Paleobiology,18(4), 1992, pp. 401-424

A review of the fossil seabirds fromthe Tertiaryof the North Pacific: plate tectonics,paleoceanography, and faunal change

Kenneth I. Warheit

Abstract.-Ecologists attempt to explain species diversitywithin Recent seabird communities in termsof Recent oceanographic and ecological phenomena. However, many of the principal ocean- ographic processes that are thoughtto structureRecent seabird systemsare functionsof geological processes operating at many temporal and spatial scales. For example, major oceanic currents,such as the North Pacific Gyre, are functionsof the relative positions of continentsand Antarcticgla- ciation,whereas regional air masses,submarine topography, and coastline shape affectlocal processes such as upwelling. I hypothesize that the long-termdevelopment of these abiotic processes has influencedthe relative diversityand communitycomposition of North Pacific seabirds. To explore this hypothesis,I divided the historyof North Pacific seabirds into seven intervalsof time. Using published descriptions,I summarized the tectonicand oceanographic events that occurred during each of these time intervals,and related changes in species diversityto changes in the physical environment.Over the past 95 years,at least 94 species of fossil seabirds have been described from marine deposits of the North Pacific. Most of these species are from Middle Miocene through Pliocene (16.0-1.6 Ma) sediments of southern California, although species from Eocene to Early Miocene (52.0-22.0 Ma) deposits are fromJapan, British Columbia, Washington,and Oregon. During the historyof the North Pacificseabirds, thee were many widespread (global) and local (California Current)oceanographic events,but the underlyingphysical processes that affectedthe diversityof seabirds throughoutthe North Pacificwere tectonicchanges thatled to sequential stages of thermal isolation and refrigerationof Antarctica.Besides these broad-scale phenomena, the uplift of the Isthmus of Panama and the initiation and intensificationof coastal upwelling in the California Currentdirectly affected the diversityof seabirds in southernCalifornia. For the most part,Middle to Late Miocene and Pliocene seabird faunas fromCalifornia resembled Recent communities,but with several exceptions: (1) the extreme diversityand abundance, but subsequent extinctionof gannets(Morus) and flightlessalcids (mancallids); (2) the comparativelylow abundance and diversity of cormorantsand shags (Phalacrocoracidae) until the Late Pliocene; and (3) the absence of marine Laridae until the Late Pliocene. By affectingboth the physical and biological environments,geo- logical factorssuch as Antarcticglaciation, eustatic changes in sea levels, and local tectonicactivities influenced and will continue to influence the structureof seabird systemsin the North Pacific.

KennethI. Warheit. Departmentof Ornithologyand Mammalogy,California Academy of Sciences,Golden Gate Park,San Francisco,California 94118-4599. Present address: Divisionof Birds,National Museum of NaturalHistory, Smithsonian Institution, Washington D.C. 20560

Accepted: December 23, 1991

Not only mightcommunity-level character- Pianka 1983; Roughgarden 1989). To this pur- isticsbear the stampof eventslong past ... pose, ecologists study organisms and popu- but so also mightthe variousproperties of lations; predation, herbivory, species-level componentspecies .... Yetsuch [past] events interactions,and Recent geographic distri- are surelyno less realfor having taken place butions are frequentlythe kinds of data col- beforethe ecologistarrives to observetheir lected. The implicit assumption here is that consequences; they are only less easily species diversity within Recent ecological studied.... communities can be understood in toto Cody (1989: p. 232) throughdata collected on extantpopulations and environments.To be sure, many ecolo- gistsare now realizing thatthe temporalcom- Introduction ponent of communitiesand ecosystemsmay One goal in the study of ecological com- extend beyond that of funding resources or munities is to identifyhow and why partic- even our own existences(as suggested by the ular species co-occur (see, e.g., Ricklefs1973 epigraph). And the haunting sounds of the C 1992 The Paleontological Society. All rightsreserved. 0094-8373/92/1804-0004/$1.00

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"ghost of competition past" (Connell 1980) communities measured temporally or spa- or the "ghost of extinction past" (Van De- tially may be the result of a combination of vender 1986) are frequentlyheard in studies these differentscale effects.I discuss these of ecological communities.However, despite scale effectsusing the California Currentsea- many exceptions(e.g., see papers in Diamond bird communitiesas an example. and Case 1986), the realization that historyis importantand the suggestion to incorporate Methods paleontological data into studies of Recent SeabirdsDefined. -My definitionof seabirds communitiesand ecosystems(e.g., Fowler and includes only the Procellariiformes (alba- MacMahon 1982; Janzen and Martin 1982), trosses, petrels, shearwaters,diving petrels, have inspired only a handful of ecologists to and storm-petrels),Pelecaniformes (pelicans, use geological data. cormorants and anhingas, sulids, frigate- Although researchon seabird communities birds, and tropicbirds),Alcidae (auks), Lari- has a historyof long-termstudies (e.g., Rich- dae (gulls), and Sphenisciformes(penguins), dale 1957; Belopol'skii 1961;Ainley et al. 1983; the last of which is unknown in the North Coulsen and Thomas 1985; Ainley and Boe- Pacific. I include in this analysis all taxa of kelheide 1990), few studies have attempted fossilseabirds fromthe North Pacificthat are to introduce data from the paleontological describedin the literature.Except for my work record.This is unfortunatebecause geological on the Sulidae (gannets and boobies), I do not factors,such as changes in sea level and tec- include unpublished seabird materialin these tonic events, have directly affectedRecent analyses. In addition to these seabird taxa, seabird systems through their effecton the gaviiforms(loons), podicipediforms(grebes), geography, circulationpatterns, and climate and marine anseriforms(ducks) have been of the oceans. Although these geological pro- described fromthe eastern North Pacific.Be- cesses may contributeto the structureof Re- cause these taxa have freshwateror terrestrial cent seabird communities,they operate on a habits, I did not include them in the follow- time-scalebeyond that of human experience. ing analyses (for listings of these taxa, see Therefore, those aspects of Recent seabird Howard 1983; Becker 1987). communities that are affectedby long-term SeabirdFaunas. -Seabird fossils are usually geological events, either directlyor through found in marinedeposits, and biostratigraph- their effectson short-termecological phe- ic time scales derived frommarine plankton nomena, cannot be explained adequately by (e.g., diatoms,foraminifera, radiolarians) and studying only Recent communities. molluscs are usually used to establish relative The purpose of this paper is to associate ages for the specimens. Typically,the strati- temporal changes in seabird diversityin the graphic informationfor the seabird-bearing North Pacificto changes in global geography, formationsare included by the authorsin their climate, and oceanography. To accomplish fossil descriptions. However, because many this, I provide a list of all species of fossil of these descriptions are fromthe older lit- seabirds from the North Pacific, and group erature, the stratigraphicdata provided by these species into faunas based on their rel- these authors is out-of-date.Therefore, to es- ative temporal occurrences. I also relate the tablish seabird faunas, I used both biostrati- changes in seabird diversitybetween succes- graphic and radiometricdata fromthe recent sive faunas to changes in continentalconfig- literature(see the Appendix for full discus- urations and physical featuresof the oceans. sion of literatureand methods). Using these I describe geological events in termsof their procedures, I described each fossil specimen scale effects.For example, large-scale events in termsof its relative or absolute age. Spec- (e.g., Antarcticglaciation) can affectthe entire imens are considered isochronous if they oc- North Pacific ecosystem,whereas other geo- cur within the same or close to the same strata logical events can be more local in their im- within the same formation,or fromanother pact (e.g., affectingonly the California Cur- formationcorrelated in time to the firstfor- rent system). Differences in seabird mation.

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CD) I recognized seven groups of seabird-bear- I cn < o LU n z ing formationsfrom the North Pacific, each o 0 C!) < produced during a single, but broadly de- Ma wL N < u Ma fined interval of PL > Irv time (fig. 1, Appendix). I o -L IV defined the assemblage of seabird fossils re- covered fromeach group of isochronous for- 5 5- mations as a seabird fauna. I thereforerec- 0 ognized seven seabird faunas fromthe North -J IU Pacific,each associated with one broadly de- z > fined time interval (fig. 1). The temporal se- w 0 quences of these faunas in California were 15 Luis~ 15 initially described in an earlier study (War- -Em heit and Lindberg 1988: fig. 9.2), although -20- -20- thatanalysis was only a general introduction. CZ C In addition, that study did not define each CZ fauna in terms of included formations(see 25- w -~25- the Appendix) and conducted the analyses at < B taxonomic levels higher than genus and spe- (5 E 30 cies. Because I restrictedmy analysis here to '' N C: the Tertiary,I did not include Fauna V (War- Sh~~C1 heit and Lindberg 1988). 0) Fossil Seabird Environments.-Paleoceanog- FIGURE 10Apoiae1 orltosamn ot a raphers reconstructthe oceanographic con- cc 0 ditions of ancient oceans from sedimentary -40- -40-

CZCu remainsof microfossils(typically diatoms, fo- CZ raminifera,and radiolarians).Because the fos- CZ A sil remains of these plants and animals are abundant, and their taxonomies are well es- w 0 8eml o UlatUint D d s e MammaAge 35 w Orl)- Beti 3ormnfra5 oe tablished,they provide refinedindices of time Pen (see, e.g., Woodruffet al. 1981). Sometimes the fossil sequences are so detailed that res- olution can be in the order of tens and hun- dreds of instead of thousands, millions, of PA Was years (see, e.g., Bolli et al. 1985). These fossil taxa are also excellent indicators of environ- FIGURE 1. Approximate correlationsamong North Pa- mental conditions, and provide detailed cific seabird faunas (FAUNAS), North American Land- chronologies of oceanographic and climatic Mammal Ages (AGES), Benthic Foraminiferal Zones (ZONES), Epochs, and absolute time (measured on a time events (see Berger et al. 1989 and references scale of millions of years [Ma]). Dashed lines, Uncertain therein). I used the published data on the boundaries between successive zone or faunas. Diagonal biostratigraphyof deep-sea ocean cores (e.g., line withinFauna I marksage of fauna ifolder formations are not included (see the Appendix). Correlationsbased Barron and Keller 1982; Keller and Barron on Addicott 1977; Armentrout1981; Armentroutet al. 1983, 1987; Barronand Larsen 1988), climatic 1983; Barron 1986a; Berggren et al. 1985; Woodburne affinitiesof diatoms and planktic foraminif- 1987; Swisher and Prothero1990. Epochs: Paleocene (PA), Pleistocene (PL); Zones: Penutian (Pen), Ulatisian (Ulat), era (e.g., Barron and Keller 1983), isotopic Relizian (Rel), Luisian (Luis), Delmontian (Delm), Re- bottom-watertemperatures (e.g., Savin et al. pettian/Venturian(Rep/Ve); Ages: Wasatchian (Was), 1975; Woodruffet al. 1981; K. Miller et al. Uintan (Uint), Chadronian (Chadron), Orellan (Orel), Whitneyan (Whitney), Hemingfordian (Hem), Barstov- 1987; Woodruffand Savin 1989), and eustatic ian (Barstov), Clarendonian (Claren), Hemphillian sea levels (e.g., Haq et al. 1987) as long-term (Hemp), Blancan (Blan), Irvingtonian(Irv). and large-scale oceanographic indices. Be- cause deep-ocean waters are formedat high latitudes, principally in the North Atlantic

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REGION / TAXON FAUNA References A B C I 11 III IV

JAPAN PELECANIFORMES SULIDAE Sula sp. 42 PELAGORNITHIDAE t Pelagomithidae 47 Osteodontornis sp. 43 PLOTOPTERIDAE t Plotoptendae 35, 36 Plotopterumsp. 37

BRITISH COLUMBIA, WASHINGTON, OREGON PELECANIFORMES PELAGORNTIHIDAE t Argillornis(?) sp. 46 Pelagomithidae sp. 46 Cyphornismagnus ? ? 1, 16, 46 Osteodontornis sp. 40 PLOTOPTERIDAE t Phocavis maritimus 45 Tonsala hildegardae 38 SULIDAE Morus sp. (1) 4 0 PROCELLARIIFORMES DIOMEDEIDAE Diomedeasp.(1) 40 PROCELLARIIDAE Hydrotherikornisoregonus (2) 6

CEDROS IS., MEXICO PROCELLARIIFORMES PROCELLARIIDAE Puffinustedfordi 26 PELECANIFORMES SULIDAE Morus sp. 2 6 CHARADRIIFORMES ALCIDAE Cerorhincaminor 2 6 Mancalla cedrosensis 26, 31 Synthliboramphussp. - 26

FIGURE 2. Seabird faunal list sortedby region and time. List includes all published accounts of seabird species from marine deposits in the North Pacific (see table 1 for seabird species from nonmarine deposits of western North America). Shaded bar, Presence of species in the fauna. Dagger (t), Extincttaxon. Footnotes: (1) probably conspecific with species fromCalifornia; (2) relationshipsin doubt (see the text);(3) includes taxa fromRosarito Beach Formation in northernmostBaja California (see Demer6 et al. 1984). References: 1, Cope 1985; 2, Lucas 1901a; 3, Lucas 1901b; 4, Miller 1925; 5, Miller 1929; 6, A. H. Miller 1931; 7, Miller 1933; 8, Miller 1935; 9, Miller 1937; 10, Miller 1946; 11, Miller 1951; 12, Miller 1961; 13, Miller 1962; 14, Miller and Bowman 1958; 15, Miller and Howard 1949; 16, Wetmore 1928; 17, Wetmore1930; 18, Howard 1949; 19, Howard 1957; 20, Howard 1958; 21, Howard 1966a; 22, Howard 1966b; 23, Howard 1968; 24, Howard 1969; 25, Howard 1970; 26, Howard 1971; 27, Howard 1972; 28, Howard 1976; 29, Howard 1978; 30, Howard 1981; 31, Howard 1982; 32, Howard 1984; 33, Howard and Barnes 1987; 34, Howard and White 1962; 35, Hasegawa 1977; 36, Olson and Hasegawa 1979; 37, Olson and Hasegawa 1985; 38, Olson 1980; 39, Olson 1981; 40, Olson 1985; 41, Barnes et al. 1981; 42, Ono 1983; 43, Ono 1989; 44, Demer6 et al. 1984; 45, Goedert 1988; 46, Goedert 1989; 47, Okazaki 1989; 48, Chandler 1990; 49, Warheit 1990; 50, Warheit in preparation. and Antarctica,"isotopic recordsprovide both caps" (Barron and Baldauf 1989: p. 343). In an estimateof the paleotemperaturesof high- addition, the development of polar ice con- latitude surfacewaters, as well as an estimate tributes(with continental and oceanic con- of the amount of water stored in polar ice figurations)to the pole-to-equator tempera-

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REGION/ TAXON FAUNA References

CALIFORNIA PROCELLARIIFORMES DIOMEDEIDAE Diomedeamilled 21, 33, 40 Diomedea californica 13, 23, 29, 40 Diomedea (?) californica 23 Diomedea sp. 23, 29,31,41 Diomedea sp. 23, 29, 31,41 Diomedea howardi 48 Diomedea sp.A 48 Diomedea sp.B 48 PROCELLARIIDAE(3) Fulmanus miocaenus 32 Fulmanwshammenr 23 Puffinusinceptor 12, 17, 21 Puffinusmitchelli 12, 44 Puffinussp. 33, 48 Puffinuspriscus 12, 21,23, 33 Puffinusbamesi 23, 29 Puffinuscalhouni 23 Puffinusdiatomicus 4, 8 Puffinusfefthami - 18 Puffinusgilmorei 48 Puffinuskanakoffi 14, 18, 48 Puffinussp. 33, 48 OCEANITIDAE Oceanodroma sp. 29, 48 Oceanodroma hubbi - 11 Oceanodroma sp. 29, 48

PELECANIFORMES SULIDAE (3) Morus vagabundus 17, 21,49, 50 Morus new sp. 12,21,49,50 Monissp. 49, 50 Morus willet_t 4, 49, 50 Morus lompocanus 4, 23, 29,50 Monus magnus 29 Morus media 4, 23, 29 Morus stocktoni 8, 20 Morus new sp. or M. recentior 49, 50 Mous recentior 18, 48 Mowushumeralis 14, 48 Sula pohli 20,23,49,50 Sula clarki _ 48 Sula sp. 48

FIGURE 2. Continued.

ture gradient and thereforeaffects oceanic scale phenomena such as oceanic currents, circulationpatterns (for a briefdiscussion and and local phenomena such as upwelling. example, see Rea et al. 1990). By recording the development of polar ice caps, the record Spatial Distribution of Fossil Seabirds of isotopic bottom-watertemperatures also Fossil seabird species frommarine deposits chroniclesthe development of global surface of the North Pacificare listed in figure2 (see currents such as the North Pacific Gyre. table 1 for a listing of seabirds from non- Therefore,the record of bottom-watertem- marine deposits of western North America). peratures provides a historyof not only the This list includes only taxa that have been development of cold and nutrient-richbot- discussed in the literatureand is subdivided tom waters, but also the evolution of large- into seabird faunas (see fig.1) and geographic

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REGION / TAXON FAUNA References A B C -I III IV

CALIFORNIA (con't) PELECANIFORMES (con't) PHALACROCORACIDAE Phalacrocoraxfemoralis 5 Phalacrocoraxkennelli 14, 18, 48 Stictocarbokumeyaay 48 Phalacrocoracidaesp. 1 48 Phalacrocoracidaesp. 2 48 PELAGORNITHIDAEt Osteodontornisorri 19, 29, 34, 40 PLOTOPTERIDAE t Plotopterumjoaquinensis 24, 27, 36

CHARADRIIFORMES ALCIDAE(3) Aethiarossmoori 23 Aethia(?) sp. 29, 31, 41 Alcasp. 23 Alcodesaff. A. ulnulus 3 3 Alcodesulnulus 23, 33 Brachyramphusdunkeli 48 Brachyramphuspliocenus 14, 18, 48 Cepphus(?) sp. 23,29 Cepphusolsoni 31, 41 Cerorhincadubia 4, 23 Cerorhincareai 48 Cerorhincasp. 48 Fraterculini,indeterm. 29 Mancallacalifomicus 2, 3, 7, 10, 18 Mancallacf. cedrocensis 31, 41 Mancalladiegensis 9, 15,31, 41 Mancallanilleni 25, 31, 41, 48 Mancallaemlongi 39, 48 Praemancallalagunensis 22 Praemancallawetmorei 28, 29, 31 Praemancallacf. P. wetmorei 31, 41 Ptychoramphustenuis 14, 48 Synthliboramphusrineyi 48 Uria(?) sp. 29 Unabrodkorbi 30 Uriapaleohesperis 31, 41 Alcidae,indetermin 44 LARIDAE Larussp. 48 Rissa estesi 48 Stemasp. 48

FIGURE 2. Continued.

regions.The bulk of the known fossilseabirds seabirds fromthe North Pacific were recov- fromthe North Pacific is fromCalifornia, al- ered from deposits between 32?N and 38?N though our knowledge of early Tertiarysea- latitude (fig.3). Therefore,at best,the known birds is based mostlyon materialfrom Japan, historyof seabirds fromthe North pacific is British Columbia, Washington, and Oregon very restrictedgeographically. Undoubtedly (fig. 2). Note that there is no known fossil this narrow geographic distributionis an ar- material from latitudes north of Vancouver tifactof insufficientsampling rather than a Island, BritishColumbia and Honshu, Japan historical fact. in the eastern and western Pacific, respec- All Tertiaryfossil seabirds fromCalifornia tively (figs. 2, 3). In fact, 88% of the fossil are fromlocalities south of San Francisco,and

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SEABIRDFOSSIL LOCALITIES:NORTH PACIFIC - TERTIARY

2z2s~ ~ ~ ~ ~~z

,;-~~- --~------38?N ------1 ~ 320 ---

FIGURE 3. Map of the North Pacific showing the geographic regions where fossil seabirds were recovered from Tertiarymarine deposits. Shaded circles,General areas where one or more fossil localities are known. Most seabird fossils fromthe North Pacificare found between 32?N and 38?N latitude (see the text).

most of this material is from Los Angeles, North Pacific Seabird Faunas Orange, and San Diego counties (fig. 4). Southern California is the only region in the Fauna A (52-38 Ma; see the Appendixfor NorthPacific where seabird fossilsare known dates).-All seabird taxa in Fauna A were re- fromFaunas I through IV, as well as Fauna covered fromlocalities in Oregon, and all but C (figs. 2, 4). Clearly, the known historyof Hydrotherikornisoregonus were described by North Pacific seabirds is mostly the history Goedert(1988, 1989; fig.2, Appendix). A. Mil- of southern California seabirds, where the ler (1931) described H. oregonusas an alcid taxonomic and temporal coverage is exten- (similar to Ptychoramphus),but according to sive. R. Chandler (personal communication 1990),

TABLE 1. Seabird taxa fromnonmarine deposits of western North America. Data fromBecker 1987.

Fauna Taxon Locality I Laridae San Bernardino Co., Calif. II Phalacrocoraxleptopus Malheur Co., Oreg. III Phalacrocoraxidahensis Owyhee Co., Idaho Laridae Mohave Co., Ariz. IV Pelecanuserythrorhynchos Malheur Co., Oreg. Pelecanushalieus Elmore, Owyhee, Twin Falls Co., Idaho Phalacrocoraxauritus Malheur Co., Oreg. Phalacrocoraxauritus Elmore, Owyhee, Twin Falls Co., Idaho Phalacrocoraxidahensis Elmore, Owyhee, Twin Falls Co., Idaho Phalacrocoraxmacer Elmore, Owyhee, Twin Falls Co., Idaho Phalacrocoraxsp. Elmore, Owyhee, Twin Falls Co., Idaho

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FAUNA

Shadedsection of circles on map correspondto one ormore seabird faunas

San Francisco

Los Angeles

FIGURE 4. Map of California showing counties with known fossil-bearingmarine deposits of seabirds. From north to south: San Mateo, Santa Cruz, Kern, Santa Barbara,Los Angeles, Orange, and San Diego counties. Each of these counties is marked with a symbol corresponding to the faunas fromwhich seabird fossils are known. The aerial distance between San Francisco and Los Angeles is roughly 550 km.

the specimen is moreclosely relatedto petrels (Diomedeaexulans), the largest extant seabird than to the Alcidae (for a contraryview, see (wingspan of 2.5-3.5 m; Harrison 1983). An Steadman,in Olson 1985: p. 183). I tentatively undescribed species fromSouth Carolina had placed the species within the Procellariidae, a wingspan of 5.5-6.0 m (Warheit and Olson but await Chandler's publication for conclu- in preparation).The structureof the wing and sive evidence. shoulder in these birdssuggested thatsoaring The remaining species in Fauna A were rather than flapping flightwas the primary membersof eitherthe Pelagornithidae or the mode of locomotion (Olson 1985). Further- Plotopteridae (extinctPelecaniformes; fig. 2). more, Zusi and Warheit (1992) suggest that The Pelagornithidae or pseudodontorns pseudodontorns obtained their food (proba- (=Odontopterygiformesin Howard [1957]and bly fishor squid) in a manner similar to frig- Harrison and Walker [1976]) were worldwide atebirds(dipping) or albatrosses(surface seiz- in distributionand are closely related either ing). Goedert (1989) described two taxa of to the clade that includes the Sulidae, Phal- pseudodontorns fromthe Late Eocene (40.5- acrocoracidae (cormorants),and Anhinga,or 39 Ma) beds of northwesternOregon and ten- to the Pelecanidae (Warheit in preparation). tatively referredone of these specimens to The taxon consisted mostly of gigantic ma- Argillornis,an eastern Atlantic taxon. rine birds equipped with bony toothlikepro- Olson and Hasegawa (1979: p. 688) de- jections on the rostrum and mandible (see scribed the Plotopteridae as "giant, flightless Olson 1985: fig.9). Although the pseudodon- penguinlike birds" whose "hindlimb and tornsvaried considerablyin size, mostspecies pelvic morphology is most similar to that of were larger than the Wandering Albatross Recent anhingas, but the wing is paddlelike

This content downloaded from 152.3.102.242 on Sun, 8 Sep 2013 20:56:41 PM All use subject to JSTOR Terms and Conditions FOSSIL SEABIRDS FROM THE NORTH PACIFIC 409 and remarkablyconvergent toward penguins with littleor no continentalshelf, and a steep and flightless auks." Unquestionably these continental slope. marine birds were wing-propelled divers, as Fauna C (24 [?]-18 Ma).-Although ploto- are penguins,but manywere largerthan pen- pteridswere present in the eastern Pacific as guins, possibly twice the height of the largest early as the Late Eocene (Fauna A; figs. 1, 2), extant penguin, the Emperor Penguin (Ap- Fauna C is the firstin which a plotopterid tenodytesforsteri) (length of femora: gigantic was recovered froma California deposit. In plotopteridfrom Japan = 225 mm,Olson 1985; addition, Plotopterumjoaquinensis, from the A. forsteri= 118.5 mm,mean of 30 specimens, Pyramid Hill local fauna (Howard 1969; 22- Livezey 1989). Phocavis maritimuswas de- 21 Ma, Woodburne 1987) is the only known scribed from a single specimen (tarsometa- plotopteridand the oldest known marinesea- tarsus) recovered fromthe same formationin bird fromCalifornia (fig. 2). northwesternOregon as Argillornissp. (see The remainingseabirds fromthis fauna are above; Goedert 1988), and is the oldest known pelagornithids from central Oregon. Olson member of this taxon. In addition, P. mariti- (1985) considered these specimens to be part mus and the two species of pseudodontorns of the genus Osteodontornis,initially de- described by Goedert (1989) are the oldest scribed fromLate Miocene (Fauna II) deposits known seabirds in the North Pacific. of southern California (Howard 1957). Fauna B (31[?]-22.8 Ma).-Only three sea- Fauna I (18 [or 151-13 [orl2] Ma).-Of the bird taxa are definitivelyknown fromFauna 102 fossil seabirds in the North Pacific(black B, and similarto Fauna A, these taxa are mem- bars in fig. 2), 91 are members of Faunas I bers of either the Pelagornithidae or Ploto- through IV, and 89 of these 91 are fromthe pteridae. Fauna B is the firstin which fossil eastern Pacific.A summaryof the taxonomic seabirds are known fromJapan (see the Ap- diversityof these eastern North Pacific sea- pendix). Although the plotopterid material birds is shown in figure 5. Except for Hy- fromJapan was not described to species, Ol- drotherikornisoregonus (see above; Fauna A), son and Hasegawa (1979) considered at least Fauna I is the firstin which extant seabird four species present. Also from Japan is an taxa are present (Alcidae, Sulidae, Procellar- incomplete humerus fromnorthern Kyushu, iidae [petrels and shearwaters],and Diome- described by Okazaki (1989) as an Odontop- deidae [albatrosses])(figs. 2, 5). In addition to terygiformes(Pelagornithidae). The third these extant taxa, Osteodontornissp. was also taxon fromthis fauna is Tonsalahildegardae, a present and widespread, found from locali- plotopterid fromnorthern Washington state ties in Japan, Oregon, and California. Al- (Olson 1980). though the specific identity of the pseud- Cyphornismagnus is a pseudodontorn (Ol- odontornfrom Japan is uncertain(Ono 1989), son 1985; Warheitand Olson in preparation) the Oregon and California specimens were from Vancouver Island, British Columbia probablyconspecific (0. orri;Warheit and Ol- (Cope 1895), and the northernmostmember son in preparation). of this taxon in the North Pacific.The age of Plotopteridsalso remained extantin Japan C. magnusis in doubt and has been described during the time of Fauna I. But unlike the alternativelyas Late Eocene (Fauna A), Oli- earlier plotopteridsfrom the western Pacific, gocene (Fauna B), and Early Miocene (Fauna these specimens were relatively small and C). I listed this species here for convenience similarin size to Plotopterumjoaquinensis from only (see the Appendix: Fauna B, Carmanah Fauna C (see above) and the Recent Brandt's Point). Drummond (1979) stated thatLate Eo- Cormorant (Phalacrocoraxpenicillatus) (Olson cene to EarlyMiocene sedimentsoff southern and Hasegawa 1979, 1985). Sulids also existed and western Vancouver Island were depos- on both sides of the Pacific during this time, ited onto a steep continentalslope in an area although the materialfrom the easternNorth without a significant continental shelf. Pacificis farmore abundant and diverse than Therefore,despite its age, I presumed thatC. that fromJapan (fig. 2). magnusfrequented an oceanic environment The taxonomic diversity of Fauna I was

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8- CHARADRIIFORMES 6.

4. w O 2 w U) 0-

0 PELECANIFORMES

0

2

A B C I 11 111 IV FAUNA

CHARADRIIFORMES PELECANIFORMES PROCELLARIIFORMES FlightlessAlcidae Sulidae Procellariidae VolantAlcidae Phalacrocoracidae_ Diomedeidae LI Laridae Pelagornithidae Oceanitidae Plotopteridae

FIGURE 5. Histograms showing the number of seabird species per higher taxon in each fauna (includes only those specimens fromthe eastern North Pacific,but does not include Cyphornismagnus because of the uncertaintyin its age; see the text). Flightless Alcidae are the mancallids. Hydrotherikornisoregonus is the Procellariidae in Fauna A. The question mark signifiestaxonomic uncertainty(see the text). dominated by the Sulidae and the Procellar- ation of gannets and shearwaters, Fauna II iidae (fig. 2). In addition, two species each of must be characterized as "the age of the Al- Alcidae and Diomedeidae were also present. cidae." The number of alcid taxa in the east- One of the two species of Alcidae (Alcodesaff. ern North Pacificincreased dramaticallydur- A. ulnulus)is considered closely related to the ing this time, when 11 sympatric species mancallids (Praemancallaand Mancalla; How- occurred in California (fig. 5). At least seven ard 1968; Howard and Barnes 1987),an extinct alcid genera were also present,including Alca group of flightlessauks, similar in morphol- and Aethia(fig. 2), known in the Recent from ogy to the Great Auk (Pinguinusimpennis; Lu- only the North Atlantic and North Pacific/ cas 1901a,b; for morphometriccomparisons, Bering Sea, respectively.Besides these volant see Livezey 1988). It is not clear from the alcids, mancallids were also represented in morphology of Alcodes sp., however, if the this fauna; two species of the flightlessPrae- individuals in this taxon were flightless,al- mancallaand Alcodesulnulus (fig. 2). though Howard (1968: p. 19) maintained that Sulids and procellariids continued their the species "was progressingtowards flight- relatively high diversity,while cormorants lessness." In summary,Fauna I can be char- and storm-petrels(Oceanitidae) made their acterized by the pan-North Pacific distribu- firstappearances in the eastern North Pacific tion of the pseudodontorns, and the initial at this time (fig. 5). Although there was con- radiation of extantfamilies of seabirds in the siderable taxonomic turnoverwithin the Su- North Pacific,in particular,the Sulidae and lidae and Procellariidaebetween Faunas I and Procellariidae. II (fig. 2), their total taxonomic diversityre- Fauna II (13-8 [6] Ma).-If Fauna I is con- mained relatively constant (fig. 5). In addi- sidered importantin the North Pacific radi- tion, the diversitycurves for the sulids and

This content downloaded from 152.3.102.242 on Sun, 8 Sep 2013 20:56:41 PM All use subject to JSTOR Terms and Conditions FOSSIL SEABIRDS FROM THE NORTH PACIFIC 411 procellariidsremained remarkablysimilar to number of albatross species decreased to one each other throughout Faunas I-IV (fig. 5). in California and none in Mexico (figs. 2, 5). Despite their relatively constant taxonomic Missing fromthis fauna are the Phalacroco- diversity,the morphologic diversity of the racidae and Pelagornithidae.The pseudodon- Sulidae increased in Fauna II. For example, torns apparently became extinctin the east- although Morus (Miosula) media and Morus ern North Pacific at this time, but were still (Paleosula) stocktoniare easily identifiedas su- present in Japan, and remained extant into lids (Miller 1925, 1935), the structureof their the Pliocene in both the South Pacific (New legs and wings revealed morphologies simi- Zealand) and NorthAtlantic (North Carolina) lar to those in cormorants and wing-pro- (Howard and Warter1969; Olson 1985; War- pelled divers,respectively (Miller 1925; War- heit and Olson in preparation). heit 1990). This suggested convergent (I am aware of additional, unpublished sea- locomotoryhabits between these species of bird material from deposits in Santa Cruz Morusand the Phalacrocoracidaeand Alcidae. County, California [Purisima Formation; F. In summary,the most distinctive charac- Perry in preparation]. Although additional teristicof Fauna II is the dramaticincrease in species ofAlcidae, Procellariidae,and Sulidae diversityof both volant and flightlessalcids. are known from this unpublished locality Other importantevents thatoccurred during [Perry in preparation], the number of taxa the time of this fauna were the initial radia- presentdoes not drasticallyalter the diversity tion of the cormorantsand storm-petrels,and curves, including the local extinctionof the the continued high diversityof the sulids and pseudodontorns [fig.5].) shearwaters.Morphologic diversityof the su- In summary,the general theme for Fauna lids also increased during this period. III is declining diversityfor all taxa except Fauna III (7 [61-4 Ma). -Fauna III is unlike the mancallids. In addition, Fauna III is the the other faunas in that declining diversity firstfauna since Fauna C where the pseud- was the general theme for all taxonomic odontorn,Osteodontornis sp., was not present groups except the mancallids (figs. 2, 5). Al- in California. It appears that the pseudodon- though there was a decline in diversityand tornsbecame extinctin the eastern North Pa- extinction of Praemancalla and Alcodes, re- cific before the time of Fauna III, but re- spectively,from Fauna II to Fauna III, Man- mained extantin Japan into Fauna III. calla increased in diversity (see figs. 2, 5). Fauna IV (3-1.5 Ma). -Fauna IV consists of Mancalla is moreadvanced in its development abundant fossil remains fromthe San Diego of a penguinlike wing than either Praeman- Formation,San Diego, California. Chandler calla or Alcodes (Howard 1966b, 1968). The (1990) reviewed this material,and the taxo- number of volant species of alcids decreased nomic listing for this fauna in figure 2 is a from eight in Fauna II to five in Fauna III summary of his work. The transition from (figs. 2, 5). If the Cedros Island, Mexico spe- Fauna III to Fauna IV was essentiallya mirror cies were not included in figure5, the drop image of the transitionfrom Fauna II to Fauna in volant Alcidae diversitywould be more III. That is, all taxa, except Mancalla sp., ex- dramatic(i.e., two of the fivespecies of volant perienced an increase in taxonomicdiversity. alcids were indigenous to Cedros Island, while Volant alcids increased from five species in the one species of mancallid found on Cedros Fauna III (three species from California) to Island also occurred in southern California; six species in Fauna IV (fig. 5). In addition, fig.2). Therefore,while other taxa of Alcidae this increase was due primarilyto the radia- declined in diversityin Fauna III, the man- tion of small alcids in the genera Brachyram- callids diversified. phus,Ptychoramphus, and Synthliboramphus(fig. A decline in diversitywas also apparent in 2). Although Mancalla decreased in diversity both the Pelecaniformes and Procellari- fromfive species in Fauna III to three species iformes.The Sulidae and Procellariidae de- in Fauna IV, their numerical dominance in clined to one species each fromsouthern Cal- this fauna was evident,with most of the 2000 iforniaand Cedros Island, Mexico, while the plus specimens from the San Diego Forma-

This content downloaded from 152.3.102.242 on Sun, 8 Sep 2013 20:56:41 PM All use subject to JSTOR Terms and Conditions 412 KENNETH I. WARHEIT tion identified as mancallids (R. Chandler Fauna IV (fig. 5). Three species of albatross personal communication). were discussed by Chandler (1990), although Althoughthe Laridae had been known from only one species was named. Chandler de- nonmarine deposits in western North Amer- scribed Diomedea howardias a medium-sized ica fromat least the time of Fauna I (table 1), albatross about the same size as the Recent Fauna IV includes the firstappearance of gulls White-capped Albatross (D. cauta) of the or terns in marine deposits from the North Southern Hemisphere. This species was Pacific (figs.2, 5). Chandler (1990) identified thereforeintermediate in size between the only one larid to species (Rissa estesi;fig. 2), large D. californicaand the very small D. mil- and considered it most similar to the Recent leri,both fromFauna I (fig. 2). The two other Black-legged Kittiwake (R. tridactyla).Chan- species of albatross described by Chandler dler also identifiedLarus sp. as a species of were identified only to genus (Diomedea). gull intermediatein size between the Recent Chandler considered species "A" similar in Ring-billed Gull (L. delawarensis)and the Re- size and possibly closely related to D. califor- centCalifornia Gull (L. californicus),and Sterna nica (size comparable to the Recent Short- sp. as a ternsimilar in size to the RecentRoyal tailed Albatross [D. albatrus]; Miller 1962; Tern (S. maxima). Howard 1966a), whereas species "B" was sim- Among the Pelecaniformes,there was an ilar in size to the small D. milleri(smaller than increase in the number of sulids from the the Recent Black-footed Albatross [D. ni- time of Fauna III to that of Fauna IV (fig. 5), gripes];Howard 1966a). Finally, Chandler de- and forthe firsttime in the North Pacific,the scribed an unidentifiedspecies of storm-pe- diversityof Sula equaled that of Morus (fig. trel (Oceanodromasp.) from the San Diego 2). The diversityof Phalacrocoracidae also in- Formation(fig. 2). creased during this time interval.Before Fau- In summary,there was an increase in di- na IV, the only specimen of cormorantor shag versity of all seabird taxa, except the man- to be recorded from marine deposits in the callids, in Fauna IV. This was a reversal of North Pacific was Phalacrocorax femoralis. the trendset in Fauna III. Although the man- Chandler (1990) listed at least a dozen spec- callids declined in diversity,they were still, imens fromat least four differentspecies of perhaps,the mostabundant taxon on the Cal- Phalacrocoracidae from the San Diego For- ifornia coast. Among the notable radiations mation. Chandler followed Siegel-Causey during thistime, was the increase in the larid, (1988) in placing the Recent Pelagic and Red- phalacrocoracid, and diomedeid diversities. faced Cormorants(=Shag in the sense of Sie- Except for the presence of sulids and flight- gel-Causey) in the genus Stictocarbo(S. pelag- less alcids (mancallids), the seabird diversity icus and S. urile,respectively), and described of Fauna IV closely resembled that of the Re- a new species of shag (S. kumeyaay),similar cent California Currentseabird communities in morphology to the Red-faced Shag. The (see Briggs et al. 1987). second phalacrocoracidspecies fromFauna IV is Phalacrocoraxkennelli, originally described Plate Tectonics and Paleoceanography: by Howard (1949: p. 189) as a cormorantin- Mechanisms for Change in the termediate in "size between [Phalacrocorax] Diversity of North pelagicus [Pelagic Shag] and [Phalacrocorax] Pacific Seabirds penicillatus[Brandt's Cormorant]." Chandler Large-scale oceanographic processes of the (1990) leftundescribed the remainder of the Recent North Pacificare, in part,functions of cormorantand shag material from the San the anticyclonicNorth PacificGyre. Physical Diego Formation,although he explicitlystat- factorsthat disrupt or alter the North Pacific ed that there were at least two more species Gyre can affectbiological characteristicsin a in the formation,and that one of these was wide geographic area. For example, during El larger and more robust than P. kennelli. Nifno-SouthernOscillations (ENSO), global The Procellariiformesalso increased in di- climatic and oceanographic patterns are al- versityfrom the time of Fauna III to that of tered, therebyaffecting the thermoclineand

This content downloaded from 152.3.102.242 on Sun, 8 Sep 2013 20:56:41 PM All use subject to JSTOR Terms and Conditions FOSSIL SEABIRDS FROM THE NORTH PACIFIC 413 upwelling regimes in the eastern boundary have changed during the historyof the North systemsof both the North and South Pacific Pacificseabirds, tectonic events may have in- Gyres (California and Peru Currents,respec- fluencedthe diversityof seabirdsin the North tively; for details see Glantz and Thompson Pacific (for the effectsof tectonic events on 1981; Ainley and Boekelheide 1990). By re- Paleocene-Eocene non-seabird diversity,see ducing the availability of nutrientsupwelled Rea et al. 1990). I will summarize these tec- into the euphotic zone, ENSOs disruptentire tonic events, and their influences on global food chains (Glynn 1988). The complete re- and Californiaoceanography in termsof their productivefailure and disappearance of a sea- affectson North Pacificseabird diversity(for bird communityon ChristmasIsland, central a summaryof physical events, see fig.6). Al- Pacific Ocean, and increased adult mortality though I present the following results as if and nesting failureof seabirds in Peru, South the temporal correspondence between tec- Africa,and the eastern North Pacific are ex- tonic events (and their affectson oceano- amples of the effectsof ENSOs on Recent sea- graphicfeatures) and changes in the diversity bird populations (see Schreiberand Schreiber of North Pacific seabirds is a causal relation- 1984; Hodder and Graybill 1985; Ainley et al. ship, I am aware that to claim causality is to 1986; Duffyet al. 1986; Hatch 1987). assume thatthe physical factorswere, in part, The availabilityof nutrient-richwaters, and responsible for changes in seabird diversity. the occurrence and timing of particularoce- Therefore,the following results are hypoth- anic currents and local upwelling, are im- eses and not statementsof fact. portantfactors in understanding the behav- Before the time of Fauna A (>52 Ma) the iors and distributionsof Recent seabirds (see, world's oceans were warm,and global climate e.g., Ainley 1977; Pocklington 1979; Brown was a functionof equatorial waters (Savin et 1980; Ainley and Boekelheide 1984, 1990; Ha- al. 1975; Barron and Baldauf 1989). At this ney 1986, 1987; Briggs et al. 1987). These fac- time,the ArcticOcean was isolated fromthe torsare also assumed to have been important remainder of the world's oceans, and the in extinctseabird systems.In other words, as southerlyposition ofboth Australiaand India in Recent seabird systems,the availability of inhibited surfaceand deep-water circulation food forextinct seabirds in the North Pacific around Antarctica(Barron and Baldauf 1989). depended, in part, on the occurrences and Although thereare no seabirds recordedfrom timing of oceanic currents and upwelling. the North Pacific at this time,I am unable to From a geological perspective, ENSOs are determineif this was the result of the ocean- short in duration, and although they may ographic and climatic conditions or the va- eliminate entire cohorts fromseabird popu- garies of the fossil record. lations (and thereforeaffect population struc- The evolution of the North Pacific ecosys- ture), they do not appear to alter the long- temand the development of itsseabird faunas term diversity or structurein seabird com- proceeded through five broadly defined munities (i.e., long-termspecies composition oceanographic stages. The firststage began in Peruvian seabird colonies and at Southeast with a major oceanic cooling event at about Farallon Island, California do not appear to 52 Ma, following the initial opening of the have been affectedby ENSOs occurringdur- Norwegian Sea (fig. 6; Barron and Baldauf ing the past century;see Ainley and Lewis 1989). The appearance of the firstNorth Pa- 1974; Duffy 1983; Ainley and Boekelheide cificseabirds (Fauna A) coincided with these 1990). However, geological events operating events,and suggestthat the shiftfrom a warm on a long temporal time scale alter the struc- to cool oceanic environmentwas important tureof large-scaleoceanographic systemsand in the initial radiation of plotopterids and may,in turn,affect radiations and extinctions pelagornithids.At about 36 Ma, two tectonic of particularspecies of seabirds. Because the events-the initial northward movement of Recent circulationpatterns of the oceans are Australia and India, and the widening of a functions of continental position, and be- previously narrow Atlantic-Arctic Ocean cause the relative positions of land masses connection-led to further cooling of the

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GLOBAL Ma CALIFORNIA

* CompleteEMERGENCE ofISTHMUS * CaliforniaCurrent dominates IV t * Globalcooling & ice growth floraand faunain V * NorthernHemisphere glaciation NW SouthAmerica * ExtensiveW. AntarcticIce 5 - * PartialEMERGENCE of ISTHMUS * Dropin sea level R*AUSTRALIAINDONESIA COLLIDE \\\. _ /*Further increasein upweilling * Beginproductivity and deep sea cold Dropin sea level circulationpatterns of modernworld 10 Pulses of Cold Water * LowerSea Level ^ . _ * IntensiveIncrease in Upwelling * PermanentE. Antarcticice cap * Cold Water * Increaselatitudinal thermal gradient 15 * Dropin sea level * PANAMICUPLIFT BEGINS * Cool CaliforniaCurrent * Regionsof highproductivity shift to * WarmTemperatures (global) * coastal NorthPacific Cr 2 - Cold bottomwater 20- C CoPuldesofinesifiedwaterW cold bottom / C \*E.rAacticy gas equatoric remains - DRAKE PASSAGE OPENS . * StrongCircum-Antarctic Current 25- B * Beginbasic oceanict watermasses B _\ of modernworld/. - E. Antarcticglaciation -30 30 .. - Latitudinalthermal gradient begins

/*AUSTRALIA& INDIAMOVE NORTH \ ' *ATLANTIC- ARCTIC CONNECTION. -35- Cold Water i e s Se1ntarctic f glaciatione t c b 1 1 We ak Circum- AntarcticCurrent a e40-

? NORWEGIANSEA OPENS _ ? Coolingevent 50-

? Warmwater ? IsolatedArctic Ocean 55- ? Equatorialwaters l dominateclimate i l

FIGURE6. Global and California Current oceanographic events from 60 to 1.6 Ma (Faunas A-IV). Major tectonic events in upper case. Black bars to the left and rightof faunal and time scales mark the durations of tectonicand oceanographic events. See figure 1 for the correlationbetween faunas and time. Based on Keller and Barron 1981, 1983, 1987; Weaver et al. 1981; Woodruffet al. 1981; Barronand Keller 1982, 1983; Barron 1986b; Domack 1986; Haq et al. 1987; K. Miller et al. 1987; Barron and Baldauf 1989; Woodruffand Savin 1989; Duque-Caro 1990. world's oceans. More importantly,these tec- The dramatic cooling of Antarctica around tonic events resulted in the initial refrigera- 31-28 Ma contributed to an enhanced lati- tion of Antarctica,bringing glaciers to East tudinal thermal gradient, with the atmo- Antarcticaand a weak Circum-AntarcticCur- sphere and oceans near the equator remain- rent (fig. 6; Savin et al. 1975; K. Miller et al. ing warm, while that of the high latitudes 1987; Barronand Larsen 1988; Barronand Bal- becoming increasinglycool (Fauna B, fig. 6). dauf 1989). In addition, the opening of Drake Passage at Building on the oceanographic effectsof about 24-20 Ma resulted in a strongCircum- the firststage, the second stage in the devel- AntarcticCurrent that helped establish the opment of the North Pacific seabird faunas basic oceanic circulation patterns of today involved continued glaciation in Antarctica. (Keller and Barron 1983; Barron and Baldauf

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1989; Fauna C, fig.6). During these two time food, similarto that seen during ENSOs) and periods,the radiationof plotopteridsand pel- pinniped radiations (and a reduction in agornithidscontinued in both Japan and the breeding habitat) played roles in the extinc- eastern North Pacific (figs. 2, 5, 6). tion of the plotopterids. Although the Recent oceanic circulation Following the high ocean temperaturesat patternswere established by 20 Ma, areas of 16.5-14.5 Ma, therewas a precipitousdecline oceanic productivitywere still restrictedto in bottom-watertemperature (Woodruff et al. equatorial regions (Keller and Barron 1983, 1981; Keller and Barron 1983; K. Miller et al. 1987; fig.6). In addition, following the steady 1987; Woodruffand Savin 1989; fig.6), and a decline in ocean temperaturesthat began at shift in areas of high oceanic productivity 52 Ma, a sharp rise in ocean temperatures fromthe equator to the coastal marginsof the occurred from22 Ma to 16.3 Ma, with maxi- North Pacific. At the same time, tectonic ac- mum temperaturesoccurring 16.5-14.5 Ma tivity increased within the panamic portal, (Woodruffet al. 1981; K. Miller et al. 1987; and "central american" waters between the Woodruffand Savin 1989). Atlanticand PacificOceans began to shallow Although some authors (Olson and Hase- (Duque-Caro 1990; fig.6). Between 15 and 13 gawa 1979; Warheitand Lindberg 1988) have Ma, a permanent ice cap in East Antarctica suggested that the plotopterid extinctionin formed, enhancing the latitudinal thermal the EarlyMiocene resultedfrom the radiation gradient (fig. 6). of cetaceans and gregarious pinnipeds, re- These oceanographic and tectonic events spectively, plotopterid extinction also coin- produced smaller-scale oceanographic cided with this sharp rise in ocean tempera- changes to the waters of coastal California. tures. Goedert (1988) proposed that this The steepened latitudinal thermal gradient warming event was a betterexplanation for intensified the gyral circulation of surface the extinction of the plotopterids than the currents,and strengthened the coastal and radiation of marine mammals. The last oc- trade winds that promote upwelling (Barron currences of a plotopteridspecies was 22-21 and Baldauf 1989). Beginning at 13.4 Ma, the Ma and 18-15 Ma in the eastern and western planktonic flora and fauna in California North Pacific,respectively (fig. 2; Appendix). switched fromsubtropical and temperateas- Because warm water persisted in the North semblages to those typicalof a cool California Pacificfrom 22 Ma to 14.5 Ma, the extinction Current(fig. 6; Barron and Baldauf 1989). In of the plotopterids in both the eastern and Recent seabird systems,prey is more easily western North Pacific occurred during this located, abundant, and predictable in cold- time interval, suggesting support for Goe- water than in warm-water environments dert's hypothesis. However, although the (Ainley 1977; Ainley and Boekelheide 1984). plotopterid extinctionin the western North Therefore,I assume that seabird prey during Pacificoccurred later than thatin the eastern the time of Fauna I switched froma patchy North Pacific,the firstoccurrence of gregar- and unpredictable resource typical of Recent ious pinnipeds in the western North Pacific subtropicalregions to a seasonal but predict- also occurred later than that in the eastern ably abundant resource similar to that seen North Pacific(Fauna I; forpinniped data, see in Recent temperateto polar regions. Dubrovo 1984; Takeyama and Ozawa 1984). This thirdstage in the development of the In other words, there is good temporal cor- North Pacific ocean produced the most dra- respondence between the extinction of the maticchanges in seabird faunasto date. While plotopterids and the radiation of pinnipeds the cool California Current became estab- in both the easternand westernNorth Pacific. lished and food became abundant and pre- This supports the hypothesis (Warheit and dictable, seabird diversity dramatically in- Lindberg 1988) thatthe extinctionof the plo- creased and shiftedfrom a fauna dominated topteridswas, in part,the result of competi- by archaic Pelecaniformesto a diverse system tion for terrestrialhabitat. It is conceivable with extantrepresentatives of both the Pele- that both warm water (and a reduction in caniformesand Procellariiformes(see Fauna

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I in figs. 2, 5). Although the genera repre- the upwelling zone." During warm-water senting these higher taxa in this fauna are events in California, and especially during commonly found today in temperatewaters, the 1983 ENSO when upwelling ceased, re- the firstof these "extantlike" faunas (Fauna productive success for alcids on Southeast I) bore little resemblance to the Recent sea- Farallon Island was extremelylow (Ainley bird communitiesof the North Pacific. and Boekelheide 1990). Apparently the suc- At least two related tectonicevents are per- cess of the Alcidae in the California Current haps responsible for the fourthstage in the is stronglytied to the evolution and main- development of the North Pacificecosystem. tenance of the upwelling system, and the The Middle Miocene collision between Aus- dramaticrise in alcid diversityin Fauna II is tralia and Indonesia narrowed the Indo-Pa- relatedto the increase in productivityand the cificseaway and caused a deflectionof equa- proliferationof predictableand local food re- torial waters northward along the western sources. In addition to the growth in alcid margin of the North Pacific (Keller and Bar- diversity,the increase in the morphologicdi- ron 1983). In the eastern Pacific,the Isthmus versityof the Sulidae during this time (see of Panama began to emerge at 13-12 Ma, lim- Fauna II above) suggests that they expanded iting the Atlantic-Pacificconnection to shal- their foraging habits from plunging (Ash- low water (Duque-Caro 1990). At this time, mole 1971; Ainley 1977) to wing-propelled or sea levels dropped, and deep-sea circulation foot-propelled diving (Warheit 1990). Ac- and phytoplankton productivity patterns cording to Ainley (1977), for seabirds forag- typical of today became established (Keller ing in Recent cold upwelling regions,diving and Barron 1983; fig. 6). The increasing lati- is a more successful strategythan plunging, tudinal thermal gradient of the third stage, and the move toward thishabit in the Sulidae and restrictedequatorial flowin both the east- suggests that they too are taking advantage ern and western Pacific in this fourthstage of an increase in food supply. caused intense upwelling of nutrient-rich Althoughthe oceanographicconditions that bottomwater in California at about 12.4-11.1 led to an increase in seabird diversityin Fau- Ma (Barron and Keller 1983; Barron 1986b; na II were similar to the conditions of today, fig. 6). The diversityof Alcidae dramatically they were not identical. The California Cur- increased during this time period (Fauna II; rent itselfwas narrower and closer to shore figs. 1, 2, 5). at 10 and 8 Ma than today's current(Domack Alcids are wing-propelled diving seabirds 1986). A narrower, inshore California Cur- restrictedto cold to temperatewater regions rent would establish a more sharply defined of the Northern Hemisphere (Storer 1960; east-west gradient from the cold nearshore Ainley 1977; Harrison 1983; Olson 1985). Ain- environment to the warmer offshoreenvi- ley (1977) showed that in Recent seabird sys- ronment of the North Pacific Gyre (Domack tems 40%-80% of the seabirds nesting in po- 1986). Because the foraginghabits of today's lar and subpolar regions are birds thatobtain California Currentseabirds are largely deter- their food by either wing-propelled or foot- mined by the characterof the current(Briggs propelled diving. He also showed that the et al. 1987), foraging habits and habitats of incidence of diving birds is highly correlated seabirds in these extinctcommunities prob- with water temperature,increasing in num- ably differedfrom those of the Recentsystem. ber as water temperaturedecreases (Ainley The decrease in seabird diversityin Fauna 1977: fig. 1; see also Ainley and Boekelheide III is associated with a drop in sea level (fig. 1984). In addition, Briggs et al. (1987: p. 66) 6; Barron 1986b) and a broad and offshore observed that alcids in California are inti- California Current (Domack 1986). In addi- matelyassociated with the upwelling zone of tion, Barronand Keller (1983: fig. 12, table 8) the California Current system,and that the showed frequentwarm-water events of short Recent "California seabird fauna is dominat- durationbetween 8 and 5 Ma (see also Wood- ed in numbers and biomass by species that ruffand Savin 1989). Although Faunas I, II, reach greatest abundance in cool waters of and III experienced both warm-and cold-wa-

This content downloaded from 152.3.102.242 on Sun, 8 Sep 2013 20:56:41 PM All use subject to JSTOR Terms and Conditions FOSSIL SEABIRDS FROM THE NORTH PACIFIC 417 ter events, the fluctuationsin global water 1986b). This suggests that animals or plants temperaturesduring Faunas I and III were that occurred during the time of Fauna III more frequentand intense than those of Fau- had a lower probability of being preserved na II (Barron and Keller 1983). Whereas the as fossilsthan those that occurredduring the more constant cold-water environment of time of Fauna II (Barron 1986b). At this time, Fauna II may have been importantin the ra- it is difficultto choose between these alter- diation of eastern North Pacific seabird taxa, native hypotheses. the resumption of a more variable and pos- The well-resolvedpaleotemperature curves sibly warmer (and thereforeless productive) of Woodruffet al. (1981), Barron and Keller environmentduring Fauna III may have con- (1983), and othersdo not include data forthe tributedto the extinctionof some seabird taxa Pliocene (Fauna IV; see fig.1). However, Sav- from Fauna II. In addition, Vermeij (1989) in et al. (1975) stated that isotopic tempera- showed that several molluscan taxa endemic tures dropped rapidly during the Pliocene, to the western North Pacific had represen- bringing the bottom-watertemperatures to tatives in the eastern North Pacific that be- today'slevels. Savin et al. (1975: fig.6) showed came extinct during the time of Fauna III. that the drop in bottom-watertemperatures (Vermeij [1989: p. 338] stated that the last ap- occurredwithin the PlanktonicForaminiferal pearances of these eastern North Pacific taxa Biochrono-zone N21 (roughly 3 Ma; Haq et occurred in the Empire Formation of Coos al. 1987 and referencestherein) or during the Bay. Armentroutet al. [1983] showed this for- time of Fauna IV. Savin et al. (1975: p. 1505) mation to be approximately10-6 Ma, putting attributed this final drop in ocean bottom the last appearances of these molluscs in sea- temperaturesto the continued "expansion of bird Fauna II.) Vermeij (1989) attributedthe [the Antarctic]ice sheets, large-scale delivery extinctionof the eastern North Pacific mol- of ice to the seas, and formationof sea ice." luscs and the survival of theirwestern North In addition, Barron and Baldauf (1989) re- Pacific counterparts to the interruption of ported a high thermalgradient and the onset productivityin the eastern Pacific only. Al- of Northern Hemisphere glaciation around though the poor fossilrecord of seabirds from 2.5 Ma. the western North Pacific fromthis time pe- The seabirds of Fauna IV experienced rapid riod does not permit an analysis similar to fluctuationsin eustatic sea levels (see Haq et thatof Vermeij,the factthat pseudodontorns al. 1987) associated with polar glaciation and remained extantin the western North Pacific intensified tectonic activity,as well as de- but became extinctin the eastern North Pa- creasing water temperatures (for effectsof cificduring the time of Fauna III is consistent mountain uplift on coastal upwelling in the with the pattern of molluscan geographical eastern North Pacific, see Ruddiman and restriction uncovered by Vermeij (1989). Kutzbach 1989). I considered these oceano- However, the increase in mancallid diversity graphic and geographic events to be the fifth in this fauna is inexplicable. stage in the development of the Recent North An alternative hypothesis is that the de- Pacificecosystem. In addition, this stage most cline in seabird diversityduring Fauna III is likely extended into the Pleistocene,and may an artifactof the fossil record. It is possible continue to affectRecent seabird systems.Al- that seabird taxa were diverse and abundant though changes in the eustatic sea level are during Fauna III but not preserved, or, that global, their regional or local effectsdepend materialwas preserved and has yet to be col- on local geography and topography and be- lected. Evidence to support this alternative havior of the seabird taxa. Thus, the effects hypothesis was suggested by the unpub- of eustaticsea-level changes on the California lished PurisimaFormation material discussed Currentsystem may be differentfrom those above. In addition, rocks deposited in Cali- in Japan and depend on the local ocean-bot- forniaduring the time of Fauna III are more tom and terrestrialtopography (see Warheit enriched in detrital components than those and Lindberg 1988). Because there are no deposited during the time of Fauna II (Barron published accounts of seabirds fromthe west-

This content downloaded from 152.3.102.242 on Sun, 8 Sep 2013 20:56:41 PM All use subject to JSTOR Terms and Conditions 418 KENNETH I. WARHEIT ern North Pacific during the time of Fauna uted to their radiations and extinctionswere IV, I am unable to compare the seabird com- importantstructuring agents in these fossil munitycomposition and diversityin eastern faunas. In addition, because the composition North Pacificwith that of the western North of Recent seabird communitiesis contingent Pacific.Nevertheless, fluctuations in sea level upon historical events (e.g., radiations and in California during Fauna IV time and into extinctions),factors governing these histori- the Pleistocene mayhave rapidlychanged the cal events (e.g., Antarcticglaciation) are, in amount and quality of available seabird and themselves,structuring agents of the Recent pinniped breeding (or haul-out) space (War- communities. heit and Lindberg 1988). Seabird taxa thatare morphologically and behaviorally equipped Conclusion to cope with these rapid changes in habitat Changes in the relative geographic posi- would have higher probabilities of survival tions of Antarctica, Australia, Central and than taxa that are unable to alter theirbreed- South America,and India during the Tertiary ing habitat preferences. produced profound effectson the paleocean- Vrba and Gould (1986 and referencesthere- ographyof the NorthPacific. Large-scale phe- in) discussed the interaction among organ- nomena, such as tectonic events in the ism-level characters (e.g., breeding-habitat Southern Hemisphere, affectedthe North Pa- preference)and the environment(e.g., avail- cific on several temporal and spatial scales. abilityof breeding space), and speciation and The continued breakup of the Antarctic/Aus- extinction. They hypothesized (p. 224) that tralian continent, and the widening of the "the probabilitythat organisms will perceive East Indian AntarcticBasin in the Late Eocene environmental changes as deterioration of resultedin a worldwide decline of ocean-bot- habitat is greater in the case of certain spe- tom temperatures(stage 1). The decline in cialists than in generalists.Thus, such steno- temperaturesin the North Pacific coincided topes [specialists]should be subject more fre- with the evolution of plotopteridsand pseud- quently to directional selection at the level odontorns in both the western and eastern of genotypes and phenotypes, and conse- NorthPacific. The widening of Drake Passage quently to fragmentationand divergence of between Antarcticaand South America dur- populations, speciation,and extinction."The ing the EarlyMiocene intensifiedthe thermal rapid rise of marine Laridae in Fauna IV (es- isolation of Antarctica and provided near- pecially between Fauna IV and the Recent) freezing ocean-bottom waters to the North and the Pleistocene extinctionof the Sulidae Pacific(stages 2 and 3). These events coincid- in the California Current system may have ed with the rise of seabird faunas moretypical been related to their relative abilities to cope of Recent seabird systems(Fauna I). Because with the environmental fluctuations (see these physical events were global in nature, Warheit and Lindberg 1988). The taxonomic they affectedthe North Pacific as a whole, decline of the flightlessmancallids between producing similar changes in the avifauna of Fauna III and IV and their Pleistocene ex- both Japan and the eastern Pacific. tinction may be related to local changes in The increase in the latitudinalthermal gra- sea level and the synchronousdiversification dient during the Middle and Late Miocene of pinnipeds (Warheit and Lindberg 1988). (stage 4; Fauna II) was also related to tectonic As with the flightlessplotopterids, mancallid events in the Southern Hemisphere and gla- extinctionmay have resulted fromcompeti- ciation on Antarctica.Nevertheless, its com- tion forbreeding space with gregarious pin- bined effectwith the contemporaneous rise nipeds ratherthan fromchanges in food re- of the Isthmus of Panama, and the presence sources (Warheitand Lindberg 1988). Because of an eastern boundary currentoff California mancallids and sulids were among the most produced local, small-scale changes in the diverse and ubiquitous taxa in the California oceanographic properties particular to the Currentseabird communities (figs. 2, 5), the California Current. The dramatic rise of the ecological and geological factorsthat contrib- Alcidae and the morphological diversifica-

This content downloaded from 152.3.102.242 on Sun, 8 Sep 2013 20:56:41 PM All use subject to JSTOR Terms and Conditions FOSSIL SEABIRDS FROM THE NORTH PACIFIC 419 tion of the Sulidae in California coincided PacificSeabird Group forinviting me to par- with these local changes in bottom temper- ticipate. Finally, I wrote a portion of this pa- atureand upwelling. Rapid changes in eustat- per as a graduate student in the Department ic sea level and the evolution of gregarious of Paleontology, University of California, pinnipeds in the eastern North Pacific (stage Berkeley.I thank my dissertationcommittee, 5) are other examples of local, small-scale K. Padian, D. Lindberg,and D. Wake fortheir phenomena thatmay have influencedseabird help on all aspects of my graduate work. I diversityin Californiaduring the timeof Fau- also thank the National Museum of Natural na IV. History (Smithsonian Institution), and the Structure and diversity of seabird com- CaliforniaAcademy of Sciences and T. Tilton munities in the North Pacific today are, in forgranting me postdoctoralfellowships, and part,functions of historicalevents operating providing the financial and administrative at several temporal and spatial scales. Simi- resources to complete this paper. larities among seabird communities within the North Pacificand between the North Pa- cificand the North Atlanticmay be more the Literature Cited product of long-term,large-scale geological Addicott, W. 0. 1977. Neogene chronostratigarphyof near- events than convergentsimilarities resulting shore marine basins of the eastern North Pacific.Pp. 151-175 from similar environmental conditions to- in T. Saito and H. Ujiie, eds. Proceedings of the FirstInterna- tional Congress on PacificNeogene Stratigraphy,Tokyo, 1976. day. Conversely,seabird communitieswithin Science Council of Japan,Tokyo. the North Pacific may differin composition Ainley, D. G. 1977. Feeding methods of seabirds: a comparison as a resultof smaller-scale,regional phenom- of polar and tropical communities.Pp. 669-685 in G. A. Llano, ed. Adaptations in Antarctic ecosystems. Gulf Publishing, ena. The interactionsamong the differently Houston. scaled geologic and ecologic factorsproduced Ainley, D. G., and R. J.Boekelheide. 1984. An ecological com- the structurein today's seabird systems.I urge parison of oceanic seabird communities of the South Pacific Ocean. Studies in Avian Biology 8:2-23. seabird biologists to use all available data, , eds. 1990. Seabirds of the Farallon Islands. Ecology, including the fossil recordand oceanograph- dynamics,and structureof an upwelling-systemcommunity. ic histories,to testhypotheses concerning the StanfordUniversity Press, Stanford,Calif. Ainley, D. G., and T. J. Lewis. 1974. The historyof Farallon structureof seabird systemsthroughout the Island marinebird populations, 1854-1972. Condor 76:432-446. world. Ainley,D. G., R. E. LeResche, and W.J.L.Sladen. 1983. Breeding biology of the Adelie Penguin. Universityof California Press, Acknowledgments Berkeley. Ainley, D. G., H. R. Carter,D. W. Anderson, K. T. Briggs,M. C. I thank L. Barnes, J. Becker, R. Chandler, Coulter, F. Cruz, J.B. Cruz, C. A. Valle, S. I. Fefer,S. A. Hatch, H. Howard, S. Olson, and F. Perry for dis- E. A. Schreiber,R. W. Schreiber,and N. G. Smith. 1986. Effects of the 1982-83 El Nifio-SouthernOscillation on Pacific Ocean cussions on North Pacific fossil seabirds. L. bird populations. Pp. 1747-1758 in H. Ouellet, ed. Acta XIX Barnes and C. Swisher helped me understand Congressus InternationalisOrnithologici. Universityof Otta- geologic time, and their knowledge of bio- wa Press, Ottawa. Armentrout,J. M. 1981. Correlation and ages of Cenozoic stratigraphyhas been essential for me in,re- chronostratigraphicunits in Oregon and Washington.Pp. 137- constructingthe seabird faunas. D. Lindberg 148 in J.M. Armentrout,ed. Pacific NorthwestCenozoic bio- has been influentialin convincing me of the stratigraphy.Geological Society of America Special Paper 184. Armentrout,J. M., D. A. Hull, J. D. Beaulieu, and W. W. Rau. importance of paleontology in understand- 1983. Correlationof the stratigraphicunits in westernOregon ing structurein Recent ecological commu- and Washington.Oregon Departmentof Geology and Mineral nities. I thank D. Lindberg, C. Niemi, K. Pa- IndustriesOil and Gas Investigation7:1-90. Ashmole, N. P. 1971. Seabird ecology and the marine envi- dian, S. Olson, M. Russell, G. Vermeij,R. Zusi, ronment.Pp. 223-286 in D. S. Farnerand J.R. King, eds. Avian and especially J. Barron for reading and im- biology, Vol. 1. Academic Press, New York. proving various draftsof this paper. Details Barnes, L. G. 1976. Outline of Eastern North Pacific fossil ce- tacean assemblages. SystematicZoology 25:321-343. of this paper were firstpresented in Victoria, Barnes,L. G., H. Howard, J.H. Hutchison,and B. J.Welton. 1981. BritishColumbia at the 1990 Pacific Seabird The vertebratefossils of the marine Cenozoic San Mateo For- Group symposium on the status and conser- mation at Oceanside, California.Pp. 53-70 in P. L. Abbott,and 0. Shannon, eds. Geologic investigations of the San Diego vation of North Pacific seabirds. I thank K. Coastal Plain. San Diego Association of Geologists,San Diego, Vermeer,K. Briggs,D. Siegel-Causey, and the Calif.

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Oceanside, San Diego County,California, with descriptionsof 1951. A Miocene petrel fromCalifornia. Condor 53:78- two new species of the genera Uriaand Cepphus(Aves: Alcidae). 80. Natural HistoryMuseum of Los Angeles County Contributions 1961. Birds fromthe Miocene of SharktoothHill, Cal- in Science 341:1-15. ifornia.Condor 63:399-402. . 1983. A list of the extinct fossil birds of California. 1962. A new albatross fromthe Miocene of California. Bulletin of the Southern California Academy of Sciences 82: Condor 64:471-472. 1-11. Miller, L. H., and R. I. Bowman. 1958. Furtherbird remains . 1984. Additional records from the Miocene of Kern fromthe San Diego Pliocene. Natural HistoryMuseum of Los County, California with the description of a new species of Angeles County Contributionsin Science 20:3-15. fulmar (Aves: Procellariidae). Bulletin of the Southern Cali- Miller,L. H., and H. Howard. 1949. The flightlessPliocene bird forniaAcademy of Sciences 83:84-89. Mancalla. Carnegie Institutionof Washington Publication 584: Howard, H., and L. G. Barnes. 1987. Middle Miocene marine 201-228. birds fromthe foothillsof the Santa Ana Mountains, Orange Obradovich,J.D., and C. W. Naeser. 1981. Geochronologybear- County, California. Natural History Museum of Los Angeles ing on the age of the MontereyFormation and siliceous rocks County Contributionsin Science 383:1-9. in California. Pp. 87-95 in Garrison and Douglas 1981. Howard, H., and S. L. Warter. 1969. A new species of bony- Okazaki, Y. 1989. An occurrence of fossil bony-toothedbird toothedbird (Family Pseudodontornithidae)from the Tertiary (Odontopterygiformes)from the Ashiya Group (Oligocene), of New Zealand. Records of the CanterburyMuseum 8:345- Japan.Bulletin of the KitakyushuMuseum of Natural History 357. 9:123-126. Howard, H., and J.A. White. 1962. A second recordof Osteodon- Olson, S. L. 1980. A new genus of penguin-like Pelecaniform tornis,Miocene "toothed" bird. Natural History Museum of bird fromthe Oligocene of Washington (Pelecaniformes:Plo- Los Angeles County Contributionsin Science 52:1-12. topteridae). Natural History Museum of Los Angeles County Janzen,D. H., and P. S. Martin. 1982. Neotropical anachronisms: Contributionsin Science 330:51-57. the fruitsthe gomphotheres ate. Science (Washington, D.C.) 1981. A thirdspecies of Mancalla fromthe Late Pliocene 215:19-27. San Diego Formationof California (Aves: Alcidae). Journalof Keller, G., and J. A. Barron. 1981. Integrated planktic forami- VertebratePaleontology 1:97-99. niferaland diatom biochronologyfor the northeastPacific and . 1985. The fossil record of birds. Pp. 79-252 in D. S.

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Farner,J. R. King, and K. C. Parkes, eds. Avian biology, Vol. through earliest Pliocene) in North America. Pp. 153-211 in VIII. Academic Press, Orlando, Fla. M. 0. Woodburne, ed. Cenozoic mammals of North America Olson, S. L., and Y. Hasegawa. 1979. Fossil counterpartsof giant geochronology and biostratigraphy.University of California penguins fromthe North Pacific. Science (Washington,D.C.) Press, Berkeley. 206:688-689. Van Devender, T. R. 1986. Climatic cadences and the compo- . 1985. A femur of Plotopterumfrom the early Middle sition of Chihuahuan Desert communities:the Late Pleistocene Miocene of Japan (Pelecaniformes:Plotopteridae). Bulletin of packrat midden record. Pp. 285-299 in J. Diamond, and T. J. the National Science Museum, Ser. C 11:137-140. Case, eds. Communityecology. Harper and Row, New York. Ono, K. 1980. Pliocene tubinarebird fromKakegawa, Shizuoka Vermeij,G. J. 1989. Geographical restrictionas a guide to the Prefecture,Japan. Memoirs of the National Science Museum, causes of extinction:the case of the cold northernoceans dur- Ser. C 13:29-34. [In Japanese with English abstract.] ing the Neogene. Paleobiology 15:335-356. . 1983. A Miocene bird (gannet) from Chichibu Basin, Vrba, E. S., and S. J. Gould. 1986. The hierarchical expansion centralJapan. Bulletin Saitama Museum of Natural History 1: of sortingand selection: sortingand selection cannot be equat- 11-15. [In Japanese with English abstract.] ed. Paleobiology 12:217-228. 1989. A bony-toothedbird fromthe Middle Miocene, Warheit,K. I. 1990. The phylogeny of the Sulidae (Aves: Pel- Chichibu Basin, Japan. Bulletin of the National Science Mu- ecaniformes)and the morphometryof flight-relatedstructures seum, Ser. C 15:33-38. in seabirds: a study of adaptation. Unpublished Ph.D. disser- Pianka, E. R. 1983. Evolutionaryecology. Harper and Row, New tation,University of California,Berkeley. York. Warheit,K. I., and D. R. Lindberg. 1988. Interactionsbetween Pocklington,R. 1979. An oceanographic interpretationof sea- seabirds and marinemammals through time: interference com- bird distributionsin the Indian Ocean. Marine Biology 51:9- petitionat breeding sites. Pp. 292-328 in J.Burger, ed. Seabirds 21. and othermarine vertebrates: competition, predation, and oth- Raschke,R. E. 1984. Earlyand Middle Miocene vertebratesfrom er interactions.Columbia UniversityPress, New York. the Santa Ana Mountains, California.Pp. 61-67 in B. Butler,J. Weaver, F. M., R. E. Casey, and A. M. Perez. 1981. Stratigraphic Gant, and C. Stadum, eds. The Natural Sciences of Orange and paleoceanographic significanceof Early Pliocene to Mid- County.Memoirs of the Natural HistoryFoundation of Orange dle Miocene radiolarian assemblages from Northern to Baja County, Newport Beach, Calif. California. Pp. 71-86 in Garrison and Douglas 1981. Rea, D. K., J.C. Zachos, R. M. Owen, and P. D. Gingerich. 1990. Wetmore,A. 1928. The systematicposition of the fossil bird Global change at the Paleocene-Eocene boundary: climate and Cyphornismagnus. Canada Department of Mines. Geological evolutionary consequences of tectonic events. Paleogeogra- Survey Bulletin 49:1-4. phy, Palaeoclimatology, Palaeoecology 79:117-128. 1930. Fossil bird remains fromthe Temblor Formation Repenning, C. A., and R. H. Tedford. 1977. Otarioid seals of near Bakersfield,California. Proceedings of the California the Neogene. United States Geological Survey Professional Academy of Sciences 19:85-93. Paper 992. Woodburne, M. O., ed. 1987. Cenozoic mammals of North Richdale, L. E. 1957. A population study of penguins. Oxford America: geochronology and biostratigraphyUniversity of UniversityPress, London. California Press, Berkeley. Ricklefs,R. E. 1973. Ecology. Chiron, Newton, Mass. Woodruff,F., and S. Savin. 1989. Miocene deepwater ocean- Roughgarden,J. 1989. The structureand assembly of commu- ography. Paleoceanography 4:87-140. nities. Pp. 203-226 in J. Roughgarden, R. M. May, and S. A. Woodruff,F., S. M. Savin, and R. G. Douglas. 1981. Miocene Levin, eds. Perspectives in ecological theory.Princeton Uni- stable isotope record: a detailed deep Pacific ocean study and versityPress, Princeton,N.J. its paleoclimatic implications.Science (Washington,D.C.) 212: Ruddiman, W. F., and J. E. Kutzbach. 1989. Forcing of late 665-668. Cenozoic NorthHemipshere climateby plateau upliftin south- Zusi, R. L., and K. I. Warheit. 1992. Evolution of the intraman- ern Asia and the American West. Journalof Geophysical Re- dibular joint of pseudodontorns.Pp. 351-360 inK. E. Campbell, search 94:18409-18427. Jr.,ed. Papers in avian paleontology honoringPierce Brodkorb. Savin, S. M., R. G. Douglas, and F. G. Stehli. 1975. Tertiary Science Series, no. 36. Natural HistoryMuseum of Los Angeles marine paleotemperatures.Geological Society of America Bul- County, Los Angeles, Calif. letin 86:1499-1510. Schreiber,R. W., and E. A. Schreiber. 1984. Central Pacificsea- Appendix birds and the El Nifno-SouthernOscillation: 1982-1983 per- The following is a list of formationsincluded in each seabird spectives. Science (Washington,D.C.) 225:713-719. fauna. Following the formationname and location are reference Siegel-Causey, D. 1988. Phylogeny of the Phalacrocoracidae. numbers (in parentheses) correspondingto the referenceslisted Condor 90:885-905. in figure2. Storer,R. W. 1960. Evolution in the diving birds. Pp. 694-707 in G. Bergman, K. 0. Donner, and L. v. Haartman, eds. Pro- FAUNA A (52-38 Ma) ceedings of the XII InternationalOrnithological Congress, Hel- sinki,June 5-12, 1958. InternationalOrnithological Congress, 1. "Cowlitz (Tejon) Eocene ... near Coos Bay" (A. Miller 1931: Helsinki. p. 23), Coos Co., Oreg. (6) Swisher,C. C., III, and D. R. Prothero. 1990. Single-crystal40Ar/ a) "Tejon" in Miles (1981) = 46-43 Ma. Planktonic Forami- 39Ardating of the Eocene-Oligocene transitionon NorthAmer- niferalZones P12-P14 (=46-41 Ma in Berggrenet al. 1985) ica. Science (Washington,D.C.) 249:760-762. b) "Cowlitz-Coalado Fauna" in Armentrout(1981) = 49-39 Takeyama, K.-I., and T. Ozawa. 1984. A new Miocene otarioid Ma. Planktonic ForaminiferalZones P10-P15 (=52-38 Ma seal fromJapan. Proceedings of the JapanAcademy, Ser. B 60: in Berggrenet al. 1985) 36-39. 2. Keasey Formation,Washington Co., Oreg. (45, 46) Tedford,R. H., M. F. Skinner, R. W. Fields, J.M. Rensberger,D. a) 40.5-39 Ma in Armentroutet al. 1983 P. Whistler,T. Galusha, B. E. Taylor, J. R. MacDonald, and S. b) Goedert (1988, 1989) considered the formationcorrelated D. Webb. 1987. Faunal succession and biochronology of the with the Priabonian ChronostratigraphicStage (40-36.6 Ma Arikareean through Hemphillian interval (Late Oligocene in Berggrenet al. 1985).

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FAUNA B (31 [?]-22.8 Ma) 4. Astoria Formation,Lincoln Co., Oreg. (40) a) 18-17 Ma in Armentroutet al. (1983) 1. PyshtFormation of Twin River Group,Clallam Co., Wash. (38) b) Goedert (1989) stated thatthis formationis correlatedwith 31(?)-24 Ma in Armentroutet al. 1983 the Newportian and not the Pillarian Molluscan Stage, as 2. Hatazu, Asagai, and Ashiya Formations,Honshu and northern reportedby Becker (1987). Armentroutshowed the New- Kyushu, Japan (35, 36, 47) portian Molluscan Stage as being 20-13 Ma. a) According to Hasegawa (1977), the Hatazu and Asagai For- 5. Nagura Formation,Chichibu, Saitama Prefecture,Japan, and mations are correlated with the Chattian Chronostrati- Akeyo Formation,Mizunami, Gifu Prefecture,Japan (37, 42, graphic Stage (30-23.7 Ma in Berggrenet al. 1985), and the 43, 47) Ashiya Formationis correlatedwith the Aquitanian Chro- Correlationswith North Americanages and formationsare nostratigraphicStage (23.7-22.8 Ma in Berggrenet al. 1985). not well understood. Olson and Hasegawa (1985: 138) b) Although Berggren et al. (1985) placed the beginning of p. stated that the Akeyo Formationis a correlativeof the Na- the Chattian at 30 Ma (Magnetic Polarity Anomaly 10 in taki Formation in Japan and "approximately correlative Chron 10), Swisher and Prothero(1990) placed this anom- with the AstoriaFormation of Oregon some 15 to 18 million aly at about 28 Ma. years ago." Ono (1989) stated that the Nagura Formation 3. Carmanah Point,Vancouver Island, BritishColumbia, Canada and fossil fromthe Mizunami Basin (=Akeyo Formation) (1, 16, 46) are Middle Miocene (approximately17-12 Ma in Berggren Becker (1987) summarized the debate concerning the age et al. 1985). of this locality. The only seabird fossil fromthis locality is Cyphornismagnus, described by Cope (1895: p. 451) as "not older than Eocene nor later than Oligocene." However, FAUNA II (13-8[6] Ma) Wetmore (1928) considered the fossil Miocene in age, 1. Laguna Hills (Leisure World locality): Monterey Formation, whereas Ray (personal communication in Becker [1987]) Orange Co., Calif. (22, 23) believed thislocality to be Oligocene. Finally,Goedert (1989) The age of this locality was discussed by Howard (1976, provided data suggesting that the Carmanah Point rocks 1978). Based on vertebratefossil correlations,the age is are Late Eocene to Early Oligocene in age. I listed this estimatedto be Clarendonian N.A. Land-Mammal Age (12- locality here, and considered C. magnusto be in Fauna B 9 Ma in Tedfordet al. 1987, but slightlyolder than Laguna for convenience only. Niguel. 2. Laguna Niguel: Monterey Formation,Orange Co., Calif. (28, FAUNA C (24-18 Ma) 29) 1. PyramidHill Local Fauna of JewettSand, Kern Co., Calif. (24, The age of this locality was discussed by Howard (1976, 27, 36) 1978). Based on vertebratefossil correlations,the age is Tedford et al. (1987) placed this local fauna at 22-21 Ma. estimated to be Clarendonian (12-9 Ma in Tedford et al. Considered late Arikareean North American (N.A.) Land- 1987), but slightlyyounger than Laguna Hills locality. Mammal Age 3. Flagstone Quarry (Tepusquet Creek): Monterey Formation, 2. Nye Formationor Mudstone, Lincoln Co., Oregon (40) Santa Barbara Co., Calif. (19) 24-18 Ma in Armentroutet al. (1983) Howard (1983) stated,without explanation,that Tepusquet Canyon is correlated with the Clarendonian N.A. Land- FAUNA I (18 [or 15]-13 [or 12] Ma) Mammal Age (12-9 Ma in Tedford et al. 1987). 4. Taylor Quarry: Santa Margarita Formation, Santa Cruz Co., The firstthree formationslisted in this fauna are in California Calif. (49, 50) and northernBaja Californiaand between 15 and 13 Ma. The last This formationwas figuredby Barron (1986a) and consid- two localities are in Japanor Oregon and slightlyolder (possibly ered by Repenning and Tedford (1977) to be 12-9 Ma. as old as 18 Ma). Unfortunatelymost of the fossil materialin this 5. Valmonte (Lomita) Diatomite: Monterey Formation,Los An- fauna is fromthe firstthree formations,with only a few speci- geles Co., Calif. (8) mens fromthe lattertwo localities. When additional fossil and a) Obradovich and Naeser (1981) placed the Valmonte Diat- stratigraphicdata are obtained, it may be possible to divide this omite at 13 (12)-8 Ma, but discussed an ash deposit 38 m fauna into two faunas,with the older two localitiesbeing referred fromtop of diatomitethat has a fission-trackdate of 6.9 ? to as Fauna D. 0.6 Ma. 1. SharktoothHill Local Fauna, Round Mountain Silt, Kern Co., b) Barron(1986a) showed theValmonte Diatomite to be roughly Calif. (12, 13, 17, 21, 32, 40, 44, 49, 50) 12-7.5 Ma. Tedford et al. (1987) placed this local fauna at 15-13 Ma. 6. Modelo Formation,El Sereno, Studio City,and Calabasas, Los Considered late Barstovian N.A. Land-Mammal Age and Angeles Co., Calif. (5, 20) Luisian Benthic ForaminiferalStage a) Obradovich and Naeser (1981) showed two fission-track 2. La Misi6n Local Fauna, Rosarito Beach Formation, north- dates of 7.8 ? 0.8 and 11.5 ? 1.2 within the Modelo For- western Baja California,Mexico (44) mation. According to their figure4, these dates are from According to Demere et al. (1984) this local fauna also the middle to lower portionsof the formation,respectively. includes silicoflagellatesindicative of the Corbisematriacan- No seabird publication indicated the place in the formation tha Zone dated at 14-15 Ma. Potassium-argonradiometric fromwhich the fossils were recovered. dates for basalts located above and below the local fauna b) Barron(1986a) providedbiostratigraphic age estimates(based are 14.3 ? 2.6 Ma and 16.1 ? 2.1 Ma, respectively(Demere on Benthic ForaminiferalZones) for the dates listed by et al. 1984). Obradovich and Naeser (1981). These ages are 8.6-6.5 Ma 3. Upper Oso Dam assemblage, Topanga Formation,Orange Co., and 13.9-13.3 Ma, respectively. Calif. (33) 7. Lompoc Diatomite: Sisquoc/Monterey Formation,Santa Bar- Based on the shark,and marine and land mammal fossils, bara Co., Calif. (4, 30) Howard and Barnes (1987) and Rashcke (1984) considered The exact location of this locality is not known. All micro- this assemblage to be of the same age as the Sharktooth fossil evidence discussed below assumes that the seabirds Hill local fauna. (and marine mammals) were recovered from the Johns-

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Manville diatomite Quarry (Barron personal communica- b) Based on diatom biostratigraphyBarron (1986a) estimated tion 1990). Barnes (personal communication 1990) sug- the age at roughly 6-4.5 Ma. gested that the marine mammals and birds fromLompoc c) Based on magnetic stratigraphyMadrid et al. (in Barron were not fromthat quarry,but froma quarry to the west 1986a) showed that the lower part of the Purisima extends of Johns-Manville. fromthe upper part of polarityChron 6 to the lower part of the GilbertReversed polarityChron (6-5 Ma in a) Biostratigraphyof marine vertebrates(see, e.g., Repenning Berggren et al. 1985) and Tedford 1977) stronglysuggests that this locality is 4. Capistrano Formation,Orange Co., Calif. (11) Clarendonian N.A. Land-Mammal Age, Mohnian Benthic a) Miller (1951) described this formationas Middle Miocene, ForaminiferalStage, and about 12-10 Ma. The GrefcoQuar- whereas Howard (1983) listed Oceanodromahubbsi (the ryis to the east of Lompoc and is roughly 11-9 Ma (Barron only seabird fromthis formation)as being Late personal communication 1991). Miocene-Early Pliocene, or Hemphillian N.A. Land-Mammal Age. Tedford b Obradovich and Naeser (1981) dated an ash bed 165 m et al. (1987) placed the Hemphillian at 9-4.5 Ma. above the footwall of the Johns-ManvilleQuarry at 7.6 ? b) Barron (1986a) figured the Capistrano Formation from 1.3 Ma. These authors also considered this locality to be Newport Beach, California as correlatedwith the Purisima within the Monterey Formation. Formation.He also showed the boundarybetween the old- c) Barron (1986a, personal communication 1990) also placed er MontereyFormation and younger Capistrano Formation the Johns-ManvilleQuarry within the MontereyFormation at 5.5 Ma. and showed it to be roughly 8-6 Ma. 5. Dainichi Sand of Kakegawa Group, Kakegawa, Shizuoka Pre- Therefore,there are two estimatesfor the age of this locality:12- fecture,Japan (47) 10 Ma and 8 (8.9)-6 Ma. Okazaki (1989) listed two seabird localities fromthe Plio- cene of Japan: Maesawa, Iwate Prefectureand Kakegawa, Shizuoka Prefecture.Ono (1980) considered the Kakegawa, FAUNAIII (7[6]-4 Ma) Shizuoka Prefecturelocality Middle Pliocene. According 1. San Mateo Formation,Oceanside, San Diego Co., Calif. (31, to Berggren et al. (1985) the Pliocene ranges fromabout 41) 5.3 to 1.6 Ma, the middle of which is 3.7 Ma (there is no Barnes (1976) stated that the San Mateo, Purisima, Capis- formal"middle Pliocene" epoch). trano, and Almejas Formations are correlated with each Based on the correlationsof Barnes (1976) and Barron (1986a) I other,and may be correlatedwith the Jacalitosand Etch- estimated the age of Fauna III to be about 7 (6)-4 Ma. egoin Formations,making these formationscorrelated with the "Jacalitos"and "Etchegoin"Provincial Molluscan Stages. FAUNA IV (3-1.5 Ma) Barnes (1976: p. 331) added that the formationsare "less directly"correlated with the Hemphillian N.A. Land-Mam- 1. San Diego Formation,San Diego Co., Calif. (9, 14, 15, 18, 25, mal Age and the late Delmontian, Repettian,and Venturian 26, 39, 48) ForaminiferalStages. Barnes did not explicitlyspecify how a) Barnes (1976: p. 332) stated that the San Diego Formation theseformations were correlated,but were presumablybased is "younger than the vertebrate-bearinglevels in the lower on the fossil cetaceans. part of the Almejas Formation ... and thereforejudged 2. Almejas Formation,Isla Cedros, Baja California,Mexico (26) indirectlyto be younger than the bulk of the Purisima, a) Howard (1971) considered this formationEarly Pliocene. Capistrano, and Drakes Bay Formations,may be broadly b) Barnes (1976) considered this formationcorrelated with the correlativewith the Blancan North American [Land Mam- San Mateo Formation(see above). mal Age], the Wheelerian foraminiferalstage, the 'San Joa- c) Repenning and Tedford(1977) estimatedthe age of otarioid quin' provincial molluscan stage...." seals fromthis formationat 8-6 Ma. b) Dem&re (1983) considered the San Diego Formation no 3. Purisima Formation,Santa Cruz Co. and San Mateo Co., Calif. older than Planktonic ForaminiferalZone N21 (3-2 Ma in (49, 40; F. Perryin preparation) Berggrenet al. 1985) and at least as young as the Emiliania a) Repenning and Tedford(1977) estimatedthe age of otarioid annulaSubzone, dated at approximately1.5 Ma. seals from this formationin Santa Cruz County at 6.7-4 c) Repenning and Tedford (1977) estimated the age of the Ma. otarioid seals fromthis formationat 4-2 Ma.

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