THE ECOLOGICAL CONTEXT OF THE EARLY PLEISTOCENE HOMININ DISPERSAL TO ASIA

by Robin Louise Teague

A.B. in Anthropology, 2001, Harvard University

A dissertation submitted to

The Faculty of The Columbian College of Arts and Sciences

of The George Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy

August 31, 2009

Dissertation directed by

Richard Potts Curator of Physical Anthropology,

National Museum of Natural History, Smithsonian Institution

Alison S. Brooks Professor of Anthropology

UMI Number: 3366726

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The Columbian College of Arts and Sciences of The George Washington University

certifies that Robin Louise Teague has passed the Final Examination for the degree of

Doctor of Philosophy as of June 16, 2009. This is the final and approved form of the

dissertation.

THE ECOLOGICAL CONTEXT OF THE EARLY PLEISTOCENE HOMININ DISPERSAL TO ASIA

Robin Louise Teague

Dissertation Research Committee:

Richard Potts, Curator of Physical Anthropology, National Museum of

Natural History, Smithsonian Institution, Dissertation Co-Director

Alison S. Brooks, Professor of Anthropology, Co-Director

Lars Werdelin, Senior Curator, Swedish Museum of Natural History,

Committee Member

iii

Copyright 2009 by Robin Louise Teague All rights reserved

iv

Acknowledgments

I would like to acknowledge a number of people who have helped me and guided

me through the process of writing my dissertation. First, I would like to thank my

committee: Rick Potts, Alison Brooks, Lars Werdelin, Margaret Lewis and Brian

Richmond. My advisor, Rick Potts, led me into a stimulating area of research and

supported me in pursuing a large and ambitious project. He has encouraged me all

through the time I have worked on this dissertation. Alison Brooks has helped me with

enthusiasm, pointing out differing perspectives and opportunities. Lars Werdelin has been

a source of detailed and helpful information and has always been available to answer

questions and provide guidance. I am also grateful to Brian Richmond and Margaret

Lewis for many helpful comments and for making time for my dissertation.

I would also like to thank my family for their love and support during my time in

graduate school and especially during the process of writing. Their encouragement was

essential to my success.

I would like to thank my fellow students at GWU for many years of friendship. I

would like to thank that faculty of the Hominid Paleobiology Doctoral Program and the

Department of Anthropology for their support. At the Smithsonian, I thank Jenny Clark,

Briana Pobiner and Matt Tocheri for their assistance and for making me feel welcome.

For access to mammalian skeletal collection, I thank Linda Gordon. I am also grateful to

the Smithsonian Libraries for letting me check out and renew many books many times.

v

Thanks go also to the many people who facilitated my access to fossils at the

Kenya National Museum and the Institute of Vertebrate Paleontology and

Paleoanthropology in Beijing, as well as many other museums. In particular, Wang Wei

traveled with me, assisting with translation and helping me make the contacts necessary

to study many of the fossil specimens in Chinese museums. I would also like to thank

Gao Xing, Deng Tao, Qiu Zhanxiang, Qi Guoqin, Huang Weiwen, Hou Yamei, Zhu

Rixiang, Deng Chenglong, Li Qing Kui and Wei Guangbao for helping me study fossil

specimens while I was in China.

For financial support, I would like to thank the IGERT program in Hominid

Paleobiology at GWU as well as the Smithsonian National Museum of Natural History

where I had a predoctoral fellowship. My years of study at GWU and at the Smithsonian

Human Origins Program have been extremely rewarding. This dissertation research was

funded by NSF Grant BSC 065092.

vi

Abstract of Dissertation

The Ecological Context of the Early Pleistocene Hominin Dispersal to Asia

The ecological context of the first known dispersal of Homo into East Asia is

investigated here using information from large mammals, and particularly from

carnivores. The aims were to determine whether hominins occurred in similar ecological

contexts compared with sites in East Africa, and whether carnivore guilds in East Asia

and East Africa were similar in composition in terms of ecologically comparable species.

To answer these questions, dental measurements were taken on large mammalian

specimens from East Asian Plio-Pleistocene sites, including hominin and non-hominin

sites, and from specimens found at Olduvai Gorge and Lake Turkana in East Africa.

Dental measurements were taken to estimate body mass and hypsodonty, as well as

ecomorphological characteristics in carnivores. Each large mammal species was

classified as an ecotype, which is a combination of body mass, diet and substrate (i.e.,

terrestrial, arboreal and aquatic) characteristics. The ecotype analysis shows that East

Asian and East African fossil sites were significantly different from each other in

ecological structure, with the Asian sites having a greater concentration of browsers and

mixed feeders, while East African sites had more grazers. The East Asian hominin sites

included varied ecological structures, implying that hominins were not tied to a single

type of environment on their initial dispersal. Carnivore ecomorphological indices related

to body mass and feeding adaptations, such as the amount of the dentition devoted to

slicing, grinding and bone-cracking. Carnivore guilds containing sets of species with

similar feeding adaptations and body mass would have presented similar opportunities for

vii

scavenging and degrees of competition for hominins. The Hyaenidae differed between

Africa and Asia in features related to fourth premolar size. Omnivorous ursids were

present in Asia but not in Africa. In East Asia, there were also decreases in the number of

species of Hyaenidae and Canidae from the Late Pliocene to the early Pleistocene.

Despite this, the remaining Asian hyaenid, Pachycrocuta, would have been a formidable

competitor for scavenging hominins. Overall, hominins occurred in varied ecological

settings, and competed with a carnivore guild that had species with different adaptations

compared with Africa.

viii

Table of Contents

Acknowledgments....iiv

Abstract of Dissertation.vi

Table of Contents... .viiii

List of Figures....ix

List of Tablesxii

Chapter 1: Introduction..1

Chapter 2: Background to ecological similarity analysis.11

Chapter 3: Methods to determine ecological similarity....41

Chapter 4: Results of the ecological structure analysis....94

Chapter 5: Background to carnivore ecomorphology.....129

Chapter 6: Carnivore ecomorphology methods......151

Chapter 7: Carnivore ecomorphology results.....176

Chapter 8: Discussion.....236

Bibliography...270

Appendices.....292

ix

List of Figures

Figure 2.1 Map of East Asian fossils39

Figure 3.1 Modern Eurasian localities used for comparison.....52

Figure 3.2 Modern African localities used for comparison...53

Figure 4.1 Scatterplot of the CA of the modern faunal assemblages and ecotypes..........99

Figure 4.2 NMDS using Euclidean distance of modern divisions..100

Figure 4.3 CA scatterplot of modern faunal sites excluding rainforests....102

Figure 4.4 NMDS of modern sites excluding rainforests...104

Figure 4.5 Scatterplot of a CA of the modern sites and ancient fossil assemblages..109

Figure 4.6 Scatterplot of a CA of the modern and ancient assemblages, axes 2 and

3..110

Figure 4.7 NMDS analysis of ancient and modern sites.....112

Figure 4.8 CA scatterplot of modern and ancient faunal assemblages, excluding modern

rainforests....115

Figure 4.9 CA scatterplot, axes 2 and 3: Modern sites (excluding rainforests) and ancient

faunas......116

Figure 4.10 NMDS plot of Plio-Pleistocene assemblages with modern sites (excluding

rainforests)......120

Figure 4.11 Correspondence analysis scatterplot of Plio-Pleistocene sites125

Figure 7.1 Scatterplot of the CA for Canidae category scores...180

Figure 7.2 Scatterplot of NMDS analysis of Hamming distances for Canidae..181

x

Figure 7.3 PCA Scatterplot of Canidae index values from East Africa and East

Asia.182

Figure 7.4 Loadings for component 1 of the PCA of Canidae fossils........183

Figure 7.5 Loadings for component 2 of the PCA for Canidae fossils.......184

Figure 7.6 CA Scatterplot of Hyaenidae category scores.......189

Figure 7.7 NMDS scatterplot of Hyaenidae Hamming distances......190

Figure 7.8 PCA Scatterplot of Hyaenidae index values.........191

Figure 7.9 Component 1 PCA loadings for Hyaenidae..........192

Figure 7.10 Component 2 PCA loadings for Hyaenidae............193

Figure 7.11 CA Scatterplot of Felidae category scores...........201

Figure 7.12 NMDS scatterplot of Hamming distances for Felidae.....202

Figure 7.13 PCA Scatterplot of Felidae index values.........203

Figure 7.14 PCA loadings for component 1 for Felidae.........204

Figure 7.15 PCA loadings for component 2 for Felidae.............205

Figure 7.16 CA scatterplot of Ursidae category scores..........208

Figure 7.17 NMDS Scatterplot of Hamming distance values for Ursidae.............209

Figure 7.18 PCA Scatterplot of Ursidae index values210

Figure 7.19 Loadings for component 1 of PCA scatterplot for Ursidae.211

Figure 7.20 Loadings for component 2 of PCA scatterplot for Ursidae.212

Figure 7.21 CA Scatterplot of Mustelidae category scores.214

Figure 7.22 NMDS Scatterplot of Hamming distances for Mustelidae......215

Figure 7.23 PCA Scatterplot for index values for Mustelidae............216

Figure 7.24 PCA of Mustelidae loadings for component 1........217

xi

Figure 7.25 PCA of Mustelidae loadings for component 2218

Figure 7.26 CA Scatterplot of category scores for Herpestidae, Prionodontidae and

Viverridae...........221

Figure 7.27 NMDS Scatterplot of Hamming distances for Viverridae, Herpestidae and

Prionodontidae species...........222

Figure 7.28 PCA scatterplot of index values for Viverridae, Herpestidae and

Prionodontidae223

Figure 7.29 Component 1 loadings for PCA of Viverridae, Herpestidae and

Prionodontidae....224

Figure 7.30 Component 2 loadings for PCA of Viverridae, Herpestidae and

Prionodontidae225

Figure 7.31 Scatterplot of CA of carnivores from East Asia and East Africa232

Figure 7.32 Scatterplot of CA of carnivores from East Asia and East Africa, second and

third axes.........233

xii

List of Tables

Table 3.1 Ecotype classifications.....43

Table 3.2 Modern comparative localities.....48

Table 3.3 Plio-Pleistocene East Asian sites and their dates.56

Table 3.4 Plio-Pleistocene African species at the Turkana Basin and Olduvai...56

Table 3.5 Plio-Pleistocene East Asian species.....62

Table 3.6 Modern specimens of Canidae.75

Table 3.7 Modern specimens of Ursidae..76

Table 3.8 Modern samples of Mustelidae, Viverridae, Prionodontidae and Herpestidae

..76

Table 3.9 Ecological characteristics of East Asian fossil site faunas.......78

Table 3.10 Summary of ecological information and ecotype assignment for African fossil

species...83

Table 4.1 The MEDC (mean Euclidean distance to the centroid) for each modern

division..97

Table 4.2 Modern site group centroids excluding rainforests.........101

Table 4.3 Mean and maximum distance to the centroid for modern and ancient

assemblages.108

Table 4.4 Mean and maximum distance to the centroid for modern and ancient sites

excluding rainforests...117

Table 4.5 MANOVA results for the centroids of African and Asian fossil sites from the

ancient and modern CA without rainforests118

xiii

Table 4.6 Mean and maximum distance to the centroid for Plio-Pleistocene sites123

Table 4.7 MANOVA results for the centroids of African and Asian fossil sites.......124

Table 6.1 Modern Felidae samples.153

Table 6.2 Modern Hyaenidae samples........153

Table 6.3 Ecomorphological measurement descriptions........155

Table 6.4 Ecological traits and ecomorphological indices.155

Table 6.5 Index values for fossil carnivore species158

Table 6.6 Index values for fossil carnivore species, continued......162

Table 6.7 Category cut-off values.......167

Table 6.8 Category scores for all carnivores...................................................................171

Table 7.1 P-values for the MANOVA of carnivore family centroids in East Asia and East

Africa..226

Table 7.2 Mean distance to the centroid (MEDC) for carnivore families......227

Table 7.3 MEDC for carnivore guilds at African and Asian sites......227

Table 7.4 MANOVA of carnivore guilds at sites in Africa and Asia.....228

Table A6.1 Canidae specimens measured from East Asia.292

Table A6.2 Felidae specimens measured from East Asia...293

Table A6.3 Hyaenidae specimens measured from East Asia.295

Table A6.4 Ursidae specimens measured from East Asia......299

Table A6.5 Mustelidae specimens measured from East Asia.302

Table A6.6 Viverridae and Prionodontidae specimens measured from East Asia.303

Table A6.7 Canidae specimens measured from East African sites303

Table A6.8 Felidae specimens measured from East African sites..304

xiv

Table A6.9 Hyaenidae specimens measured from East African sites........305

Table A6.10 Mustelidae specimens measured from East African sites.........306

Table A6.11 Herpestidae specimens measured from East African sites........306

Table A6.12 Viverridae specimens measured from East African sites..307

1

Chapter 1: Introduction to the dissertation

Anthropologists have long been interested in the environments that hominins

inhabited and in the way hominins interacted with the other members of the mammalian

community, in particular with the large-bodied members of the order Carnivora

(carnivores). Large carnivore kills might have been scavenged by hominins for meat.

Carnivores interacted with hominins as predators, competitors, suppliers of scavengeable

carcasses, and later as sources of skins and ornamentation. The circumstances

surrounding the earliest currently known dispersal of hominins from Africa around 1.8

Ma are particularly interesting with regard to hominin ecology and interactions with other

mammals because the localities in which the dispersing hominins have been found (the

Caucasus, continental East Asia and Java) are geographically distant from Africa and

have taxonomically different faunas. The East Asian localities are in temperate and

subtropical zones, which would be expected to have a different ecology compared with

tropical and subtropical African sites. However, the comparative ecological contexts of

these locations are not well known.

The ecology of the localities in which dispersing hominins have been found is the

focus of this dissertation. The ecological context of hominin dispersal is addressed by

comparing the ecological properties of mammalian species from initial dispersal sites in

East Asia and contemporaneous sites in East Africa to determine whether hominins

colonized places that were ecologically similar or whether hominins were capable of

adapting to different environmental settings on their initial dispersal. A subset of the

study concerns carnivore feeding adaptations to determine whether the carnivore guilds

were similar in East Asia and East Africa, and if not, in what ways they differed. The

2

implications for resource and niche availability for hominins in new environments are

considered, as is the range of ecological contexts in which hominins were found in East

Asia and East Africa.

Current evidence points to an initial dispersal out of Africa around 1.8 Ma.

However, it is possible that hominins dispersed earlier and that new sites or new dates

will be found that push the date back further. Dmanisi is dated to 1.77-1.75, immediately

following the Olduvai subchron (Gabunia et al. 2000a, Vekua et al. 2002, and Rightmire

et al. 2006). The Yuanmou hominin layer is dated to ~1.7 Ma (Zhu et al. 2008), while the

oldest artifacts known from the Nihewan Basin are dated to ~1.66 Ma (Zhu et al. 2004).

Hominins in Java are dated to 1.8 to 1.6 Ma at Mojokerto (Swisher et al. 1994, 1997,

Larick et al. 2001, Huffman et al. 2006) and to ~1.6 Ma at Sangiran (Swisher et al. 1994,

Antn and Swisher 2004). These hominins were most likely members of the genus

Homo. Archaeological evidence from Africa and Asia indicates that Homo was most

likely an omnivore, obtaining meat from scavenging or predation. Dmanisi, sites within

the Nihewan and Yuanmou all have Oldowan stone tools.

The geographic spread of initial dispersal sites shows that hominins were able to

survive in regions very distant from East Africa, with mammalian faunas consisting of

many different genera and species. Dmanisi and the Nihewan Basin are located relatively

far north, at about 40N latitude, raising the possibility of that hominins had to adapt to

environmental conditions quite different from the tropical and subtropical latitudes

occupied by probable source populations.

3

Ecological Similarity of the Large Mammal Fauna

Environmental similarity has been thought to have facilitated hominin dispersal.

Dennell (2004) argued that a belt of savanna habitats across Asia and Africa provided

both environmental similarity and a wide corridor of ecologically suitable habitats for

hominins, resulting in dispersal into Asia. Dennell (2003, 2004) hypothesized that

hominins were constrained to environments that were sufficiently similar in temperature

and seasonality patterns to Africa, leading hominins to be only found south of 40N in

the early Pleistocene1. At Ubeidiya, the presence of Pelorovis was thought to imply the

extension of savannas, while Kolpochoerus may have indicated the occurrence of gallery

forests (Martnez-Navarro 2004). Dispersing hominins might have been part of a small

group of African taxa that expanded out of Africa at that time, implying that an

ecological opportunity, such as the expansion of suitable habitats, existed for certain

similar species (Turner 1999). Thus, the expansion of African savannas is thought to be a

facilitating factor for the initial hominin dispersal. However, there is evidence that some

of these sites are not similar in their faunal structure to that of African savannas.

Belmaker (2005) found that African savanna mammals were not abundant at Ubeidiya,

and that overall the faunal structure was more similar to that of Mediterranean

environments. Other than hominins, very few African species dispersed at this time into

Europe or Asia (Martnez-Navarro 2004), showing that it was unlikely that hominins

were part of a hypothetical group of African taxa entering East Asia simultaneously. The

hypotheses tested in this dissertation concern the degree to which environmental or

ecological similarity was an important factor in hominins ability to adapt to the new

1 Pleistocene and Pliocene are used to refer to their date range prior to June 29, 2009.

4

places they colonized. Each hypothesis is tested using data from the ecological properties

of large mammals.

1) Did the ecological settings and faunas associated with early Homo in East Asia

differ from those in East Africa at this time, and if so, in what ways?

2) Were there ecological differences between hominin and non-hominin sites in East

Asia?

The community or ecological structure of the mammalian fauna was evaluated

using ecostructure methods. In these methods, each species is classified using a

combination of ecological variables including body size, diet and substrate (i.e.,

terrestrial, arboreal or aquatic). Ecostructure methods have been used, for example, by

Andrews (1979, 1996), Reed (1997, 1998, 2008), Rodrguez 2004, 2006a, b), and

Mendoza (2004, 2005). Methods that classify species by ecological properties are

particularly useful in comparing sites with taxonomically different faunas in order to

determine how the sites were ecologically similar despite the taxonomic differences. This

type of method was used by Rodrguez (2004) to determine whether ecological change

was occurring along with taxonomic change at Atapuerca. Reed (1997, 1998, 2008) used

ecological classifications to reconstruct the paleoenvironments of hominins at

Makapansgat, Hadar and other East and South African sites. Ecostructure methods are

useful for comparison because they show which types of animals are the sources of

ecological similarity or difference between taxonomically different sites. The similarities

or differences between ancient East Asian and East African faunal assemblages are

5

described using the results of correspondence analysis and comparison of the ecotype

numbers and proportions between sites. The species within the ecotypes that contribute to

similarities or differences are then investigated to determine how differences in their

proportions could have impacted hominins.

Ecomorphological Similarity of the Carnivores

During the Plio-Pleistocene, hominins and carnivores had the potential to interact

while competing for carcasses. Archaeological evidence shows that Plio-Pleistocene

hominins and carnivores overlapped in their resource use, and therefore would have been

competitors (de Heinzelin 1999; Semaw et al. 2003; Dominguez-Rodrigo 2005; Semaw

2000; Potts, 1988, 2003; Bunn and Kroll 1986; Blumenschine 1995; Shipman 1986).

Hominins may have interacted with many different carnivore species in different ways.

While certain carnivores, such as saber-toothed felids, may have produced carcasses that

still contained flesh and marrow (Ewer 1954, Blumenschine 1987, Marean 1989, Arribas

and Palmqvist 1999), other carnivores, such as bone-cracking hyaenids, may have

consumed many of the carcasses on the landscape (Blumenschine 1987, Blumenschine et

al. 1994, Turner 1992). Also, carcass theft after a kill may occur depending on the body

size and grouping behaviors of the species involved (Van Valkenburgh 2001).

The prospects for hominins as hunters or scavengers during the Plio-Pleistocene

would have depended in part on the group of carnivore species present and their

ecological traits, such as body size and feeding adaptations. Feeding adaptations include

morphological specialization for behaviors such as flesh-slicing or bone-cracking. Body

6

size is an important determinant of prey size and competitive interactions (Carbone et al.

1999, Van Valkenburgh 2001).

Feeding adaptations and body size are termed ecomorphological traits because

they are based on morphological measurements that relate to the ecological

characteristics of a species. These ecomorphological measurements can be used to

characterize carnivores from different species according to their behaviors. For instance,

ecomorphological characteristics are used to compare bone-cracking adaptations in

hyenas in East Asia and East Africa, regardless of the taxonomic relationship between the

species. This comparison shows differences in adaptations to bone-cracking and in the

probable amounts of competition from carnivores that hominins would have faced in East

Asia and East Africa. Ecomorphological comparisons are used to determine whether

specific carnivores are avatars. Avatars here are species from different regions that have

similar feeding adaptations and body size (Damuth 1985). Measurements of feeding

adaptations classify carnivores into dietary classes such as highly carnivorous,

omnivorous, or bone-crackers. However, avatars that are similar in diet and in body size

may have been different in other aspects of behavior, such as locomotion, that are not

researched here.

The combination of ecological characteristics in the carnivore guild as a whole in

a particular region and time would have shaped potential interactions with hominins that

used meat and marrow and that may have scavenged from other animals. A guild refers to

all species of a particular group that obtain and use resources in a similar manner (Root

1967). Here, the carnivore guild refers to members of the order Carnivora that are over 1

kg in body mass. Lewis (1995, 1997) hypothesized that there were ecological differences

7

in carnivore locomotion and prey capture behavior between East Africa and South Africa

that would have led to differences in hominin scavenging opportunities. Likewise, large

numbers of bone-cracking species may have consumed many carcasses, making it more

difficult for hominins to scavenge (Blumenschine 1987, Blumenschine et al. 1994, Turner

1992). This shows that the adaptations of the guild as a whole - the numbers of species

with bone-cracking or flesh-slicing adaptations, as well as the numbers of omnivorous or

carnivorous taxa that may have been competitors would have been relevant to a

scavenging or hunting hominins ability to obtain meat and bone marrow. Hominin use of

marrow also occurred outside of Africa; percussion marked bones have been found dating

to 1.66 Ma at Majuangou in the Nihewan Basin (Zhu et al. 2004). If, therefore, hominin

behavioral potential was similar, then the composition of the carnivore guild in East Asia

would have affected the possibilities for hominins living there. Carnivore adaptations

were also important for dispersing hominins. Animal products have constant properties,

unlike plant foods. Edible plants may vary in distribution, especially in the temperate

latitudes of East Asia. In order to obtain those animal products, hominins would have had

to interact with the carnivore guild. In this dissertation, similarities and differences in the

carnivore guilds of East Asia and East Africa are determined in part by the presence of

avatars. Guilds containing many similar avatars probably led to similar niches for

carnivorous hominins because of similar relations between species. Specific differences

between guilds could imply new competitors or sources of potentially scavengeable

carcasses.

The structure of the East Asian carnivore guild is also relevant because hominins

were a new immigrant taxon to East Asia and they were likely using resources formerly

8

exploited only by members of the order Carnivora. Hominins would have been entering

the guild of East Asian carnivores as a type of partially carnivorous mammal that was

unknown and unlike the others present.

Research on dispersal and immigration into new communities in general suggests

that communities that are successfully colonized have suffered recent extinctions

(Vermeij 1991) or are less diverse than other communities that are saturated (Brown

1989, Ricklefs and Schluter 1993, Vermeij 1991). Immigrant taxa rarely cause

replacement by competitive exclusion (Vermeij 1991), but may instead cause enrichment

in the recipient community when an immigrant adds to the species diversity (Flynn et al.

1991, Vermeij 1991). Immigrant taxa may use resources in a different way compared

with the incumbent taxa in order to be successfully integrated into the endemic

community.

The circumstances of hominin colonization of East Asia during the early

Pleistocene with regard to the carnivore guild are investigated here. Older carnivore

guilds from Pliocene faunal assemblages from Longdan, Longgupo and the Haiyan

Formation in the Yushe Basin are compared with the Pleistocene guilds from the other

East Asian sites. Comparisons of the carnivore guild prior to and after hominin arrival

could show whether hominins took advantage of unrepresented roles, such as flesh-

slicing, bone-crushing or group hunting, or whether hominins were likely to have

enriched the carnivore guild, using resources in a different way. Character displacement

in anatomical traits minimizes overlap of resource use and competition among carnivore

guild members (Mooney and Cleland 2001). It may occur after the immigration of a new

species into the guild (Ricklefs and Schluter 1993). However, the possibility of character

9

displacement with regard to the East Asian carnivore guild must be evaluated in terms of

both hominin immigration and general environmental change. Environmental changes

may have resulted in changes in patterns of resource consumption (Sher and Hyatt 1999,

Davis et al. 2000, Shea and Chesson 2002) and provided opportunities for invaders

(Lozon and MacIsaac 1997). Environmental changes in both the Asian and African

regions during the Plio-Pleistocene are discussed in chapter two. The questions asked

about carnivores in this dissertation are as follows:

1) Were there carnivore avatars in East Asia and East Africa? Were the carnivore

guilds as a whole similar, with a similar distribution of ecotypes? What were the

differences in the ecological characteristics of the carnivores in these regions?

2) Were there changes in carnivore ecomorphology between the Pliocene and

Pleistocene of East Asia? Were there changes in the structure of the East Asian

carnivore guild? Prior extinctions without replacement by another carnivore

avatar may have indicated unfilled niches, whereas a lack of change in the

distribution of avatars may indicate enrichment or increased ecological diversity

of the East Asian fauna when hominins arrived. Opportunities for hominins in a

guild with unfilled niches would have differed from those in a saturated guild or

one with increasing ecological diversity.

The ecological characteristics of the fossil carnivores from East Africa and East

Asia are evaluated using ecomorphological measurements of the dentition designed to

sort carnivores into feeding categories including flesh-specialists or hypercarnivores,

10

bone-crackers and omnivores. These measurements show quantifiable similarities and

differences between species. For each ecomorphological index, categories are created for

ecologically different subsets of measurements. These analyses show which species are

avatars, and are used to compare the guilds of East Asia and East Africa, as well as the

East Asian guilds through time.

Organization of the Dissertation

This dissertation is organized into two sections, the first concerned with questions

about the overall ecological similarity of the large mammalian community, and the

second with the comparative ecomorphology of the carnivore guild. Background to the

question of overall mammalian ecological similarity, as well as detailed information

about the sites from which the ancient faunal assemblages are drawn is contained in

chapter two. Chapter three describes the methods used to analyze ecological similarity of

ancient East Asian and East African faunas. The results of these analyses are given in

chapter four. Background to the section on carnivore ecomorphology is in chapter five.

Chapter six describes the methods used to analyze comparative carnivore

ecomorphology, and chapter seven describes the results. Discussion of all results and

general conclusions are presented in chapter eight.

11

Chapter 2: Background to Ecological Similarity Analysis

Hominins are an integral part of the mammalian community (Foley 1987).

Mammalian remains found with hominins have been used to interpret hominin habitat

preferences. The mammalian ecological structure (or community structure), which is

defined as the proportions of mammals that have certain classes of adaptations, is

correlated with environmental conditions, including the amount of vegetation,

precipitation and the temperature range. The types of mammals present in a community

may affect the animal resources available for a hominin, through scavenging or hunting.

The mammal community also reflects the vegetative community, which is also a food

source for hominins. These aspects of habitat and mammalian community structure are

particularly interesting when considering the ecological context of hominin dispersal to

East Asia and how those conditions compare with East Africa.

This chapter discusses the use of mammalian adaptations to make environmental

determinations, with reference to ecological structure methods. The modern comparative

environmental divisions used in the analysis are described. Theoretical expectations for a

dispersing mammal, information about mammalian dispersals from Africa during the

early Pleistocene, and environmental conditions conducive to dispersal are discussed.

Finally, information about the Plio-Pleistocene East African and East Asian research

sites, with emphasis on their environmental conditions, is summarized.

12

Mammals as Environmental Indicators

Mammals in hominin sites have been used to determine the type of environment

in which hominins lived. Functional morphology of single species or groups of species

(such as bovids or carnivores) found with hominins has been used to estimate aspects of

habitat such as vegetation cover (Kappelman 1988, 1997; Lewis 1997; Spencer 1997;

Elton 2001, 2002; Vrba 1974, 1975, 1980). Abundance data for mammals that are

correlated to particular habitat types (such as closed or open) reflect environmental shifts

(Bobe and Eck 2001, Bobe et al. 2002, Bobe and Behrensmeyer 2004).

Ecological structure in the mammalian community is commonly defined as the

proportions of adaptations related to diet, body size, locomotion and substrate use

(Andrews 1996, Reed 1998, Rodrguez 2004). Patterns of ecological structure are based

on physical factors such as climate, vegetation and precipitation, and are correlated with

habitat types (Andrews et al. 1979). Communities from locations with similar physical

conditions converge on a similar structure, even if the sets of species from those

communities are taxonomically different. Community structure methods describe faunas

by the ecological rather than taxonomic composition of the fauna. Higher temperatures

and greater amounts of water lead to greater plant productivity, which in turn increases

the number of herbivores (Ritchie and Olff 1999, Janis et al. 2002) and the number of

species relying upon arboreal substrates. African habitats range from rainforests to

deserts, with differing amounts of moisture and different temperature regimes in each.

Africa has a number of different habitats, in which different ecological structures and

proportions of adaptations are found (Reed 1997, 1998, 2008; Andrews et al. 1979,

Andrews 1996). African forests have similar ecological proportions to tropical forests in

13

Australia, Malaya and Panama (Andrews et al. 1979). Some ecological types are

particularly useful for distinguishing habitat types. Andrews (1996) found that temperate

environments tend to have more terrestrial animals compared with tropical ones. Tropical

and non-seasonal habitats, such as evergreen forests, have more frugivorous, arboreal,

and scansorial species than environments that were drier, such as savannas (Andrews

1996). Mendoza et al. (2005) found that grazers and mixed feeders are more common in

bushland and savannas than in forests or arid environments. Mendoza et al. (2005) also

found that highly carnivorous species (including bone-cracking animals) are more

common in open environments. Within Africa, Reed (2008) found that adaptations such

as arboreality, terrestriality, frugivory, grazing and mixed feeding are most useful in

distinguishing habitats, with arboreality and frugivory signaling more vegetation cover,

or the presence of riverine gallery forests, while other adaptations signify more open

landscapes.

Ecological or community structure methods use different modern environments to

model how the ecological structure changes with habitat. Ecological structure methods

are also used to compare among ancient faunas to determine how they differ. Comparison

of ancient and modern faunas described using ecological structure methods may show

whether ancient faunas are analogous to modern ones. This dissertation compares Plio-

Pleistocene fossil faunas located in East Africa and East Asia. The East Asian fossil

localities occur at higher latitudes compared with the East African comparative sites.

While most seasonal shifts in modern African localities concern the amount of

precipitation, higher latitudes also experience temperature shifts (Reed and Rector 2007).

Construction of an ecological structure system to compare localities from distant

14

geographic locations, as well as from tropical and temperate habitats, requires the use of

relatively broad environmental categories (Mendoza et al. 2005). Here, a set of fauna

from modern African and Eurasian localities is classified into environmental categories

using Baileys ecoregions (Bailey 1998), which are described in more detail below.

Biogeography and Ecological Structure:

Though ecological structures are similar in different locations under similar

ecological conditions, historical factors affect the distribution of species and the

proportions of ecological types, producing geographic differences in structure. For

instance, Andrews (1996) found geographic effects in an ecological analysis of modern

tropical evergreen forests, temperate forests, savanna woodlands, steppe, and tundra

habitats. While the tropical forests were separated from the other environments,

geographic substructure was evident in the separation between African and Asian tropical

forests. Likewise, temperate deciduous forests in Eurasia and North America had

different structures, possibly resulting from different environmental conditions

unaccounted for in the study, different histories and different regional species pools.

An ecological structure study of modern localities in Eurasia and North America

looked at the relative roles of convergence in mammalian communities from similar

environments compared with the influence of geographic location (Rodrguez et al.

2006). Both biogeography and environmental variation played a role in the positioning

these faunas in multivariate space (Rodrguez et al. 2006). Arid communities, such as

deserts and steppes, were particularly convergent, perhaps because there are few ways to

structure such a community with the limited available resources (Rodrguez et al. 2006).

15

There were significant differences between New World (Nearctic) and Old World

(Palearctic) faunal communities overall, which relate to differences in the composition of

the species pools in these regions.

Another analysis compared the ecological structure of mammalian communities

grouped by vegetation type in African and Asia to generate a predictive model (Mendoza

et al. 2005). The discriminant function analysis grouped broadly similar vegetational

communities from the two continents together showing that ecological structure can

identify environmental convergence (Mendoza et al. 2005). However, some vegetation

types are only found in Africa or Asia, meaning that some communities could not be

compared (Mendoza et al. 2005). Evergreen forest, bushland and arid communities,

which are found in both Africa and Asia, are similar in structure. Asian deciduous forests,

which also contain grass areas, are similar to African wooded savannas. By grouping the

habitats into relatively broad categories when comparing distant geographic localities, it

is possible to see the general features of ecological structure (Mendoza et al. 2005).

Ancient Communities without Modern Analogs:

Some aspects of past ecosystems (or past ecosystems as a whole) may not have a

modern analog, a phenomenon called historical non-equivalence. When analyzing the

fauna of Makapansgat, Reed (1998) found that proportions of some extant taxonomic and

ecological groups were very different compared with modern sites. Andrews et al. (1979)

also noted some localities seemed to have a distribution of ecological types that is not

represented in current African settings. In other cases, such as an Olduvai fauna from the

middle of Bed I, ecological information from faunas does not match current habits of

16

close relatives, leading to an interpretation of greater structural complexity in that ancient

habitat compared with the modern location (Soligo and Andrews 2004). Andrews (1996)

recommended comparing ecological variables individually to determine the

characteristics of ancient habitats that do not correspond to modern categories.

Environmental Profiles of Modern Comparative Sites:

Baileys ecoregions were used to classify modern localities. This is a hierarchical

system in which the world is divided into domains and those domains are each divided

into divisions. Each division may be either lowland or mountainous. Temperature and

moisture patterns divide the world into tropical humid, humid temperate, polar and dry

domains (Bailey 1998). Within these domains, latitude, precipitation, continental

position, altitude and seasonality produce vegetation patterns that are described in the

divisions. Each division has a typical series of altitudinal vegetational zones that occur

when that division contains areas of mountainous terrain. Descriptions below are based

on characteristics described in Bailey (1998) unless otherwise noted.

Dry Domain:

Temperate Deserts:

Temperate deserts are found in the interior of the Eurasian continent. They

receive very little precipitation and have hot summer temperatures and very cold winter

temperatures. The lack of water and extreme temperature range limits vegetation to

woody shrubs. As altitude increases, the vegetation changes first to semi-desert woodland

and then to meadow.

17

Temperate Steppe:

Temperate steppes typically feature grasslands with scattered scrubland and trees.

Most fauna are grazers. Winters are cold and dry, while summers are hot or warm with

rainfall. If rainfall decreases, temperate steppes may become deserts. The altitudinal

sequence from lower lands to higher ground for temperate steppe is: steppe, coniferous

forest, tundra or in other areas, steppe, mixed forest and meadow.

Tropical-Subtropical Steppe:

Tropical-subtropical steppes are arid and hot. Precipitation occurs irregularly from

year to year. The vegetation consists mainly of grass, but may include shrubs or trees.

This division may also be described as an acacia-grassland savanna. Tropical-subtropical

Steppe Mountains include a gradient that runs from steppe or semi-desert to mixed or

coniferous forest to alpine meadow or steppe.

Tropical-Subtropical Desert:

These deserts are extremely arid with large variations in temperature between day

and night. Very sparse vegetation includes shrubs, cacti and grass. Tropical-subtropical

deserts include the Sahara, the Arabian Peninsula and the Thar. The altitudinal sequence

is from lower to higher altitudes is semi-desert, shrub, open woodland and finally steppe

or meadow.

Humid Temperate Domain:

Prairie:

Although the precipitation in prairies is sufficient to support grassland, it does not

support trees unless the prairie is close to a wetter division. In that case, mosaics of

18

deciduous forest and grassland may occur. Mountains cause the following zones: forest-

steppe, coniferous forest and meadow.

Subtropical:

The subtropical division is characterized by a climate without a dry season.

Streams contain water for most of the year. The average annual rainfall for subtropical

forests of the broadleaf schlerophyllous type is 1283.7mm (Wang 1961). Precipitation is

increased during the summer. The average temperature for Chinese subtropical forests is

15.9C (Wang 1961). Subtropical divisions typically contain forests with evergreens such

as oak, laurel and magnolia. The forest floor is thickly vegetated with bamboo, shrubs

and herbs. At northern borders, subtropical forests may also have deciduous broadleaf

trees. The subtropical mountainous zones range from mixed forests to meadows.

Hot Continental:

Hot continental vegetation includes tall broadleaf deciduous trees, with a seasonal

herb layer on the ground. This is the native division type for areas in northern China and

was originally found between 20 and 50N latitude (Ching 1991). Currently, it is not well

represented in China because of the large human population (Ching 1991). The hot

continental division has hot summers and cool winters, without a dry season. A

mountainous area will have deciduous or mixed forest, coniferous forest and finally

meadows.

Humid Tropical Domain:

Savanna:

Savannas are a very variable type of division, with different subtypes of

vegetation. These vegetation types include scrub woodlands (with a discontinuous

19

canopy layer) and woodland savanna, in which grassland, trees and shrubs are

interspersed. Savannas are found in Africa, as well as in India and Southeast Asia.

However, the human population in the Asian areas is large and has altered the vegetation

and the faunas substantially (Cole 1986). Cole (1986) notes that dry deciduous

woodlands in India and Burma are similar to savanna woodlands in Africa. In Southeast

Asia, deciduous forests are found in areas with 1000-2000 mm of rain and a four to seven

month dry season (Cole 1986). These Southeast Asian savannas include discontinuous

canopied woodlands interspersed with denser areas of deciduous or rainforest (Cole

1986). Blasco (1983) describes this type of vegetation as an open forest with grass

covering the ground. Savannas have wet and dry seasons. Streams dry out in the dry

season or flood surrounding grasslands during rainy seasons. Mountainous savannas

include open woodlands, deciduous forest, coniferous forest and then a steppe or

meadow.

Rainforest:

Rainforests include many species of trees able to thrive in a setting with high

temperatures and abundant rainfall. A subtype of rainforest (tropical deciduous) occurs in

areas that have a dry season. Tropical rainforest has a continuous canopy layer of

broadleaf trees. The fauna is especially rich and includes many arboreal species.

Mountainous rainforests shift from evergreen forest to meadows.

20

Dispersal and Biogeography:

Theoretical Expectations for Dispersal:

The dispersal of hominins into East Asia can be considered in light of

biogeographic theoretical expectations. According to Vermeijs (1991) study of historical

biotic exchanges, in which species from one geographic locality colonize another

location, very few species actually disperse when a geographic exchange opportunity

occurs. A new colonizing species may have a competitive advantage over species in the

recipient biota, especially with regard to disease or pathogen resistance (Vermeij 1991).

The study also reveals that biotic exchange often occurs primarily in one direction,

leading to speculation that one ecological community is competitively superior over the

other. A mediating factor in exchange asymmetry is the presence of suitable habitats for

immigrant species (Ricklefs and Schluter 1993). Similarity in physical aspects of the

environment is important to successful colonization (Brown 1989). Environmental and

physical similarity is likely to result in similar food resources and similar types of species

in the communities (Brown 1989). However, many species are able to tolerate a range of

environmental conditions when there are few predator and competitor species (Brown

1989). Prior extinctions may increase a communitys vulnerability to colonization

(Vermeij 1991). Brown (1989) also noted that less diverse communities are more likely

to be colonized. In particular, a deficit of predators could be an important factor.

Conversely, a stable community that has not suffered extinctions could be said to be

saturated (Ricklefs and Schluter 1993, Vermeij 1991) and thus less susceptible to

invasion. If a saturated community were invaded, the process of competitive exclusion

21

would cause extinctions among the incumbent species. However, Vermeij (1991) found

that colonizing species rarely caused extinctions. Instead of replacement, dispersers find a

place within the new community in a process of enrichment (Flynn et al. 1991, Vermeij

1991), perhaps because the disperser is exploiting available resources in a new way

(Ricklefs and Schluter 1993). Brown (1989) also found that dispersing species succeed in

colonization more often when they can occupy new niches compared with the native

species.

Community Structure:

The composition of local communities is determined by climate, habitat and local

landscape (Ricklefs and Schluter 1993), as well as by competitive and predatory

interactions between species (Morin 1999). Local community structure and composition

may also be influenced by the sequence in which organisms colonize the location

(Robinson and Dickinson 1987, Robinson and Edgemon 1988, Drake 1991, Drake et al.

1993, Wilson 1992). Above the local populations are metapopulations, which are local

populations in a region linked by dispersal of species between them (Morin 1999).

Species from the regional metapopulation may replace species that become extinct in the

local populations depending on their dispersal ability and their habitat and landscape

preference (Morin 1999). The regional species pool is an important factor in maintaining

local diversity (Brown and Gibson 1983). Community structure at a local level is greatly

influenced by the composition of the regional species pool (Mooney 1977, Schluter 1986,

Ricklefs 1987, 1989, Lawton 1984, Cornell and Lawton 1992, Ricklefs and Schluter

1993, Brown 1995). The species present at the regional level are determined by

differences in environments as well as different interspecific interactions (Paine 1966,

22

1974, Lubchenco 1978, 1980, Menge 1995). Presence or absence of certain individual

species may also cause differences in regional species pools (Tonn and Magnuson 1984,

Rahel 1984, McPeek 1990, Werner and McPeek 1994). Species in the regional species

pool may be supplied by diversification within clades (Webb et al. 2002), or by dispersal

due to linkages with other regional species sets (Ricklefs and Schluter 1993).

Diversification processes may result from adaptive radiation (Rosenzweig 1978, 1995,

Pimm 1979, Feder et al. 1988, 1990, Schluter and McPhail 1992, Schluter 1993, Rice and

Hostert 1993, Schluter and Nagel 1995, Losos et al. 1998, McPeek and Brown 2000),

sexual selection (Lande 1981, 1982, Lande and Kirkpatrick 1988, West-Eberhard 1983,

Kaneshiro 1983, 1988, 1989, Seger 1985, Kaneshiro and Boake 1987, Turner and

Burrows 1995, Seehausen et al. 1997, Payne and Krakhauer 1997), the evolution of

specific mate recognition systems (Paterson 1978, 1993), or chromosomal

rearrangements (King 1993).

Each species has a fundamental niche of conditions in which it can survive as a

viable population (Hutchinson 1957). One of the aspects of the niche is the species

geographic range. In phylogenetic niche conservatism, the ancestral niche characteristics

of a species are conserved in its descendants, leading to similarities in environmental

tolerance and failure to expand into adjacent but environmentally different territory

(Weins 2004, Peterson et al. 1999, Ricklefs and Latham 1992, Ackerly 2003, Weins and

Donoghue 2004). Niche evolution, either in expansion of environmental tolerance or a

shift to a new environmental specialization, would enable a species to colonize new

habitats (Weins and Donoghue 2004).

23

The role of neutral processes in community assembly is debated. In his neutral

theory of biodiversity and biogeography, Hubbell (2001) asserts that ecological

communities of trophically similar sympatric species are structured by chance, historical

factors and random dispersal of individuals. These communities are open to immigration

and are not at equilibrium (Hubbell 2001). This neutral view contrasts with a niche

assembly theory in which members of the community interact strongly with each other,

competition plays a strong role and the composition of the community may be deduced

from functional roles of the species (MacArthur 1970, Diamond 1975). The relative

importance of random or neutral processes compared with interactions between species

and between species and their environments has also been investigated (Kembel and

Hubbell 2006, Kelly et al. 2008, Jabot and Chave 2009).

Dispersal of African Mammals:

Plio-Pleistocene African mammals are found in Asia at the Levantine site of

Ubeidiya, dated to approximately 1.6 and 1.2 Ma (Belmaker 2005). Although the fauna

includes a mix of species from different realms, such as the oriental, most elements were

from the Palearctic (Tchernov 1992b). The sub-Saharan species identified from that

period are Pelorovis oldowayensis, Oryx cf. gazella, Kolpochoerus oldovaiensis, Equus

tabeti, Theropithecus cf. oswaldi, Hippopotamus gorgops, Mellivora sp., Herpestes sp.,

Megantereon sp. and Crocuta sp. (Belmaker 2005). However, many of the lineages with

African affinity were derived from in situ evolution of previously dispersed lineages

(Tchernov 1992a, b). Other genera, such as Crocuta and Megantereon, have been found

in Pliocene Asian sites and may not have been recent immigrants or may not have been

24

African-derived. The earlier Pliocene site of Bethlehem shows many open country

mammals in an environment interpreted as similar to an African savanna (Tchernov

1992a, b, Turner 1999). Martnez-Navarro (2004) suggested that the presence of

Pelorovis at Ubeidiya implied the extension of savannas, while Kolpochoerus indicated

the occurrence of gallery forests. Belmaker (2005), however, found that African-derived

species were not particularly abundant at Ubeidiya and instead reconstructed the site as

similar to Mediterranean environments. Most of the African species found at Ubeidiya

did not disperse further into East Asia. The exceptions are Theropithecus oswaldi, which

is found in Europe and India, and Homo (Martnez-Navarro 2004).

Environment and Dispersal:

Environmental and geographic changes may have presented opportunities for

hominins to expand into Eurasia, by the opening of physical pathways or by the spread or

existence of environments in which hominins were able to survive. Environmental

factors, including seasonal climate, temperature range, and ecological factors, such as

food availability, would have played a role in determining whether hominins were able to

survive in new dispersal sites for the long term.

Dennell (2004) tied hominin dispersal to the presence of grassland habitats.

According to climatic reconstructions, grasslands were present in Asia at 3 Ma (Dowsett

et al. 1999). Based on information that places East Asia in tropical and subtropical

environments and describes Indonesian settings as savanna or open woodland, Dennell

(2004) concluded that hominins would have been able to disperse across Asia because of

the similarity in environments, specifically the presence of savanna-like settings across

25

Asia. Vegetational and faunal contrasts between different latitudes were not as strong

during the late Pliocene and early Pleistocene as they are today, especially since modern

desert barriers were not yet fully formed (Dennell 2004). The appearance of savannas and

woodlands in Asia and Africa may have been tied to potential times of dispersal, which

means that dispersal prior to the early Pleistocene is possible (Dennell and Roebroeks

2005).

East Africa

Evidence of Hominins and Dates:

East African sites have long been a source of hominin fossils, as well as those of

other mammals and have provided information about hominin anatomy, culture and

habitat. Faunas from the well-known sites in Koobi Fora, West Turkana and Olduvai

Gorge are used here to compare to the East Asian Plio-Pleistocene sites. Turkana Basin

faunas were analyzed by stratigraphic members. At Koobi Fora, these members included

the Upper Burgi, KBS, Okote and Chari. The Chari member has a very sparse fauna

(Turner et al. 1999). At West Turkana, the members Lokalalei, Kalachoro, Kaitio, Natoo,

and Nachukui were included. Olduvai Beds I and II were also analyzed. The East

Turkana sites date from 2.68 to 0.74 (1.39 if the Chari is excluded) (Feibel et al. 1989,

Brown et al. 1985). The West Turkana members date from 2.52 to 0.7 Ma (Feibel et al.

1989, Brown et al. 1985). These sites were dated by correlation with tuffs dated by K/Ar

dating. Olduvai Bed I dates to 2.03 Ma to 1.78 and Bed II from 1.78 to 1.33 Ma (Walter

et al. 1991, 1992, Tamrat et al. 1995).

26

Environmental History of the Turkana Basin:

Environmental evidence as a whole shows increasing aridity and variability in

East Africa after 3 Ma (deMenocal 2004). Trauth et al. (2005) found evidence of deep

lakes in the periods of 2.7 to 2.5 Ma, 1.9 to 1.7 Ma and 1.1 to 0.9 Ma in East Africa,

leading them to conclude that those were relatively humid periods within the overall

trend toward aridification. However, those periods were highly variable in climate, with

both arid and humid intervals (Owen et al. 2008). A series of temporary lakes formed in

the Turkana Basin beginning at 2.0 Ma, but lacustrine facies disappeared after 1.7 Ma

(Feibel et al. 1991, Feibel 1997). Also, river channels of the Omo dried up between 1.7

Ma and 1.4 Ma (Brown and Feibel 1991).

Pedogenic carbonates show a transition between woodland to more open savanna

between 3 and 1 Ma at the Turkana Basin and Olduvai Gorge (Cerling 1992, Cerling et

al. 1988). More arid-adapted mammalian taxa appear between 2.5 and 1.8 Ma

(Behrensmeyer et al. 1997). Based on pollen data, Bonnefille (1995) found that the

Lower Burgi had vegetation, first signaling relative cold, and then dry climate. During the

time of the upper Burgi and through the Okote, climate fluctuated between humid and

arid conditions. Pedogenic carbonates sampled at Koobi Fora indicated a trend of change

from closed woodlands to open woodlands or shrublands between 2 and 1.75 Ma (Quinn

et al. 2007). Between 1.75 and 1.5 Ma, different types of low shrubland environments

were found, which Quinn et al. (2007) interpreted as fragmentation of woodland habitats.

After 2.0 Ma, the Turkana Basin experienced a period of faunal turnover and

grassland expansions (Bobe and Behrensmeyer 2004). Many grassland mammal species

have first appearances during the interval of 2.0 to 1.8 Ma, including hypsodont bovids

27

and suids, while the species that went extinct included forest and closed habitat dwellers

(Bobe and Behrensmeyer 2004). Omo mammals associated with forest habitats decreased

in abundance after 3.2 Ma, while secondary grassland taxa became more abundant after

2.5 Ma (Bobe et al. 2002).

Reeds (1997) ecological analysis of the Upper Burgi, KBS and Okote faunas

shows environmental changes. Whereas the Burgi fauna was interpreted as a mixture of

open woodland, edaphic grasslands and riparian woodland, with frugivores/folivores,

fresh grass grazers and terrestrial/arboreal animals, the KBS had fewer arboreal taxa and

a greater proportion of grazers (Reed 1997). The KBS was interpreted as scrub woodland

or arid shrubland with grasslands. The Okote was described as edaphic grasslands, having

many grazers, but also contained arboreal animals from gallery forests (Reed 1997).

Overall, hominins in the Turkana Basin lived in different habitat types while the climate

fluctuated, but tended towards aridification.

Environments in Olduvai Gorge:

A broad and shallow lake was present during the deposition of Bed I (Hay 1976).

Faunal analyses have been used to show what types of environment were present. Butler

and Greenwood (1973) and Gentry and Gentry (1978a,b) found conditions that signaled

increased aridity at the top of Bed I. Analyses based on bovid ecomorphology found that

closed or intermediate habitats prevailed (Kappelman 1984, Plummer and Bishop 1994).

Pedogenic carbonates sampled from an interval of 1.845 to 1.785 Ma showed variation in

climatic conditions and fluctuation between woodlands with open canopies and grass, and

wooded grasslands (Sikes and Ashley 2007). The amount of C4 grassland varied between

40-60% (Sikes and Ashley 2007). Using an ecological structure analysis, Andrews et al.

28

(1979) concluded that Olduvai Bed I had a similar fauna to that of the Serengeti and to

woodland-bushland communities. During the deposition of Bed II, the lake was reduced

in size and the area was aridified (Hay 1976). Based on pedogenic carbonates, Sikes

(1994) found that lower Bed II supported a riparian forest, with grassy woodland further

away. Kappelman (1997) found that bovid ecomorphology supported a range of cover

from open to heavy cover, though there were no forest species. Carnivores and hominins

have been primary accumulators for some of the assemblages in Beds I and II

(Dominguez-Rodrigo et al. 2007a, b, Egeland 2007, Egeland and Dominguez-Rodrigo

2008, Leakey 1971, Potts, 1988, Monahan 1996, Blumenschine and Masao 1991).

East Asia

Environments in East Asia:

Environments in East Asia most likely played an important role in facilitating or

impeding hominin dispersal and in determining whether occupation was long-term or

short-term. Evidence from East Asia, including 18O from deep sea cores and loess

deposition analysis, indicates climate change during the Plio-Pleistocene. The 18O

record from deep sea cores records increases in ice volume after the late Pliocene

(Shackleton et al. 1985; Shackleton et al. 1990, Shackleton et al. 1995). The northern

hemisphere ice sheet increased during the intervals of 3.6 to 2.7 Ma, 2.7 to 2.1 Ma and

1.5 to 0.25 Ma (Tian et al. 2002).

Loess, carried by the winter monsoon from the northwest of China, reflects

aridification of central Asia (Liu 1985). The formation of deserts in north and northwest

China is linked to the uplift of the Tibetan plateau, which blocks moisture from the Indian

29

Ocean (Guo et al. 2002). Loess particles deposited at specific sites are coarser during

glacial intervals due to southward migration of deserts and to increased wind intensity

(Ding et al. 2005). The summer monsoon is responsible for approximately 80% of the

moisture in the loess-desert margin area, with the desert margin moving north as the

summer monsoon strengthens and moves north (Ding et al. 2005). Changes in the sizes of

loess particles indicates that the desert margin moved south at 2.6, 1.2, 0.7 and 0.2 Ma,

corresponding decreased strength of the summer monsoon and ultimately attributable to

glaciation (Ding et al. 2005).

The mineral record provides another proxy suggesting aridification. The mineral

hematite is formed by chemical weathering. The production of hematite is decreased

during glacial periods so that the content of hematite, measured by remnant

magnetization, reflects the degree of chemical weathering and the degree of aridification.

The patterns coincide with the 18O record to suggest aridification and cooling

throughout the Quaternary during both glacial and interglacial periods (Deng et al. 2006).

Despite the overall trends of aridification and cooling, considerable environmental

fluctuation probably occurred at specific sites. The pollen record from a location on the

Chinese Loess Plateau at 357 N and 10712 E shows changes in vegetation,

temperature and the moisture regime in that area (Wu et al. 2007). Between 3 and 2.6 Ma,

arboreal pollen was dominant, in a climate that was mostly warm and humid. This

interval was followed by a drier and cooler period from 2.6 to 1.85 Ma, which featured

arid adapted plants and fewer trees. The location sampled was reconstructed as having

trees on the hills and grass-filled valleys. During the 1.85 to 1.5 Ma interval, Pinus, as

well as firs and spruce trees are dominant, leading to an interpretation of a forest-steppe

30

with a cool and humid climate. In the next time interval (1.5 to 0.95 Ma), Pinus remains

very common, but broadleaved trees and plants thriving in temperate environments are

present, showing a warm-temperate and humid climate. The species of Pinus present is

believed to be one restricted to warm, temperate environments with more than 400 mm of

rain annually. Subsequent samples, from the interval 0.95 to 0.5 Ma, show a decrease in

tree pollen and an increase in herbs and shrubs, suggesting an open steppe with

grasslands.

Other lines of evidence suggest climatic changes in areas east of the loess plateau

in China. Using data from soil, loess, pollen and the biogeographic distribution of apes

and cercopithecids, Jablonski et al. (2000) reconstructed most of southern China as a

tropical environment suitable for pongids and hylobatids during the late Pliocene and

early Pleistocene, while parts of northern China were thought to have had a more

subtropical climate.

East Asian Focus Sites: Environment, Fauna, and Dating

Chronology of East Asian Sites:

The East Asian sites are dated by a combination of paleomagnetic stratigraphy

and biochronological inferences and comparisons with better dated localities. The

Nihewan sensu stricto is a typical fauna. Many other faunas in East Asia, particularly in

North China, have been compared with it in order to assess similarity in terms of how

many species are shared and thus to infer whether the fauna comes from approximately

the same time period as the classic Nihewan fauna. Past studies have also looked at the

proportion of extinct taxa as a means of judging relative age (e.g., Han and Xu 1985).

31

Recent work has produced land mammal ages for China typified by combinations of taxa,

and correlations with European mammalian biozones (Li et al. 1984, Tedford 1995, Tong

et al. 1995, Qiu and Qiu 1995, Deng 2006). Studies in the Yushe Basin (Tedford et al.

1991, Flynn et al. 1991, 1997), at Lantian (Zhang et al. 2002) and Lingtai (Zheng and

Zhang 2001) have served to better integrate mammalian biochronology with the

paleomagnetic timescale.

Nihewan Basin:

The Nihewan Basin has produced some of the earliest evidence of hominin

presence in China. It is also known as a source of mammalian fossils, which with

environmental data, produces important evidence about the ecological context of

hominins in East Asia. The Nihewan Basin sites examined here include the

archaeological sites of Majuangou, Donggutuo and Xiaochangliang, as well as the non-

hominin fauna known as the Nihewan sensu stricto or the Xiashagou fauna. The Nihewan

basin contains fluvial, lacustrine and eolian sediments (Zhu et al. 2003, Deng et al. 2008).

Xiaochangliang:

The Xiaochangliang site, located in the Nihewan Basin at 40.2N, 114.65E,

contains artifacts and a fossil fauna (Figure 2.1). The artifact layer, which includes many

small flakes, is dated by magnetostratigraphic correlation to 1.36 Ma (Zhu et al. 2001,

2003). The fauna reported by Tang et al. (1995) included typical Nihewan taxa and

corresponded to an early Pleistocene age. Most remains are highly fragmented (Peterson

et al. 2003). From a sample of bones, Peterson et al. (2003) found that although 8.1% had

carnivore toothmarks, this percentage was too small for the fauna to have been

accumulated primarily by carnivores. Shen and Chen (1999) also found carnivore,

32

possibly hyena, modifications on the bones. The assemblage was most likely

hydraulically transported (Peterson et al. 2003, Shen and Chen 2003). The assemblage is

associated with a conglomerate.

Donggutuo:

The Donggutuo site is located at 402 N and 114.67 E. It contains lakeshore

sediments. Schick et al. (1991) report cores and flakes. The site was dated to

approximately 1.1 Ma using paleomagnetic stratigraphy (Li and Wang 1982). This was

confirmed by Schick and Dong (1993), Li et al. (2002), Wang et al. (2005) and Zhu et al.

(2003). The fauna is listed in Wei (1985, 1991), and in Deng et al. (2008).

Majuangou:

Majuangou is located at 4013.517 N and 11439.844 E in the Nihewan Basin.

The four artifact layers contain cores and flakes (Zhu et al. 2004). Paleomagnetic

stratigraphy was used to determine the following dates for the artifact layers: 1.32, 1.55,

1.64 and 1.66 Ma (Zhu et al. 2004). Fossil bones show percussion marks, indicative of

processing for marrow (Zhu et al. 2004). Biochronologically, the fauna is typical of the

Plio-Pleistocene and is similar to that of Xiaochangliang (Tang et al. 1995). Sediments

show that the artifact layers were deposited in wetlands or in lake margins. Pollen data

indicates considerable variation in vegetation over time at the time (Zhu and Potts, pers.

comm.)

Xiashagou or Nihewan sensu stricto:

The Nihewan fauna contains many mammal species and has come to be

considered a standard north China fauna for the late Pliocene and early Pleistocene

(Lucas 2001). However, the fauna does not include any hominin specimens. This fauna

33

was documented by Teilhard de Chardin and Piveteau (1930) and further studied by Qiu

(2000). Deng et al. (2008) estimated the age of the Nihewan faunas to be between the

onset of the Olduvai normal and the Brunhes-Matuyama boundary. Biochronological

studies show that the fauna corresponds taxonomically to the Olivola fauna at about 1.8

Ma (Qiu 2000). About 20% of the mammals are from the Tertiary (Lucas 2001). Many of

the species are forest browsers (Lucas 2001).

Gongwangling, Lantian:

Gongwangling is located at 3412 N and 10928 E. A Homo erectus cranium

was found at Gongwangling. The fossil was found in the L15 Loess Layer, which An and

Ho (1989) dated to 1.15 Ma using magnetostratigraphy. Heslop et al. (2000) estimated

the age of the L15 loess at 1.22 to 1.19 Ma. The complete fauna was described by Hu and

Qi (1978). An environmental analysis of Gongwangling based on the fauna concluded

that this site experienced relatively warm and moist conditions (Dong et al. 2000). The

presence of forests was inferred based on a large number of forest-dwelling taxa (Dong et

al. 2000). Gongwangling is located on the northern edge of the Qingling Mountains,

which divide north and south China, and its fauna includes a number of typically

southern Chinese forest mammals (Hu and Qi 1978). These southern taxa may indicate a

warm period in which certain mammals were able to spread further north. Wang et al.

(1997) described the environment as a cold or cool dry winter with a warm, semi-humid

summer based on stable isotope ratios from the last glacial-interglacial cycle.

Yuanmou:

Yuanmou is located in south China at 2540 N and 10154 E. The Yuanmou

incisors and artifacts, found in a layer dated to ~ 1.7 Ma using magnetostratigraphy and

34

the sedimentation rate, are the earliest evidence for hominins in continental East Asia

(Zhu et al. 2008). The incisor morphology has affinities with Homo erectus and Homo

habilis (Zhu et al. 2008). The fauna contains some Pliocene survivor species, while other

species are typical of the early Pleistocene (Qian and Zhou 1991). Pollen showed the

presence of pine and other tree species, as well as herbaceous vegetation, indicating a

cool and temperate environment (Qian and Zhou 1991, Zhu et al. 2008). While many

grazing species are found in the fauna, taxa associated with other habitats, such as

bushland and forests, also occur (Qian and Zhou 1991).

Longgupo or Wushan

Longgupo is a cave site located in South China at 30.4N, 109.1E. It was

formerly thought to be a hominin site (Huang and Fang 1991, Huang et al. 1995) but

those remains are now thought to represent an ape (Wu 2000). Rocks with crude,

sometimes overlapping facets were also found and considered to be stone tools by the

excavation team (Huang and Fang 1991, Huang et al. 1995). The fauna from this site is

used here as a non-hominin comparator site. Huang et al. (1995) estimated that the site

dates to 1.9-1.8 Ma. Biochronological analyses of the fauna based on the co-occurrence

of species showed that the site has to be Late Pliocene to early Pleistocene (Huang et al.

1995). Electron spin resonance was used to assign the ape level to the Olduvai subchron

(Huang et al. 1995). Many species in the ape zone have also been found at

Gigantopithecus Cave (Huang and Fang 1991). However, mammals from north China, as

well as the local area, are also present in the assemblage, indicating a mixture of species.

From the overall inferred habitat preferences of the species, Huang and Fang (1991)

inferred the presence of forests and a relatively moist climate. However, climate

35

fluctuations may have caused grasslands to develop during some phases. Pollen indicates

climate change during the period when the middle hominoid zone was deposited. There

was a transition from a cold and dry period with herbaceous vegetation, to a climate that

was warm and wet, with forests of evergreen trees (Huang and Fang 1991).

Mohui Cave:

Mohui Cave, located at 233454 N and 1070008 E, is part of the Bubing

Basin, adjacent to the Bose Basin, South China. This cave is the uppermost in a sequence

of caves. The caves were formed when groundwater dissolved limestone. As the

groundwater sank to lower levels, new caves were formed, leaving the oldest caves in the

uppermost position. Flowstones from one of the younger caves were dated by U-series

analysis yielding a formation date of 350-200 ka (Wang et al. 2007). Many of the bones

were gnawed by rodents or carnivores (Wang et al. 2007). Some species typical of the

late Pliocene and early Pleistocene, Ailuropoda microta and Hesperotherium, are present

in the assemblage and supported an early age assignment. The fauna is also similar in

taxonomic composition to Longgupo and Gigantopithecus Cave (Wang et al. 2007),

which are also dated to the late Pliocene or early Pleistocene. The ecological assessment

of the fauna was aided by stable isotope analysis of some of the teeth. Results showed a

closed, forest habitat (Wang et al. 2007).

Jianshi or Longgudong:

Jianshi is a multi-layered cave site located at 303914.9 N, 1100429.1E.

Paleomagnetic information was used to date the site. The younger layers were reported to

be from the Olduvai subchron, while older layers (including a potential hominin) were

dated to greater than 2.15 Ma. The potential hominin teeth found during recent

36

excavations included an upper third molar, a lower first molar and an upper third

premolar. Other teeth attributed to hominins have been obtained earlier. Zheng (2004)

concluded after metrical comparison that the specimens are similar to Meganthropus,

Australopithecus or Pithecanthropus (based on specimens now sunk into Homo).

However, the teeth may represent a species of non-hominin hominoid (Schwartz et al.

1995, Ciochon 2009). Most micromammalian genera come from a geographic class

labeled as the middle subtropical forest type (Zheng et al. 2004). Environmental

classifications of large mammals based on extant relatives show that many came from

forested tropical or subtropical environments (Zheng et al. 2004). Pollen records showed

climate differences for different layers, although the site overall is dominated by conifers

from mountainous areas and by broadleaf trees (Zheng et al. 2004).

Linyi:

Linyi is a non-hominin site in Shanxi, located at 3612 N and 11030 E. The

fauna was found in sands that underlie loessic beds in a lacustrine-alluvial deposit (Tang

et al. 1983). Many of the mammalian species found at this site are typical of northern

China, with the same genera or species being found at the Nihewan Basin or at Xihoudu

(Tang et al. 1983). Due to that faunal resemblance and the fact that the fauna contains

archaic and extinct species, it is thought to date to the Middle or Late Villafranchian

period (Tang et al. 1983). Many of the species (such as Equus, Paracamelus, Gazella,

and Coelodonta) are typical of steppe faunas and are thought to have come from a

grassland environment.

37

Longdan:

Longdan is located at 35 N and 103 E. The Longdan fauna is dated to between

2.55 and 2.16 Ma by paleomagnetic stratigraphy (Qiu et al. 2004). Based on evidence

from faunal resemblance, Qiu et al. (2004) concluded that the fauna was similar to that of

the late Pliocene site St. Vallier, France and dated to about 2.2 Ma. It is definitely older

than that of the Nihewan Basin, since Longdan contains some primitive species or

primitive forms of species (Qiu et al. 2004). Specimens from this site were obtained from

private collections, so detailed information about provenance is unavailable. Collection

bias may have resulted in the composition of this assemblage including many species of

carnivores. Qiu et al. (2004) also noted a taphonomic bias against small animals. There is

evidence that Longdan included steppe or open environments, as well as forested areas.

Climate change may have led to changes in the local habitat. Coelodonta nihowanensis

and Hipparion sinense specimens were both relatively hypsodont; six of the other

herbivores were hypsodont, leading Qiu et al. (2004) to infer the presence of steppe or

open habitats. Six herbivore species were thought to have either lived in forested

environments or to have been browsers or frugivores, supporting the inference of the

presence of bushland, shrubland or forest habitats (Qiu et al. 2004).

Haiyan Formation, Yushe Basin:

The Haiyan Formation is located in the Yushe Basin in North China, at 375 N

and 11259 E. The sediments have been dated to the late Pliocene (Flynn at al. 1991).

Based on magnetostratigraphy, the Haiyan Formation corresponds to the lower

Matuyama reverse chron, and was deposited prior to the Olduvai event, with dates

between 2.5 and 1.9 Ma (Flynn et al. 1991). Biochronological correlation also supports

38

this age (Qiu 1990). Micromammal faunas show considerable turnover between the

preceding Mazegou Formation and the Haiyan, which has 11 first appearances (Flynn et

al. 1991). Turnover also occurred at that boundary among the large mammals (Flynn et

al. 1991). Seven large mammal species also made last appearances in the Haiyan

Formation (Flynn et al. 1991). This fauna is unpublished and information about it is

limited.

Figure 2.1 Map of the East Asian fossil localities. The Nihewan includes the sites of

Xiaochangliang, Donggutuo and Majuangou, as well as the Nihewan

39

Map of the East Asian fossil localities. The Nihewan includes the sites of

Xiaochangliang, Donggutuo and Majuangou, as well as the Nihewan sensu stricto

Jianshi

0 700 km

Map of the East Asian fossil localities. The Nihewan includes the sites of

sensu stricto fauna.

40

Summary:

This chapter introduces ecological structure methods, which describe mammalian

communities using proportions of species with adaptations relating to diet, body size and

substrate. Differences in ecological structure correlate to differences in climate and

environment. However, ecological structure is also affected by biogeographic and

historical processes, especially as these processes affect the composition of the regional

species pool, from which species found in specific assemblages are drawn. In order to

show how ecological structure relates to environmental differences, modern sites were

classified into environmental groups based on factors such as latitude, precipitation and

temperature using Baileys ecoregions.

Another focus of this chapter is a review of theories about the dispersal of African

mammals, and Homo in particular, to new regions. Ideas considered include the

simultaneous dispersal of a group of African mammals, including hominins, out of

Africa, and the idea that hominin dispersal was linked to the spread of savanna habitats.

These theories, as well as other habitat information about the Plio-Pleistocene sites will

be considered in light of results presented in the following chapters of the dissertation.

Finally, the specific sites in East Asia and East Africa to be analyzed were

introduced, along with general climatic and environmental conditions in the two regions.

East African sites were from Olduvai Beds I and II and East and West Turkana. East

Asian sites included both hominin and non-hominin localities. The East African Plio-

Pleistocene shows a trend toward increasing aridity and variability after 3 Ma, with

habitats becoming more open, while East Asia experienced glaciation and cooling after

3.5 Ma, with decreases in precipitation after 2.6 Ma.

41

Chapter 3: Methods to determine ecological similarity

This research is concerned with the ecological context of the initial hominin

dispersal out of Africa. Specifically it looks at the degree of ecological similarity between

communities of mammals in East Asia and East Africa and compares the ecology of East

Asian communities during the Plio-Pleistocene. Ecological similarity is defined as the

similarity between animals based on the ecological properties of diet, body mass and

substrate use (i.e., terrestrial, arboreal or aquatic). Similarity in community or ecological

structure implies communities with similar proportions of ecologically comparable

animals. Ecological community structure methods are based on the principle of

convergence of environmental conditions; i.e., communities from similar environments

will have similar structures (Andrews 1996). Ecological structu