.07

2.55

-2.6

5 2.

40

2.20

k

0.22

1.90

-2.6

5 2.

40

k

0.32

2.07

-2.7

0 1.

65

2.15

1.

80

i

0.22

1.35

-2.4

0 1.

85-2

.30

2.63

-3.0

5

3.10

f

0.47

2.25

f

0.28

2.05

-4.6

0

1.90

-3.0

5

'Mea

n,

stan

dard

devi

atio

n,

and

rang

e

give

n

in

mm

TA

BL

E

4.

Den

tal

indi

ces

Spec

ies

Mi

Mic

roco

lobu

s

tuge

nens

is

KN

M-N

A

305

Mes

opith

ecus

pent

elic

i

Vic

tori

apith

ecus

Col

obus

veru

s

Col

obus

badi

us

C.

poly

kom

os

C.

guer

eza

C.

ango

lens

is

Rhi

nopi

thec

us

roxe

llana

e

Cer

coce

bus

albi

gena

C.

torq

uatu

s

C.

gale

ritu

s M

acac

a

nem

estr

ina

M.

sile

nus

M.

nigr

a

M.

radi

ata

M.

fasc

icul

aris

M.

mau

ra

Cer

copi

thec

us

aeth

iops

C.

ham

lyni

C.

tala

poin

C

olob

inae

C

erco

pith

ecin

ae

(exc

ept

Cer

copi

thec

us)

N

1

1

13

1

2 19

3

15

2 1

15

2 15

8

3 2

2 20

2

1 1

1 42

69

NC

NR

80

100

137 f

27.9

92-1

59

64

141 f

0.71

140-

141

123 i

32.0

74-1

78

73 +

18.0

57-9

3 10

6 f

25.0

68-1

61

153 f

2.12

152-

155

111

37

&

10.8

14-6

4 56

f

7.8

50-6

1 42

f

17.0

20-6

9 45

f

18.4

26-7

4 44

f

10.8

31-5

1 38

F

12.7

29-4

7 71

f

44.5

39-1

02

50

f

24.0

23-1

14

42

f

0.71

41-4

2 48

60

46

11

6 +_

31.2

57-1

78

45

F

19.0

14-1

14

NC

/MB

27

36

41

f

4.9

32-4

8 29

51

i

0.71

51-5

2 46

f

6.9

34-5

7 31

i

6.5

27-3

8 40

f

5.5

31-4

8 52

f

9.89

45-5

9 40

18

f

4.9

8-28

26

f

4.2

23-2

9 11

-30

14-3

7 24

f

6.2

17-2

9 14

-23

30 i

14.9

19-4

0 23

k

8.6

13-4

7 21

f

0.0

25

27

23

43

+_

7.9

26-5

9 21

f

7.3

8-47

20

f

6.5

23

i

7.7

19 f

6.4

NC

L

22

27

35 f

4.8

30-3

7 24

37

f

0.0

34

f

5.2

26-4

7 27

f

4.1

23-3

1 31

f

4.4

20-3

6 39

f

6.36

34-4

3 32

14

+_

3.3

6-19

22

f

2.1

20-2

3 16

f

5.0

10-2

5 18

k

6.0

10-2

6 18

f

3.7

14-2

0 16

f

4.9

12-1

9 15

-30

17

&

6.8

11-3

9 17

f

0.0

19

20

18

33

f

5.2

20-4

7 17

i

5.6

6-39

23

f

10.6

NR

NB

34

38

31

f

5.4

24-4

3 45

37

f

0.71

36-3

7 39

f

6.2

29-5

0 42

f

3.3

40-4

6 29

i

4.8

29-5

0 34

f

7.07

36

42-5

9 47

f

0.7

46-4

7 48

i

4.6

41-5

8 42

-58

54

f

1.5

53-5

6 49

f

0.0

44

f

6.4

39-4

8 48

f

5.7

38-5

7 50

f

1.4

49-5

1 53

45

50

39

f

5.4

29-5

1 49

i-

5.1

38-5

9 29

-39

49

F

5.0

52

f

4.9

NR

L

27

28

27

f

3.9

20-3

2 37

27

f

0.71

26-2

7 20

-35

33-4

0 23

-40

25 i-

4.24

22-2

8 29

40

f

3.7

34-4

7 38

f

1.4

37-3

9 42

f

5.1

34-5

1 40

f

4.3

34-4

7 42

i

2.0

40-4

4 41

f

0.71

40-4

1 35

f

7.8

29-4

0 27

-46

41

f

0.0

40

33

39

29

f

4.8

20-4

0 39

F

4.

7

27-5

1 27

f

3.9

37

f

3.8

30

f

4.5

36

f

4.6

NR

ICH

56

50

43

f

5.4

35-5

2 61

42

* 0.0

46

f

6.7

36-5

7 58

f

5.9

52-6

4 49

i-

5.8

39-5

9 40

f

0.71

39-4

0 47

73

f

5.8

61-8

8 65

f

3.5

62-6

7 71

k

8.4

59-8

3 70

f

8.4

57-8

0 70

f

5.5

66-7

6 73

f

7.07

68-7

8 61

i

15.6

50-7

2 47

-81

71

f

0.7

70-7

1 68

61

68

47

i

7.0

36-6

4 70

f

8.2

47-8

8 68

F

9.

7

LIM

B

125

75

115 f

8.6

99-1

30

121

139

k

0.71

138-

139

141 f

6.9

120-

149

114

k

12.9

100-

125

129 f

8.9

116-

154

134

I4.2

4

131-

137

125

125 ?r 4.0

116-

133

117-

126

116 f

5.6

106-

129

115-

155

131 f

9.1

123-

141

121 i

0.71

120-

121

128 f

9.2

121-

134

131

k

11.8

119-

161

122 f

6.4

131 f

14.0

127 f

0.0

76

73

77

134 f

11.0

100-

154

126 t

10.7

106-

161

MS

LL

29

23

12

.7

17-2

5 31

27

i

0.0

23

F

2.8

19-3

0 26

f

2.3

24-2

8 22

t

2.4

17-2

5 22

f

0.0

26

31 i-

1.3

28-3

3 30

f

1.4

29-3

1 31

f

1.5

29-3

4 28

If- 1.

5

27-3

1 28

f

1.8

27-3

0 30

k 1.4

29-3

1 27

f

2.8

25-2

9 29

i

2.1

26-3

3 27

f

0.0

31

29

31

23

k 2.8

17-3

0 30

2

2.0

25-3

4 (c

ontin

ued)

TA

BL

E

4.

Den

tal

indi

ces

(Con

tinu

ed)

-

Spec

ies

M2

Mic

roco

lobu

s

tuge

nens

is

Mes

opith

ecus

pent

elic

i

Vict

oria

pith

ecus

Cnl

obus

ueru

s

C.

hadi

us

C.

poly

kom

os

C.

guer

eza

C.

ango

lens

is

Rhi

nopi

thec

us

roxe

llana

e

Cer

coce

bus

albi

gena

C.

tnrq

uatu

s

C.

gale

ritu

s M

acac

a

nem

estr

ina

M.

sile

nus

M.

nigr

a

M.

radi

ata

M.

fasc

icul

aris

M.

mau

ra

Cer

capi

thec

us

aeth

iops

C.

negl

ectu

s

C.

tala

poin

C

olob

inae

C

erco

pith

ecin

ae

(exc

ept

Cer

copi

thec

us)

N

1

15

7 2

26

1

18

1

2 20

2

6 11

1

3 2

27

3 1

1

1

50

75

NC

/NR

94

125 i

32.0

89-1

58

12-7

5 16

8 f

38.2

141-

195

157

rf

36.5

94-2

30

134

122

rf

31.5

65-1

76

172

116 f

26.9

97-1

35

43

k

12.4

27-7

7 59

rf

0.

1

58-5

9 32

k

19.1

11-6

4 60

f

21.0

33-1

06

22

59

f

24.3

42-8

6 54

f

0.7

53-5

4 52

k

17.8

3-81

46

f

4.3

43-5

2 75

65

59

14

3 k

37.4

64-2

30

49

rt

17.9

3-10

6 55

i

20.7

NU

MB

36

39 k

5.8

31-5

0 20

f

6.4

6-25

52

f

6.3

47-5

6 49

f 5.8

40-5

9 41

43

f

6.8

28-5

5 57

42

f

4.2

39-4

5 19

f

4.1

13-2

9 23

k

1.4

22-2

4 15

rt 8.1

5-28

27

f

6.7

16-4

0 12

23

k

8.3

17-3

3 26

f

2.1

24-2

7 22

f

6.5

2-30

23

+ 1.8

21-2

4 31

28

28

47

rt 6.9

28-5

9 22

f

6.6

2-40

NC

L.

30

35

k

6.6

27-5

0 18

rf

5.4

6-21

41

rf

5.6

37-4

5 38

3.7

31-4

3 39

36

5.6

24-4

8 46

34

f

4.2

31-3

7 17

f

3.4

12-2

5 23

f

0.0

15

rf

8.1

5-25

23

i- 5.

5

14-3

3 11

21

5

6.9

16-2

9 22

5

0.7

21-2

2 18

I

5.3

2-26

20

rf

0.9

19-2

0 26

23

26

37

f

4.8

24-4

8 19

k

5.4

2-33

NR

fMB

38

32 i

5.0

25-4

2 39

i

6.4

32-5

1 31

k 2.8

29-3

3 33

k

4.8

24-4

3 30

36

f

4.6

28-4

4 33

37

f

4.2

34-4

0 47

f

5.3

37-5

5 39

&

2.

0

38-4

0 48

f

4.3

44-5

6 47

f

8.7

35-6

6 54

41

k

3.0

38-4

4 49

rt 4.9

45-5

2 46

f

8.2

36-7

6 48

-55

41

43

48

34

rt 4.9

24-4

4 46

rt 6.9

35-7

6 50

f

4.3

NR

iL

32

29 i

4.6

23-3

4 34

i

6.5

28-4

7 25

k

2.8

23-2

7 25

+ 4.2

18-3

3 29

30

k

4.3

22-3

7 27

30

k

3.5

27-3

2 41

+ 4.1

33-4

7 39

k

0.

47

rf

7.3

39-5

7 40

f

7.3

31-5

3 51

37

_+

3.9

34-4

1 40

f

0.7

39-4

0 37

16

.2

27-5

8 43

rf

3.

4

39-4

6 34

35

44

27

+ 4.5

18-3

7 40

k

6.1

27-5

8

NR

KH

51

45

i

5.8

33-5

2 66

i

10.8

57-8

9 38

f

5.7

34-4

2 40

i

5.9

30-5

2 43

4.

6 f

6.7

36-6

1 37

47

f

5.7

43-5

1 71

+ 5.6

56-7

9 63

f

0.

77 f

10.5

61-9

0 63

f

7.6

49-7

5 82

64

i

9.1

54-7

1 66

k

0.7

65-6

6 67

k

9.4

55-1

03

69

f

2.0

66-7

0 53

64

61

42

&

6.

7

30-6

1 68

f

8.6

49-1

03

LIM

B

84

112 i

9.2

101-

131

114

f 4.7

110-

124

124 k

0.0

130 &

7.8

118-

147

105

122 + 5.0

112-

129

124

125

rf

2.1

123-

126

113

&

6.1

102-

129

100 f

.3

95-1

04

106 f

12.2

81-1

20

119 f

10.2

100-

131

109

109 * 3.5

106-

113

121 f

14.8

110-

131

122 k

8.5

108-

140

118 k

3.9

114-

121

122

121

108

126 f

7.9

105-

147

116 rt 9.9

81-1

40

MSL

IL

26

26 i

2.7

23-3

0 26

i

2.4

23-3

1 23

i

2.8

21-2

5 24

k

2.5

20-3

0 27

24

k

2.0

20-2

8 22

24

k

0.7

23-2

4 30

rf

1.9

27-3

4 33

f

2.8

31-3

5 33

f 5.3

28-4

3 31

&

2.

5

27-3

5 31

32

If-

0.

9

31-3

3 29

I

2.8

27-3

1 24

-37

30

f

1.8

28-3

2 27

34

31

24

+ 2.2

20-3

0 31

f

3.0

24-4

3 30

f

3.0

M3

Mic

roco

lobu

s

tuge

nens

is

Mes

opith

ecus

pent

elic

i

Vic

tori

apith

ecus

Col

obus

ueru

s

C.

badi

us

C.

poly

kom

os

C.

guer

eza

C.

ango

lens

is

Rhi

nopi

thec

us

roxe

llana

e

Cer

oceb

us

albi

gena

C.

gale

ritu

s M

acac

a

nene

stri

na

M.

nigr

a

M.

radi

ata

M.

fasc

icul

aris

M.

mam

a C

erco

pith

ecus

aeth

iops

C.

negl

ectu

s C

olob

inae

C

erco

pith

ecin

ae

1

13

29

1

23

2 12

1

1

19

5 3

2 1

16

3 1

1

40

49

112

122

k

39.0

66-1

64

1-20

6 17

8 15

1 + 54

.9

57-3

21

99

f

59.4

57-1

41

133 f

31.7

94-2

17

119

224

49

&

13.3

25-7

2 34

&

11.7

21-5

3 59

f

4.9

54-6

4 57

k

9.2

50-6

3 66

53

5

19.7

1-81

46

k

13.5

36-6

1 63

67

14

5 f

49.5

57-3

21

67

5

37.2

50

f

15.8

41

38

f

5.7

30-4

7 25

k

9.2

1-56

51

47

f

6.7

29-6

0 33

f

12.7

24-4

2 45

f

5.2

41-5

8 37

58

23

k

5.1

13-3

3 16

k

4.2

11-2

3 22

-29

24 f

2.8

22-2

6 32

1-

31

24 f

3.6

21-2

8 33

25

46

f

7.3

24-6

0 23

k

6.3

1-33

26

&

3.8

23

f

8.0

29

21-3

5 26

&

8.4

17

k

6.7

1-42

35

31

i

3.9

20-4

0 24

f

7.1

19-2

9 30

f

4.6

25-3

7 42

39

18

f

4.1

9-26

14

&

3.5

9-19

21

_+

0.6

20-2

2 18

f

2.1

16-1

9 21

15

+ 5.1

1-20

17

f

2.5

14-1

9 27

19

31

f

5.0

19-4

2

37

33

f

7.3

23-4

7 41

f

8.1

19-6

8 29

34

8.3

19-5

1 36

&

8.5

30-4

2 35

k

5.2

27-4

9 31

26

47

+ 4.4

38-5

4 49

* 3.5

42-5

7 45

f

9.9

35-5

5 44

* 2.1

42-4

5 49

46

k

8.2

37-7

3 54

k

7.0

46-6

0 52

38

34

f

7.2

19-5

1 47

k

6.5

25-73

26

22 ir

8.0

16-3

4 29

&

6.

2

11-4

5 20

23

i

5.8

15-3

8 27

i

9.19

21-3

4 23

k

3.0

17-2

7 36

18

37

k

4.1

29-4

6 42

jI

6.2

35-4

9 36

f

3.8

33-4

0 31

?

1.

4

30-3

2 33

31

k

5.1

25-4

4 38

?

6.

4

31-4

3 44

29

24

&

5.4

15-3

8 35

t. 5.

8

25-4

9

47

47

k

7.9

34-5

4 62

f

11.6

33-1

01

36

42

i

8.5

24-6

4 53

2

15.6

42-6

4 44

f

5.0

32-5

2 46

31

68

f

6.0

58-8

0 75

k

6.3

66-8

3 61

-65

64

f

4.2

61-6

7 60

67

i

10.8

55-1

02

69

jI

6.1

62-7

4 63

60

42

f

8.1

24-6

4 63

t

1.9

14 1

137 i

6.1

129-

146

142 f

10.8

122-

167

147

149 i

17.1

120-

191

135 t

15.5

124-

146

152 I

15.7

131-

186

86

147

126

&

9.4

108-

140

117

k

8.2

106-

124

126 f

16.8

107-

136

140 k

1.4

139-

141

152

150

k

9.8

132-

164

143

k

12.9

128-

152

84

75

147 k

18.8

86-1

91

23

22

_+

2.5

18-2

4 22

F 3.3

15-2

8 32

17

-25

22 f

1.4

21-2

3 20

f

2.1

16-2

4 38

21

27

+_

2.7

22-3

2 29

k

3.6

26-3

5 29

f

4.7

26 F 0.

7

25-2

6 26

24

f

1.9

25 f

2.0

24-2

7 29

29

21

k

4.2

19 F

2.4

29-3

0 20

-27

16-3

8

17 f

4.4

68

5 8.0

135 jI

15.8

26 i

3.0

1-81

- __

1-26

-.

._ __

_-

55-1

02

106-

164

20-3

5

460 B.R. BENEFIT AND M. PICKFORD

M3, and the mesial width is almost equal to the distal width on the M2. This pattern ap- pears in neither extant Asian nor African colobines, but does occur in Rhinocolobus.

The premolars of Microcolobus resemble those of Mesopithecus and African fossil co- lobines more than those of extant Asian co- lobines. Unlike many living colobines the P3 of Microcolobus possesses a well-developed heel distally. The lingual margin of the Ps is clearly defined and does not slope rootward and lingually as it does in several Asian lan- gurs. The P3 and P4 are longer and narrower in Microcolobus, Mesopithecus, and African colobines than in their Asian counterparts. Contrary to the suggestion that the P4 pro- toconid is less developed than the metaconid in African colobines (Delson, 1975), the fossil African colobines Cercopithecoides, Rhinoce lobus, and Paracolobus each have equally de- veloped protoconids and metaconids on their P4s (Leakey, 1982). Microcolobus shares this trait with these fossil colobines from Africa.

The anterior dentition of Microcolobus most closely resembles females of Mesopithecus and Colobus, although some differences exist between these genera. The narrow canine of Microcolobus has a flatter distal heel than in many extant colobines. The protoconid of the Microcolobus canine does not curve labially from cervix to apex as it does in Mesopithe- cus. The I2 of Mesopithecus possesses a small sulcus between midline and mesial margin, unlike Microcolobus.

SYSTEMATIC DESCRIPTION

Subfamily Colobinae Jerdon, 1867 Genus Indeterminate

Material KNM-NA 305 from Nakali. A slightly worn

lower left molar, probably MI, in a small fragment of mandible.

MORPHOLOGICAL DESCRIPTION AND COMPARISON

The lower molar from Nakali is much longer than it is wide, as indicated by a value of 133 for index L/MB (Table 3). Based on its narrow shape the tooth is identified as a n MI rather than an M2. The molar is distinctly colobine, with all index values falling within the colobine range.

The Nakali molar is similar to that of Mi- crocolobus, with mesially sloping lingual cusps, high lingual notch, moderately devel- oped talonid basin, shallow mesial and distal

buccal grooves, and a distinct buccal cleft. The molar is considerably longer and nar- rower than the MI and M2 of Microcolobus. Unlike Microcolobus the distal shelf is slightly longer than the mesial shelf, and both the mesial and distal foveae are deeper. While some of the differences between the Nakali molar and those of Microcolobus tug- enensis may be due to distinct stages of wear, the magnitude of the size and shape differ- ences (LiMB) indicate that it may belong to a separate species.

SYSTEMATIC DESCRIPTION

Subfamily Indeterminate

Material KNM-BN 1251 from Ngorora locality 2/1,

Member B. A right P4. MORPHOLOGICAL DESCRIPTION AND

COMPARISON

This specimen is unusual in possessing an accessory cuspule distal to the metaconid, which is connected to the metaconid and pro- toconid by distinct crests. A fovea occurs be- tween the metaconid and the crests that are connected to the accessory cuspule. The me- taconid is shorter than the protoconid. These cusps are slightly worn with dentine expo- sure limited to the protoconid. An anterior fovea, bounded by the preprotocristid, is po- sitioned on the lingual side of the mesial shelf. The distal heel is flat and is bordered by a raised margin with thickened enamel on its distolingual edge. The mesial and dis- tal buccal grooves are slight.

The P4 is 25% longer than that of Microce lobus and is proportionately narrower (Table 5). The narrow shape of the P4 is similar to Cercopithecus and unlike other cercopithe- cines and colobines. Since the reduced meta- conid aligns the specimen with Colobinae, and the narrow shape aligns it with Cercopi- thecinae, the P4 cannot be assigned unequi- vocally to either subfamily. The specimen is considered to belong to a species distinct from Microcolobus tugenensis. Its size does not preclude it from belonging to the same spe- cies as the Nakali molar, but as yet there is insufficient evidence to suggest such an affinity.

DISCUSSION

Material described in this paper documents the presence of at least two species of (2010- binae in East Africa between 8.5 to 10.5 m.y. Microcolobus tugenensis is extremely small. The lower molar from Nakali is longer and

MIOCENE FOSSIL ( 2ERCOPITHECOIDS 461

TABLE 5. Anterior dentitiom Measurements of extant species taken from Swindler (1976)

Tooth Lendh (L) Width (W) W L

Microcolobus tugenensis RP3 LP3 RP4

4.65 2.65 57 5.10 2.70 53 3.70 3.15 85

85 LP4 3.80 3.25 RI1 2.45 3.20 LIl 2.65 3.25

2.65 3.05 2.30 3.20

LCX 4.30 3.05 Cercopithecoidea indet. KNM-BN 1251 RPA 5.55 4.00 73

RI2 LI2

W L sex Mean Range

F 67 49-81 Colobinae P3 M 61 54-67

~. ~~ - .

Cercopithecinae P3 M 41 28-63 F 50 37-57

Colobinae P4 M 90 81-96 F 91 80-

1 no _. .

Cercopithecinae P4 M 82 69-95 F 83 74-95

Cercooithecus Pd M 14 69-79 F 76 74-78

Theropithecus P4 M 16 F 78

Cercocebus, Papio M 90 83-95

F 90 82-95 and Macaca P4

narrower than both the MI and M2 of M. tugenensis, indicating that it represents a distinct species, although its generic affini- ties are indeterminate. The Ngorora premo- lar is not assigned to subfamily due to its unusual morphology. It is too large to belong to M. tugenensis, but may have belonged to an animal similar in size to that represented by the Nakali molar.

Little is known about the evolution of Old World monkeys during the Miocene. The partial mandible and two isolated teeth de- scribed here represent the only cercopithe- coids known between 15 and 7 m.y., with the possible exception of a single Ma from Ongo- liba, assigned to ?cf. Macaca c.q. Mesopithecus by Hooijer (1963) and later to?Macaca sp. nov. by Delson (1975). The age of the Ongoliba de- posits is uncertain. Comparison of Microcob bus with Late Miocene colobines from North Africa was not productive since ?Colobus pan- drini from Marceau (7 m.y.) is represented by a few isolated teeth (Arambourg, 1959; Del- son, 1975), and one very worn lower molar of

Libypithecus is preserved (Delson, 1973). In contrast several mandibles with complete sets of lower dentition of the Eurasian Mesopithe- cuspentelici are preserved. Comparison of M e sopithecus with Microcolobus proved highly informative.

Morphological differences between Mesopi- thecus pentelici and Microcolobus are exhib- ited in the shape of the mandible. The mandible of Microcobbus is gracile with lim- ited lateral flare as in Colobus and Presbytis, whereas the mandible of Mesopithecus is more robust with considerable flare adjacent to the M3 as in Nasalis and Rhinopithecus. The short, steeply sloping planum alveolare of Mesopithecus also resembles the condition found in Nasalis and Rhinopithecus. The symphyseal morphology of Microcolobus is most like that of C. guereza kikuyuensis in which the planum alveolare is of moderate length, vertically sloping, but lacks the infe- rior transverse torus.

The absence of the inferior transverse to- rus in some individuals of C. guereza kiku- yuensis is a variation observed only in that subspecies and is hardly characteristic of the species and genus as a whole. The fact that the variation occurs in the extant subspecies and in Microcobbus merely supports the con- clusion that Microcolobus is a true colobine and is not unique in this respect.

What can be surmised from the examina- tion of mandibular morphology is that Mese pithecus and Microcolobus are distinct genera. Neither genus possesses the suite of characters that might be expected in the common ancestor to all colobines. It is pre- dicted that such a common ancestor, unlike Mesopithecus, would have limited lateral flare of the corpus, and a planum alveolare of moderate length and slope, and unlike Mi- crocobbus, would have possessed an inferior transverse torus above the area of insertion for the digastrics and below the genioglossal fossa.

The dentitions of Microcobbus and Meso- pithecus are similar to each other and to the Nakali molar. The height of the metaconid above the lingual notch of Microcolobus and KNM-NA 305 is lower than in many extant colobines, but is much higher than in cerco- pithecines. Lower cusp relief may indicate that these early, small colobines were less specialized than later species. The premolars of Mesopithecus and Microcolobus are not specialized as they are in extant colobines. In both genera the premolars preserve flat

462 B.R. BENEFIT AND M. PICKFORD

distal heels, enabling the tooth to function both as a shearing and as a grinding apparatus.

Delson (1973, 1975; Simons and Delson, 1978:Szalay and Delson, 19791, suggested that the ancestral colobine is probably Vic- toria-pithecus macinnesi from Maboko Island.

Delson (1973, 1975; Simons and Delson, 1978; Szalay and Delson, 1979) suggested that the ancestors ofboth Colobinae and Cerco- pithecinae can be found in distinct species (or perhaps genera) of Victoriapithecus from Ma- boko Island. Delson's theory is based primar- ily on his observation that trigonid length on specimens assigned to V: macinnesi is short, as in extant colobines, and long in V: leakeyi, a cercopithecine characteristic. In this study measurements expressing trigonid length (MSL and MSLL, Tables 3, 4) clearly sepa- rated extant colobines from cercopithecines. However, values of these variables for speci- mens Delson (1973, 1975; Simons and Del- son, 1978; Szalay and Delson, 1979) assigned to V macinnesi and to V: leakeyi both fell within the colobine range (KNM-MB 1 M2:

MSL = 1.77, MSLL = 22.55). Indices ex- pressing the distance between the base of the lingual notch and cervix (NR/MB and NRL, Table 41, which also separate colobines from cercopithecines, similarly fell within the co- lobine range for both species (KNM-MB 1 M2: MR/MB = 35.6, NR/L = 32.8; KNM-MB 34 M2: NRMB = 35.7, NR/L = 28.6). All other indices for Maboko cercopithecoids fell within the cercopithecine range. Based on measure- ments presented here and observations made by the authors it seems that only one morph is represented in the Maboko Victoriapithecus dental sample, and that ancestral colobines and cercopithecines cannot be distin- guished within it.

Von Koenigswald (1969) originally placed Victoriapithecus upper molars possessing crista obliqua into the species V: leakeyi, and those without into V: macinnesi. Delson (1973, 1975; Simons and Delson, 1978; Szalay and Delson, 1979) followed this rule when separat- ing specimens into his revised hypodigms. Numerous Victoriupithecus specimens re- cently collected by M.P. indicate that the crista obliqua is present in various stages of development on the up er molars, and is ex-

on M3. It is never completely absent on M1. This pattern of expression is in accor- dance with the dental field hypothesis of But-

MSL = 1.68, MSL = 24.6; KNM-MB 34 Ma:

pressed most often on M '2 , less on M2, and least

ler (1939), and is compatible with a single spe- cies model. This and evidence that the level of metric variation in the Maboko Victoriapithe- cus dental sample is equal to that found in ex- tant species suggest that all Victoriapithecus teeth may belong to one species, or that if two species are present, we cannot distinguish them on the basis of their teeth alone.

Victoriapithecus has been placed into a distinct subfamily, Victoriapithecinae (Von Koenigswald, 1969; Leakey, 19851, based on features not observed in the extant cerco- pithecoid subfamilies: obliquely rotated P4, almost square MI, occasional presence of the crista obliqua, and considerable flare at the base of the lower molars. Molar features shared by Victoriapithecinae and one extant subfamily to the exclusion of the other are probably primitive for Cercopithecoidea. Long trigonids and greater distance between the base of the crown and base of the lingual notch, which are unique to cercopithecines, are probably derived for that subfamily. Sim- ilarly, increased height of the cusps above the lingual notch, which is unique to colobines, is derived in that taxon.

Rather than assume that both extant cer- copithecoid subfamilies are represented in the Maboko Victoriapithecus sample, as main- tained by Delson (1973,1975; Simons and Del- son, 1978; Szalay and Delson, 19791, we suggest a new hypothesis. If, as Delson pro- poses, Victoriapithecus contains both extant subfamilies, this would imply that features shared by Cercopithecinae and Colo- binae to the exclusion of Victoriapithecinae (loss of the crista obliqua, development of com- plete bilophodonty, elongation of the MI, and reduction in buccalward flare of the mesiob- uccal P4 flange) evolved independently in both subfamilies. This is difficult to accept. It seems more probable that one extant subfamily evolved from Victoriapithecinae and later gave rise to the other. Alternatively the evo- lutionary changes mentioned above might have evolved in an as-yet-unknown common ancestor to both extant subfamilies and de- scended from Victoriapithecinae.

CONCLUSIONS

Descriptions of fossil colobine specimens from Ngeringerowa and Nakali, and an in- termediate cercopithecoid premolar from Ngorora, have been presented. Radiometric and biostratigraphic comparisons indicate these sites are between 8.5 and 10.5 m.y. and are older than other known colobine-bearing

MIOCENE FOSSIL CERCOPITHECOIDS 463

deposits. At least two species are represented in this material, which helps to fill a gap in our knowledge of monkey evolution between 15 and 7 m.y.

Morphological and metric analysis of the mandible from Ngeringerowa indicates that it belongs to a new genus and species of Co- lobinae, Microcolobus tugenensis, which was slightly smaller than Colobus uerus. The low height of the metaconid above the lingual notch indicates that Microcolobus and the taxon represented by KNM-MA 305 may have been less specialized for folivory than later species. The common ancestor of the Late Miocene colobines is likely to have been small to medium in body size and more ver- satile in dietary habits than extant colobines.

The mandibular morphology of Microcole bus resembles that of C. guereza kikuyuensis, while Mesopithecus resembles Nasalis. Pos- sible affinities of Microcolobus with extant taxa are difficult to assess due to the absence of further skeletal remains. Neither Micre colobus nor Mesopithecus appears to have the mandibular morphology expected of the ancestor of all colobines, which would have had limited lateral flare as in Presbytis, Col- obus, and Microcolobus, a planum alveolare moderate in length and in slope, and an in- ferior transverse torus positioned as in all colobines except Microcolobus.

Victoriapithecus is unlikely to have been the common ancestor of both colobines and cercopithecines since the evolution of com- plete bilophodonty, elongation of the M1, and orientation of the P4 would have to have occurred independently in both groups. It is more likely that characters shared between Victoriapithecinae and Colobinae are primi- tive retentions in Colobinae rather than in- dicative of a phylogenetic relationship.

The ancestral colobine could have evolved from a lineage intermediate in dental mor- phology between Victoriapithecinae and the extant subfamilies, from Victoriapithecus, or from Cercopithecinae. Its dietary adaptation would have been more eclectic than extant leaf-eating monkeys due to its small body size and dental adaptations. Microcolobus and Mesopithecus are probably derived from such an ancestral colobine.

ACKNOWLEDGMENTS

We wish to thank the following individuals and museums for permission to study fossils and comDarative material. The government of Kenya' and R.E.F. Leakey, diructor of the ,,".

National Museums of Kenya; Dr. Musser of the American Museum of Natural History; Dr. Thomas of the Laboratoire de Paleonto- logie, Museum National d'Historie Natu- relle, Paris; Prof. Helm and Dr. Mayr of the Bayerische Staatssamlung fur Paleontologie, Munchen; Dr. Franzen of the Senkenber- gische Museum, Frankfurt; and Dr. Patton of the Museum of Comparative Zoology, Uni- versity of California, Berkeley. Special thanks go to Dr. Meave G. Leakey, Mr. Monte L. McCrossin, Dr. Terry Harrison, Dr. Alan C. Walker, Dr. Eric Delson, and Dr. Clifford J. Jolly, for their valuable comments, sugges- tions, and encouragement. Funding for B.R.B. was provided by an ITT International Fellowship to Kenya, and an N.Y.U. Doctoral Dissertation Fellowship. The National Gov- ernment Research Council of the United Kingdom funded M.P. Specimens were drawn by Laura Tindimubona.

LITERATURE CITED

Arambourg, C (1959) Vertebres Continentaux du Mio- cene Superieur de 1'Afrique du Nord. Publications Ser- vice Carte Geol. Algerie (Nouvelle Serie). Paleontologie 4:5-159.

Barry, J, Lindsay, EH, and Jacobs LL (1982) A biostrati- graphic zonation of the middle and upper Siwaliks of the Potwar Plateau of North Pakistan. Paleogeogr. Paleoclimat. Paleoecol. 37:95-130.

Bishop, WW, Chapman GR, Hill AP, and Miller JA (1971) Succession of Cainozoic vertebrate assemblages from the northern Kenya Rift Valley. Nature 223:389-394.

Bishop, WW, and Pickford M (1975) Geology, fauna and palaeoenvironments of the Ngorora Formation, Kenya Rift Valley. Nature 254:185-192.

Butler, PM (1939) Studies of the mammalian dentition. Differentiation of the post canine dentition. Proc. Zool. Soc. Lond. B109:1-36.

Chapman, GR, and Brook M (1978) Chronostratigraphy of the Baringo Basin, Kenya. In WW Bishop (ed): Geo- logical Background to Fossil Man. Scottish Academic Press, Edinburgh: pp. 207-224.

Delson, E (1973) Fossil Colobine Monkeys of the Circum- Mediterranean Region and the Evolutionary History of the Cercopithecidae (Primates, Mammalia). Ph.D. thesis. Columbia University, New York.

Delson, E (1975) Evolutionary history of the Cercopithe- cidae. In F.S. Szalay (ed.): Approaches to Primate Pa- leobiology Vol. 5: Contributions to Primatology. Karger, Basel, pp. 167-217.

Gaudrey, A (1862) Animaux Fossiles et Geologie de 1'At- tique. Paris: F. Savy.

Heinz, E, Brunet M, and Battail, B (1981) A cercopithe- coid priamte from the late Miocene of Moloyan, Af- ghanistan, with remarks on Mesopithecus. Int. J. Primatol. 2(3):273-284.

Hooijer, DA (1963) Miocene Mammalia of Congo. Ann. Mus. R. Afr. Cent., Ser. 8, Sci. Geol. 461-71.

Hooijer, DA (1975) Miocene to Pleistocene Hipparions of Kenya, Tanzania and Ethiopia. Zool. Verhandl. 1423- o n

464 B.R. BENEFIT AND M. PICKFORD

Koenigswald, G.H.R. von (1969) Miocene Cercopithecoi- dea and Oreopithecoidea from the Miocene of East Africa. Fossil Vertebrates I :13-51.

Leakey, MG (1982) Extinct large the colobines from the Plio-Pleistocene of Africa. Am. J. Phys. Anthropol., 58:153-172.

Leakey, MG (1985) Early Miocene cercopithecids from Buluk, Northern Kenya. Folia Primatol. 44:l-14.

Pickford, M (1978) Geology, paleoenvironment and ver- tebrate faunas of the Mid-Miocene Ngorora Formation, Kenya. In WW Bishop (ed): Geological Background to Fossil Man. Edinburgh: Scottish Academic Press, pp. 237-262.

Pickford M (1981) Preliminary Miocene mammalian biostratigraphy for western Kenya. J. Hum. Evol. 1073-97.

Simons, EL, and Delson E (1978) Cercopithecidae and Parapithecidae. In VJ Maglio and HBS Cooke (eds): Evolution of African Mammals. Cambridge: Harvard University Press, pp. 100-119.

Swindler DR (1976) Dentition of Living Primates. Lon- don: Academic Press.

Szalay, FS, and Delson E (1979) Evolutionary History of the Primates. New York Academic Press.