Twelve Million Years of Bird History: a Specimen-Based Approach to Reconstructing the Late Neogene Bird Communities of California ______

Home , Brachyramphus, Capistrano Formation, Heron, Late Miocene, Merced Formation, Middle Miocene

TWELVE MILLION YEARS OF BIRD HISTORY: A SPECIMEN-BASED APPROACH TO RECONSTRUCTING THE LATE NEOGENE BIRD COMMUNITIES OF CALIFORNIA ______

A Thesis

Presented to the

Faculty of

California State University, Fullerton ______

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

Geological Sciences ______

Peter Alfred Kloess

Thesis Committee Approval:

Dr. James Parham, Chair Dr. Nicole Bonuso, Department of Geological Sciences Dr. Adam Woods, Department of Geological Sciences

Fall, 2015

ABSTRACT

California has experienced significant climate change from the onset of the

Miocene (~23Ma) to the present. The impact of past climate change is often recorded in the fossil record, and can be revealed by studying how ecological communities change through time. Fossil seabirds are the ideal taxon for studying faunal responses to environmental changes because they are numerous in collections, easily identified from fragmentary remains, and since modern seabirds respond quickly to immediate changes in their environments, we expect the fossil record of seabirds to faithfully represent past environments. The first study to look at fossil seabird diversity through the Tertiary of the

North Pacific relied entirely on literature records to describe the appearance and disappearance of seabird species and correlated these patterns to geologic and climatic events. My thesis utilizes an empirical, specimen-based approach to accurately describe the seabird response to climate and tectonic change during ~12 million years of coastal

California’s geologic history (middle Miocene to early Pliocene). The foundation of my dataset is a previously unstudied collection of 305 bird specimens from the John D.

Cooper Center for Archaeology and Paleontology, representing a relatively complete sequence of strata (Topanga Group, Monterey Formation-equivalent, and Capistrano

Formation). Representing the middle Miocene to early Pliocene of Orange County, these strata form the basis for delineating chronostratigraphic bins used for studying the

diversity of the fossil seabird community of California. Comparison of this new collection with 378 seabird specimens from three other institutions across California provides a more complete and detailed view of the seabird community during this period.

Diversity, taxonomic richness, and relative abundance were examined using quantitative statistical methods to understand the change in seabird populations over time and depth of deposition. Using these statistical techniques, my data show a clear increase of pan- alcid abundance and decline of sulid abundance that is coincident with global climatic and tectonic changes as well as enhanced nutrient upwelling. Upwelling through this time also accounts for morphological changes in salmon and speciation in marine mammals.

In the future, the specimen-based methodology used here can be applied to contemporaneous taxa, such as marine mammals, to quantitatively analyze diversity and relative abundance during the late Neogene and further explore the relationship between physical drivers and faunal change.

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TABLE OF CONTENTS

ABSTRACT ...... ii

LIST OF TABLES ...... vi

LIST OF FIGURES ...... vii

ACKNOWLEDGMENTS ...... ix

Chapter 1. INTRODUCTION ...... 1

2. TECTONICS AND STRATIGRAPHIC UNITS OF CALIFORNIA FROM THE MIDDLE MIOCENE TO EARLY PLIOCENE ...... 4

Neogene Plate Tectonics of Southern California ...... 5 Seabird-Bearing, Marine Rock Formations of California ...... 7 Middle Miocene Rock Units (Time Bin 1) ...... 7 Late Miocene Rock Units (Time Bin 2) ...... 13 Mio-Pliocene Rock Units (Time Bin 3) ...... 17

3. FOSSIL SEABIRDS FROM THE MIDDLE MIOCENE TO EARLY PLIOCENE OF CALIFORNIA ...... 26

Nomenclature ...... 28 Collections ...... 28 Orange County Paleontology Collection ...... 28 Museum Collections Across California ...... 29 Identification ...... 30 Seabird Clades Examined in this Study ...... 34 Pan-Alcidae (Charadriiformes) ...... 34 Mancallinae ...... 34 Procellariidae (Procellariiformes) ...... 35 Sulidae (Suliformes) ...... 35 Other families present ...... 35 Seabirds Through Time ...... 36 Time Bin 1 (14.7 to 17.0 Ma) ...... 36 Time Bin 2 (10.0 to 14.7 Ma) ...... 37 Time Bin 3 (4.9 to 10.0 Ma) ...... 38

4. STATISTICAL ANALYSIS OF CALIFORNIA’S FOSSIL SEABIRD COMMUNITY ...... 40

Analyses ...... 41 Diversity ...... 41 Richness ...... 42 Abundance ...... 43 Multivariate Techniques ...... 44 Results ...... 45 Diversity ...... 45 Richness ...... 46 Abundance ...... 49 Multivariate Techniques ...... 53

5. PHYSICAL DRIVERS OF SEABIRD COMMUNITY EVOLUTION DURING THE LATE NEOGENE ...... 60

Potential Taphonomic Bias from Osteosclerosis within Pan-Alcidae ...... 62 Pacific Circulation Patterns and Plate Tectonics ...... 65 The Monterey Formation-equivalent of Orange County ...... 67 Response of Contemporaneous Non-Avian Taxa ...... 68 Changes in Diversity During The Pliocene/Pleistocene ...... 68 Conclusions ...... 71

APPENDICES ...... 72

A. Fossil Seabird Species in Middle Miocene to Early Pliocene California Strata ...... 72 B. Extant Bird Specimens Used for Comparison and Identification ...... 75 C. Identified Seabird Material from middle Miocene to Early Pliocene California Strata ...... 78

REFERENCES ...... 91

LIST OF TABLES

Table Page

1. Taxa listed as seabirds ...... 27

2. Counts of identified fossil bird specimens from middle Miocene to early Pliocene strata across California, organized by repository ...... 30

3. Counts of identified fossil bird specimens organized by anatomical element ..... 32

4. Richness and evenness metrics of fossil bird specimens from middle Miocene to early Pliocene strata across California, organized by chronostratigraphic time bin 45

5. Counts of Pan-Alcidae, Procellariidae, and Sulidae humeri and femora...... 64

LIST OF FIGURES

Figure Page

1. Development of the San Andreas Fault system ...... 5

2. Neogene sedimentary basins of California ...... 6

3. Fossil seabird-bearing, marine strata of middle Miocene to early Pliocene age included in this study ...... 8

4. Localities of seabird-bearing rock formations of California included in Time Bin 1 (14.7 to 17.0 Ma) ...... 11

5. Localities of seabird-bearing rock formations of California included in Time Bin 2 (10.0 to 14.7 Ma) ...... 16

6. Localities of seabird-bearing rock formations of California included in Time Bin 3 (4.9 to 10.0 Ma) ...... 21

7. Posterior views of extant seabird humeri used for comparison with fossil specimens ...... 33

8. Relative abundance pie chart of fossil seabird specimens collected from strata within Time Bin 1 ...... 36

9. Relative abundance pie chart of fossil seabird specimens collected from strata within Time Bin 2 ...... 37

vii

10. Relative abundance pie chart of fossil seabird specimens collected from strata within Time Bin 3 ...... 39

11. Shannon Index and Simpson’s Diversity Index of middle Miocene to early Pliocene seabirds ...... 46

12. Rarefaction curves for chronostratigraphic bins of seabird fossils from the middle Miocene to the early Pliocene ...... 47

13. Margalef’s and Menhinick’s richness indices of middle Miocene to early Pliocene seabirds, calculated based on a rarefied subsample of chronostratigraphic bins ...... 48

14. Rank abundance curve of Time Bin 1 organized by stratigraphic formation ...... 50

15. Rank abundance curve of Time Bin 2 organized by stratigraphic formation ...... 50

16. Rank abundance curve of Time Bin 3 organized by stratigraphic formation ...... 51

17. Rank abundance curve of Time Bins 1 through 3 ...... 52

18. NMDS plot of the 16 samples of fossil seabirds from different formations...... 54

19. Cluster Dendrogram of the nine stratigraphic formations containing more than five fossil seabird specimens ...... 55

20. NMDS plot of the samples from different formations containing more than five fossil seabird specimens ...... 56

21. Stratigraphic formations plotted against depositional depth and time ...... 58

22. Relative percentages of Procellariidae, Sulidae, and remaining taxa across chronostratigraphic bins calculated without Pan-Alcidae present ...... 59

23. Cross-sections of seabird humeri showing cortical thickness ...... 63

24. Global sea surface temperature and relative abundance of Pan-Alcidae from the middle Miocene to early Pliocene ...... 66

25. Global eustatic sea level and relative abundance of Pan-Alcidae from the middle Miocene to early Pliocene ...... 69

viii

ACKNOWLEDGMENTS

I would like to thank my thesis advisor, Dr. James Parham, for his help and guidance over the last two years. Through countless conversations regarding research and the willingness to review multiple drafts of documents, you have greatly improved my abilities as a student and scientist. More so than these academic qualities, your mentorship and the standard you set have also made me a better person. I would also like to thank Dr. Nicole Bonuso and Dr. Adam Woods for sitting on my thesis committee and providing valuable insight to improve this thesis. Thank you to the members of the

Parham Lab for lively discussions and camaraderie. In particular, Gabe Santos and Tara

Redinger gave much-needed strength and reassurance through this entire process. The support and encouragement from Dr. Andrew Farke and Dr. Don Lofgren helped me prepare for my return to academics after several years away. Thank you to my family for believing in my childhood dream of becoming a paleontologist and standing by my side as I’ve worked to achieve it. I gratefully acknowledge the Doris O. and Samuel P. Welles

Research Fund of UC Berkeley, the Associated Students, Inc. of CSUF, and the Natural

Science and Mathematics Interclub Council of CSUF for providing funding to conduct and present this research.

CHAPTER 1

INTRODUCTION

California has experienced significant climate change from the onset of the

Miocene (~23Ma) to the present, including multiple periods that were much warmer or cooler than today (Naish et al., 2009). Recent, human-induced increases in global temperature have prompted investigations of the impact of ancient climate change on past ecosystems (Solomon et al., 2007). By doing so, we can better understand the potential impacts of recent climate change (Norris et al., 2013). The impact of past climate change is often recorded in the fossil record, and can be revealed by studying how ecological communities change through time (e.g., Marx and Uhen, 2010; Pyenson et al., 2014). For example, rates of sea level change and marine productivity affected the diversity and morphology of marine reptiles during the Mesozoic (Kelley et al., 2014; Polcyn et al.,

2014); the diversity of whales and the development of filter-feeding strategies were responses to increased productivity of the world’s oceans and climate change during the

Paleogene (Marx and Uhen, 2010; Clementz et al., 2014); and the paleobiogeography of seagrasses was tracked through the Cenozoic using sirenians, e.g., manatees, and related to circulation and tectonic changes (Vélez-Juarbe, 2014).

One group that holds great promise for showing responses to past environmental change is seabirds. Fossil seabirds are ideal for studying faunal responses to environmental changes because they are numerous in collections, easily identified from fragmentary remains, and since modern seabirds respond quickly to immediate changes in their environments, we expect the fossil record of seabirds to faithfully represent past environments (Warheit, 2002).

The first study to look at fossil seabird diversity through the Tertiary of the North

Pacific (Warheit, 1992) relied on species descriptions from the literature to describe patterns of seabird species richness through time. The appearance and disappearance of seabird species was then correlated to geologic and climatic events. This study identified an initial radiation of extant seabird taxa during a warm period called the Middle

Miocene Climatic Optimum (MMCO). The late Miocene saw dropping temperatures resulting in increased speciation of pan-alcids. These changes were also occurring at the same time as the formation of the Los Angeles Basin and the development of upwelling systems (Barron and Baldauf, 1989; Ingersoll and Rumelhart, 1999).

Contrary to Warheit (1992), who relied entirely on literature records to describe the appearance and disappearance of seabird species, my thesis utilizes an empirical, specimen-based approach to accurately describe the seabird response to climate and tectonic change during the ~12 million years of coastal California’s geologic history

(middle Miocene to early Pliocene). The foundation of my dataset is a previously unstudied collection of 305 seabirds from Orange County, California, housed at the John

D. Cooper Archaeological and Paleontological Center (Cooper Center). By adding data from the Cooper Center specimens to new data from the collections of other museums

3 throughout California, I can rigorously answer questions such as how seabirds were affected by tectonic and climate change along the California coast during the late

Neogene and how study of seabird fossils can explain the broader impact of physical drivers on marine vertebrates during the Miocene.

To understand the effect of physical drivers on seabird communities during the

Miocene, the geology of the stratigraphic formations containing the specimens in this dataset is examined first (Chapter 2). The geography, geology and depositional depth are described to provide context of the past environment. Chronostratigraphic bins were established based on the ages of the Orange County strata, as a means to organize the dataset. Identification of the fossil seabird elements was critical to understanding the composition of the seabird community through time (Chapter 3). Once identified, organization into the aforementioned time bins elucidated the relative abundance of taxa and community composition through time. Statistical analyses were conducted using the taxonomic abundance data within each time bin (Chapter 4). Diversity, richness and relative abundance metrics were calculated across time bins, in an effort to understand the pattern of faunal change over time. Description of these patterns requires interpretation and placement of taxonomic response into the context of physical drivers (Chapter 5). In doing so, my thesis shows how physical drivers impact fossil seabird communities, and by extension other coeval marine taxa, while elucidating potential biases (e.g., taphonomy) in the fossil record.

CHAPTER 2

TECTONICS AND STRATIGRAPHIC UNITS OF CALIFORNIA FROM THE MIDDLE MIOCENE TO EARLY PLIOCENE

The Neogene fossil record of seabirds in California begins in the middle Miocene and continues through the end of the Pliocene (Warheit, 1992). The marine sediments and seabird fossils deposited from this time reflect a period of regional and global tectonism and climate change. The Los Angeles Basin of Southern California and other contemporaneous depositional basins contain strata representative of the middle Miocene to early Pliocene (~17 to ~5 Ma) and provide the means to study these changes in climate and tectonism (e.g., Yerkes et al., 1965). Because Orange County rock formations record the geologic history of the region from the middle Miocene to early Pliocene, the dates of deposition for these strata are used to establish chronostratigraphic delineations for studying the changes in diversity, richness, and relative abundance in the seabird community. Similarly, depth of deposition of these formations provides information regarding the paleoenvironment (e.g., distance from shore) and will also be examined against changes in seabird diversity and relative abundance.

Neogene Plate Tectonics of Southern California

During the Oligocene (~29 Ma), the spreading ridge separating the Pacific Plate from the Farallon Plate reached the western edge of the North American Plate (Figure 1)

(Atwater, 1970; Blake et al., 1978). As this spreading ridge migrated along the North

American Plate boundary, the subducting Farallon Plate divided into the Cocos and Juan de Fuca plates, and the San Andreas Fault formed (Stoffer, 2010).

Figure 1. Development of the San Andreas Fault system. BC: Baja California; CP: Cocos Plate; JdFP: Juan de Fuca Plate; M: Mendocino Triple Junction; MZ: Manzanillo; R: Rivera Triple Junction; S: Seattle; SF: San Francisco. Modified from Stoffer, 2010.

Miocene marine strata and numerous seabird specimens included in this study were deposited in marine basins that formed from the right-lateral, transform movement of the San Andreas Fault (Figure 2) (Blake et al., 1978; Behl, 1999). In particular, the three-step development (transrotation, transtension, and transpression) of the Los Angeles

Basin (LA Basin hereafter) of Southern California (Ingersoll and Rumelhart, 1999) is synchronous with the deposition of a relatively complete sequence of Orange County marine strata (middle Miocene Topanga Group, middle to late Miocene Monterey

Formation-equivalent, and Mio-Pliocene Capistrano Fm.).

Figure 2. Neogene sedimentary basins of California with the LA Basin highlighted in orange. Depositional basins containing seabird fossils included in this study include: Contra Costa Basin (Mulholland Fm.), Salinas Basin (Etchegoin), San Joaquin Basin (Temblor Fm. and Round Mountain Silt), Santa Maria Basin (Sisquoc Fm.), Santa Barbara Basin (Monterey Formation-equivalent), Los Angeles Basin (Topanga Group, Monterey Formation-equivalent, Modelo, and Capistrano Fms.), and San Diego Basin (San Mateo Fm.). Modified from Behl, 1999.

Seabird-Bearing, Marine Rock Formations of California

Nearly half of the fossil seabird specimens (247 of 527 specimens) included in this study were recovered from LA Basin strata. Strata from the LA Basin (Topanga

Group, Modelo Formation, Monterey Formation-equivalents of Los Angeles and Orange

Counties, and Capistrano Formations) represent the entire span of time from the middle

Miocene to the early Pliocene (Figure 3). Because of this continuous sequence, I identified the LA Basin formations and their stratigraphic age ranges, as well as coeval paleoceanographic events, to form the basis for delineating chronostratigraphic bins used for studying the diversity of the fossil seabird community of California.

Using these identified age ranges, contemporaneous marine rock formations from

California and Baja California can be grouped into time bins for the purpose of analyzing the seabirds contained therein. Depositional information for these rock formations was collected from the literature in the vicinity of the identified fossil localities when possible. Ages of these strata were based on paleomagnetic and isotope ages from adjacent sediments and volcanic rocks (using 40Ar/39Ar, K/Ar, and 87Sr/86Sr dating methods), microfossils (diatoms, foraminifera, and pollen), and macrofossils (terrestrial and marine mammals).

Middle Miocene Rock Units (Time Bin 1)

The first time bin for sorting contemporaneous California strata and analyzing the fossil seabird community over time is based on the stratigraphic age range of the Middle

Miocene Climatic Optimum (MMCO) from 14.7 to 17.0 Ma (Holbourn et al., 2014). This period also records the intial phase of transrotation of the San Andreas fault (Ingersoll and Rumelhart, 1999). Fossil seabirds are known from four coeval strata within this

Figure 3. Fossil seabird-bearing, marine strata of middle Miocene to early Pliocene age included in this study. Left to right indicates geographic divisions (California counties and Mexican states) North to South. Gray lines indicate time bins used and strata are color- coded for grouping fossils: Time Bin 1 = 14.7 to 17.0 Ma, Black; Time Bin 2 = 10.0 to 14.7 Ma, Gray; Time Bin 3 = 4.9 to 10.0 Ma, White. Los Angeles Basin shown in Orange. For sources of age ranges of individual strata, see text below. Geologic time scale follows Gradstein et al. (2012). Benthic foraminiferal stages and diatom zones from Barron and Isaacs (2001).

9 period: the Topanga, the Rosarito Beach Formation, Round Mountain Silt, and Temblor

Fm.

Topanga Group. Originally identified along the Topanga anticline within the central Santa Monica Mountains of Los Angeles County, the Topanga Formation is described as a medium- to coarse-grained sandstone and conglomerate with volcanic intrusions, unconformably bracketed by the overlying Modelo Formation and underlying

Vaqueros Formation (Kew, 1924). Subsequently, the Topanga Formation (of the Santa

Monica Mountains) was elevated to group status with its constituent members (Topanga

Canyon, Conejo Volcanics, and Calabasas) becoming formations (Yerkes and Campbell,

1979). The lowest unit, the Topanga Canyon Formation, was deposited in a neritic, nearshore environment (Yerkes and Campbell, 1979) and the highest unit, the Calabasas

Formation contains bathyal fan turbidites with interbedded silty shales (Campbell et al.,

2009).

Correlation of the Topanga Canyon Formation with strata to the southeast (i.e.,

Orange County) was made when the Topanga Formation was established (Kew, 1924).

Based on distance from the type locality and lithologic differences, Howard and Barnes

(1987) indicated uncertainty in using the Topanga Formation for sediments in Orange

County. Contrary to this, some workers (Blake, 1991; Morton and Miller, 2006) determined the Topanga of the San Joaquin Hills and Newport Bay area should not only maintain the same name but also raised it to group status with the Paularino, Los Trancos, and Bommer members (Vedder et al., 1957) elevated to formation rank. Within Orange

County, the Topanga Group represents neritic environments in the northern and eastern portions of the county and upper to middle bathyal depths of deposition in the western

10 area (e.g., San Joaquin Hills) (Blake, 1991). Because the bird-bearing localities are located closer to the Santa Ana Mountains in the east than the Orange County coastline, I recognized a sublittoral depth of deposition for further discussion of the Topanga Group.

The presence of diagnostic land mammals places the initiation of Topanga deposition during the early late Hemingfordian North American Land Mammal Age

(NALMA) (Whistler and Lander, 2003; Tedford et al., 2004). Benthic foraminifers within the conformably overlying El Modeno Volcanics (Yerkes, 1957, Bjorkland et al.,

2002) and within the Topanga Group (Vedder et al., 1957; Ingle, 1979; Raschke, 1984;

Boessenecker and Churchill, 2015) have yielded an age of deposition from the lower

Luisian to Relizian foraminiferal stages (14.9 to 17.1 Ma) (Barron and Isaacs, 2001) and roughly corresponds to the MMCO (14.7 to 17.0 Ma; Holbourn et al., 2014).

Included in this study are 37 fossil seabird elements from the Topanga Group.

Localities of seabird-bearing Topanga Group outcrops include: LACM 4464, LACM

4546, LACM 4547, LACM 4961, and OCPC 415 (Figure 4).

Rosarito Beach Formation. The Rosarito Beach Formation is located in the coastal northwest portion of Baja California (Figure 4) (Minch et al. 1984). It consists of marine sandstones that have been attributed to an open marine, inner shelf (sublittoral) depositional environment and dated at 15.51 ± 0.14 Ma to 16.2 ± 0.3 Ma based on

40Ar/39Ar dating of adjacent basalt flows (Deméré et al., 1984; Luyendyk et al., 1998;

Ferrusquía-Villafranca, 2003). Using the maximal age range from these estimates (15.37 to 16.5 Ma) merits inclusion of the Rosarito Beach Formation into Time Bin 1 (14.7 to

17.0 Ma) (Figure 3).

Figure 4. Localities of seabird-bearing rock formations of California included in Time Bin 1 (14.7 to 17.0 Ma).

Included in this study are 18 fossil seabird elements from the Rosarito Beach

Formation. Localities of seabird-bearing Rosarito Beach Formation outcrops include:

SDSNH 3452, SDSNH 3459, and SDSNH 4778.

Round Mountain Silt. The Round Mountain Silt is located within Kern County

(Figure 4) and the majority of the middle Miocene-aged seabird elements included in this study were collected from the Sharktooth Hill locality, a well-known marine bonebed

12 containing multiple taxa, including pinnipeds, whales, and invertebrates (Pyenson et al.,

2009). The age of the bonebed has been identified as 15.2 to 15.9 Ma based on diatoms and paleomagnetic data with much of the surrounding Round Mountain Silt deposition occurring between 14.5 and 16 Ma, also based on diatoms, land mammals, and paleomagnetic data (Pyenson et al., 2009). The Round Mountain Silt is classified using the latter, broader, age range (14.5 to 16 Ma) because not all the bird specimens included in this study come from the Sharktooth Hill bonebed, and thus incorporating the rock formation into Time Bin 1 (14.7 to 17.0 Ma) (Figure 3). Sedimentary facies within the

Round Mountain Silt record initial inner to outer shelf deposits, transitioning to upper bathyal depths, and back to middle to outer shelf depths (Olson, 1988, 1990). The seabird specimens included in this study were collected from sediments deposited during the deepening transition from outer shelf to deeper, upper bathyal depths of Round Mountain

Silt deposition (Olson, 1990) and are therefore included with other bathyal formations.

Included in this study are 128 fossil seabird elements from the Round Mountain

Silt. Localities of seabird-bearing Round Mountain Silt Formation outcrops include:

LACM 1625, LACM 1655, LACM 3160, LACM 3162, LACM 3205, LACM 3230,

LACM 3499, LACM 4173, LACM 4672, LACM 4874, LACM 4956, LACM 6069,

LACM 6688, UCMP -1292, UCMP V2401, UCMP V6323, UCMP V6843, UCMP

V69169, UCMP V71013, and UCMP V74021.

Temblor Formation. The Temblor Formation outcrops in Fresno and Kern counties (Figure 4) (Hosford Scheirer and Magoon, 2007). Though the Temblor

Formation consists of shallow marine deposits (Bartow, 1991), the fossil locality that contains the seabird elements is comprised of landslide debris (Zaborsky, 2004) and is

13 thus interpreted as littoral in deposition. Kelly and Stewart (2008) used the presence of horse and camel remains also found at the fossil locality to identify an early to early late

Barstovian NALMA range (14.8 to 15.8 Ma; Tedford et al., 2004) for deposition of the

Temblor Formation. Based on this age range, the Temblor Formation is assigned to Time

Bin 1 (14.7 to 17.0 Ma) alongside the Topanga Group of Orange County (Figure 3).

One fossil bird element from Temblor Formation outcrops is included in this study from one locality: UCMP V99563.

Late Miocene Rock Units (Time Bin 2)

To designate the second time bin for sorting contemporaneous strata and analyzing the fossil seabird community, the minimum age of the MMCO (14.7 Ma) and the minimum age of the Monterey Formation-equivalent of Orange County at 10.0 Ma.

This age of 10.0 Ma is coincident with dramatic lowering of global sea level (10.5 Ma;

Haq et al., 1987) and a temporary shift in upwelling along the California coast from broadly ranging offshore to occurring closer to shore (Domack, 1986; Lyle et al., 2000) resulting from reduced strength of the California Current (Barron et al., 2002). Marine strata that were deposited in this age range include: the Monterey-equivalents (of Orange and Santa Barbara Counties) and the Santa Margarita Formation.

Monterey Formation-equivalent. The type section for the Monterey Formation was designated near the city of Monterey, in Northern California (Bramlette, 1946).

Though the Monterey Formation was originally described in Monterey County, rocks similar in lithology and fossil content are identified in outcrops from numerous counties throughout California (e.g., from Marin County to Orange County; Blake et al, 2000;

Morton and Miller, 2006). Although lithologically similar, variability in geochemistry, as

14 well as time and depth of deposition (Katz and Royle, 2001), and a lack of lateral continuity from the type section warrants caution when using the “Monterey Formation” to describe these rocks in the LA Basin and outside of the type area. For example, the siliceous Miocene rocks of the LA Basin had been assigned to the Monterey, but subsequent workers differentiated coeval units from the west and northern parts of the

Basin as the Modelo and Puente Formations, respectively (Woodring et al., 1946;

Campbell et al., 2009). For this study I will use “Monterey Formation-equivalent” to refer to the siliceous rocks of the middle to late Miocene traditionally ascribed to the Monterey

Formation. Bird-bearing localities of this study within the Monterey Formation- equivalent are located within the LA Basin (Los Angeles and Orange Counties) and northwestern Santa Barbara County.

The Monterey Formation-equivalent (of Orange County) represents filling of the

LA Basin with diatomaceous mud at water depths of 1500 to 2000 m (upper to middle bathyal) (Blake, 1991; Ward and Valensise, 1994). This upper to middle bathyal zone defines the deepest point of deposition amongst the late Miocene strata examined.

Within Orange County, deposition dates for the Monterey Formation-equivalent are variable. The age of the Monterey-equivalent at Newport Beach is determined at 6.7 to 15.9 Ma based on the presence of diatoms (i.e., subzone A of the Nitzschia reinholdii

Zone through subzone A of the Denticulopsis lauta Diatom Zone) (Blake, 1991; Barron and Isaacs, 2001). Deposition dates of the Monterey-equivalent from San Juan Capistrano using unspecified biostratigraphic and lithostratigraphic correlations (Buckeridge and

Finger, 2001) and from Mission Viejo using benthic foraminifera (late early Mohnian;

Finger et al., 2008) recovered age ranges of 8.2 to 11.3 Ma and 9.4 to 11.2 Ma,

15 respectively. In the area around Aliso Viejo, within close proximity of referred fossil seabird localities, diatoms from Monterey-equivalent outcrops have yielded a maximum age at the base of subzone b of the Denticulopsis lauta Zone age of 14.9 Ma (Parham, unpublished data) and a minimum age of 10 to 11 Ma based on stratigraphic association just below the North Pacific Diatom Zone NDP 5D (Barnes, 2013).

Locally variable in age and composition (Behl, 1999), the Monterey Formation- equivalent from California’s central coast can be as old as the Saucesian Foraminiferal

Stage (22.7 to 17.1 Ma) near Maricopa, Kern County and as young as Delmontian (8.3 to

5.1 Ma) at the type locality near Monterey, California (Bramlette, 1946; Barron and

Isaacs, 2001; Hall, 2002). The Monterey Formation-equivalent of Santa Barbara County is also wide-ranging in age (Isaacs, 2001) but has been estimated at 10 to 16 Ma in the

Santa Maria area based on fossil spores and pollen (Srivastava, 1984). Although this age range extends into Time Bin 1, most of this Monterey-equivalent deposition is synchronous with the Monterey Formation-equivalent of Orange County and justifies incorporation into Time Bin 2 (10.0 to 14.7 Ma) (Figure 3). Upper to middle bathyal deposition depths have been observed for the Monterey Formation-equivalent of the nearby Naples Beach section in Santa Barbara County (Isaacs, 2001).

Included in this study are 93 fossil seabird elements from the Monterey

Formation-equivalents of Orange and Santa Barbara Counties. Localities of seabird- bearing Monterey Formation-equivalent outcrops in the LA Basin include: LACM 1945,

LACM 3172, LACM 5078, LACM 6902, LACM 7136, OCPC 213, OCPC 409, OCPC

3123, OCPC 3136, and UCMP V91135 (Figure 5).

Figure 5. Localities of seabird-bearing rock formations of California included in Time Bin 2 (10.0 to 14.7 Ma).

Santa Margarita Formation. The Santa Margarita Formation is located along the southern Santa Cruz Mountains in Santa Cruz County (Figure 5) (Boessenecker, 2011).

The formation is composed of sandstones and conglomerates deposited in a shallow, inner neritic environment during the initiation of a transgressive phase (Clark, 1981;

Phillips, 1984). The inner neritic depositional environment places the Santa Margarita

Formation alongside the other sublittoral formations in this study. Based on marine and

17 terrestrial mammals (Clarendonian NALMA) found at the same localities as the seabird fossils in this study, workers have assigned an age range of 9 to 12.5 Ma to the Santa

Margarita Formation of Santa Cruz County (Repenning and Tedford, 1977; Barron, 1986;

Tedford et al, 2004). Though the range of deposition extends into Time Bin 3, the majority of the Santa Margarita Formation is within Time Bin 2 (10.0 to 14.7 Ma)

(Figure 3).

Included in this study are 16 fossil seabird elements from the Santa Margarita

Formation. Localities of seabird-bearing Santa Margarita Formation outcrops include:

UCMP V4004, UCMP V6200, UCMP V6857, and UCMP V71196.

Mio-Pliocene Rock Units (Time Bin 3)

The minimum age of Capistrano deposition (4.9 Ma) and the minimum age of the underlying Monterey Formation-equivalent of Orange County (10.0 Ma) define the third time bin (Time Bin 3) for sorting contemporaneous California strata and analyzing the fossil seabird community. As stated previously, 10.0 Ma approximately marks a period of weakening of the California Current and resulting upwelling regime along the California coast (Barron et al. 2002). The subsequent rebound in ocean productivity (described as a

“biogenic bloom;” Farrell et al., 1995) ends with another decline in California Current strength (4.6 Ma; Barron et al., 2002). The Etchegoin, Modelo, Monterey-equivalent (of

Los Angeles County), Mulholland, Purisima, San Mateo, Santa Margarita, Sisquoc, and

Wilson Grove Formations are contemporaneous with this chronostratigraphic bin.

Capistrano Formation. The Capistrano Formation is late Miocene to early

Pliocene in age and was named for the area outside San Juan Capistrano, Orange County

(Woodford, 1925). The Capistrano Formation is composed of coarse- to fine-grained

18 sandstones and siltstones, interbedded with diatomites (Ehlig, 1979; Barnes and Raschke,

1991). It shows a gradational contact with the underlying Puente Formation in the Santa

Ana Mountains (Ehlig, 1979) and the Monterey Formation-equivalent in the type area

(Vedder, 1972), but unconformably overlies the Monterey-equivalent to the south, near

San Clemente (Campion et al., 2005). The Capistrano Formation was deposited following movement of the Christianitos Fault and marks the resumption of clastic sedimentation in the Capistrano Embayment, following the sediment-starved deposition of the Monterey

Formation-equivalent (Ingle, 1963; Ehlig, 1979; Bachman and Crouch, 1989; Campion et al., 2005; Jester, 2013). The Capistrano of the Newport Bay area had been dated from the upper Mohnian to the Repettian Benthic Foraminifer Stages (Kleinpell, 1938, 1980;

Ingle, 1979). The presence of diatoms from Newport Beach and San Juan Capistrano indicate an age of 4.9 to 6.4Ma (lower Thalassiosira oestrupii Diatom Zone to subzone b of the Nitzschia reinholdii Zone) (Barron, 1986; Deméré and Berta, 2005).

In the Lake Forest area (formerly El Toro), much of the thickness of the

Capistrano Formation is comprised of the Oso Sand Member, the nearshore facies component of the Capistrano Formation (Vedder, 1972; Barnes and Raschke, 1991). The

Oso Sand consists of white to light grey, poorly bedded, friable sandstones (Ingle, 1979) and grades to the south into the Capistrano Formation, indicating deepening deposition to

1500 m or deeper near Dana Point (Vedder, 1972; Ingle, 1979). Because most of the

Capistrano Formation seabird fossils included in this study come from the inland portion of Orange County (near Lake Forest), the Capistrano is included with other contemporaneous sublittoral formations.

Included in this study are 113 fossil seabird elements from the Capistrano

Formation. Localities of seabird-bearing Capistrano Formation outcrops include: OCPC

317, OCPC 323, OCPC 324, SDSNH 4160, SDSNH 6316, UCMP V5049, and UCMP

V72103 (Figure 6).

Modelo Formation. Though the Modelo Formation does not contribute to the demarcation of the chronostratigraphic bins used in this study, the fact that it outcrops within the LA Basin warrants its inclusion in this section. The Modelo Formation contains seabird elements from the Santa Monica Mountains of western Los Angeles

County (Figure 5). Deposited within a submarine fan complex at upper to middle bathyal depths, the Modelo Formation consists of shales and sandstones derived from erosion of mountains to the north of the Los Angeles Basin (Sullwold, 1960; Blake, 1991; Dibblee,

1991; Redin, 1991; Rumelhart and Ingersoll, 1997).

The Modelo has been dated from 5.1 to 13.5 Ma in age based on Mohnian to

Delmontian Benthic Foraminiferal Stages (Barron, 1986; Barron and Isaacs, 2001; Saul and Stadum, 2005). Although the range of possible deposition extends into Time Bin 2, much of the age range warrants inclusion into Time Bin 3 (4.9 to 10.0 Ma) (Figure 3).

Included in this study are four fossil seabird elements from the Modelo

Formation. Localities of seabird-bearing Modelo Formation outcrops include: LACM

1267 and UCMP V3430.

Monterey Formation-equivalent. The Monterey Formation-equivalent (of Los

Angeles County) represents continuous filling of the LA Basin from the middle to late

Miocene (Yerkes et al., 1965). These rocks contrast with equivalent rocks of Orange

County that were exposed during late Miocene declines in global sea level (Yerkes et al.,

1965; Haq et al., 1987). The Monterey-equivalent of Los Angeles County deposits include diatomaceous mud from upper to mid-bathyal depths (Blake, 1991; Ward and

Valensise, 1994).

Based on outcrops in the Palos Verdes Hills (Los Angeles County), the Monterey

Formation-equivalent of the Los Angeles Basin is separated into three members (in ascending order, the Altamira Shale, Valmonte Diatomite, and Malaga Mudstone;

Woodring et al., 1946), though regional differences make such delineations difficult to determine in all Monterey Formation-equivalent outcrops (Conrad and Ehlig, 1987). The

Palos Verdes section of the Monterey-equivalent was dated using diatoms (the

Thalassiosira oestrupii Zone to Denticulopsis lauta Zone) and tuffs at 4.42 ± 0.57 to 16

Ma (Obradovich and Naeser, 1981; Barron, 1986; Barron and Isaacs, 2001). The

Valmonte Diatomite Member yields one seabird locality from the Palos Verdes Peninsula

(Woodring et al., 1946) and ranges in age from the lower part of the Nitzschia reinholdii, subzone A to the Denticulopsis hustedtii Zone (6.7 to 9.2 Ma) (Blake, 1991; Barron and

Isaacs, 2001). Because the Los Angeles County equivalent of the Monterey Formation was deposited at a younger interval than the equivalent in Orange County, it is placed with contemporaneous strata in Time Bin 3 (4.9 to 10.0 Ma).

One seabird locality (UCMP V36118) bearing one seabird specimen included in this study was found in the Monterey Formation-equivalent of Los Angeles County

(Figure 6).

Etchegoin Formation. Within Monterey County, the San Joaquin Basin is interpreted to have remained shallow (~15 m) through the late Miocene into the early

Pliocene based on the presence of shallow-water, nearshore marine mollusks within the

Etchegoin Formation (Figure 6) (Bowersox, 2005). This shallow water deposition places the Etchegoin Formation with the other littoral strata of this study. The age of the

Etchegoin Formation, extrapolated from the Kettleman Hills, ranges from 7.0 Ma to 4.83

± 0.04 Ma based on analyses of 87Sr/86Sr from fossil shells, fission track of detrital zircons, and K/Ar dating of an upper tuff unit (Hosford-Scheirer and Magoon, 2007; May et al., 2011). Based on this age range, the Etchegoin Formation is assigned to Time Bin 3

(4.9 to 10.0 Ma) (Figure 3).

Figure 6. Localities of seabird-bearing rock formations of California included in Time Bin 3 (4.9 to 10.0 Ma).

One fossil seabird element from Etchegoin Formation outcrops is included in this study from one locality: UCMP V71130.

Mulholland Formation. A combination of estuarine, lacustrine, and fluvial depositional environments, as evidenced by the presence of marine and nonmarine ostracods, are found within the Mulholland Formation of Contra Costa County (Figure 6)

(Liniecki-Laporte and Andersen, 1988). These shallow depositional environments warrant consideration with the other littoral rock formations. A member of the Contra

Costa Group (Andersen et al., 1995), the Mulholland Formation was deposited between

6.5 Ma and 7.7 Ma based on Hemphillian-aged vertebrate fossils (Liniecki-Laporte and

Andersen, 1988; Tedford et al., 2004). This range of calculated ages falls within the limits set for inclusion in Time Bin 3 (4.9 to 10.0 Ma) (Figure 3).

Three fossil bird elements from the Mulholland Formation are included in this study. Localities of bird-bearing Mulholland Formation outcrops include: UCMP V3303 and UCMP V4717.

Purisima Formation. The Purisima Formation is found along the California coast from Marin County to Santa Cruz County (Figure 6) (Powell et al., 2007). The fossil seabird-bearing localities of the Purisima Formation are contained within the Santa Cruz structural block (within Santa Cruz County), which is bound by the San Andreas and San

Gregorio Faults (Powell et al., 2007). This tectonic block initially records the end of a transgressive period during the early late Miocene, with sediment deposited on the outer shelf and upper slope, giving way to a regressive trend when most of the block was deposited in middle and inner shelf environments (Powell et al., 2007). The Purisima

Formation was deposited in sublittoral environments, ranging from the continental shelf

23 break to the shoreface (Norris, 1986). Deposition of the Purisima Formation of the Santa

Cruz block has been dated from 2.47 to 6.9 ± 0.5 Ma based on K/Ar dating, diatoms, and paleomagnetic sampling (Madrid et al., 1986; Powell et al., 2007). Based on this age range, the Purisima Formation is assigned to Time Bin 3 (4.9 to 10.0 Ma) alongside the

Capistrano Formation of Orange County (Figure 3).

Included in this study are 45 fossil seabird elements from the Purisima Formation.

Localities of seabird-bearing Purisima Formation outcrops include: UCMP V6875,

UCMP V7078, UCMP V83013, UCMP V92056, and UCMP V92060.

San Mateo Formation. The San Mateo Formation is a marine sedimentary formation with sandstone and gravel units that contain numerous fossil bird elements.

The formation is found within northwest San Diego County (Figure 6) and was deposited in a shallow, sublittoral environment (Berta and Morgan, 1985; Deméré and Berta, 2005).

The age of the San Mateo Formation has been determined to be ~5.0 to 10.0 Ma based on marine vertebrates and terrestrial mammals (late Clarendonian to late Hemphillian

NALMA) that make up two distinct faunal assemblages within the formation (Barnes et al., 1981; Howard, 1982; Domning and Deméré, 1984; Tedford et al., 2004; Smith,

2011). Workers have proposed the San Mateo Fm. near Oceanside (where all the fossil bird localities are located) is likely equivalent (temporally and lithologically) to the

Capistrano Formation (Domning and Deméré, 1984; Deméré and Berta, 2005), and thus warrants incorporation in Time Bin 3 (4.9 to 10.0 Ma) (Figure 3).

Included in this study are 55 fossil seabird elements from the San Mateo

Formation. Localities of seabird-bearing San Mateo Formation outcrops include: SDSNH

2957 (=UCMP V68144), SDSNH 3003, SDSNH 3134 (=UCMP V68147), SDSNH 3177,

UCMP V6880, UCMP V68106, and UCMP V68145.

Sisquoc Formation. The Sisquoc Formation of Santa Barbara County is the product of rapid sedimentation and basin filling following the siliceous deposition of the

Monterey Formation-equivalent at upper to middle bathyal depths (Figure 6) (Compton,

1991; Tennyson and Isaacs, 2001). Seabird-bearing outcrops of the Sisquoc Formation from Lompoc Quarry (UCMP V2502) are dated within the Thalassiosira hyalinopsis

Diatom Assemblage Zone (5.35 to 5.6 Ma) (Dumont and Barron, 1995; Barron, 1998).

This range of calculated ages for the Sisquoc Formation falls within the limits set for inclusion in Time Bin 3 (4.9 to 10.0 Ma) (Figure 3). Nine fossil seabird elements from the Sisquoc Formation locality UCMP V2502 are included in this study.

Wilson Grove Formation (re-assigned from Merced Fm.). Merced Formation rocks within the Sebastapol Block of Sonoma County (Figure 6) are later referred to the

Wilson Grove Formation based on lithology (Fox, 1983; Powell et al., 2004). The Wilson

Grove Formation was deposited under beach and shallow marine conditions, indicating a marine embayment and littoral depositional environment (Travis, 1952; Blake et al.,

2002). Within the vicinity of the seabird-bearing fossil localities (Bloomfield Quarry), an andesite underlying the Wilson Grove Formation and a tuff exposed near the top of the formation have been K/Ar dated to 7.83 ± 0.29Ma and 6.26 ± 0.1Ma, respectively (Fox et al., 1985; Sarna-Wojcicki, 1992; Powell et al., 2004). Using the maximal age range from these estimates (6.16 to 8.12 Ma), the Wilson Grove Formation merits inclusion into

Time Bin 3 (4.9 to 10.0 Ma) (Figure 3).

One seabird locality (UCMP V81134), bearing three seabird specimens from the

Wilson Grove Formation was included in this study.

CHAPTER 3

FOSSIL SEABIRDS FROM THE MIDDLE MIOCENE TO EARLY PLIOCENE OF CALIFORNIA

Seabirds are defined as birds that are adapted to life in the marine environments of the world, such as coastal areas, estuaries, and oceanic islands. These birds possess relatively long lifespans, travel away from the shoreline to feed across oceans, and use coastal areas or offshore islands for breeding, where they produce small clutches (Furness and Monaghan, 1987; Schreiber and Burger, 2002; Hunt, 2009). Most of modern

California’s seabird species belong to three clades: Procellariiformes, Suliformes, and

Charadriiformes (Jones et al., 1981; California Birds Records Committee, 2015). These clades, as well as the less speciose groups considered seabirds, are presented in Table 1.

Although the seabird fossil record stretches back to the Late Cretaceous of New Jersey

(Tytthostonyx glauconiticus; Olsen and Parris, 1987), modern seabird taxa do not appear until the early to middle Miocene (Warheit, 1992). Fossil seabirds have been known from

Neogene marine formations of California for over 100 years (e.g., Lucas, 1901), but are poorly studied. Most previous work was descriptive (e.g., Howard, 1957, 1971) or focused on the phylogenetic relationships of certain clades (Smith and Clarke, 2014a).

The few synthetic, multi-taxon, works are based on data from the literature (Warheit,

1992). In his study, Warheit (1992) gathered presence and absence data of seabird species across the Tertiary of the North Pacific to describe patterns of richness change over time,

27 coincident with several major tectonic and oceanographic events. My study utilizes a specimen-based approach to understand the relative abundance, diversity, and temporal distribution of fossil seabirds in order to determine how seabird communities have changed through the Neogene marine formations of California.

Table 1. Taxa listed as seabirds. Modified from BirdLife International (2010).

Order Family Common Name Anseriformes Merginae Seaducks Alcidae Auks Laridae Gulls Charadriiformes Stercorariidae Skuas Sternidae Terns Gaviiformes Gaviidae Divers Phaethoniformes Phaethontidae Tropicbirds Podicipediformes Podicipedidae Grebes Diomedeidae Albatrosses Hydrobatidae Storm petrels Procellariiformes Pelecanoididae Diving petrels Fulmars, prions, shearwaters, Procellariidae gadfly and other petrels Sphenisciformes Spheniscidae Penguins Fregatidae Frigatebirds Suliformes Phalacrocoracidae Cormorants Sulidae Gannets and boobies

This chapter examines the seabird fossils housed in museum collections across

California, collected from the aforementioned middle Miocene to early Pliocene marine strata, and places them into the chronostratigraphic bins based on the ages of Orange

County rock formations (Chapter 2). Proper identification of these fossil collections is integral to understanding the composition of the past avian community and its relation to the changing tectonic environment and climate of the Neogene, recognized via feeding ecology of modern analogues.

Nomenclature

Two means for organizing taxa are used by different workers: the ranked hierarchy of the Linnaean taxonomic system (International Code of Zoological

Nomenclature; ICZN, 2000) and the phylogeny-based International Code of Phylogenetic

Nomenclature (PhyloCode; Cantino and de Queiroz, 2010). In this study, the Linnaean nomenclature of “Orders” and “Families” is used for ease of discussion and to organize tables (e.g., Table 1 and Appendix 1). However, the PhyloCode definitions of taxa are employed to compare the specimens within each chronostratigraphic bin and evaluate diversity and relative abundance across time. Most notably in this study, “Pan-Alcidae” is a phylogenetically-based clade which encompasses Alcidae and its sister taxon

Mancallinae that I will consider of the same rank as Linnaean families, such as Sulidae and Procellariidae, for the purposes of analyzing diversity and relative abundance.

Collections

Orange County Paleontology Collection

Previously collected specimens representing the middle Miocene to early Pliocene marine strata of California (Chapter 2), housed at museums across California form the dataset for this research. The foundation of this study is the Orange County Paleontology

Collection (OCPC) housed at the John D. Cooper Archaeological and Paleontological

Center (Cooper Center) in Santa Ana, CA. Representing middle Miocene to early

Pliocene strata from Orange County (Chapter 2), the Cooper Center contains 305 catalogued bird fossils collected through paleontological mitigation efforts over the past three decades of construction and development in Orange County

Paleontological mitigation began with the passage of the National Environmental

Policy Act (1969) and the California Environmental Quality Act (1970), which allowed for the care and protection of numerous non-renewable environmental resources, including paleontological resources i.e., fossils (Scott and Springer, 2003). Orange

County was one of the first counties in the United States to protect paleontological resources during the increased development of the region in the 1970s and 1980s

(Babilonia et al., 2013). Following additional legislation, which required Orange County fossils be donated to the County (Babilonia et al., 2013), the John D. Cooper

Archaeological and Paleontological Center was established in 2009 as a collaboration between the County of Orange and Cal State Fullerton to house and curate the millions of fossils recovered over the decades of mitigation efforts from construction projects in

Orange County.

Museum Collections Across California

Of the Cooper Center seabird collection, 149 specimens were identified by anatomical element to the family level or finer. The data from the 149 identified Cooper

Center specimens were supplemented by data from 378 specimens housed in museums across California (Natural History Museum of Los Angeles County, LACM; San Diego

Natural History Museum, SDNHM; University of California Museum of Paleontology,

UCMP) to understand changes to the avian community across the breadth of California’s coast through the late Miocene (Table 2; Appendix A). This dataset represents 16 middle

Miocene to lower Pliocene marine formations from Northern California to Baja

California (Figure 3). For this study, the Monterey Formation-equivalents of Santa

Barbara, Los Angeles, and Orange Counties were counted separately based on spatial and

30 lithologic differences. The combined dataset was separated into three chronostratigraphic bins based on age ranges of the Orange County strata: Bin 1 (14.7 to 17.0 Ma), Bin 2

(10.0 to 14.7 Ma), and Bin 3 (4.9 to 10.0 Ma).

Table 2. Counts of identified fossil bird specimens from middle Miocene to early Pliocene strata across California, organized by repository.

Time Bin Time Bin Time Bin Total Institution 1 (14.7 – 2 (10.0 – 3 (4.9 – Number 17.0 Ma) 14.7 Ma) 10.0 Ma) Cooper Center 5 36 108 149 LACM 145 56 3 204 SDSNH 18 0 47 65 UCMP 16 17 76 109 Total 184 109 234 527

Identification

Identification of the seabird fossil material was necessary to understand the composition of California’s seabird community through time. Descriptions from the published literature yield anatomical identification of the elements within the avian body plan (e.g., Gilbert, 1985; Baumel and Witmer, 1993). Of the 305 middle Miocene to early

Pliocene seabird specimens housed at the Cooper Center, 268 were identified to anatomical element.

Once identified to anatomical element, identifications were made to the lowest taxonomic level possible, usually to the family-level clade. The study of hundreds of extant skeletons and previously identified fossil material from nearby institutions

(Natural History Museum of Los Angeles County, Ralph B. Clark Regional Park, San

Bernardino County Museum, San Diego Natural History Museum, Santa Barbara

Museum of Natural History, and the University of California Museum of Paleontology)

31 resulted in the development of a photographic database which proved invaluable in identifying specimens to taxa (Appendices B and C). Out of the 268 anatomically identified OCPC specimens, 149 of these could be identified to the family level or finer.

The majority of the avian specimens identified to anatomical element were humeri and ulnae (Table 3).

Example Identification. Humeri are the most abundant, identified element of the seabird dataset (Table 3). The humerus is the first bone of the wing (forelimb) and is vital to avian flight mechanics (Figure 7). It articulates proximally with the coracoid and scapula at the shoulder joint and distally, moving towards the wingtips, with the ulna and radius. Differences in humeri among the most abundant fossil taxa allow for identification beyond Aves.

Because the fossil record includes incomplete and fragmentary specimens, I examined the articular (most diagnostic) surfaces. The proximal end (humeral head) of sulid humeri tapers gradually from the humeral shaft, the deltoid crest is low, and the capital groove points dorso-medially. The capital groove in procellariid humeri also points dorso-medially but the deltoid crest is pronounced and the caudal surface

(containing the pneumatic fossa) projects sharply, caudally from the humeral shaft. Pan- alcid humeral heads have a rounded appearance with the capital groove pointing caudally. The capital groove is divided by a narrow wall from the ligamental furrow on the palmar side of the humerus.

Table 3. Counts of identified fossil bird specimens organized by anatomical element. Specimens containing multiple appendicular elements from a particular region of the body, e.g., all wing bones, were included under “forelimb” or “hindlimb.” Specimens consisting of skeletons or containing multiple elements from various regions of the body were included under “multiple elements.” Refer to Appendix C for provenance of specimens.

Time Bin Time Bin Time Bin Total Elements 1 (14.7 – 2 (10.0 – 3 (4.9 – Number 17.0 Ma) 14.7 Ma) 10.0 Ma) Axial Skull 3 2 7 12 Vertebrae 1 1 5 7 Pectoral Girdle Scapula 3 1 5 9 Coracoid 14 19 32 65 Furcula 0 1 1 2 Synsacrum 1 3 3 7 Sternum 2 1 0 3 Appendicular Forelimb (wing) 6 0 0 6 Humerus 65 19 67 151 Ulna 31 24 45 100 Radius 5 0 0 5 Carpometacarpus 12 6 3 21 Hindlimb (leg) 0 1 3 4 Femur 9 5 7 21 Tibiotarsus 14 2 14 30 Tarsometatarsus 14 23 28 65 Phalanges 1 0 0 1 Multiple elements 3 1 14 18 Total 184 109 234 527

Some of the humeral specimens observed for this study consist only of the distal end. The distal end of procellariid humeri contain a noticeable ectepicondylar process that projects cranially from the humeral shaft and the olecranon fossa is wide and gently curved. In sulids, the olecranon fossa is wide but its sides are steeply sloped when viewed from the articular surface. The distal ends of pan-alcid humeri are narrow and compact

33 medio-laterally. The olecranon fossa is shallow and offset caudally from the midline of the humeral shaft.

Figure 7. Posterior views of extant seabird humeri used for comparison with fossil specimens. Proximal ends of humeri to the left. A: Left alcid humerus from SDSNH 48840 (Cerorhinca monocerata); B: Right procellariid humerus from SDSNH 51860 (Puffinus bulleri); C: Right sulid humerus from SDSNH 51044 (Sula dactylatra). cg: capital grove; dc: deltoid crest; ep: ectepicondylar process; of: olecranon fossa; pf: pneumatic fossa. Scale bars are 2 cm.

Specimen Counts for Analysis. Individual, identifiable avian elements were each counted once for calculating diversity and relative abundance through time. Previously curated specimens containing multiple elements were also counted once, as it was presumed this was done based on association during collection and thus, represented a

34 single bird individual. Had these specimens been separated into individual catalogue numbers and counted multiple times during analysis, unnecessary inflation would have resulted (Scott et al., 2003).

Seabird Clades Examined in this Study

Similar to the modern California seabird community, the middle Miocene to early

Pliocene fossil record was dominated by Charadriiformes, Procellariiformes, and

Suliformes. Four taxa within these clades encompass the majority of the California fossil seabird community: Pan-Alcidae, Mancallinae, Procellariidae, and Sulidae. Because of their frequency within the dataset, the feeding ecology of these taxa will be examined as foraging method should correlate with depositional environment and habitat. The remaining avian taxa identified include members of: ospreys (pandionids), ducks

(anatids), storks (ciconiids), falcons (falconids), loons (gaviids), cranes (gruids), bony- toothed birds (pelagornithids), herons (ardeids), flamingoes (palaelodids), and grebes

(podicipedids).

Pan-Alcidae (Charadriiformes)

Strictly found in the Northern Hemisphere, auks, murres, and puffins are some of the most recognizable, extant species within the Pan-Alcidae (Sibley, 2000). Pan-alcids are wing-propelled, pursuit divers that forage for fish and zooplankton within range of the continental shelf (Vermeer et al., 1987; Shealer, 2002).

Mancallinae

The sister taxa to alcids within Pan-Alcidae (Smith, 2011), Mancallinae are described as wing-propelled diving birds based on similar forelimb morphology to penguins and the Great Auk, indicating adaptation to movement underwater at the

35 expense of flight (Lucas, 1901). Also based on similar morphology, it is presumed that this extinct group of seabirds actively hunted fish at depth (Smith, 2011). Mancallinae are restricted to the northern Pacific Ocean basin (Smith, 2011).

Procellariidae (Procellariiformes)

The most numerous and diverse of the tubenoses (Procellariiformes), the

Procellariidae includes seabirds such as fulmars, shearwaters, and petrels (Sibley, 2000;

Brooke, 2002). Known for venturing far distances from the coastline to forage and for transequatorial migrations, procellarids typically feed at the water’s surface or by shallow dives (Prince and Morgan, 1987; Shealer, 2002).

Sulidae (Suliformes)

Gannets and boobies are the two groups within the Sulidae (Sibley, 2000) and they have a temperate to tropical distribution across the world’s oceans (Brooke, 2002).

The Sulidae are known for flying offshore and plunge-diving to capture prey (plunge into the water from flight) (Shealer, 2002).

Other Families Present

Several other bird families are present within this study but make up a small proportion of the overall avian community when compared to the aforementioned families. Analogs of extant seabirds, such as loons (Gaviidae), grebes (Podicipedidae), herons (Ardeidae), gulls and waders (Laridae and Scolopacidae), albatrosses and storm petrels (Diomedeidae and Hydrobatidae), and cormorants (Phalacrocoracidae), as well as extinct bony-toothed birds (Pelagornithidae), were identified in this study. Other non- seabird specimens that were identified from these marine strata include: ospreys

(Pandionidae), ducks (Anatidae), storks (Ciconiidae), falcons (Falconidae), cranes

(Gruidae), and flamingoes (Palaelodidae).

Seabirds Through Time

Time Bin 1 (14.7 to 17.0 Ma)

Fresno, Kern, and Orange Counties, as well as the Mexican state of Baja

California, contain 29 localities with 184 fossil seabird specimens in rock formations spanning the time period from 14.7 to 17.0 Ma (Chapter 2; Figure 8). Nearly half of the specimens observed from middle Miocene-aged collections were identified as Sulidae

(48.91%), with procellariid specimens next at 30.43% of the total identified. Pan-alcids comprise a small proportion of this avian community (2.17%) with no mancallines identified. Examples of Anatidae, Ciconiidae, Diomedeidae, Palaelodidae, and

Pandionidae are also identified from this time period (Appendix A).

Figure 8. Relative abundance pie chart of fossil seabird specimens collected from strata within Time Bin 1. Charadriiformes shown does not include Pan-Alcidae, Procellariiformes shown does not include Procellariidae, and Suliformes shown does not include Sulidae. “Other” includes: Accipitriformes, Anseriformes, Ciconiiformes, and Phoenicopteriformes. Refer to Appendix C for provenance of specimens.

Time Bin 2 (10.0 to 14.7 Ma)

Included in this study, 15 fossil localities from Santa Cruz, Santa Barbara and

Orange Counties contain 109 seabird elements in sediments ranging in age from 10.0 to

14.7 Ma (Chapter 2; Figure 9). Sulid specimens comprise most of the late Miocene collections (35.78%). Procellariid and pan-alcids each represent approximately a quarter of the community (27.52% and 26.60%, respectively). Mancallinae make their first appearance in the late Miocene. Specimens of Gaviidae from the Monterey-equivalent of

Orange County extend the known range of this taxon into the middle Miocene from the previously known late Miocene portion of the San Mateo Fm. (Howard, 1982). Examples of Anatidae, Gaviidae, and Pelagornithidae are also identified from this time period

(Appendix A).

Figure 9. Relative abundance pie chart of fossil seabird elements collected strata within Time Bin 2. Charadriiformes shown does not include Pan-Alcidae, Procellariiformes shown does not include Procellariidae, and Suliformes shown does not include Sulidae. “Other” includes: Anseriformes, Gaviiformes, and Odontopterygiformes. Refer to Appendix C for provenance of specimens.

Time Bin 3 (4.9 to 10.0 Ma)

Strata dated from 4.9 to 10.0 Ma provide 30 fossil seabird-bearing localities from

Contra Costa, Los Angeles, Monterey, Orange, San Diego, Santa Barbara, Santa Cruz, and Sonoma Counties and contain 234 specimens (Chapter 2; Figure 10). During the transition from Miocene to Pliocene, pan-alcids comprise the majority of the specimens observed (70.09%) with over half of this total identified as Mancallinae (37.61% of total).

Sulids and procellarids each consist of 8.97% of the avian community. Identified representatives of Laridae from the Purisima Fm. extend the known temporal range of this taxon (San Diego Formation of the late Pliocene; Chandler, 1990). A heron (Ardea sp.) from the Mulholland Fm. also extends the known range of this taxon into the late

Miocene from the Pleistocene sediments of San Miguel Island (Guthrie, 1992). Examples of Anatidae, Ardeidae, Falconidae, Gaviidae, Gruidae, Hydrobatidae, Laridae,

Pelagornithidae, Phalacrocoracidae, Podicipedidae, and Scolopacidae, were also identified from this time period (Appendix A).

Figure 10. Relative abundance pie chart of fossil seabird specimens collected from strata within Time Bin 3. Charadriiformes shown does not include Pan-Alcidae, Procellariiformes shown does not include Procellariidae, and Suliformes shown does not include Sulidae. “Other” includes: Anseriformes, Falconiformes Gaviiformes, Gruiformes, Odontopterygiformes, Pelecaniformes, and Podicipediformes. Refer to Appendix C for provenance of specimens.

CHAPTER 4

STATISTICAL ANALYSIS OF CALIFORNIA’S FOSSIL SEABIRD COMMUNITY

A total of 527 bird specimens were collected from 16 stratigraphic formations, identified to the family level or finer within four California museum repositories (Chapter

3), and organized by age of deposition to one of three chronostratigraphic time bins based on the ages of Orange County strata (Chapter 2). This chapter utilizes these previously identified seabird fossils to analyze the avian community response to the changing tectonics and climate of the late Neogene of California.

Diversity, taxonomic richness, and relative abundance were examined using univariate quantitative methods to understand the change in seabird populations over time and depth of deposition. Changes in diversity were measured using the Shannon Index and Simpson Diversity Index. Margalef’s and Menhinick’s richness indices provided methods to asses taxonomic richness within the time bins, once the differing sample sizes were normalized using rarefaction. Rank abundance curves and pie charts were used to understand relative abundance within the stratigraphic formations and chronostratigraphic bins. Multivariate quantitative methods, such as non-metric multidimensional scaling, were employed to understand the underlying patterns of similarity within this dataset.

Analyses

Diversity

The number of taxa in a given area (richness) is the simplest measure of biodiversity within a community (Hammer and Harper, 2006). Though a useful and easily understandable index, richness is strongly dependent on the sample size being used, as well as the evenness of the taxa present (distribution of relative abundances) (Jost, 2010).

The Shannon Index, also known as Shannon entropy, the Shannon-Wiener Index, and the

Shannon and Weaver Index (Shannon, 1948; Spellerberg and Fedor, 2003), utilizes both taxonomic richness and proportion of specimens in a sample to estimate diversity (Chao et al., 2013). The Shannon Index is calculated as:

푆

퐻′ = − ∑(푝푖) ln(푝푖) 푖

where S is the richness, pi is the relative abundance of taxon i, and ln is the logarithm to the base of e. Measured from zero to a maximum value of Hmax = ln S (Hammer and

Harper, 2006), a high value denotes high diversity and high evenness (Olszewski, 2004,

2010). The Shannon Index value for each chronostratigraphic bin (Chapter 2) was calculated using the identified seabird specimens contained therein. Once calculated, these Shannon Index values were compared to each other to understand changes in diversity at the family level over time.

Simpson’s Diversity Index (the complement to Simpson’s Index of Dominance, also known as Hurlbert’s probability of interspecific encounter) uses the richness and proportions of taxa present in a sample to examine the likelihood that two randomly 41

42 selected specimens are of the same taxa (Simpson, 1949; Hurlbert, 1971; Hammer and

Harper, 2006). This index factors in the relative frequency, as well as the number of taxa included in a sample. Simpson’s Diversity Index (1 - D) is calculated as:

2 1 − 퐷 = 1 − ∑(푝푖 )

Simpson’s Diversity Index values range from 0 to 1. A higher score on this index indicates greater likelihood that two specimens pulled from the same sample are dissimilar and thus, the sample is more evenly distributed amongst its constituent taxa.

The Simpson’s Diversity Index was calculated for each time bin and compared with one another to assess changes in evenness of the seabird community over time.

Both the Shannon and Simpson Diversity Indices have been utilized in this study because they emphasize different aspects of community diversity. By using the square of the relative abundance in a sample (pi), Simpson’s Diversity Index places emphasis on abundant taxa and evenness; the Shannon Index utilizes the logarithm of the relative abundance giving more weight to rarer taxa and richness (Nagendra, 2002). By examining both of these indices, a well-rounded view of the relative abundance, richness, and diversity of the seabird community through the late Neogene is described.

Richness

To assess taxonomic richness between samples (chronostratigraphic bins in this study) of varying size, the rarefaction method was employed. Sample size is a factor when evaluating richness, i.e., larger samples are more likely to recover less common taxa; rarefaction was used to calculate the expected number of taxa for a given subsample

size within a group (Hammer and Harper, 2006). This process normalized the differing 42

43 sample sizes from the time bins and allowed for richness comparisons using Margalef’s

(1958) and Menhinick’s (1964) richness indices. By rarefying the sample sizes to compare taxonomic richness, potential differences observed in the Shannon and Simpson diversity indices could be evaluated based on richness and evenness. Rarefaction,

Margalef’s and Menhinick’s richness indices are calculated as follows:

푁 − 푁 푠 ( 푖) Rarefaction: 퐸(푆 ) = ∑ [1 − 푛 ] 푛 푁 ( ) 푖=1 푛

(푆 − 1) Margalef richness index = ln 푁

푆 Menhinick richness index = √푁

where E(Sn) is the expected number of a taxa for sample of size n, S is the number of taxa present, N is the total number of specimens in the sample, and Ni is the number of individuals within taxon i.

Abundance

Rank abundance curves and pie charts (Figures 11 – 13; Chapter 3) were used to assess the relative abundance of fossil seabird lineages within the chronostratigraphic bins. Also known as Whittaker plots, rank abundance curves display the relative abundance of taxa present in order of decreasing proportion within each rock formation.

When plotted, these curves show the universally accepted “hollow curve law” of ecological communities, wherein a few taxa are very common and many more are rare

and less abundant (McGill et al., 2007). Despite this ubiquitous total shape, differences in 43

44 the angle of the curve can provide information regarding the relative proportions from rank to rank: steep curves indicate a taxon that is drastically more abundant than the succeeding ones; a shallow or flat curve shows taxa that are present in relatively even proportions.

Multivariate Techniques

Multivariate techniques are commonly used in ecological studies where datasets contain more than two variates, e.g., multiple taxa within a locality (Hammer and Harper,

2006). Non-metric multidimensional scaling (NMDS) and hierarchical clustering are multivariate techniques for visualizing trends in a dataset by utilizing a distance measure, also known as a similarity index, to test similarity between groups (Kruskal, 1964;

Hammer and Harper, 2006). Data points of similar composition, i.e., taxonomic richness and relative abundance within stratigraphic formations in this study, will plot closer together than samples differing in their constituents. Before applying a distance measure, the dataset was log-transformed (log (1+y)) in an effort to downweight the contribution of the most abundant taxa and increase the contribution of rarer taxa (Clarke and

Warwick, 2001; Hammer and Harper, 2006). In this study, the Bray-Curtis distance measure was implemented as it was originally introduced for ecological studies, which utilized abundance data (Bray and Curtis, 1957; Hammer and Harper, 2006). The assessment program Paleontological Statistics version 3.06 (PAST; Hammer et al., 2001) was used to perform statistical analyses of diversity, richness, evenness, and NMDS on the fossil seabird dataset.

Results

Fossil seabird diversity within each of the chronostratigraphic bins was evaluated using Shannon Index, Simpson’s Diversity Index, and the rarefaction method. The raw number of lineages represented within the time bins decreases from eight in Time Bin 1

(14.7-17.0 Ma) to seven in Time Bin 2 (10.0-14.7 Ma) and then doubles in Time Bin 3

(4.9-10.0 Ma) with 14 families present.

Diversity

Taxonomic richness and relative abundance are used to calculate changes in diversity of the seabird community using the Shannon and Simpson diversity indices. The

Shannon Index was measured as 1.306 for Time Bin 1, rose to 1.434 for Time Bin 2, and dropped in Time Bin 3 to 1.197 (Table 4; Figure 11). Increasing Shannon Index values indicate higher diversity and decreasing values denote less diversity.

Table 4. Richness and evenness metrics of fossil bird specimens from middle Miocene to early Pliocene strata across California, organized by chronostratigraphic time bin. Margalef’s and Menhinick’s richness indices were calculated based on subsamples of 109 specimens, following rarefaction of the chronostratigraphic bins.

Time Bin 1 Time Bin 2 Time Bin 3 (14.7 – 17.0 Ma) (10.0 – 14.7 Ma) (4.9 – 10.0 Ma) Observed Lineages 8 7 14 Number of Specimens 184 109 234 Shannon Index 1.306 1.434 1.197 Simpson’s Diversity 0.654 0.722 0.491 Rarefied # of taxa 6.994 7.000 10.665 (n = 109) ± 0.798 ± 1.349 Margalef’s richness index 1.149 1.279 1.772 Menhinick’s richness index 0.516 0.671 0.697

Simpson’s Diversity Index is a statistical metric used to determine the evenness

within a given sample when selecting two specimens. Time Bin 1 produces a Simpson’s 45

Diversity Index of 0.654, 0.722 for Time Bin 2, and 0.491 for Time Bin 3 (Table 4;

Figure 11). Evenness decreases as a sample is dominated by a smaller number of taxa and the Simpson’s Diversity Index decreases.

Both diversity metrics show an increasing trend of diversity as time progresses from bin 1 to bin 2 and a decreasing trend transitioning to bin 3. Because both of the indices (Shannon and Simpson’s Diversity Index) use taxonomic richness and the relative abundance of taxa present in a sample to calculate diversity, those factors (richness and relative abundance) are examined to explain the observed changes in diversity.

1.6

1.4

1.2

0.8 Shannon Index

Index 0.6 Simpson's Diversity

0.4

0.2

0 17.0 - 14.7 Ma 14.7 - 10.0 Ma 10.0 - 4.9 Ma Chronostratigraphic Bins

Figure 11. Shannon Index and Simpson’s Diversity Index of middle Miocene to early Pliocene seabirds.

Richness

The rarefaction method is utilized as a means for comparing taxonomic richness across time bins composed of dissimilar samples sizes. Using the smallest sample size of 46

47 the three time bins, the expected number of taxa was calculated if the other time bins were subsampled at a smaller number of specimens. Time Bin 2 yields the smallest number of specimens (n = 109) and contains seven families. Using rarefaction to subsample 109 specimens produces 6.994 ± 0.798 expected families from Time Bin 1 and 10.665 ± 1.349 expected families from Time Bin 3 (Figure 12). Because the number of families identified in Time Bin 1 falls within the confidence interval of Time Bin 2

(subsampled for 109 specimens), we cannot reject the hypothesis that the richness of bin

1 is the same as the richness of bin 2 (Gotelli and Colwell, 2011).

Figure 12. Rarefaction curves for chronostratigraphic bins of seabird fossils from the middle Miocene to the early Pliocene. 95% confidence intervals shaded for each curve. Dotted line indicates subsampling of 109 specimens.

The expected numbers of taxa for each time bin generated from the rarefaction method (when subsampled for 109 specimens) are used to calculate taxonomic richness using the Margalef and Menhinick richness indices (Table 4; Figure 13). Both richness 47

48 indices show an increase from Time Bin 1 to Time Bin 2 (Margalef: 1.149 to 1.279 and

Menhinick: 0.516 to 0.671). Both indices show a continued increase in taxonomic richness between bins 2 and 3, though less pronounced using the Menhinick index

(Margalef: 1.772; Menhinick: 0.697). This pattern of overall increase in number of taxa over time agrees with observations of the raw richness numbers, although the effect of increased sample size (i.e., not normalized via rarefaction) is evident by the noted increase in taxa between bins 2 and 3 of the raw numbers.

2 16

1.8 14 1.6 12 1.4

1.2 10

1 8 Margalef's Index 0.8 Menhinick's 6 0.6 Raw richness 4 Lineages Observed 0.4

0.2 2

0 0 17.0 - 14.7 Ma 14.7 - 10.0 Ma 10.0 - 4.9 Ma Chronostratigraphic Bins

Figure 13. Margalef’s and Menhinick’s richness indices of middle Miocene to early Pliocene seabirds, calculated based on a rarefied subsample of chronostratigraphic bins. Raw richness of observed lineages across time bins displayed against the secondary axis.

Unlike the diversity indices that show a peak in diversity in Time Bin 2 followed by a dip in Time Bin 3, the richness indices (Margalef and Menhinick) indicate the number of lineages present increases into Time Bin 2 and continue to rise slightly into

Time Bin 3. Because diversity is measured by the richness and relative abundance of taxa

49 present, the observed decrease in diversity into the last chronostratigraphic bin must be caused by a change in relative abundance if richness is gradually increasing.

Abundance

Rank abundance curves, or Whittaker plots, are used to show the relative abundance of fossil seabird taxa for each stratigraphic formation within the designated chronostratigraphic bins. In the first time bin (14.7 to 17.0 Ma; Figure 14), three of the four formations show gradual slopes progressing from the first ranked taxon to the fourth or fifth ranked taxon. Gradually sloped curves indicate certain taxa may be dominating the samples (higher proportion) and the subsequently ranked taxa comprise progressively smaller proportions within each stratigraphic formation. The Temblor Formation sample is the exception to this observed pattern by dropping off sharply after the first ranked taxon, indicating that it only has one taxonomic family present that makes up the entire sample.

In Time Bin 2 (10.0 to 14.7 Ma), a marked flattening of the rank abundance curves (Figure 15) relative to Time Bin 1 is described. The Santa Margarita Formation curve shows a similar gradual sloping to what is observed in Time Bin 1. Much like the

Temblor Formation of Time Bin 1, the Monterey Formation-equivalents of Santa Barbara

County contains one taxon and shows a steeply sloped curve. However, the sample from the Monterey-equivalent of Orange County shows a flattened slope, which indicates a relatively even distribution of taxa. Because the Monterey Formation-equivalent from

Orange County contributes the most specimens to the overall sample from Time Bin 2, its flattening influence on the total rank abundance curve is evident.

Rank Abundance, Time Bin 1 1 Rosarito Beach

0.8 Temblor Round Mountain

0.6 Topanga

Total

0.4 Relative Abundance Relative 0.2

0 1 2 3 4 5 6 7 8 Rank

Figure 14. Rank abundance curve of Time Bin 1 organized by stratigraphic formation.

Rank Abundance, Time Bin 2 1 Monterey (OC)

0.8 Monterey (SB)

0.6 Santa Margarita

Total

0.4 Relative Abundance Relative 0.2

0 1 2 3 4 5 6 7 Rank

Figure 15. Rank abundance curve of Time Bin 2 organized by stratigraphic formation. Abbreviations: OC, Orange County; SB, Santa Barbara County.

The rank abundance curves for the Modelo and Mulholland Formations in Time

Bin 3 (4.9-10.0 Ma) show flattened trends, similar to the Monterey Formation-equivalent of Orange County (Time Bin 2), indicating evenly distributed taxa (Figure 16). The remaining plots for the formations in Time Bin 3 show a steeply plotted curve between the first (most abundant) and second ranked taxa, relative to the abundance curves of bins

1 and 2. This steep plot indicates that the most abundant taxa comprises a high proportion of the specimens within each formation and the following ranked taxa are relatively even in their distribution (shown by the low sloped curves after the first rank). The Etchegoin

Formation and Monterey-equivalent (of Los Angeles County) contain one taxon each, explaining the steep curve in their plots.

Rank Abundance, Time Bin 3 1 Capistrano Etchegoin Modelo 0.8 Monterey (LA) Mulholland San Mateo 0.6 Sisquoc Purisima Wilson Grove Total

0.4 Relative Abundance Relative 0.2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Rank

Figure 16. Rank abundance curve of Time Bin 3 organized by stratigraphic formation. Abbreviations: LA, Los Angeles County.

The total rank abundance curves were plotted using the accumulation of 51

specimens within each time bin (Figure 17). This plot allows for a comparison of the

52 relative abundances between the three time bins. Time Bin 1 shows a curve dominated by two taxa (Sulidae, then Procellariidae) and the remaining six taxa present contribute gradually less to the overall community. The curve for Time Bin 2 shows the first three taxa (in order, Sulidae, Procellariidae, and Pan-Alcidae) maintain relatively even proportions within the overall community, with the remaining four taxa less abundant.

Time Bin 3 is dominated by one taxa (Pan-Alcidae) and the second and third-ranked taxa

(Procellariidae and Sulidae) are exactly even in their relative abundance. The subsequent

11 taxa of Time Bin 3 comprise approximately 12 percent of the overall seabird community.

Rank Abundance Over Time 1 Time Bin 3 (4.9 - 10.0 Ma) 0.8 Time Bin 2 (10.0 - 14.7 Ma) 0.6 Time Bin 1 (14.7 - 17.0 Ma)

0.4 Relative Abundance Relative 0.2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Rank

Figure 17. Rank abundance curve of Time Bins 1 through 3.

When assessing diversity of the seabird community of California across the late

Neogene, an increase in diversity is observed from Time Bin 1 (14.7 – 17.0 Ma) to Time

Bin 2 (10.0 – 14.7 Ma) followed by a drop in diversity in Time Bin 3 (4.9 – 10.0 Ma).

The Whittaker plots provide a means for understanding the role relative abundance plays in the observed change in diversity over time. During the first two time bins, much of the seabird community is occupied by two to three taxa and their proportions reach maximum evenness in Bin 2. The seabird community during Time Bin 3 experiences a decrease in evenness as it becomes dominated by Pan-Alcidae (70.09%), coeval with the increase in taxonomic richness, which is reflected in the drop in diversity at this time.

Multivariate Techniques

Non-metric multidimensional scaling is a multivariate technique used to visualize similarities between samples (strata, in this study) (Clarke and Warwick, 2001).

Abundance data of the fossil seabird dataset was log-transformed to reduce the influence of the most common taxa. The transformed abundance data was run through the Bray-

Curtis distance measure to assess similarities and differences between samples before visualizing with NMDS (Figure 18).

Within the NMDS plot, the formations contributing less than five specimens to the dataset plot along the periphery, e.g., Mulholland and Etchegoin Formations. The remaining formations tend to cluster towards the center of the NMDS plot. Because of the importance placed on the specimens contained within these smaller samples, their inclusion makes the patterns within the remaining, centrally-located formations difficult to discern e.g., the rare pelagornithids appear more important to the entire plot because of their relative abundance within the Modelo Formation and the Monterey Formation- equivalent of Santa Barbara County.

Figure 18. NMDS plot of the 16 samples of fossil seabirds from different formations (after log transformation and using the Bray-Curtis distance measure). Specimen counts are included with formations that contain five specimens or less.

Construction of a cluster dendrogram using the formations containing more than five specimens elucidates patterns within these stratigraphic samples (Figure 19). Two clusters become evident: the samples from the Sisquoc, Santa Margarita, Rosarito Beach, and Topanga Formations cluster together with a similarity value over 0.6, and the samples from the San Mateo, Purisima, Capistrano, and Monterey-equivalent of Orange

County, cluster together with a similarity value over 0.5. These clusters have a similarity of ~0.35 when grouped with the Round Mountain Silt sample.

Figure 19. Cluster dendrogram of the nine stratigraphic formations containing more than five fossil seabird specimens (after log transformation and using the Bray-Curtis distance measure). Similarity in composition and abundance within the samples increases upward. Abbreviations: OC, Orange County.

The grouping pattern observed in the cluster analysis can be observed in the revised NMDS containing samples with more than five specimens (Figure 20). By constructing polygons based on the clustering analysis, which used composition and relative abundance of specimens, we can also observe similarities in age a depositional depth of the strata. The lower polygon encompasses the samples depostited at deeper depths (sublittoral to mid-bathyal) and older ages, whereas the upper polygon is defined as those strata deposited at younger ages and/or shallower (littoral to sublittoral) depths.

Figure 20. NMDS plot of the samples from different formations containing more than five fossil seabird specimens (after log transformation and using the Bray-Curtis distance 56 measure). The x-axis shows increasing sulids and procellariids to the left and more pan- alcids to the right. The y-axis increases upward with sample size. Polygons delineate differences in depositional depth and age of strata.

Coordinate 1 (the x-axis) of the NMDS plot shows increasing relative abundance of pan- alcids to the right and increasing proportions of sulids and procellariids to the left. For

Coordinate 2 (the y-axis), sample size increases moving upward in the graph.

By plotting the proportions of taxa for each stratigraphic formation (as pie charts) on a graph of depositional depth versus geologic age (Figure 21), the patterns of relative abundance and diversity change over time become even clearer. Many of the formations that were deposited in shallower, younger sediments also contain a high proportion of pan-alcids, with the notable exceptions being the Mulholland and Temblor Formations which contain less than five specimens each. The formations deposited at older times and/or deeper depths contain a low percentage of pan-alcids and higher proportions of procellariids and sulids. The exception to the pattern of the older, deeper strata is the

Monterey Formation-equivalent of Orange County where a sizeable, though not dominant, alcid presence (25%) is found. This exception will be discussed in Chapter 5.

To understand whether this change in taxa over time and depositional depth is based on an over-abundance of pan-alcids (i.e., drowning out the signal from the other seabirds) or due to a true decline in the remaining seabird populations, a simple percentage calculation was conducted removing the possible influence of Pan-Alcidae

(Figure 22). The procellariid population remains relatively constant within the seabird community through the chronostratigraphic bins (between 30 and 37 percent of the remaining seabirds), indicating the observed decline across progressively younger strata is an artifact of the relative influence of pan-alcid numbers within the entire community.

The sulid population drops from almost 50 percent of seabirds in Time Bin 1 to 30 57

percent in Time Bin 3, indicating the relative absence over time of their numbers may

Figure 21. Stratigraphic formations plotted against depositional depth and time. Composition of samples from each of the 16 stratigraphic formations presented as pie charts. Black bars indicate the temporal range of deposition; gray bars mark the chronostratigraphic bins and delineations of depositional depth. Size of pie charts indicates the number of specimens included in this study from a given formation.

59 actually be a reduction within the community and not just by comparison with the pan- alcid presence.

Figure 22. Relative percentages of Procellariidae, Sulidae, and remaining taxa across chronostratigraphic bins calculated without Pan-Alcidae present.

CHAPTER 5

PHYSICAL DRIVERS OF SEABIRD COMMUNITY EVOLUTION DURING THE LATE NEOGENE

A study of North Pacific Miocene seabird diversity based on a literature compilation (Warheit, 1992) associates the patterns of appearance and disappearance of seabird lineages with contemporaneous movement of continents that resulted in shifting circulation currents and coastal upwelling in the North Pacific. Physical and environmental factors, such as these, can help to drive species diversification, changes in abundance, and extinction (Pyenson et al., 2014). Warheit (1992) found sulids, procellariids, and volant alcids increased in species richness between his seabird faunas I and II (defined by stratigraphic formations across the North Pacific and roughly correlates temporally with my Time Bins 1 and 2) and declined into seabird fauna III

(approximately my Time Bin 3). Through the late Miocene, mancalline alcids experienced an increase in speciation and declined later in the Pliocene to extinction in the Pleistocene (Warheit, 1992; Smith, 2011). Bolstering the association of speciation to climate change, Smith and Clarke (2014a) used fossil-calibrated molecular divergence dating to suggest that the proliferation of Pan-Alcidae (volant and mancalline alcids) occurred during and after the Middle Miocene Climatic Optimum (MMCO).

My study of relative abundance in seabird communities during the late Neogene complements these studies by using a specimen-based approach to quantify diversity

61 change through time. In addition to yielding statistically testable observations, this methodology eliminates the influence of collector and publication bias. Because seabird postcranial material is easily identifiable (Ando and Fordyce, 2014), it is unlikely that found specimens would go uncollected. Using the data from all known fossil specimens in collections to detail patterns of taxonomic change, publication bias is completely eliminated. The ease in identification and greater number of specimens, compared to other marine vertebrates, allows for more abundance data to be collected than for contemporaneous taxa. By understanding the response of seabirds to physical drivers, it may be possible to better understand the avian response to similar drivers during different geologic periods or allow comparison to contemporaneous taxa to assess the impact of late Neogene global changes.

My data show a clear increase of pan-alcid abundance and decline of sulid abundance through the Late Neogene. During this period of abundance change, global climatic and tectonic changes, leading to enhanced nutrient upwelling, were affecting the

California coast. Taxonomic richness of the fossil seabird community increased from

Time Bin 1 to Time Bin 3 (Figure 13). This corresponding with an initial increase in diversity between Time Bin 1 and Time Bin 2 followed by a decrease in diversity in Time

Bin 3 (Figure 11). Because diversity is composed of richness and relative abundance of taxa, the change in proportions of taxa found in Time Bin 3 (Figure 17) must account for this observed change in diversity. Within the seabird community of Time Bin 2, sulids, procellariids, and pan-alcids are present in relatively equal proportions (35.78, 27.52, and

26.60 percent, respectively) but transition to dominance by pan-alcids (70.09%) in Time

Bin 3 with sulids and procellariids each making up 8.97% of the community. By

62 examining the seabird community through time without the influence of pan-alcids

(Figure 22), procellariids are found to maintain a fairly stable proportion of the community (30-37%) whereas sulids drop from nearly half (49.72%) to less than a third

(30.00%) over the observed time period. With the increased abundance of pan-alcids in

Time Bin 3 and the partial overlap in their feeding ranges (Shealer, 2002), the decline in sulid populations may be related to an increased competition for prey resources with pan- alcids.

Potential Taphonomic Bias from Osteosclerosis Within Pan-Alcidae

The observed increase in pan-alcid abundance is likely a product of tectonic and climate changes occurring in the late Neogene, although taphonomic bias may also play a role. Pan-alcids are wing-propelled divers that use their forelimbs to swim through water in pursuit of prey. Anatomical adaptations resulting from the higher energy requirements of swimming through water, such as thickened cortical bone and shortened, compressed forelimbs, provide structural strength and ballast (Habib, 2010; Ando and Fordyce,

2014). Within this study, mancallines exemplify these adaptations compared to alcids, procellariids and sulids, owing to their flightless lifestyle (Figure 23). The expansion of cortical bone into the medullary cavity (osteosclerosis), as well as shortened length of limb bones, may lead to preferential preservation. Cortical wall thickness varies taxonomically and by element within the skeleton and may have an influence on a given element’s survivorship (Dirrigl, 2001; Prassack, 2011). Long bones which feature the presence of air sacs (pneumaticity) typically have thinner cortical walls, making them ideal for volant species but susceptible to post-deposition fracture (Higgins, 1999). Pan-

63 alcids exhibit shortened humeri, ulnae, and carpometacarpi with thickened cortical bone

(Figures 10 and 23; Habib, 2010; Smith and Clarke, 2014b).

Figure 23. Cross-sections of seabird humeri showing cortical thickness. All bones are left humeri with posterior aspect pointing upward. Feeding ecology and locomotion relate to cortical thickness: mancallines are flightless, wing-propelled divers, alcids are volant, wing-propelled divers, procellariids are volant, surface feeders and wing-propelled divers, and sulids are volant, plunge-divers. Scale bar is 1 cm.

Humeri are the most abundant skeletal elements within the dataset, particularly those from pan-alcids within the early Pliocene (Table 5), and the observed dominance attributed to their presence could be the product of preferential preservation rather than reflecting an actual increase in population. Smith and Clarke (2014b) found that among

Charadriiformes, flightless mancallines possessed the thickest humeral cortical walls, followed by volant pan-alcids and lastly volant, non-divers. Some members of

Procellariidae (shearwaters) maintain mechanical similarities with pan-alcids attributed to a similar foraging strategy, wing-propelled diving (Habib and Ruff, 2008; Habib, 2010).

This indicates some procellariids may share similar cortical thickness as alcids (Figure

23). Of the most abundant taxa included in my study, the expected order of humeral preservation which would confirm taphonomic bias based on cortical thickness,

64 beginning with most likely to preserve, is as follows: mancallines, remaining pan-alcids and procellariids, followed by sulids. Time Bin 1 found too few alcid and mancalline specimens to compare against the numbers of procellariid and sulid humeri (Table 5).

Numbers of seabird humeri recovered in Time Bin 2 are generally low though a greater number of alcid humeri is observed relative to procellariid and sulid humeri (Table 5).

Within Time Bin 3, mancalline humeri outnumber, the remaining pan-alcids, procellariids, and sulids, indicating that preservation bias may have an effect during this time (Table 5).

Table 5. Counts of Pan-Alcidae, Procellariidae, and Sulidae humeri (H) and femora (F). Specimens containing multiple appendicular elements from a particular region of the body, e.g., all wing bones, were included. Specimens consisting of skeletons or containing multiple elements from various regions of the body were not included.

Pan-Alcidae Procellariidae Sulidae Total Alcidae Mancallinae H 1 0 28 33 62 Time Bin 1 F 0 0 1 3 4 H 8 1 5 3 17 Time Bin 2 F 0 2 0 3 5 H 15 40 6 4 65 Time Bin 3 F 1 5 0 1 7 Total (H/F) 24/1 41/7 39/1 40/7

I did not recover a sufficient number of femora to compare cortical thickness among the most abundant taxa (Table 5). In addition to studying cortical thickness of humeri within Charadriiformes, Smith and Clarke (2014b) also compared the cortical thickness of femora but found they are not significantly different in thickness between volant and flightless taxa. De Mendoza and Tambussi (2015), employing Smith and

Clarke’s (2014b) methodology on diving ducks representing different modes of

locomotion, found the thickness of femora increased in foot-propelled divers relative to 64

65 wing-propelled specimens and flightless birds over volant specimens. Because there are not enough femora within the dataset, taphonomic bias cannot be ruled out as a factor in the dataset. Future study into the relative thickness of pan-alcid, procellariid, and sulid appendicular elements should provide direct comparisons of the cortical thickness within the bones of these taxa.

Pacific Circulation Patterns and Plate Tectonics

Beyond regional fault movements and deposition of strata, global plate tectonics affected the climate along the west coast of North America during the Miocene. The timing of tectonic-driven climatic changes corresponds to observed changes in the seabird abundances and provides a means for understanding the mechanisms driving this pattern. The closure of the Isthmus of Panama is dated between 13 and 15 Ma based on detrital zircons (Montes et al., 2015). The northward movement of Australia into

Indonesia, which began 25 Ma, obstructed the Indo-Pacific Seaway by ~13 Ma (Kuhnt et al., 2004). These tectonic changes affected circulation patterns in the Pacific Ocean, forcing westward equatorial currents to redirect along the Western Pacific to higher latitudes before returning east (Keller and Barron, 1983; Coates et al., 2005). The shift from circum-equatorial currents to those confined to the Pacific Ocean, coupled with growth and semi-permanence of the East Antarctic Ice Sheet ~13.9 Ma (Verducci et al.,

2007), resulted in the newly formed California Current. The California Current intensified nutrient upwelling and was coincident with the transition from high temperatures of the MMCO (ca. 17 to 14.7 Ma; roughly correlates with Time Bin 1) to the cooling trend of the late Miocene to the earliest Pliocene (Time Bins 2 and 3; Figure

24) (Holbourn et al., 2014). Increased trophic productivity along the coast of western

North America associated with upwelling has been implicated as supporting a diverse range of predators, including seabirds (Lipps and Mitchell, 1976; Jacobs et al., 2004).

Figure 24. Global sea surface temperature (red) and relative abundance of Pan-Alcidae (alcids in dark orange, mancallines in light orange) from the middle Miocene to early Pliocene. Dots are used to indicate the middle of each time bin and orange stripes show the range of time these specimens were collected from. “†” indicates the last occurrence of mancallines. Temperature data from Zachos et al. (2001).

Modern areas of upwelling have been shown to increase nutrients, decrease water clarity, and support large populations of apex predators, such as whales and wing- propelled diving seabirds. By measuring whale, prey, and nutrient abundance in

Monterey Bay, Croll et al. (2005) linked periods of upwelling (cold, nutrient rich waters)

67 to productive trophic webs. Seabirds that hunt from above water, e.g., sulids and procellariids, are adversely affected by the density of phytoplankton and reduced visibility due to these stocks in upwelling zones (Ainley, 1977). In addition to selecting against surface hunters, upwelling zones favor wing-propelled divers because the energy demands associated with underwater locomotion become mitigated as prey abundance increases (Hunt and Schneider, 1987; Ballance and Pitman, 1999).

The Monterey Formation-equivalent of Orange County

In addition to providing a mechanism for the steadily increasing abundance of pan-alcids over time, upwelling can also explain an aberration from the previously noted pattern between pan-alcids and stratigraphic formations (Chapter 4). It is found that pan- alcids are more prevalent in strata deposited at shallow depths and more recent in time, i.e., Time Bin 3. The Monterey Formation-equivalent of Orange County was deposited between 10 and 15 Ma at upper to mid-bathyal depths and 25% of the seabirds contained therein are pan-alcids, causing the rock unit to stand out from the other coeval formations of similar depositional depth (Figure 21). The presence of pan-alcids in this stratigraphic formation is attributed to the cooling temperatures and intensified upwelling of the time period (Pisciotto and Garrison, 1981). A modern analogue to this habitat is the Monterey

Bay Submarine Canyon. Reaching depths up to 1000 m, this canyon fosters seasonal upwelling events sufficiently productive enough to support blue whales (Croll et al.,

2005) and high numbers of pan-alcids (Benson, 2002). Thus, the apparent anomaly of a high proportion of pan-alcids in the Monterey Formation-equivalent of Orange County is reconciled by observations of a modern submarine canyon with the necessary productivity to foster high numbers of pan-alcids.

Response of Contemporaneous Non-avian Taxa

Non-avian marine taxa during the late Miocene show similar responses to climate and tectonic changes, including increased diversification and morphological adaptations.

For example, Marx and Uhen (2010) relate the increased speciation of cetaceans during the late Miocene to increased plankton diversity and productivity. Other marine mammals, i.e., pinnipeds, also diversified greatly during this time (Barnes and Hirota,

1994; Deméré et al., 2003). The increase of plankton associated with upwelling at this time also impacted the evolutionary morphology of salmon. Eiting and Smith (2007) describe changes in the gill raker morphology of late Miocene salmon species (e.g.,

Oncorhynchus rastrosus) that correlate with a transition from fish predation to filter feeding on plankton. Furthermore, similar to the pattern of increased abundance observed in pan-alcids, the abundance of late Miocene salmon populations increases as plankton productivity increases in response to improved nutrient availability (Eiting and Smith,

2007). Thus, the development of upwelling systems in the Eastern Pacific is a physical driver that explains patterns of diversity and distribution in fish, marine mammals, and seabirds. My study of seabirds provides the first rigorous correlation between faunal change and upwelling through quantitative analysis of multiple seabird lineages during the late Neogene.

Changes in Diversity During the Pliocene/Pleistocene

Taxonomic and morphological diversifications of seabird, marine mammal, and fish through the middle Miocene to earliest Pliocene are linked to upwelling resulting from tectonic and climatic correlations (Lipps and Mitchell, 1976; Jacobs et al., 2004; this study). However, variations in Earth’s obliquity during the early Pliocene resulted in

69 fluctuations of the West Antarctic Ice Sheet and eustatic sea level (Figure 25), increased global temperatures, decreased upwelling (Filippelli and Flores, 2009; Naish et al., 2009;

Boessenecker, 2013), and resulted in subsequent declines in diversity and extinctions of vertebrate taxa. Fluctuations in eustatic sea levels associated with polar glaciation are linked to the decline in seabird richness in the early Pliocene and eventual extinction of mancallines in the Pleistocene (Warheit, 1992; Smith, 2011). Early Pliocene

Oncorhynchus (salmon) specimens possessed fewer gill rakers, compared to middle

Miocene salmon, consistent with reduced plankton productivity (Eiting and Smith, 2007).

Figure 25. Global eustatic sea level (blue) and relative abundance of Pan-Alcidae (alcids in dark orange, mancallines in light orange) from the middle Miocene to early Pliocene. Blue stripes indicate the average sea level within a time bin. “†” indicates the last

occurrence of mancallines. Sea level data from Haq et al. (1987).

By the late Pliocene (~3 Ma), Northern Hemisphere and Antarctic glaciation was occurring, global temperatures were cooling, and upwelling resumed (Zachos et al., 2001;

Filippelli and Flores, 2009). These drivers prompted the return of marine productivity and the rebound of seabird species richness, despite the extinction of some taxa (e.g., pelagornithids) (fauna IV of Warheit, 1992; Boessenecker and Smith, 2011). Unlike the early Pliocene, late Pliocene marine mammal assemblages indicate the extensive replacement of extinct taxa with modern genera, due to changes in global temperatures and circulation patterns (Whitmore, 1994; Fordyce et al., 2002; Deméré et al., 2003;

Fitzgerald, 2005). These observed taxonomic and morphologic changes across multiple taxa during the Pliocene, in addition to the observations made from the seabird community during the middle Miocene to early Pliocene, highlight the correlation between physical drivers and taxonomic changes during the Neogene.

To further enhance the understanding of the effects of physical changes on

Miocene marine vertebrates, continued specimen-based research could include datasets of other contemporaneous taxa, such as fish or marine mammals. Specimen-based studies of relative abundance in these taxa would also increase understanding of taxonomic responses to Neogene climate change. Specimen-based studies of seabirds from contemporary upwelling regions, e.g., the west coasts of South America or Africa, could elucidate similar responses to the global changes occurring at this time. Better time- calibrated, quantitative, comparative morphological studies of anatomical change across taxa, e.g., filter feeding in salmon and whales, could show similar responses to environmental stimuli and provide information of underlying mechanisms for these global transitions.

Conclusions

My thesis tested the hypothesis that tectonic movements and climate change caused changes in seabird species richness from the middle Miocene to the early Pliocene

(Warheit, 1992). Using quantitative statistical techniques, my study found changes in diversity during this time were not due to changes in taxonomic richness but the result of increased relative abundance of pan-alcids. The increase of pan-alcids into the early

Pliocene is attributed to the synchronous increase in upwelling because pan-alcid feeding ecology (wing-propelled diving) is favored in upwelling regions (Shealer, 2002).

Upwelling through this time also accounts for morphological changes in salmon and speciation in marine mammals (Eiting and Smith, 2007; Marx and Uhen, 2010).

Although collector and publisher bias are excluded as potential causes for the observed increase in pan-alcid abundance, taphonomic bias related to the increased preservation potential of thickened pan-alcid humeri cannot be eliminated. In the future, the specimen- based methodology used here can be applied to contemporaneous taxa, such as marine mammals, to quantitatively analyze diversity and relative abundance during the late

Neogene and further explore the relationship between the physical drivers and faunal change.

APPENDIX A

FOSSIL SEABIRD SPECIES IN MIDDLE MIOCENE TO EARLY PLIOCENE CALIFORNIA STRATA

Time Bin Time Bin Time Bin 1 (14.7 – 2 (10.0 – 3 (4.9 – 17.0 Ma) 14.7 Ma) 10.0 Ma) Accipitriformes Pandionidae Pandion homalopteron X Anseriformes Anatidae X X X Bucephala sp. X Megalodytes sp. X Megalodytes morejohni X Presbychen abavus X Presbychen abavus? X Charadriiformes Laridae X Pan-Alcidae X X X Aethia rossmoori X Alca sp. X Brachyramphus sp. X Cepphus sp. X X Cepphus olsoni X Cerorhinca sp. X X Cerorhinca dubia X cf. Cerorhinca X Divisulcus demerei X Synthliboramphus sp. X Uria paleohesperis X cf. Uria cf. paleohesperis X Mancallinae X X Mancalla sp. X Mancalla cedrosensis X Mancalla vegrandis X Miomancalla howardi X

Miomancalla wetmorei X X 72

Time Bin Time Bin Time Bin 1 (14.7 – 2 (10.0 – 3 (4.9 – 17.0 Ma) 14.7 Ma) 10.0 Ma) Scolopacidae X Limosa vanrossemi X Ciconiiformes Ciconiidae X Falconiformes Falconidae X Gaviiformes Gaviidae X X Gavia sp. X X Gavia concinna X Gruiformes Gruidae X Odontopterygiformes Pelagornithidae Osteodontornis sp. X X Osteodontornis orri X X Osteodontornis orri? X Pelecaniformes Ardeidae Ardea sp. X Phoenicopteriformes Palaelodidae Megapaloelodus sp. X Podicipediformes Podicipedidae X Podiceps sp. X Procellariiformes Diomedeidae Diomedea sp. X Diomedea californica X Diomedea californica? X Diomedea milleri X Hydrobatidae Oceanodroma hubbsi X Procellariidae X X Fulmarus sp. X Fulmarus miocaenus X Puffinus sp. X X X cf. Puffinus X Puffinus calhouni X Puffinus calhouni? X Puffinus diatomicus X 73

Time Bin Time Bin Time Bin 1 (14.7 – 2 (10.0 – 3 (4.9 – 17.0 Ma) 14.7 Ma) 10.0 Ma) Procellariidae continued Puffinus mitchelli X Puffinus mitchelli? X Puffinus priscus X X Puffinus priscus? X X X Puffinus cf. priscus X Suliformes Phalacrocoracidae X X Phalacrocorax femoralis X Sulidae X X X Microsula sp. X Miosula media X X Miosula? X Morus sp. X X X Morus howardi X Morus humeralis X Morus lompocanus X X Morus magnus X Morus vagabundus X Morus vagabundus? X Paleosula stocktoni X Sula sp. X Sula hutchisoni X Sula willetti X X Sula willetti? X

APPENDIX B

EXTANT BIRD SPECIMENS USED FOR COMPARISON AND IDENTIFICATION

Institution Specimen Family Species Number LACM 87288 Alcidae Cepphus columba 90051-90068 Alcidae Pinguinis impennis 100390 Alcidae Uria aalge 103475 Alcidae Alca torda 103924 Alcidae Fratercula corniculata 111998 Procellariidae Puffinus griseus 112482 Phalacrocoracidae Phalacrocorax pencillatus 114086 Laridae Larus thayeri 115079 Diomedeidae Phoebastria immutabilis 115338 Sulidae Morus capensis 115471 Alcidae Synthliboramphus antiquus Ralph B. Clark Park Accipitridae 2 skeletons- Buteo jamaicensis Accipitridae Accipiter cooperii Anatidae 2 skeletons- "Goose" Anatidae Chen caerulescens Ardeidae Ardea herodias Ardeidae Butorides virescens Cathartidae Cathartes aura Laridae "Gull" Laridae Larus argentatus Pelecanidae 2 skeletons- Pelecanus occidentalis Phalacrocoracidae Phalacrocorax auritus Tytonidae 2 skeletons- Tyto alba SBCM A64-3463 Alcidae Synthliboramphus craveri A64-3593 Laridae Sterna maxima A500-2046 Alcidae Uria aalge A500-979 Procellariidae Fulmarus glacialis Sulidae Sula leucogaster

Institution Specimen Family Species Number SBMNH 1295 Laridae Larus marinus 3418 Podicipedidae Podiceps grisegena 4724 Diomedeidae Phoebastria immutabilis 5079 Gaviidae Gavia immer 9279 Diomedeidae Phoebastria immutabilis B-5104 Podicipedidae Podiceps grisegena B-5861 Stercorariidae Stercorarius pomarinus SDSNH 38347 Podicipedidae Podiceps major 38348 Podicipedidae Podiceps major 43061 Sulidae Morus bassanus 43398 Anhingidae Anhinga anhinga 44651 Pelecanoididae Pelecanoides urinatrix 48840 Alcidae Cerorhinca monocerata 50304 Scolopacidae Numenius phaeopus 50314 Sternidae Sterna caspia 50403 Laridae Larus delawarensis 50801 Alcidae Cepphus columba 51044 Sulidae Sula dactylatra 51098 Rynchopidae Rynchops niger 51229 Charadriidae Pluvialis squatarola 51683 Gaviidae Gavia stellata 51761 Diomedeidae Phoebastria immutabilis 51860 Procellariidae Puffinus bulleri 52435 Alcidae Uria aalge 52885 Hydrobatidae Oceanodroma melania UCMP 66672 Diomedeidae Diomedea sp. 111780 Alcidae Fratercula sp. 117158 Procellariidae Fulmarus sp. 117160 Sternidae Sterna sp. 117338 Gaviidae Gavia sp. 119124 Alcidae Cerorhinca sp. 119125 Alcidae Uria sp. 119140 Cathartidae Coragyps sp. 119150 Pelecanidae Pelecanus sp. 119161 Corvidae Corvus sp. 119223 Phasianidae Meleagris sp. 119225 Phasianidae Gallus sp. 125960 Phoenicopteridae Phoenicopterus sp. 129669 Anatidae Branta sp. 129738 Sternidae Anous sp. 76

Institution Specimen Family Species Number UCMP continued 129743 Phaethontidae Phaethon sp. 129745 Stercorariidae Stercorarius sp. 129747 Cathartidae Cathartes sp. 130418 Phoenicopteridae Phoenicopterus sp. 130421 Sternidae Larosterna sp. 130457 Phalacrocoracidae Phalacrocorax sp. 130626 Laridae Larus sp. 131061 Accipitridae Elanus sp. 131062 Accipitridae Circus sp. 131106 Cuculidae Geococcyx sp. 131111 Accipitridae Buteo sp. 131254 Accipitridae Aquila sp. 131523 Accipitridae Accipiter sp. 131530 Procellariidae Puffinus sp. 131531 Alcidae Cepphus sp. 131539 Falconidae Falco sp. 131545 Anatidae Cygnus sp. 131858 Alcidae Ptychoramphus sp.

APPENDIX C

IDENTIFIED SEABIRD MATERIAL FROM MIDDLE MIOCENE TO EARLY PLIOCENE CALIFORNIA STRATA

Appendix C. Table of identified seabird material from the middle Miocene through the early Pliocene. Ant: anterior; dist: distal; Inst: institution; L: left; LACM: Natural History Museum of Los Angeles County; loc: locality; OCPC: Orange County Paleontological Collections (John D. Cooper Archaeological and Paleontological Center); post: posterior; prox: proximal; R: right; SDSNH: San Diego Natural History Museum; UCMP: University of California Museum of Paleontology; V: vertebrate.

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