morphological affinities of recently discovered …digital.auraria.edu › content › aa › 00 ›...

MORPHOLOGICAL AFFINITIES OF RECENTLY DISCOVERED

CERCOPITHECIDS FROM THE PLIOCENE UPPER LAETOLIL BEDS IN

LAETOLI, TANZANIA

by

ELICIA F. ABELLA

B.S., The Pennsylvania State University, 2012

A thesis submitted to the

Faculty of the Graduate School of the

University of Colorado in partial fulfillment

of the requirements for the degree of

Master of Arts

Anthropology Program

2014

ii

© 2014

ELICIA F. ABELLA

ALL RIGHTS RESERVED

iii

This thesis for the Master of Arts degree by

Elicia Frances Abella

has been approved for the

Anthropology Program

by

Charles Musiba, Chair

Zaneta Thayer

Tammy Stone

May 2, 2014

iv

Abella, Elicia F. (M.A, Anthropology)

Morphological Affinities of Recently Discovered Fossil Cercopithecids from the Pliocene

Upper Laetolil Beds in Laetoli, Tanzania

Thesis directed by Associate Professor Charles Musiba

ABSTRACT

The Laetoli paleoanthropological site in northern Tanzania continues to yield one

of the oldest Australopithecus afarensis collection as well as other well preserved non-

hominin primate remains, including primate cercopithecids. The Laetoli primates are

highly diversified, including fossil galagines, parapithecids and paracolobines. These

primate species are indicative of highly variable depositional environments at Laetoli that

would have been more wooded or forested with patches of bushes, thorn scrubs and open

habitats. For example, extant cercopithecines tend to thrive in a wide range of habitats

from grasslands to dense woodlands, forests and tree-covered rocky outcrops. This thesis

presents qualitative descriptions and a computational statistical analysis of odontometrics

for the posterior teeth of fossil and extant primates in order to classify recently recovered

Laetoli fossil primate remains by the University of Colorado Denver Tanzania field

school in paleoanthropology. The results of this analysis will help give a better

understanding of the ecological diversity exploited at Laetoli.

The form and content of this abstract are approved. I recommend its publication.

Approved by: Charles Musiba

v

TABLE OF CONTENTS

CHAPTER

I. INTRODUCTION………………………………………………………......….....1

II. BACKGROUND RESEARCH ………………………………...………...………3

Theoretical Background………………………………………...…………3

Current Literature: Geology and Paleoecology………….….....…………4

Current Literature: Primates ……………..……………………….……..11

III. MATERIALS AND METHODS...........................................................................20

Sample……………………………………………………………………20

Craniofacial Descriptions………………………………………………...22

Methods: Dental Metrics…………………………………………………37

Methods: Statistical Analysis……………………………………….……42

IV. RESULTS………………………………………………………………………..44

P3……………………………………………………………...…………44

P4………………………………………………………………………...46

M1…………………………………………………………………..……48

M2…………………………………………………..……………………50

M3………………………………………………………………………..52

Summary: Results………………………...………………………..........54

V. DISCUSSION…………………………………………………...……................55

VI. CONCLUSION………………………………………………………………..…66

REFERENCES…………………………………………………………………………..68

vi

APPENDIX

A. Summary of Collected Cercopithecine and Colobine Odontometrics…………...71

B. Summary of Eigenvalues from the PCA for P3-M3 ...............................................72

C. Summary of Percentage of Total Variance from

the PCA for P3-M3 .................................................................................................72

D. Summary of the DFA Results for P3-M3................................................................72

E. Summary of the Correctly Classified and Misclassified

Percentages from the DFA for P3-M3....................................................................72

vii

LIST OF TABLES

TABLE

1. Summary of Cercopithecines and

Colobines used in the quantitative and qualitative

analysis…………………………………………..………………………….21

2. Method of mandibular odontometrics taken for

proposed Cercopithecid specimens from Laetoli

(Swindler 2002)……………………………..………………………....……38

3. Mandibular odontometrics from the proposed

Cercopithecid sp. from Laetoli, Local 2 and

LP 061703-01&02 fragment; right mandibular

segment from P3-M3 in mm………………………………………………....41

viii

LIST OF FIGURES

FIGURES

1. Geological map of Laetoli .......……………………………………...……………5

2. Map of the Laetoli area and the

location of localities…………………...................................................…………..8

3. Figure 3: Sections showing the sequence exposed in Loc. 6.................................10

4. Cladogram of extant cercopithecid

genera and subgenera.............................................................................................19

5. Left maxillary M1-M

3 fragment of

the Laetoli cercopith from Locality 6....................................................................23

6. Right maxillary P3-P

4 fragment of

the Laetoli cercopith from Locality 8....................................................................25

7. Left maxillary M1 of the Laetoli

cf. Rhinocolobus sp. (specimen 04-1-01)

from Locality 1......................................................................................................28

8. Right mandibular M1-M2 fragment

of Parapapio ado from Locality 1.........................................................................31

9. Mandibular specimen of Parapapio ado

from Locality 2; occlusal view..............................................................................35

10. Mandibular specimen of Parapapio ado

from Locality 2; lateral view..................................................................................35

11. Comparative mandibular specimens

for the Parapapio ado Laetoli specimen

from Locality 2......................................................................................................36

12. Odontometric landmarks........................................................................................39

ix

13. Identification of cercopithecid dental

landmarks on the right mandibular M3

of Theropithecus ...................................................................................................40

14. 3D score scatterplot for the P3 PCA.......................................................................45

15. 3D score scatterplot for the P4 PCA.......................................................................47

16. 3D score scatterplot for the M1 PCA.....................................................................49



1

CHAPTER I

INTRODUCTION

Laetoli, one of the most important paleontological and paleoanthropological sites

located in northern Tanzania, has yielded the second largest sample of Australopithecus

afarensis specimens and is also famous for its preserved trails of hominin footprints (Su

& Harrison 2007). However, having a better understanding of the paleobiology of

Australopithecus afarensis continues to be one of the most controversial topics today. For

example, previous interpretations of the paleoecology at Laetoli suggest that

Australopithecus afarensis inhabited an arid to semi-arid grassland with scattered bush

and tree cover containing patches of woodland which are all characteristics of present day

Serengeti Plains (Leakey et al. 1976).

However, studies by Andrews (1987), Reed (1997) and Musiba (1999) have also

suggested that Laetoli had more of a dense bush cover and more extensive tracts of

woodland and forest galleries. Reed (1997) suggests that based on the high taxonomic

diversity of mammalian fossil assemblages, which include arboreal and frugivorous

mammals, Laetoli must have had significant components of bushland and woodland. The

existence of more than three species of cercopithecines and paracolobines also strongly

suggest the existence of forested environments during the Pliocene at Laetoli (Andrews

1987).

Mammalian fauna found at Laetoli further support the notion that Laetoli must

have had more wooded, bush, and thorn scrub habitats than present day. Laetoli primate

species including, Galago sadimanensis, Parapapio ado, and Paracolobus sp., is

2

suggestive of a closed woodland environment or forest; though, cercopithecids do tend to

presently thrive in a range of habitats from grasslands to forests, stands of trees and rocky

outcrops as common sleeping quadrants. Even though rocky outcrops are not generally

seen in Laetoli, larger trees would have been important sites of refuge for cercopithecid

primates (Su & Harrison 2007).

In order to reconstruct an accurate paleoenvironment of Laetoli, a better

understanding of the Laetoli primates must be considered. By utilizing odontometrics in a

statistical analysis with qualitative descriptions and comparisons between fossil and

extant African primates, determining the species of the recently recovered Laetoli

primates is suggestive of their depositional environments and dietary adaptations during

the Pliocene. Qualitative descriptions and comparisons help support the quantitative

measures to distinguish primate species.

Specific aims of this thesis include:

1. Establishing a comparative odontometric dataset on extant and fossil

Cercopithecids (subfamily: Cercopithecinae and Colobinae) found in Africa.

2. Investigating primate species from Laetoli to better understand their habitats

during the Pliocene.

3. Utilizing Principle Component Analysis (PCA) and Discriminant Function

Analysis (DFA) of odontometrics to differentiate primate species from Laetoli.

3

CHAPTER II

BACKGROUND RESEARCH

Theoretical Background

Evolutionary ecology suggests that behaviors are adaptive in terms of

environmental variability in which an organism is able to thrive by enhancing their

reproductive success. However, Behavioral Ecology (BE) focuses on behaviors as a

phenotypic result of natural selection favoring adaptive options that have the ability to

solve fitness-related trade-offs (Bird & O’Connell 2006). Also BE peers into historical,

ontogenetic and other external factors that may be relatable to the cost and benefits of

certain behaviors.

By using the environment of evolutionary adaptedness (EEA), it can refer to the

selective environment in which an individual thrives. Here, the EEA creates a functional

link between the cognitive systems and the context in which they have evolved (Foley

2005). In order to apply the EEA to paleoanthropology, Foley (2005) suggests that

speciation is best analyzed by considering distinctive morphologic characteristics within

the appropriate comparative biological framework. Utilizing odontometrics and its

functional biomechanical capabilities, this research distinguishes species within

Colobinae and Cercopithecinae from the Upper Laetolil Beds. In turn, understanding the

sequence and accumulation of distinctive odontometric traits can establish proximate and

ontogenetic factors that influence dietary adaptations in the fossil record (Foley 2005).

Incorporating this theoretical framework allows this research to focus on the

selected ecological niche a species has and how each species reacts differently to

4

environmental pressures, such as the cercopithecid evolutionary trend for an expanded

diet due to terrestriality.

Current Literature: Geology and Paleoecology

Laetoli, located in the southern part of the Eastern Rift Valley, is surrounded by a

series of tilted fault blocks with lake basins and plateaus. However, Laetoli can be found

on an upthrown fault block to the north of Lake Eyasi and Olduvai Gorge (Hay 1987).

The Laetolil Beds were first studied by Kent (1941) who used the Vogel River Series to

divide the lower unit (Laetolil Beds) and the upper unit (Ngaloba Beds). The Laetolil

Beds were first described as subaerially deposited tuffs having an irregular surface

overlain by agglomerate and nephelinite lava where it separates from the Ngaloba Beds

by a grey limestone with bright red pebble-like bodies that continues to the southwest of

Laetoli (Kent 1941).

5

Figure 1: Geological map of Laetoli (taken from Dr. Charles Musiba’s personal archive)

6

From 1974 to 1979, Hay conducted a stratigraphical investigation that revealed

more stratigraphical units in the Laetoli area, such that the Ngaloba Beds are followed by

the Olpiro Beds, Naibadad Beds, Ndolanya Beds and the Laetolil Beds. The Laetolil Beds

are then divided into the lower and upper units, where these two units can be

distinguishable. The lower unit of the Laetolil Beds consists mostly of aeolian tuff

interbedded with air-fall and water-worked tuff that also contains a few beds of

conglomerate and breccia sediments. Like the lower unit, the upper unit consists mostly

of aeolian tuff but contains some air-fall tuffs and a few horizons of xenoliths (Leakey et

al. 1976). The Yellow Marker Tuff is a distinctive pale yellow vitiric tuff that forms the

topmost stratum of the upper unit and is used to distinguish the Upper Ndolanya Beds

from the Upper Laetolil Beds (Hay 1987). The Upper Laetolil Beds consist of the

Australopithecus afarensis specimens that are radiometrically dated to 3.85−3.63 Ma

(Deino 2011). Furthermore, the Upper Beds are able to be sub-divided into marker tuffs

from a series of narrow temporal zones (Hay 1987). According the Hay (1987), the faunal

assemblage in the Upper Laetolil Beds represents a grassland savanna with areas of

thicker vegetation cover where most of the bovid remains indicate an open-country fauna.

On the other hand, Musiba (1999) suggests that the Laetoli Pliocene environment

contains more woodland areas than previously thought (Leakey et al. 1987). Localities 8

and 9 suggest that both grasslands and galleries of woodland were present due to bovid

functional morphologies relating to mosaic environments. Although this research focuses

on specific localities of the Upper Laetolil Beds, other reanalysis of the Upper Beds

7

support the notion of a prolonged, consistent record of a mosaic environment during this

time period.

Although some aspects of the faunal evidence indicates a range of habitats, which

includes a more dense bush cover and more extensive tracts of woodland than seen in the

region today, a high frequency of grazers and terrestrial mammals coupled with a low

occurrence of arboreal and frugivorous mammals indicate that the paleoecology of

Laetoli is a mosaic habitat that is dominated by grassland and shrubland with some areas

of woodland (open-, medium- and closed- woodlands) and gallery forests along seasonal

rivers (Su & Harrison 2007).

Galigo sadimanensis and at least three species of cercopithecids (Parapaio ado,

Paracolobus sp., and an unspecified larger colobine monkey) are suggestive of a closed

woodland, forest or rocky outcrop; however reconstructions of the landscape at Laetoli

show an absence of rocky outcrops implying that trees were the main site of refuge for

these primates (Su & Harrison 2007). Although extant species of these primates do

occupy a range of habitats such as grasslands and forests, other mammals (Paraxerus,

Rhychocyon, Subulona, Euonyma) can be used in the reconstruction of Laetoli to show its

mosaic environment (Su & Harrison 2007). The current paleoecological reconstructions

of the Upper Laetolil Beds show that this time period represents a heterogeneous mosaic

environment of grassland, savannah and woodland habitats. Su & Harrison (2007) also

found that there were no significant differences in ecological diversity between the

different localities or stratigraphic zones in the Upper Laetolil Beds. This implies that the

composition of the mammalian fauna was essentially identical throughout the entire

Upper Laetolil sequence and a consistent ecological structure was maintained throughout

8

this time regardless of regional or local environmental disturbances (Su & Harrison

2007). However, their study suggests that the mosaic environment of the Upper Laetolil

sequence was relatively stable, rather than a mixture of time-averaged habitats. The

specimens being examined in this research are derived from Locality 1 (between Tuff 6

and Yellow Marker Tuff), Locality 2, Locality 6 (between Tuffs 5 and 7) and Locality 8.

Figure 2: Map of the Laetoli area and the location of localities (taken from Dr. Charles

Musiba’s personal archive

Tuff 6 from Locality 1 consists mostly of a brown tefra with a clayey-sand

consistency that contains mostly aeolian tuff with patches of xenoliths; whereas Tuff 7

and 8 consists mostly of grey clayey-sand tefra that contains a patch of xenoliths near the

9

topmost part of Tuff 8. Tuff 9 and the Yellow Marker Tuff from Locality 1 contains

mostly yellow-grey colored sediment where it is comprised mostly of air-fall tuff and a

water-worked tuff toward the bottom of Tuff 9. However, present in Tuff 9 is an orange

colored air-fall tuff that can be seen on the upper segment of Tuff 9 (Hay 1987; see Fig.

2.1 and Fig. 2.3) According to Hay (1987), the most fossiliferous tuffs at Locality 1 are

found between Tuff 6 and the Yellow Marker Tuff, which is consistent with the findings

of the Laetoli primate specimens being examined. Locality 1 is situated in the northeast

section of Laetoli, which is also northeast of Locality 23 (Hay 1987; see Fig. 2.9).

Tuff 5 to Tuff 7 from Locality 6 contains a dominantly grey, clayey-sand that is

mostly of aeolian tuff with patches of water-worked tuffs and xenoliths. However, toward

the lower end of Tuff 5 is a yellow and yellow-grey aeolian tuff which is overlain by a

brown clayey, aeolian tuff (Hay 1987; see Fig. 2.1 and Fig. 2.3). Hay (1987) also

suggests that the most fossiliferous tuffs in Locality 6 are found between Tuff 5 and Tuff

6, which is also consistent with the findings presented. Locality 6 is situated on the mid-

eastern section of Laetoli, north of Locality 7 and east of the Laetoli camp site (Hay

1987; see Fig. 2.9).

10

Figure 3: Sections showing the sequence exposed in Loc. 6 Note the stratigraphic gaps in

the section are not shown to scale. (Taken from Ditchfield and Harrison 2011; See Fig

3.10 pg. 58)

11

According to Su and Harrison (2008), the fossil cercopithecid assemblage found

at Laetoli consists mostly of craniodental specimens; a pattern also similar to the rarity of

fossil hominins. They also suggest that this pattern is not only seen in hominins and

cercopithecids, but in large mammals found at Laetoli. Their findings suggest that the

craniodental remains are significantly overrepresented compared with postcranial

elements and that a phenomenon related to broader taphonomic factors must be occurring

at Laetoli. Although teeth are the most resilient skeletal structures in the mammalian

skeleton, they suggest that the disproportionality is due to carnivore scavenging and

periodical ash falls at Laetoli (Su & Harrison 2008).

Current Literature: Primates

In 1976, Delson conducted a systematic study pertaining to the classification of

subgroups of cercopithecids with the use of cranial morphologies and factor analysis. His

findings showed that the primary distinction within Cercopithecidae can be determined

between the longer-face cercopithecines and the shorter-more upright-faced colobines.

Given its overall cranial morphologies, the facial height is much greater in

cercopithecines in the suborbital zygomatic region when compared to colobines, whereas

colobines have a relatively wider facial region (Delson 1976). Because of these facial and

cranial morphological differences between cercopithecines and colobines, the dental

morphology will relate to such anatomical changes in the craniofacial region, including

the mandible.

Typically, cercopithecid dentition involves molariform teeth with asymmetrically

high crowns with four marginal cusps connected by lophids (transverse ridges) and three

foveas separated by two ridges. The maxillary teeth are usually mirror images of the

12

mandibular teeth where the buccal and lingual characteristics are reversed (Szalay and

Delson 1979).

On the other hand, the mandible in colobines and cercopithecines possess

specialized characteristics for each subfamily, indicative of specializations in masticatory

functions. Colobine mandibles tend to have a relatively upright ascending ramus; whereas

most cercopithecines have an extremely back-tilted ramus, especially found in larger

papionins. However, all colobines possess an expansion of the gonial angle with inferior

bulging beneath the rear molars which corresponds to its overall deeper corpus. The

corpus in colobines also tend to possess a relatively constant height and a mesially

shallowing corpus, whereas cercopithecines tend to have an increasingly mesial depth

which is shared by other hominoids (Delson 1976).

Cercopithecids have an increased relief of buccal teeth, producing longer

marginal shearing crests, which is indicative of folivory. However, since cercopithecids

are terrestrial animals, the tendency to maintain folivory is unlikely and a broadening diet

toward omnivorous foods is attributed to the expansion into the range of habitats that

cercopithecids occupied by the Plio-Pleistocene (Szalay and Delson 1979). Features such

as a reduced cingulum with increased crown relief, an increase of mandibular molar

trigonid length with a reduction of the hypoconulid, and an elongation of the maxillary

premolars and molars, all exhibit signs of morphological evolution toward omnivory for

cercopithecids (Szalay and Delson 1979).

Cercopithecids were first discovered at Laetoli in 1935 by L.S.B. Leakey;

however more fossil cercopithecids have been discovered since then. A year later,

13

Hopwood (1936) described Cercocebus ado from Kenya, which is the holotype for this

Pliocene species. Following these integral cercopithecid finds, Kohl-Larsen made an

extensive vertebrate collection in the Laetoli region, including 38 cercopithecids, where

most of his finds were found in the Upper Laetolil Beds (Harrison 2011). Futhermore,

Dietrich (Harrison 2011:Dietrich 1942) erected a new cercopithecine species within

Kohl-Larsen’s collection, Papio (Simopithecus) serengetensis, assuming that this species

was distinct from the holotype Cercocebus ado specimen. Finally, from 1959 to 1964,

L.S.B. Leaky and M.D. Leakey recovered additional cercopithecid material from Laetoli,

where most of the specimens were collected from Localilty 10 (Localities 10, 10W and

10E) (Harrison 2001).

Mary Leakey discovered 81 cranio-dental specimens from Laetoli expeditions

spanning from 1974 to 1979, where she and Delson (1987) recognized four

cercopithecids – Parapapio ado, Papionini gen. et sp. indet., cf. Rhinocolobus sp., and

Cercopithecoides sp.—mostly recovered from a wide variety of localities from the

Laetoli and Ndolanya Beds (Leakey & Delson 1987). Harrison then recovered an

additional 212 cranio-dental specimens and 25 postcranial specimens of cercopithecids at

Laetoli spanning from 1998 to 2005, which were all found in the Upper Laetolil Beds

except for a Parapapio incisor from the Upper Ndolanya Bed at Locality 7E.

Galago sadimanensis is represented by a number of partial mandibles found in the

Upper Laetolil Beds (Walker 1987). However, the fossil record of galagids from the Plio-

Pleistocene is relatively poor and the only other extinct species found is Otolemur

howelli, which is found in the Omo Valley, Ethiopia (Wesselman 1984). Another galagid

species was discovered in 2003 from Locality 10W in the Upper Laetolil Beds and is the

14

most complete specimen of a Pliocene galagid (Harrison 2011). Although Galago

sadimenensis is the only galagid found from Laetoli, this specimen indicates that it may

have been a primitive sister taxon to crown galagids (Harrison 2010). Due to the scarcity

of fossil galagids, not much can be deduced about the paleoecology of Laetoli; however,

Galago senegalensis can be found in riverine and open acacia woodland suggesting that

the vegetation at Laetoli during the Pliocene included at least open woodland or thorn

scrub (Harrison 2010).

Harrison recently collected an additional 83 dental specimens of cercopithecids

from the Upper Laetolil Beds, except for a deciduous I1 of Parapapio ado from the Upper

Ndolanya Beds where most of his findings were recovered from numerous localities

throughout the Laetoli area (Harrison 2011; see Table 6.1). Recovered were Parapaio

ado, cf. Rhinocolobus sp., Cercopithecoides sp., and Papionini gen et. ep. indet.

craniodental isolated teeth specimens. Although most of his findings constituted isolated

fragments, no partial or complete crania and mandibles were recovered (Harrison 2011).

Most of the current literature suggests that Galagids and Cercopithecids thrived in

the Laetoli environment during the Pliocene era; however the number of species within

Galagids and Cercopithecids seem to be inconclusive and many are lumped into certain

species despite their morphological variation (Walker 1987; Jablonski 1994; Frost 2001;

Frost & Delson 2002; Harrison 2011) . This research investigates odontometric data and

its biomechanical implications of craniodental cercopithecid specimens from the Upper

Laetolil Beds in order to provide more insight on its paleoecology. This research focuses

on a systematic method in which speciation can be distinguished based on quantitative

odontometric data of P3, P4, M1, M2, and M3 tooth types and the qualitative characteristics

15

of its biomechanical capabilities. This suggests that odontometric data will support and

focus on the biomechanical morphologies that indicate certain dietary adaptations. In

addition to, this research describes unclassified primate specimens found at Localities 1,

6, and 8 from Laetoli.

Extinct large colobines can be found across eastern Africa (Ethiopia, Kenya, and

Tanzania) during the Plio-Pleistocene epoch; however their distribution throughout

eastern Africa is contained in a diversified environment (Leakey 1982). A fossil

assemblage of Rhinocolobus and Paracolobus taxa have been found in the Omo Valley

of Ethiopia consisting of a paleoenvironment that includes a riverine forest that bordered

a river, whereas Cercopithecoides is expected to be found at Omo where the

paleoenvironment indicates an open savanna, away from a river (Leakey 1982). Although

Koobi Fora has a paleoenvironment similar to Omo, it contains more fluvial deposits

indicating perennial rivers with woodland and open country savanna that borders a

fluctuating lake (Leakey 1982: Harris 1978). The mosaic environment at Koobi Fora

may have been an ideal environment for Plio-Pleistocene primates, such that

Cercopithecoides williamsi, Cercopithecoides kimeui, Rhinocolobus and Paracolobus

indicates both terrestrial and forested paleoenvironments (Leakey 1982). However, since

cercopithecines are mostly found at Laetoli and Olduvai Gorge, the paleoenvironment

suggest that this area is predominately a dry open country savanna that contains areas of

dense woodland forests (Leakey 1982).

The extant cercopithecid species used in this research are derived from various

ecologies throughout Africa, ranging from Central, South, West and East Africa.

16

Within cecopithecinae is the genus Cercocebus, which include C. galeritus, C.

agilis, C. chrysogaster and C. torquatus. These species are generally found in equatorial,

western and eastern African regions ranging from Cameroon to Kenya (Wolfheim 1983).

The Tana River mangabey (C. galeritus) thrives primarily in an open canopy gallery

forest along the Tana River. Similarly, the Agile mangabey (C. agilis) are forest old

world monkeys and thrive in environments such as swamp-forests or riparian forests;

however, western populations, like the Golden-bellied mangabey (C. galeritus

chrysogaster), thrive along riverine forests. Like the others, the Collared mangabey (C.

torquatus) is also a moist forest species that typically thrives in mangroves, coastal,

gallery and inland swamp forests (Wolfheim 1983).

Also within cercopithecinae are the papionins, which include the genera

Mandrillus, Papio and Theropithcus. There are two species within Manrillus; Drills

(Mandrillus leucophaeus)which thrive in tropical-forested environments with open

countries and rock outcrops, while Mandrills (Mandrillus sphinx) tend to thrive in

tropical-forests that border a savanna or in a low elevated river basin with flat,

mountainous and plateau terrains (Wolfheim 1983). The genus Papio consists of 5

species: P. anubis, P. cynocephalus, P. hamadryas, P. papio and P. ursinus. Papio anubis

(Olive baboons) are found throughout Africa and is the most widespread and abundant

papionin species. This species thrive in a variety of habitats ranging from semidesert

steppe, arid thorn scurb, open grassland with patches of dense scrub, rocky hills and

forest-savannas; however, they can be found in areas that are higher, cooler and more

humid. In addition to their mosaic preferential habitat, they also thrive in woodlands,

gallery forests and tropical rainforests. Papio cynocephalus (Yellow baboons) are usually

17

found in southern and eastern regions of Africa, including coastal regions in the east. This

species primarily live in savanna and woodland habitats, typically perennial grass-

covered savannas with variable tree densities or a range of forested environments. Papio

hamadryas (Hamadryas or Sacred-heart baboons) are located in the northeast region of

Africa and southwestern region of the Arabian peninsula where they prefer habitats that

contain arid subdesert steppe, dry short-grass plains, alpine meadows and montane

grasslands (Wolfheim 1983). Papio papio (Guinea baboons) are specifically found in

western Africa, where they occupy wooded steppes, woodlands, savannas, dry forests and

gallery forests. Papio ursinus (Chacma baboons) live across southern Africa from the

Atlantic coast to the Indian Ocean. This species typically occupy wooded habitats and

open habitats, including subdesert steppe and savannas. Chacma baboons have a wide

habitat tolerance where they can occupy temperatures and humidity levels ranging from

near desert conditions to mountainous snowy areas. Papionins also tend to use tall trees

or rocky outcrops as sites for refuge (Wolfheim 1983).

The subfamily Colobinae includes 59 species into 10 genera; however, Colobus

and Procolobus genera are used in this research. Colobus angeolensis (Angolan Black

and White colobus monkey) are found in equatorial Africa from the Congo River to the

coast of the Indian Ocean in present day Tanzania (Wolfheim 1983). This species is

forest-dwelling and is predominately found in lowland and montane rain forests; however

it can be found in forest patches in savannas, lakeside forest borders, riparian forests and

coastal forests. Within C. angolensis, are a few subspecies such as the Tanzanian Black

and White colobus monkey (C. angolensis palliates) and Sandberg’s Angolan colobus

monkey (C. angolensis sandbergi), which the Tanzanian species tend to live in montane

18

forests and grasslands, alpine bamboo forests and solid-stemmed bamboo brush in the

highlands of Tanzania. Colobus polykomos (Western Black and White colobus monkey)

occupy along the southern coast of West Africa from Senegal to Nigeria. They are a

forest species that prefer primarily wet evergreen, moist evergreen, moist deciduous and

dry semideciduous forests. Generally, this species can be found in a variety of closed

forests formations except tickets and can also be found in patches of riverine forests in

savanna environments (Wolfheim 1983). Colobus versus (Olive colobus monkeys)

occupy western regions of Africa and thrive in many kinds of forest vegetation such as

moist semideciduous forest and evergreen rain forests. Unlike the Western Black and

White colobines, the Olive colobines thrive in dense thickets or dense undergrowths near

rivers or swamps. However, Olive colobnes tend to utilize regenerating forests, dry

semideciduous forests and riparian forests in savanna environments. Procolobus badius

(Red colobus monkeys) are closely related to Black and White colobines; however they

occupy a discontinuous distribution in western, central, and eastern Africa. Like all

colobines, they are a forest species that typically live in a moist lowland or gallery forest.

East African species of Red colobus monkeys primarily occupy moist, evergreen forests,

acacia woodland and woodland-evergreen mixtures (Wolfheim 1983).

19

Figure 4: Cladogram of extant cercopithecid genera and subgenera. Nodes, in numerical

order, identify reconstructed morphotypes for: (1) family Cercopithecidae; (2)

subfamilies Colobinae and Cercopithecinae; (3) tribes Cercopithecini and Papionini; and

(4) subtribes Presbytina and Colobina. Homonoidea is nearest extant sister taxon to

Cercopithecidae. Sub generi names enclosed in parentheses. “Lophocebus” enclosed in

quotation marks to indicate controversy as to its rank. (Strasser & Delson 1987; Figure 1

pp. 82)

20

CHAPTER III

MATERIALS AND METHODS

Sample

The five Laetoli specimens being described and examined were collected during

the University of Colorado Denver Tanzania Field School from 1999-2003. These

specimens were found at different localities throughout the Laetoli area and were found

in the Upper Laetolil Beds, dating from 3.85−3.63 Ma (Deino 2011). All of the

specimens are craniodental fragments with the exception of a preserved unknown

cercopithecid mandible.

Due to the fragmented nature of the craniodental specimens, only two of the

specimens will be used in this statistical analysis; however a qualitative description of the

all the specimens is presented. A total of 171 cercopithecines and colobines are

examined, where 166 are of extant cercopithecids, 3 extinct fossil primates and 2

unknown Laetoli cercopithecids (See Table 1.0). Collecting quantitative data such as

mesiodistal length, buccolingual breadth and other mandibular metrics allows an accurate

investigation of the type of species found in Laetoli during the Pliocene era. Extant

primate data is obtained from numerous datasets from the Primate Research Institute

from Kyoto University, Royal Museum for Central Africa (RMCA) and the University of

Colorado Denver Anthropology Collection; whereas the fossil cercopithecids data

(Theropithecus and cf. Rhicocolobus) is obtained from Leakey and Delson’s Laetoli

cercopithecidae Collection (1987), Plio-Pleistocene cercopithecids from Kanam East

21

(Harrison & Harris 1995), and New Fossil Cercopithecid Remains From the Humpata

Plateau, Southern Angola (Jablonski 1994).

Table 1: Summary of the cercopithecines and colobines used in the quantitative analysis

N

Cercopithecidae

Cercopithecinae

Cercopithecini

Cercopithecus sp.* 2

Papionini

Cercocebus 4

galeritus+ 1

galeritus agilis+ 20

chrysogaster+ 10

Mandrillus

leucophaeus* 2

sphinx* 2

Papio

anubis*= 5

anubis anubis+ 3

anubis (doguera

tessellatus) +

22

nigeriae+ 1

cynocephalus+ 3

Cynocephalus

jubilaeus+

1

cynocephalus 10

kindae+

cynocephalus

lestes+

2

hamadryas* 14

ursinus+ 4

Theropithecus

baringensisJ,L

2

Colobinae

Colobus

angolensis+

17

angolensis

palliatus+

1

angolenisis

sandbergi+

1

polykomos* 10

verus* 2

Procolobus

badius* 7

+Odontometric data taken from the Royal Museum for Central Africa

*Odontometric data taken fromKyoto University Primate Research Institute

=Odontometric data taken from the University of Colorado Denver Anthropology Collection

J Fossil Theropithecine from Southern Angola (Jablonski 1994)

L Fossil Theropithecine from Laetoli (Leakey 1969)

http://en.wikipedia.org/wiki/Cercopithecini

22

Craniofacial Descriptions

Order Primates Linnaeus, 1758

Infraorder Catarrhini Geoffroy, 1812

Superfamily Cercopithecoidea Gray, 1821

Family Cercopithecoidae Gray, 1821

A left maxillary fragment was found during a surface collection of the Upper

Laetolil Bed from Locality 6. This fragment contains a well preserved maxillary M1, M

2

and M3

of an unknown cercopithecid from Laetoli. P4 is partially present on the most

mesial aspect of the specimen; however, a coronal cross-section of both the lingual and

buccal roots of P4

is easily recognizable where the root canal of the lingual root can is

preserved. The distal neck of P4 is present, but there are no recognizable features of cusp

morphology. The protocone and hypoconee, which are the mesiolingual and distolingual

cusps, are heavily worn on M1, M

2 and M

3, indicating that the enamel on the lingual

aspect is diminished due to attrition. According to Harrison and Harris (1994),

Cercocebus is usually distinguishable by having worn down lingual cusps; however, a

more extensive analysis must be considered in order to distinguish the specimen. The

enamel on the paracone of M1 and M

2 is slightly worn down, whereas the enamel on the

metacone is still intact for both. However, the paracone height on M3 is significantly

longer than in the metacone with no present wear due to attrition, whereas the enamel on

the metacone of M3 is slightly lost due to attrition. The inferior maxillary alveolar process

is present on both the internal and external aspect of the specimen, where the body of the

maxilla is absent. The internal inferior maxillary border has a curvilinear rounding

indicating it is the part of the distal lingual arch of the molar tooth row. The external

inferior maxillary border also possesses a curvilinear rounding with a lateral flaring

23

superior to M2, which indicates a partial segment of the alveolar process diverging into

the inferior aspect of the zygomatic process of the maxilla.

Figure 5: Left maxillary M1-M

3 fragment of the Laetoli cercopith from Locality 6; A)

buccal view B) lingual view C) occusal view





A highly fragmented right mandibular P3 and P4 specimen from Locality 8 was

found 50 centimeters NW of LH 5 located just below the T7 layer. The maximum

mesiodistal length is of the specimen, including the superior aspect of the alveolar ridge

24

of the mandible, is about 25.47 mm and the maximum buccolingual width is 11.35 mm.

The most mesial aspect of the specimen contains the distal portion of the alveoli for the

canine and the cusps for P3 and P4 are complete obliterated due to taphonomic processes.

The cervical margin of P3 and P4 are contained within the superior aspect of the alveolar

margin on the buccal and lingual side; however majority of the mandibular body is

absent. The superior aspect of the lingual alveolar margin has somewhat of a vertical

slant, indicating the curvilineal lingual aspect of the mandible. On the other hand, the

superior aspect of the buccal alveolar margin is more vertical and does not possess any

curvilinear pattern. The inferior view of the specimen contains the apical roots of P3 and

P4, which are both contained in a calcified matrix. Due to the high degree of

fragmentation, this specimen will not be included in the analysis. However, this specimen

lacks diagnostic features and therefore cannot be ascribed to a primate species.

25

Figure 6: Right maxillary P3-P

4 fragment of the Laetoli cercopith from Locality 8; A)

occlusal view B) buccal view C) lingual view

26





Subfamily Colobinae Jerdon, 1867

Genera Colobus Illiger, 1811

Species cf. Rhinocolobus sp. Leakey, 1982

Laetoli specimen LP 04-1-01 was found in the Upper Laetolil Beds from Locality

1. This specimen is an isolated left upper M1 in which the protocone, hypocone and

paracone are visibly present. Although the apical aspect of theses cusps are slightly

absent, there are numerous features on this isolated specimen. The protocone and

hypocone are similar in height, but possess a difference between the pyramidal shaped

protocone and conical shaped hypocone. The paracone is also pyramidal in nature, but it

shows no sign of attrition; whereas the protocone possesses features attributed to

attritional wear. Remnants of the most mesial aspect of the metacone cervical margin are

present on the distobuccal aspect. The lingual maxillary root of M1 is highly preserved;

however the distobuccal maxillary root is fragmented and the apical tip is absent. On the

other hand, the mesiobuccal root is absent while still retaining a slight portion of the neck

leading into the paracone of M1.

This M1 isolated tooth is very similar to cf. Rhinocolobus sp. found at Laetoli,

sharing characteristics such as its overall square shape in outline with a slight elongation

mesiodistally, subequal in size of the protocone and hypocone, higher buccal cusps, a

larger paracone than metacone, and a presence of a D-shaped mesial fovea that is weakly

bordered by a marginal crest (Harrison 2011). These similarities indicate that this M1

specimen can be qualitatively classified as cf. Rhinocolobus from Laetoli. Rhinocolobus

turkanensis is principally known to be found in Koobi Fora and Omo Shungura

27

Formations of the Turkana Basin in Kenya and Ethiopia ranging from 3.4 to 1.5 Ma

(Harrison 2011). Rhinocolobus tukanensis contributes to the diversity of large colobines

from the Plio-Pleistocene in East Africa, where cf. Rhinocolobus sp. is the second most

common cercopithecid found at Laetoli (Harrison 2011).

28

Figure 7: Left maxillary M1 of the Laetoli cf. Rhinocolobus sp. (specimen 04-1-01) from

Locality 1; A) occlusal view B) buccal view C) lingual view D) mesial view

29





Subfamily Cercopithecinae Gray, 1821

Tribe Papionini Burnett, 1828

Genera Parapapio Hopwood, 1936

Species Parapapio ado Hopwood, 1936

Specimen 061703—01&02 is a right mandibular fragment found in S 3°11.248”

E 35.13.485” of Locality 1 from the Upper Laetoli Beds. It was found on 17 June 2003

from a surface collection. This specimen contains a partial P4 and an intact M1 (061703—

01) and M2 (061703—02) that is heavily worn from the buccal aspect. The mesiobuccal

root of P4 is well preserved and borders the most mesial aspect of the specimen; however

the cusp is destroyed and cannot be measured. The lingual aspect of M1 is partially

missing; however the roots are still intact and can be seen from the apical aspect of the

specimen. The superior external alveolar process is present, but the mandibular corpus is

completely absent. On the other hand, the superior internal alveolar process is present

towards the mesial dimension and is partially missing in the distal dimension. Since the

mandibular corpus is absent, the apical roots can be seen of P4, M1 and M2. The mesial

apical root of P4 is intact, but the distal root is partially missing. The apical roots of M1

and M2 are still intact; however the mesial and distal apical tips of M2 are slightly absent.

The protoconid and hypoconid of M1 is heavily worn where the enamel on the

buccal aspect of the M1 is diminished due to attrition. The distal portion of M2 talonid

cusp appears to be partially missing; however, the distal root is still intact and is the most

distal portion of the specimen itself. M2 is partially missing the hypoconid and

hypoconulid; however the protoconid, metaconid and entoconid can be seen. Although

30

the distal region of the entoconid is partially missing, the enamel on the lingual cusps is

not heavily worn. The enamel on the buccal cusps, however, are diminished due to

attrition.

31

Figure 8: Right mandibular M1-M2 fragment of Parapapio ado from Locality 1; A)

occlusal view B) buccal view C) lingual view

32





Subfamily Cercopithecinae Gray, 1821

Tribe Papionini Burnett, 1828

Genera Parapapio Hopwood, 1936

Species Parapapio ado Hopwood, 1936

The second specimen being examined is a nearly complete mandible from

Locality 2 of the Upper Laetolil beds. Absent from this specimen is the inferior base of

the mandibular corpus, the right ascending ramus and the base of the left gonial angle.

The inferior portion of the left ascending ramus is still intact (while still missing the

inferior base of the mandibular corpus nd gonial angle); however, the coronoid process

and the condylar process are absent. On the internal aspect of the left ascending ramus is

the mandibular foramen with a superoposterior to inferoanterior displacement. Also

present on the left interior ascending ramus is a partial lingula and a mylohyoid groove

with a similar displacement as the mandibular foramen.

The relative shape of the mandible is narrowly parabolic and has a relatively deep

mandibular planum. The specimen contains a strong simian shelf (inferior transverse

torus) that extends posteriorly to the level of P4-M1. The interior aspect of the simian

shelf is a shallow depression inferior from the incisors and premolars; however there is a

deep digastric fossa placed anteriorly with a pitted depression on the internal side of the

mandibular symphysis. On the external surface of the corpus is a well preserved

mandibular symphysis that contains two grooves running superoanterior to the

inferoposterior aspect, ending at the mental foramen on either side of the specimen.

33

The mandibular breadth at M1 is 33.7 mm and the mandibular length at M1 is

30mm giving a symphyseal ratio of 0.89 (symphyseal ratio = mandibular

length/mandibular breath). This indicates that the mandibular specimen has a lesser

degree of symphyseal curvature than comparatively sized cercopithecines (Ravosa 1996).

Colobines tend to have shorter mandibular lengths at a common mandibular breadth

suggesting that they exhibit similar levels of positive allometry of mandibular length

versus mandibular breadth. Since the mandibular length is shorter than the mandibular

breadth, this suggests that this mandibular specimen from Laetoli may be colobine.

The intact dental arcade consists of complete right and left I1, I2, P3, P4, M1, M2,

and M3. The occlusal cusps are still intact for all dentition and there is relatively little

sign of wear, except the left I1, where the occlusal surface is partially missing due to

taphonomic processes not due to wear. However, the distal aspect of the left I2 is missing

a small portion of the enamel and dentine on the labial surface of the tooth itself. There is

a diastema present between the canines and P3, and present on P3 is a cingulum due to the

diastema formation. The buccal cusps from P4 to M3, which include the protoconid and

hypoconid, are slightly worn compared to the lingual cusps—a general conformity to a

typical papionin (cercopithecine) wear pattern (Harrison & Harris 1994). Present on the

distal aspect of the left M3 is a fovea located posterior to the oblique line. The fossa

accommodates for the 5th

distal cusp, the hypoconulid, on M3 which is nearly erupted

from its alveoli.

Present on the lingual aspect of the anterior teeth is a cingulum, located on the

neck of the anterior teeth. According to Harrison and Harris (1994) a cingulum is present

in all extant African colobines; however, this feature is highly variably developed and is

34

better preserved on females. Although the cingulum is present on this mandibular

specimen, it also supports the notion that this specimen is a colobine, though more

diagnostic features are needed in order to distinguish the sex of the mandible once a

species is determined.

The overall mandibular morphology of the specimen is similar to colobine

mandibular morphology due to its relatively upright ascending ramus, a mandibular

corpus with a relatively constant height, and a simian shelf that is relatively shallow

mesially (Delson 1976). Although the gonial angle is absent, the expansion of this feature

is easily recognizable due to the rear molar ‘bulging’, which creates a deeper corpus

(Delson 1976).

35

Figure 9: Mandibular specimen of Parapapio ado from Locality 2; occlusal view

Figure 10: Mandibular specimen of Parapapio ado from Locality 2; lateral view

36

Figure 11: Comparative mandibular specimens for the Parapapio ado Laetoli specimen

from Locality 2; (Top: Papio Anubis; Middle: Colobus polykomos; Bottom: Parapapio

ado specimen from Locality 2

37

Methods: Dental Metrics

Using Darius Swindler’s Primate dentition: An introduction to the teeth of non-

human primates (2002), odontometric measurements were taken with digital dental

calipers accurate to 0.01mm. The mesiodistal (MD), buccolingual (BL) measurements

were also taken on each individual tooth. However, if certain measurements cannot be

taken due to taphonomic processes, those odontometrics were omitted in this research.

More information on the measurements taken are described in Table 2.. The

measurements of the right mandibular posterior teeth (P3-M3) of the unknown Laetoli

specimens are summarized in Table 3, whereas the summarized MD and BL

measurements of the right mandibular posterior teeth of the extant and fossil primates are

summarized in Appendix A. Crown Shape (Cshape) and Crown Area (Carea) were also

calculated using the MD and BL data (Cshape= BL/MD * 100; Carea=MD*BL).

The qualitative cusp terminology used in this discussion is taken from Delson

(1976) and Szalay and Delson (1979).

38

Table 2: Method of mandibular odontometrics taken for proposed Cercopithecid

specimens from Laetoli (Swindler 2002)

Dental Type Dimensions taken

Incisors MD: diameter at the incisal edge of the lower

incisors

BL: diameter taken at the cementoenamel

junction at a right angle to the MD diameter

Canines MD: (Lower Canines) MD diameter measured at

the level of the mesial alveolar margin

BL: diameter taken at the cementoenamel

junction at a right angle to the MD diameter

Pre-molars MD: Maximum MD diameter taken btween the

contact point. If the mesial contact is lacking on

P3 or P3 owing to a diastema between it and the

canine, the maximum horizontal distance is

measured from the distal contact point to the most

mesial point on the surface of the premolar. Same

method was utilized on primates with three

premolars.

BL: Maximum BL diameter taken at a right angle

to the MD diameter

Molars MD: Maximum MD diameter taken on the

occlusal surface between the mesial and distal

contact points

BL: Maximum BL diameter measured at right

angles to the MD dimension. The dimensions of

both the tigonid and talonid were taken in this

manner.

39

Figure 12: Odontometric landmarks. B = buccolingual breadth; L = mesiodistal length.

Darius (2002) Primate Dentition: An Introduction to the Teeth of Non-Human Primates:

Reprinted from Swindler, D.R. (1976) Dentition of Living Primates

40

Figure 13: Identification of cercopithecid dental landmarks on the right lower M3 of

Theropithecus [modified after Jolly 1972] A = Occusal aspect; B = lingual aspect; C=

buccal aspect; D= mesial aspect; (stippling indicates contact facet with M2; E = distal

aspect. a = Mesial buccal cleft; b = protoconid; c = median buccal cleft; d = buccal

margin; e = hypoconid; f = distal buccal cleft; g = hypoconulid; h = tuberculum sextum; I

= distal fovea; j = hypolophid; k = entoconid; l = lingual margin; m = talonid basin; n =

metaconid; o = metalophid; p = trigonid basin (mesial fovea); q = mesial shelf; r =

median lingual notch; s = distal lingual notch; t = distal buccal notch; u = median buccal

notch. In this, elevated features (crests, ridges, outlines) are represented by solid lines,

depressed features (groove, clefts) by dotted lines. (Delson 1975 pp.176, Fig. 2)

41

Table 3: Mandibular odontometrics from the proposed Cercopithecid sp. from Laetoli,

Local 2 and LP 061703-01&02 fragment; right mandibular segment from P3- M3 in mm

TOOTH MD* BL*

Unknown

Cercopithecid

sp from Laetoli

LP 061703-01

& 02

Unknown

Cercopithecid

sp from Laetoli

LP 061703-01

& 02

P3 5.79

------------- 5.62

-------------

P4 6.97

------------- 6.67

-------------

M1 8.91

8.85

7.63

6.51

M2 10.91

9.90

8.87

9.10

M3 14.74

------------- 9.68

-------------

*MD – Mesiodistal length, BL – Buccolingual breadth (Maximum buccolingual breadth

were used as the BL for all molars)

42

Methods: Statistical Analysis

In order to interpret the specimens from Laetoli, extant and fossil primates had to

be considered in the analysis. The values taken from this dataset include the right portion

of the mandible, so that it can be compared to the nearly complete mandible from

Locality 2 and the LP mandibular fragment from Locality 1. This comparative sample

consist mostly of extant primate data; however the Rhinocolobus fossil will be grouped

with its extant population based on their morphological similarities they share, whereas

the fossil Theropithecus data will be grouped as their own group.

Computational statistical analysis is performed in order to distinguish the recently

recovered fossilized cercopith specimens found at Laetoli. A Principle Component

Analysis (PCA) and Discriminant Function Analysis (DFA) are used in this study. The

PCA produces extraction factors, where the first extracted factor accounts for the largest

variance of the total variance inherent in the odontometric data. The eigenvalue also

provides information on the equivalent number of variables the new factor represents.

The DFA will be used to distinguish whether or not odontometric data can be used to

classify primate species by using a weighted combination of predictor values to classify a

species into the predisposed criterion species groups. However, since the number within

each species varies, a prior probability was specified in the DFA based on the

proportionality of occurrence of the species in the total sample of cercopithecines and

colobines. Also, the grouping variables used for the PCA and DFA consisted of the

genera that is associated with each species; therefore a total of 7 grouping variables were

used (Cercocebus, Cercopithecus, Colobus, Mandrillus, Papio, Theropithecus, and the

unknown Laetoli specimens). High correct classification for the DFA means that there is

43

a high probability for the observed grouping variable to match the expected grouping

variable; whereas the low correct classification means that there is a low probability for

the observed grouping variable to match the expected grouping variable.

44

CHAPTER IV

RESULTS

P3

The first two factors show distinct groupings between cercopithecids occupying

forested habitats versus mosaic habitats. However, the PC I has an eigenvalue of 3.06 and

explains 76.66 % of the total variance, whereas PC II has an eigenvalue of 0.86 and

explains for 21.61% of the total variance. Since PC I has the largest eigenvalue, the

corresponding eigenvector exhibits the direction of the greatest variation (76.66%). The

eigenvectors associated with PC I shows that Cshape is extracted, where MD, BL and Carea

are retained variables since they are moderately correlated (rMD=0.56, rBL=0.49,

rCarea=0.56). Figure 14 shows the graphical representation of the PCA for P3.

45

Figure 14: 3D score scatterplot for the P3 PCA ● Cercocebus ● Cercopithecus ● Colobus

● Mandrillus ● Papio ● Theropithecus ● unknown LP

In the DFA, Wilks’ Lamda describes the proportion of total variance in the

discriminant scores not explained by the differences among groups. In this instance, the

null hypothesis is that the means of MD, BL, and Carea on the discriminant function at

group centroids are equal. In other words, Wilks’ Lambda shows which variables

contribute a significant amount of prediction to discriminant the groups. Since Wilks’

Lamba in the output is below 1 (λ=0.22;p<0.001), it indicates that MD, BL, and Carea

means differ. However, since the Wilks’ Lambda is not near 1, it indicates that function 1

46

has more discriminatory ability. Given this, eigenvalues indicate the proportion of

variance explained. The high eigenvalue of 1.89 indicates that the discriminatory power

of the function is strong and the high canonical correlation (r=0.81) indicates a strong

positive association between discriminant scores and grouping which demonstrate a

strong discriminating function for P3.

Of the 170 cases of MD, BL, and Carea variables, 112 cases of the variables were

correctly classified within their respective primate species, where 65.88% of the

predicted group membership matched the observed group membership of species.

However, 58 cases of the variables were misclassified within the predicted group

membership, where 34.12% of the predicted group membership did not match the

observed group membership.

P4

The first two factors show less of a distinct grouping pattern, where forested

cercopithecids and cercopithecids that exploit more mosaic environments are still

separated in two groups with much more overlap between the loading factors. However,

the PC I has an eigenvalue of 2.91 and explains 72.86 % of the total variance, whereas

PC II has an eigenvalue of 1.07 and explains for 26.81% of the total variance. Since PC I

has the largest eigenvalue, the corresponding eigenvector exhibits the direction of the

greatest variation (72.86%). The eigenvectors associated with PC I shows that Cshape is

extracted which is also seen in P3, where MD, BL and Carea are retained variables since

they are moderately correlated (rMD=0.57, rBL=0.57, rCarea=0.58). Figure 15 shows the

graphical representation of the PCA for P4.

47

Figure 15: 3D score scatterplot for the P4 PCA ● Cercocebus ● Cercopithecus ● Colobus


As stated earlier, Wilks’ Lambda shows which variables contribute a significant

amount of prediction to discriminant the groups in a DFA. Since Wilks’ Lamba in the

output is below 1 (λ=0.18;p<0.001), it indicates that MD, BL, and Carea means differ.

However, since the Wilks’ Lambda is not near 1, it indicates that function 1 has more

discriminatory ability. The high eigenvalue of 2.67 indicates that the discriminatory

48

power of the function is strong and the high canonical correlation (r=0.85) indicates a

strong positive association between discriminant scores and grouping which demonstrate

a strong discriminating function for P4 even though the grouping variables in the PCA

were not clearly distinct.







M1

Like P4, the first two factors show less of a distinct grouping pattern, where

forested cercopithecids and mosaic range cercopithecids are still separated in two groups

with much less overlap between the loading factors but more of a spread between PC I

and PC II. However, the PC I has an eigenvalue of 2.95 and explains 73.77 % of the total

variance, whereas PC II has an eigenvalue of 1.04 and explains for 25.99% of the total

variance. Since PC I has the largest eigenvalue, the corresponding eigenvector exhibits

the direction of the greatest variation (73.77%). The eigenvectors associated with PC I

shows that Cshape is also extracted, where MD, BL and Carea are retained variables since

they are moderately correlated (rMD=0.57, rBL=0.58, rCarea=0.58). Figure 16 shows the

graphical representation of the PCA for M1.

49

Figure 16: 3D score scatterplot for the M1 PCA ● Cercocebus ● Cercopithecus ● Colobus


Since Wilks’ Lamba in the output is below 1 (λ=0.11;p<0.001) for the DFA, it

indicates that MD, BL, and Carea means differ. However, since the Wilks’ Lambda is not

near 1, it indicates that function 1 also has more discriminatory ability, similar to P3 and

P4. The high eigenvalue of 4.60 indicates that the discriminatory power of the function is

strong and the high canonical correlation (r=0.91) indicates a strong positive association

between discriminant scores and grouping which demonstrate a strong discriminating

function for M1 even though the grouping variables in the PCA were not clearly distinct.

50







M2

Like P4 and M1, the first two factors show less of a distinct grouping pattern,

where forested- and mosaic- dwelling cercopithecids are still separated in two groups

with some overlap between the loading factors but more of a spread between PC I and PC

II. However, the PC I has an eigenvalue of 2.96 and explains 74.10% of the total

variance, whereas PC II has an eigenvalue of 1.03 and explains for 25.63% of the total

variance. Since PC I has the largest eigenvalue, the corresponding eigenvector exhibits

the direction of the greatest variation (74.10%). The eigenvectors associated with PC I

shows that Cshape is also extracted (as seen in P3, P4 and M1), where MD, BL and Carea are

retained variables since they are moderately correlated (rMD=0.58, rBL=0.57, rCarea=0.58).

Figure 17 shows the graphical representation of the PCA for M2.

51

Figure 17: 3D score scatterplot for the M2 PCA ● Cercocebus ● Cercopithecus ● Colobus


Wilks’ Lamba for the M2 output is below 1 (λ=0.10;p<0.001), which indicates

that MD, BL, and Carea means differ. However, since the Wilks’ Lambda is not near 1, it

indicates that function 1 also has more discriminatory ability, similar to P3, P4, and M1.

The high eigenvalue of 6.07 indicates that the discriminatory power of the function is

strong and the high canonical correlation (r=0.93) indicates a strong positive association

between discriminant scores and grouping which demonstrate a strong discriminating

function for M1 even though the grouping variables in the PCA were not clearly distinct.

52







M3

Like P3 the first two factors show a distinct grouping pattern, where forested- and

mosaic- dwelling cercopithecids are still separated in two groups with no overlap

between the loading factors with more of a variation between PC I and PC II. However,

the PC I has an eigenvalue of 2.96 and explains 74.04 % of the total variance, whereas

PC II has an eigenvalue of 1.03 and explains for 25.67% of the total variance (which

resembles M2 PCA output). Since PC I has the largest eigenvalue, the corresponding

eigenvector exhibits the direction of the greatest variation (74.04%). The eigenvectors

associated with PC I shows that Cshape is extracted (which is similar to all tooth types),

where MD, BL and Carea are retained variables since they are moderately correlated

(rMD=0.58, rBL=0.57, rCarea=0.58). Figure 18 shows the graphical representation of the

PCA for M3.

53

Figure 18: 3D score scatterplot for the M3 PCA● Cercocebus ● Cercopithecus ● Colobus


In the DFA, the Wilks’ Lamba for the M3 is the lowest of all the DFA performed

and is below 1 (λ=0.07;p<0.001), which indicates that MD, BL, and Carea means highly

differ. However, since the Wilks’ Lambda is not near 1 and is the lowest of the values

compared to P3, P4, M1 and M2, it indicates that function 1 also has the most

discriminatory ability in M3. The high eigenvalue of 8.17 indicates that the discriminatory

power of the function is strong and the high canonical correlation (r=0.94) indicates a

54

strong positive association between discriminant scores and grouping which demonstrate

a strong discriminating function for M3.

Of the 170 cases of MD, BL, Cshape and Carea variables, 143 cases of the variables

were correctly classified within their respective primate species, where 84.12% of the





Summary: Results

The PCA output shows that only Cshape is extracted from the data for all tooth

types. MD, BL and Carea are retained variables for all tooth types since they are all

moderately correlated to one another. MD, BL and Carea are correlated because

mesiodistal length and the buccolingual width are related to overall tooth morphology.

Also, since Carea=MD*BL, we can assume that all three variables are significant to each

other since calculation of Carea includes both MD and BL variables. Further analysis of

the DFA will be discussed in the section below; however since Cshape is not a significant

variable (as shown in the PCA), the DFA will exclude the Cshape variable into the

analysis. The overall DFA shows that the buccal teeth (M1, M2 and M3) have a much

higher discriminatory power than the premolars. Here, the discriminatory ability

increases with M1 and M3, but M2 has the lowest discriminatory power from all the

molars, yet still retains a higher discriminatory ability than the premolars.

55

CHAPTER V

DISCUSSION

Within Cercopithecidae are two sub families: Colobinae which are leaf-eaters and

Cercopithecinae which are cheek-pouched monkeys (Delson 1975). Cercopithecines can

then be subdivided into two tribes: Cercopithecini and Papionini. As stated earlier, the

prominent difference within Cercopithecidae is between the longer-faced cercopithecines

and the shorter- more upright-faced colobines, although there is much overlap in

proportions for the two (Delson 1975). According to Delson (1975) colobines are

relatively wider in the face, as seen in the wider interorbital region, especially in the

smaller species. However, there is some overlap between cercopithecines and colobines

within the posterior aperture of the nasal cavity leading into the nasopharynx region

(Delson 1975).

The PCA results show a distinct grouping between forest- and mosaic- dwelling

cercopithecids; such that the predominately forests cercopithecids include Colobus,

Cercopithecus, and Cercocebus genera, and the mosaic-dwelling cercopithecids include

Mandrillus, Papio and Theropithecus. The two groups show distinctness since both

groupings show that cercopithecids can be divided by the type of environment they prefer

and the overlap may be due to the mosaic environments preferred by papionins.

Papionins are known to occupy a range of habitats such as tropical rainforest that usually

borders a savannah, mountainous and plateau terrains, open grasslands with patches of

dense thicket, and savanna-woodlands.

56

Mandrillus, Papio and Theropithecus all follow a similar dental pattern, even

though Theropithecus does possess specialized features from the other Papionin groups.

The PCA may have grouped these genera together based on characteristics such as

accessory cuspules, lower molar width relationships, and moderate flaring and reduction

of the mandibular incisor enamel (Delson 1975), indicating a more broad diet. However,

the greatest difference between Theropithecus and the other Papionins is its great crown

height and heightened relief with deepened foveas. If the overall crown height were

measured for each tooth type instead of the mesiodistal length and buccolingual width,

Theropithecus would probably have its own classification in the principal component

analysis.

The second grouping of the other cercopithecines and colobines exploit

predominately forested environments, such as a riverine forest, swamp forests, moist

evergreens, montane forests, and dense tickets found in savanna regions. This grouping

also follows cercopithecini dental patterning which is characterized by the loss of M3

hypoconulid and a reduction of M3, which is also indicative of a predominately leaf-

eating diet. Other typical characteristics include elongate and low flaring teeth; however,

there have been instances where cercopithecines have distinctive lateral flaring (as seen

in Cercocebus), an increase of mesial width, and trigonid size from the mandibular M1 to

M3. Cercopithecini also share the same general characteristics of papionins (stated

before); however, they do not possess accessory capsules and have unreduced lower

incisor enamel as seen in colobines (Delson 1975). It is assumed that Cercopithecus

would group closer with Colobus and Cercocebus since most Cercopithecus species are

arboreal frugivores and some are considered to be leaf-eaters (Szalay & Delson 1979).

57

Studies have demonstrated that Cercocebus possesses a flatter crown surface of the

molars suggesting a more frugivorous diet with teeth adapted to crushing rather than

slicing (Szalay & Delson 1979). On the other hand, Kay (1978) found that unworn

Cercocebus teeth plotted out closer to colobines and other folivorous Lophocebus species

(Szalay & Delson 1979: Kay 1978).

The unknown LP mandible groups slightly with the forest-dwelling

cercopithecids (tooth types P3, P4 and M2) in the PCA; however for the M1 tooth type, the

mandible is situated between both groups and its M3 is situated in the mosaic-dwelling

cercopithecid group. On the other hand, specimen 061703—01&02 (fragmented M1 and

M2 specimen) classifies with the mosaic-dwelling cercopithecid group in the principle

component analysis. We can see that the LP mandible possesses an intermediate

classification between both groupings, as seen in the qualitative analysis; whereas

specimen 061703—01&02 categorizes primarily with papionins indicating a preference

of a more mosaic environment.

The DFA for P3 shows that 35 Cercocebus measurements are correctly classified

within the Cercocebus genus, whereas 13 are misclassified into Colobus and 3 are

misclassified into Papio genera. Twenty-five Colobus measurements were correctly

classified into the Colobus genus, whereas 16 are misclassified into the Cercocebus, 4 are

misclassified into Papio and 1 is misclassified into Cercopithecus. 2 of the Mandrillus

measurements are correctly classified, whereas 2 are misclassified into Papio and finally,

48 Papio measurements are correctly classified with 4 misclassified for both Colobus and

Mandrillus and 3 misclassified in Theropithecus. On the other hand, the 2 Cercopithecus

58

and Theropithecus measurements were correctly classified. The LP mandible is

misclassified into Theropithecus; however, this is only for the P3 tooth type.

The DFA for P4 shows that 41 Cercocebus measurements are correctly classified,

whereas 8 measurements are misclassified into Colobus, 1 measurement is misclassified

for both Papio and the LP mandible. Only 1 measurement of Cercopithecus is correctly

classified and the other measurement is misclassified as Colobus. 33 Colobus

measurements are correctly classified, whereas 8 measurements are misclassified into

Cercocebus, 4 measurements misclassified into Cercopithecus and 1 measurement

misclassified into Papio. Like P3, 2 of the Mandrillus measurements are correctly

classified, whereas 2 are misclassified into Papio. Fourty-nine Papio measurements are

correctly classified, whereas 15 of the measurements are misclassified into Cercoebus.

The only correctly classified measurement without any misclassifications is for

Theropithecus. The LP mandible is misclassified into Cercocebus; however, this is only

the case for the P4 tooth type.

The results of the DFA shows that the posterior teeth (M1 and M3 specifically)

increase in discriminatory power and a have a lower percentage of misclassification than

the premolars (decrease in misclassification by 7.75% from P4 to M1).

The DFA for M1 shows that 46 Cercocebus measurements are correctly classified,

whereas only 5 are misclassified into Colobus; 33 of the Colobus measurements are

correctly classified, whereas 9 measurements are misclassified into Cercocebus, 3

measurements misclassified into Cercopithecus and 1 measurement is misclassified into

Papio, and finally 57 Papio measurements are correctly classified with 7 measurements

59

misclassified into Cercocebus. Measurements of Cercopithecus, Mandrillus, and

Theropithecus are correctly classified for the M1 tooth type. Like P4, the LP mandible is

misclassified into Cercocebus, whereas LP specimen 061703—01 is misclassified into

Papio.

Although M2 has a lower discriminatory power than M1 and M3, 19.3% of the

measurements were misclassified; however, M2 has a lower percentage in

misclassification when compared to P4 (decrease in misclassification by 6.58%). Fourty-

three of the Cercocebus measurements are correctly classified, whereas 8 of the

measurements are misclassified into Colobus; 38 of the Cercocebus are correctly

classified, whereas 3 measurements are misclassified into Cercocebus, 4 measurements

are misclassified into Cercopithecus and 1 measurement is misclassified as Papio; and

finally 57 Papio measurements are correctly classified with 6 measurements misclassified

into Cercocebus. Like M1, Cercopithecus, Mandrillus, and Theropithecus are correctly

classified for the M2 tooth type. Similar to M1, the LP mandible for M2 is misclassified

into Cercocebus, whereas LP specimen 061703—02 is misclassified into Papio.

A stated earlier, M3 has a high eigenvalue of 8.17, which indicates that the

discriminatory power of the function is strong and the high canonical correlation (r=0.94)

indicates a strong positive association between discriminant scores and grouping which

demonstrate a strong discriminating function for M3. M3 has the lowest percentage of

misclassification (15.88%) where 43 Cercocebus measurements are correctly classified

with only 8 measurements misclassified as Colobus; 37 Colobus measurements correctly

classified with 7 measurements misclassified as Cercocebus and 1 measurement

misclassified in Cercopithecus and Papio; and finally 61 Papio measurements correctly

60

classified with 3 measurements misclassified as Cercocebus. Similar to M1 and M2,

Cercopithecus, Mandrillus, Theropithecus are all correctly classified for the M3 tooth

type. Unlike M1 and M2, the LP mandible misclassifies as Papio instead of Cercocebus

which is similar to the LP specimen 061703—01&02 misclassification.

Although the unknown LP specimens were misclassified into different subtribes

for all tooth types, they can all be classified into Papionini indicating that the tooth type

for both specimens are similar to papionins. However, this contradicts the mandibular

morphology seen in the LP mandible since it resembles colobines instead of

cercopithecines (which papionins are taxonomically classified under cercopithecines).

The conclusion is that the LP mandibular specimen probably depended on a similar diet

as cercopithecines rather than a typical leaf-eating diet of colobines. Studies have shown

that colobines and gibbons share many ancestral cranial and craniofacial patterns, while

Cercopithecinae are the most derived and specialized group (Delson 1975, Vogel 1966).

However, it is assumed that early cercopithecid facial skeleton may have been much

more similar to colobines than present day cercopithecines (Delson 1975, Vogel 1966).

The LP mandible is a clear example of having derived tooth morphologies, as seen in

papionins; yet still retains a colobine facial skeleton, a characteristic of early

cercopithecids.

The unknown LP mandible has a symphyseal ratio of 0.89, which indicates that

the mandibular specimen has a lesser degree of symphyseal curvature than comparatively

sized cercopithecines (Ravosa 1996). As stated earlier, colobines tend to have shorter

mandible lengths at a common mandibular breadth suggesting that they exhibit similar

levels of positive allometry of mandibular length versus mandibular breadth. Since the

61

mandibular length is shorter than the mandibular breadth, this suggests that this

mandibular specimen from Laetoli retains colobine, ancestral features with more derived

tooth morphology during the Pliocene epoch.

According to Jolly (1966), the original adaptive niche of the cercopithecids was

leaf-eating and that the molar pattern is the most primitive character state. However,

other studies have shown that colobines are morphologically ancestral in all character

states since they are arboreal and could not be descended from terrestrial cercopithcines,

which is more indicative of environmental functionality than ancestry (Delson 1975,

Napier 1970). The most appropriate understanding of cercopithecid evolution comes

from the work of Vogel (1966), where colobine and gibbon cranium are probably

representative of an ancestral condition for catarrhines (Delson 1975). Modern colobines

are able to process large amounts of foliage through an enlarged and sacculated stomach

and modified digestive tract. However, Delson (1975) suggests that although this

characteristic may seem derived in nature, it may actually be an ancestral trait for

Colobinae. Modern cercopithecines possess buccal pouches for temporary storage of food

prior to mastication, but acquired a digestive system similar to other hominoids (Delson

1975) that may relatively affect tooth morphology.

Another aspect of catarrhine evolution that may be useful in speciation is the

number of chromosomes in a eukaryotic cell (Delson 1975). Gibbons and some colobines

share the same number of diploid chromosomes (2n=44), which Delson suggests may be

the ancestral number for all catarrhines. On the other hand, papionins have a diploid

number of 42, indicating that papionins and colobines have a “closely-knit” ancestry.

62

However, species of Cercopithecini have a diploid number of chromosomes that range

from 48 to 72, which indicates the strongest specialization according to Delson (1975).

Napier (1970) suggest that Old World monkeys originated as an adaptive unit

where there was a selective advantage for primates that were able to subsist on leaves

rather than fruits when necessary, implying that forests and the surrounding environment

were seasonal. However, the ancestors of cercopithecids may not have been dependent on

leaves, but were able to supplements the basic primate diet of fruit with foliage in habitats

where they were abundant (or seasonal changes where foliage were abundant during that

time of year). Considering Napier’s hypothesis and other studies on cercopithecid

evolution (Napier 1970, Delson 1975, Jolly 1966), early cerecopithecids probably had a

colobine-like cranium with macaque-like teeth (Tribe: Papionini) and long limbs. Delson

(1975) suggests that the early cercopithecids were arboreal quadrupeds who ate fruits

when possible but supplemented their diet with leaves under certain ecological

conditions.

By the Middle Miocene, colobine ancestors shifted to a more folivorous diet with

associated changes to teeth morphology and more specialized gut; whereas

cercopithecine ancestors started to shift towards a omnivorous diet leading into the

specialization of the buccal pouches and allometrically longer faces. The unknown

Laetoli specimens follow the latter trajectory, where the colobine-like mandibular

morphology retains the primitive state, yet develops specialization for a more omnivorous

diet that are seen in early cercopithecids.

63

The DFA statistical analysis for the unknown Laetoli specimens classify into

Theropithecus, Cercocebus and Papio, all derived from the same papionini tribe.

Although the mandibular morphology resembles extant colobines, the teeth morphology

is indicative of papionini, which is a quality of an early cercopithecid. Knowing that the

unknown species classifies under papionini, this narrows down which species these

specimens are. By utilizing the statistical analysis and qualitative descriptions, the

unknown Laetoli specimens can be attributed to Parapapio ado (Pp. ado), which is also

the most common cercopithecid found at Laetoli. Parapapio ado also possesses a

relatively short face during its subadult phase (Harrison 2011), which is recognizable

through the overall shape and breadth of the LP mandibular specimen.

The LP mandibular specimen is a subadult female due to the mid-erupted M3 and

reduced canine size and morphologies seen in P3, which is also a sexually dimorphic

tooth. However, the LP specimen 061703—01&02 cannot be classified as a male or

female due to the lack of qualitative diagnostic features. A more comprehensive analysis

must be completed in order to classify the sex of the specimens; however based on the

qualitative and statistical analysis, the LP mandible implies subadult female

characteristics.

The recovered LP mandible exhibits similarities to Parapapio ado by the

presence of 3 mental foramen; however most species (and is present on the LP mandible)

of Parapapio ado have a common mental foramen found on the inferior two-thirds of the

mandibular corpus located below P4 and M1 which is positioned anterolaterally (Harrison

2011). Like Parapapio ado, the P3 of the LP mandibular specimen is short and relatively

narrow with a slight crown extension mesiobuccally. Its P3 also has a distinctive

64

protoconid with a mesial crest that extends to the lingual cingulum. As stated earlier, the

P4 of the LP mandible possesses a pyramidal protoconid; however, the metaconid is

unrecognizable and may be worn due taphonomic processes or attrition. On the other

hand M1, the buccal cusps (protoconid and hypoconid) are more conical and are seen

slightly more elevated than the lingual cusps (metaconid and entoconid); however, this

height differential will decrease with the amount of wear (Harrison 2011). Although the

protoconid and hypoconid are usually seen equal in size for Parapapio ado, the LP

mandible shows a very slight increase in protoconid height. M2 has similar characteristics

to M1; however it is clear that the LP mandible possesses a protoconid and hypoconid

that are subequal in size. Like Parapapio ado, the M3 of the LP specimen possesses a

hypoconulid that is positioned relatively low on the crown on the distal aspect, where the

entoconid is situated closer to the hypoconid than the protoconid to the metaconid. Also

present on the M3 is a triangular distal fovea with a distolingual tuberculum sextum on

the occlusal surface, which is also variably present on other Parapapio ado specimens

(Harrison 2011).

As stated earlier, the LP specimens classify under Theropithecis, Cercocebus, and

Papio. However, the Cercocebus and Papio material are from extant species, whereas the

Theropithecus used in the analysis is from the fossil Theropithecine material from

Southern Angola (Jablonski 1994) and Laetoli (Leakey 1969). Parapapio ado has many

similarities with extant Cercocebus (Lophocebus) and Papio such as a broader and

shorter P3 crown, relative P4 size that is intermediary between Cercocebus-Mandrillus

and Lophocebus-Papio-Theropithecus, and share basic configuration of molar

65

morphologies (Freedman 1957; Szalay and Delson 1979; Leakey and Delson 1987; Frost

and Delson 2002).

66

CHAPTER VI

CONCLUSION

Parapapio ado and other fossil cercopithecids, such as Galago sadimanensis and

Paracolobus sp., is suggestive of a closed woodland environment or forests at Laetoli.

However, extant cercopithecids tend to thrive in a range of habitats from grasslands to

forests, where stands of trees and rocky outcrops are common sleeping quadrants. Given

this, the newly recovered specimens that were able to be quantifiable can be attributed to

Parapapio ado. This particular species is the most common cercopithecid found at

Laetoli during the Pliocene epoch which also supports the existing literature that the

paleoenvironment of Laetoli consisted of a denser forested environment than previously

thought. Previous analysis of odontometric data (Delson 1975; Vogel 1966; Jablonski

1994; Frost 2001) has been shown to compare fossil and extant cercopithecids; however,

establishing speciation is usually based on qualitative data. Although three of the five

specimens were unable to be classified into a particular species due to the high

fragmentation and poor preservation, two specimens were able to be measured and

quantified.

This research has demonstrated that quantitative data can be utilized in

deciphering fossil and extant species of cercopithecids since tooth morphology is

representative of dietary adaptations and environmental contexts. The principle

component analysis demonstrated that odontometric data can be used in general

groupings of speciation based on dietary adaptations and habitat preferences; however

Cshape was irrelevant to the analysis and was extracted. MD, BL and Carea were all retained

67

variables that were highly correlated and could be used for a better approximation of

speciation for the discriminant functional analysis. The DFA showed that the posterior

buccal teeth had a higher discriminatory power than the premolars; however M3 had the

highest discriminatory ability in deciphering primate species and exhibited the lowest

misclassification percentage for all tooth types.

The Parapapio ado specimens have shed light on the evolutionary context of

cercopithecids during the Pliocene at Laetoli, which is also supported by the ancestral

colobine-gibbon like cranium and derived papionin tooth morphology. The characteristics

of these specimens suggest and support that cercopithecids during the Pliocene may have

had a combination of ancestral and derived characteristics that helped them evolve

towards a more omnivorous diet.

68

REFERENCES

Bird DW & O’Connell JF (2006) Behavioral Ecology and Archaeology. J Archaeol Res

14:143–188.

Deino AL (2011) Paleontology and Geology of Laetoli: Human Evolution in Context.

Volume 1: Geology, Geochronology,Paleoecology and Paleoenvironment, Vertebrate

Paleobiology and Paleoanthropology: “Chapter 4:40Ar/39Ar Dating of Laetoli,

Tanzania”. Springer.77-97.

Delson E (1975) Evolutionary history of the Cercopithecidae. In F.S. Szalay (Ed.)

Approaches to primate paleobiology. Contributions to primatology (Vol. 5, pp.167—217.

Basel: Karger.

Foley R (2005) The adaptive legacy of human evolution: a search for the environment of

evolutionary adaptedness. Evolutionary Anthropology. 194—203.

Freedman L (1957) The fossil Cercopithecoidea of South Africa. Annals of the Transvaal

Museum. 23:121-262.

Frost SR (2001) New Early Pliocene Cercopithecidae (Mammalia: Primates) from

Aramis, Middle Awash Valley, Ethiopia. American Museum of Natural History. 3350:1-

36.

Frost S (2001) Fossil Cercopithecidae of the Afar Depression, Ethiopia: Species

Systematics and Comparison to the Turkana Basin. PhD Dissertation from the City

University of New York.

Frost SR & Delson E (2002) Fossil Cercopithecidae from the Hadar formation and

surrounding areas of the Afar Depression, Ethiopia. Journal of Human Evolution.

43:687—748.

Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World

(3rd ed.). Baltimore: Johns Hopkins University Press. p. 165. OCLC 62265494. ISBN 0-

801-88221-4..

Harris JM (1978) Palaeontoloy. In MG Leakey and RE Leakey (Eds.): Koobi For a

Research Project. Col. I, The Fossil Hominids and an Introduction to Their Context.

Oxford. Clarendon Press. 32—53.

Harrison T (2011) Paleontology and Geology of Laetoli: Human Evolution. Volume I :

Geology, Geochronology, Paleoecology and Paleoenvironment. Chapter

3:Sedimentology, Lithostratigraphy and Depositional History of the Laetoli Area.

Springer Science+Business Media B.V.

69

Harrison T (2011) Paleontology and Geology of Laetoli: Human Evolution. In Volume II:

Fossil Hominins and the Associated Fauna, Vertebrate Paleobiology and

Paleoanthropology. Chapter 6: Cercopithecids Cercopithecidae, Primates. Springer

Science+Business Media B.V.

Harrison T & Harris EE (1995) Plio-Pleistocene cercopiths from Kanam East, western

Kenya. Journalof Human Evolution 30:539-561.

Hay RL (1987) Geology of the Laetoli area. In: Leakey MD, Harris JM (Eds.), Laetoli: A

Pliocene Site in Northern Tanzania. Clarendon Press, Oxford, pp. 23—47.

Jablonski N (1994) New Fossil Cercopithecid Remains From the Humpata Plateau,

Southern Angola. American Journal of Physical Anthropology 94:435—464.

Kay RF (1978) Molar Structure and Diet in xtant Cercopithecidae. In: Studies in the

Development, Function, and Evolution of Teeth (PM Butler and K Joysey, eds.) pp.309-

339. Academic Press, London.

Leakey MG (1982) Extinct Large Colobines From the Plio-Pleistocene of Africa.

American Journal of Physical Anthropology 58:153-172.

Leakey MD & Hay RL (1979) Pliocene footprints in the Laetolil Beds at Laetoli,

northern Tanzania. Nature 278, 317—323.

Leakey MG (1982) Extinct Large Colobines From the Plio-Pleistocene of Africa.

American Journal of Physical Anthropology 58:153—172.

Leakey MD, Hay RL, Curtis GH, Drake RE, Jackes MK, & White T. (1976) Fossil

hominids from the Laetoli Beds. Nature 262: 460—466.

Leakey MG & Delson E (1987) Fossil Cercopithecids from the Laetoli Beds. In MD

Leakey & JM Harris (Eds), Laetoli: A Pliocene site in northern Tanzania (pp.91-107).

Oxford: Clarendon Press.

Musiba C (1999) Laetoli Pliocene paleoecology: a reanalysis via morphological and

behavioral approaches. Ph.D. Dissertation, University of Chicago, Chicago, Illinois.

Napier JR (1970) Paleoecology and catarrhine evolution. In Napier and Napier (Eds), Old

World Monkeys, Academic Press, New York. 55-95.

Ravosa MJ (1996) Jaw Morpology and Function in iving and Fossil Old World Monkeys.

International Journal of Primatology 17: 909—932.

Reed KE (1997) Early hominin evolution and ecological change through the African Plio

Pleistocene. Journal of Human Evolution 32:289—322.

70

Strasser E and Delson E (1987) Cladistic analysis of cercopithecid relationships. Journal

of Human Evolution 16:81-99.

Su DF & Harrison T (2007) The paleoecology of the Upper Laetolil Beds at Laetoli: A

reconsideration of the large mammal evidence. In Bobe Z, Alemseged Z, &

Behrensmeyer (Eds), Hominin Environments in the East African Pliocene: An

Assessment of the Faunal Evidence, Springer. 279—313.

Su DF & Harrison T (2008) Ecological implications of the relative rarity of fossil

hominins at Laetoli. Journal of Human Evolution 55:672-681.

Swindler DR (2002) Primate dentition: An introduction to the teeth of non-human

primates. Cambridge: Cambridge University Press.

Vogel C (1966) Morphologische Studien am Gesichtsschadel catarrhiner Pimaten. Bibl.

Primat., No. 4, pp. 1-226 (Karger, Basel 1966)

Walker AC (1987) Fossil Galaginae from Laetoli. In: Leakey MD, Harris JM (Eds.),

Laetoli: A Pliocene Site in Northern Tanzania. Clarendon Press, Oxford. 88—91.

Wesselman HB (1984) The Omo micromammals: Systematics and paleoecology of early

man site from Ethiopia (Contributons to vertebrate evolution, Vol. 7). Basel: Krager.

Wolfheim, JH (1983) Primates of the World: Distribution, Abundance and Conservation.

New York Zoological Society, University of Washington Press. Seattle and London.

71

SPEC

IES

NM

DBL

P3P4

M1

M2

M3

P3P4

M1

M2

M3

MEA

NST

D. D

EVM

EAN

STD.

DEV

MEA

NST

D. D

EVM

EAN

STD.

DEV

MEA

NST

D. D

EVM

EAN

STD.

DEV

MEA

NST

D. D

EVM

EAN

STD.

DEV

MEA

NST

D. D

EVM

EAN

STD.

DEV

Cerco

cebu

s gale

ritus

agilis

206.

820.

656.

670.

617.

330.

458.

330.

568.

580.

474.

330.

445.

670.

566.

120.

437.

230.

536.

710.

47

Cerc

oceb

us g

aler

itus c

hrys

ogas

ter

106.

840.

926.

490.

467

0.4

7.81

0.43

8.66

0.42

3.83

0.62

50.

595.

460.

556.

20.

466.

250.

62

Cerc

oceb

us g

aler

itus

17.

357.

197.

588.

469.

044.

596.

026.

517.

727.

43

Cerc

oceb

us4

5.54

0.21

5.65

0.41

7.2

0.42

8.34

0.21

9.26

0.82

3.92

0.33

4.54

0.34

5.72

0.28

6.35

0.88

70.

33

Cerc

oceb

us to

rqua

tus a

tys

166.

670.

816.

770.

687.

830.

598.

470.

539.

161.

124.

070.

485.

530.

486.

270.

337.

20.

636.

680.

69

Cerco

pithe

cus s

p.2

5.32

0.32

4.26

0.19

5.2

0.35

6.02

0.16

5.31

0.01

3.15

3.26

0.18

3.91

0.21

4.98

0.61

4.21

0.01

Colob

us ba

dius

75.

980.

825.

160.

416.

570.

477.

180.

538.

190.

553.

730.

383.

990.

354.

890.

385.

450.

25.

350.

24

Colo

bus p

allia

tus a

ngol

ensis

15.

826.

837.

177.

448.

995.

385.

315.

577.

46.

61

Colob

us po

lykom

os10

6.14

0.47

6.08

0.61

6.85

0.34

7.18

0.4

8.8

0.63

4.59

0.64

4.57

0.35

5.46

0.17

6.13

0.2

5.97

0.16

Colo

bus p

olyk

omos

ang

olen

sis17

6.38

0.46

6.17

0.52

6.77

0.46

7.39

0.44

8.58

0.39

4.35

0.41

4.45

0.28

5.13

0.3

5.84

0.26

5.75

0.33

Colo

bus s

andb

ergi

16.

565.

817.

017.

748.

34.

424.

295.

365.

845.

96

Colob

us ve

rus

95.

050.

554.

320.

225.

670.

355.

550.

586.

720.

493.

450.

663.

350.

234.

140.

264.

820.

164.

790.

17

Man

drillu

s leu

coph

aeus

212

.76

1.29

10.4

70.

9411

.01

0.34

12.7

90.

8114

.85

0.4

7.05

0.67

7.37

0.11

7.94

0.04

9.81

0.35

10.6

20.

83

Man

drillu

s sph

inx

210

.92.

6310

.15

0.54

9.88

0.27

12.5

30.

4115

.08

0.64

7.92

7.17

0.72

7.79

0.06

9.71

0.16

10.5

80.

52

Papi

o an

ubis

510

.11.

568.

510.

39.

980.

712

.14

0.43

15.3

31.

155.

560.

666.

840.

527.

990.

619.

910.

6210

.80.

9

Papi

o an

ubis

(cyno

ceph

alus

)3

11.0

90.

349.

110.

5111

.26

0.26

13.8

11.

0717

.96

0.27

6.38

0.52

7.54

0.34

9.84

0.62

11.5

20.

412

.17

0.98

Papi

o an

ubis

(dog

uera

tess

ellat

us)

2212

.47

2.24

10.3

40.

8312

.01

0.84

14.1

10.

8616

.98

1.07

7.02

0.8

8.12

0.53

9.46

0.61

11.7

50.

8212

.34

0.88

Papi

o an

ubis

anub

is3

19.0

43.

6110

.16

0.89

11.6

91.

3413

.63

0.82

16.8

91.

076.

890.

347.

830.

69.

041.

4310

.76

1.45

11.4

41.

1

Papi

o an

ubis

nige

riae

123

.58

10.6

411

.65

15.0

617

.45

7.21

7.31

9.16

12.0

413

.29

Papi

o cy

noce

phal

us ju

bila

eus

111

.69.

6911

.94

13.6

516

.32

5.91

7.06

8.56

10.1

910

.11

Papi

o cy

noce

phal

us ki

ndae

107.

11.

456.

540.

698.

470.

8210

0.84

12.4

91.

14.

490.

475.

470.

336.

880.

448.

230.

538.

40.

69

Papi

o cy

noce

phal

us le

stes

28.

180.

788.

870.

110

.40.

2912

.91

1.48

15.5

70.

984.

890.

536.

871.

078.

230.

7910

.38

1.81

10.9

91.

79

Papi

o ha

mad

raya

s13

9.57

1.97

8.29

0.83

10.1

20.

8512

.52

0.94

15.5

51.

385.

540.

626.

750.

637.

590.

559.

890.

9410

.52

1.38

Papi

o ur

sinus

410

.55

2.59

9.61

0.91

11.6

90.

5613

.78

0.96

17.6

21.

185.

850.

67.

180.

368.

930.

4710

.74

0.57

12.0

70.

47

APPENDIX

A. Summary of Collected Cercopithecine and Colobine Odontometrics

72

B. Summary of Eigenvalues from the PCA for P3-M3

Principle Component I Principle Component II

P3 3.06 0.86

P4 2.91 1.07

M1 2.95 1.04

M2 2.97 1.03

M3 2.96 1.03

C. Summary of Percentage of Total v=Variance from the PCA for P3-M3

Principle Component I Principle Component II

P3 76.66 21.61

P4 72.86 26.81

M1 73.77 25.99

M2 74.10 25.63

M3 74.04 25.67

D. Summary of the DFA Results for P3-M3

Tooth Type N Wilke’s λ

(p<0.001)

Eigenvalue Canon

Correlation

(r= )

P3 170 0.22 1.89 0.81

P4 170 0.18 2.67 0.85

M1 171 0.11 4.60 0.91

M2 171 0.10 6.07 0.93

M3 170 0.07 8.17 0.94

E. Summary of the Correctly Classified and Misclassified Percentages from the DFA

for P3-M3

Tooth Type Percent (%) Correctly

Classified

Percent (%) Misclassified

P3 65.88 34.12

P4 74.12 25.88

M1 81.87 18.13

M2 80.70 19.30

M3 84.12 15.88

morphological affinities of recently discovered …digital.auraria.edu › content › aa › 00 ›...

Documents