Eocene-Oligocene Climatic and Biotic Evolution

Eocene-Oligocene Climatic and Biotic Evolution

Donald R. Prothero
William A. Berggren
Copyright Date: 1992
Pages: 582
https://www.jstor.org/stable/j.ctt7zvp65
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  • Book Info
    Eocene-Oligocene Climatic and Biotic Evolution
    Book Description:

    The transition from the Eocene to the Oligocene epochs was the most significant event in earth history since the extinction of dinosaurs. As the first Antarctic ice sheets appeared, major extinctions and faunal turnovers took place on the land and in the sea, eliminating forms adapted to a tropical world and replacing them with the ancestors of most of our modern animal and plant life. Through a detailed study of climatic conditions and of organisms buried in Eocene-Oligocene sediments, this volume shows that the separation of Antarctica from Australia was a critical factor in changing oceanic circulation and ultimately world climate. In this book forty-eight leading scientists examine the full range of Eocene and Oligocene phenomena. Their articles cover nearly every major group of organisms in the ocean and on land and include evidence from paleontology, stable isotopes, sedimentology, seismology, and computer climatic modeling. The volume concludes with an update of the geochronologic framework of the late Paleogene.

    Originally published in 1992.

    ThePrinceton Legacy Libraryuses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

    eISBN: 978-1-4008-6292-4
    Subjects: Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-viii)
  3. LIST OF CONTRIBUTORS
    (pp. ix-xii)
  4. PREFACE
    (pp. xiii-xiv)
  5. EOCENE-OLIGOCENE CLIMATIC AND BIOTIC EVOLUTION: AN OVERVIEW
    (pp. 1-28)
    William A. Berggren and Donald R. Prothero

    The middle Eocene-early Oligocene was a critical period in earth history in that major changes in ocean circulation and global climate, reflected in significant turnovers in marine and terrestrial biotas, occurred over an approximately 10 m.y. interval. Because of its strategic importance intermediate between the globally warm (non-glaciated) Late Cretaceous and the cooler (glaciated) Neogene, and because of the flood of new information becoming available on mid-Paleogene geology, we organized a symposium devoted to the subject in August, 1989 (Prothero et al., 1990). The topic which forms the title of this book was vigorously discussed over the period of a...

  6. PART I: THE CHRONOLOGICAL FRAMEWORK
    • 1. TOWARD A REVISED PALEOGENE GEOCHRONOLOGY
      (pp. 29-45)
      William A. Berggren, Dennis V. Kent, John D. Obradovich and Carl C. Swisher III

      It is six years since we published a time scale for the Paleogene (Berggren et al., 1985a, b). All available first-order correlations between Paleogene calcareous plankton and magnetostratigraphy were compiled in Berggren et al. (1985a). Since that time there have been several additions and refinements to this data set; those relevant to late Eocene – early Oligocene geochronology are shown in Tables 1.1 (planktonic foraminifera) and 1.2 (calcareous nannoplankton). Inasmuch as we view a time scale to consist of a data set which integrates information from biostratigraphy, radioisotopes, magnetostratigraphy and sea-floor anomalies (Aubry et al., 1988), we believe that a thorough...

    • 2. MAGNETOSTRATIGRAPHY AND GEOCHRONOLOGY OF THE TERRESTRIAL EOCENE-OLIGOCENE TRANSITION IN NORTH AMERICA
      (pp. 46-73)
      Donald R. Prothero and Carl C. Swisher III

      Since the first discovery of fossil vertebrates in the Big Badlands of South Dakota in 1846, terrestrial rocks and fossils of the North American Eocene-Oligocene transition have been extensively studied. The highly fossiliferous deposits of the White River Group in the Big Badlands of South Dakota (and in Nebraska, Wyoming, Colorado, and North Dakota) have been an irresistible magnet to both amateur and professional collectors (Figure 2.1). Early in this century, the Uinta Basin provided a window on the middle and late Eocene in North America. As a result, Wood et al. (1941) used fossils from these two areas to...

    • 3. MAGNETOSTRATIGRAPHY OF THE LOWER AND MIDDLE MEMBERS OF THE DEVIL’S GRAVEYARD FORMATION (MIDDLE EOCENE), TRANS-PECOS TEXAS
      (pp. 74-87)
      Anne H. Walton

      The Eocene North American Land Mammal “Ages” (NALMAs) were recognized and named in the Rocky Mountain basins of the Northern Interior. Precise correlation of these well-known faunas with those of other areas, such as the semitropical and tropical regions of North America or with other continents, could greatly refine the reconstruction of Eocene-Oligocene paleoclimates and biotic evolution. Eocene-Oligocene faunas from the boundary region between North America and Mesoamerica(sensu lato)are preserved in Texas. The Devil’s Graveyard Formation (Stevens et al., 1984), in the Trans-Pecos volcanic field, includes four distinct vertebrate faunas ascribable to the Bridgerian to Chadronian NALMAs. The...

    • 4. REDEFINITION OF THE DUCHESNEAN LAND MAMMAL “AGE,” LATE EOCENE OF WESTERN NORTH AMERICA
      (pp. 88-105)
      Spencer G. Lucas

      Wood et al. (1941) proposed a sequence of land-mammal “ages” to discriminate intervals of Cenozoic time in western North America. With the exception of Dragonian, a Paleocene LMA based on a fauna from Utah, all the LMA’s of Wood et al. (1941) are still in use (Woodburne, 1987a). Yet, despite their durability, the validity of a few LMA’s has been a source of contention. This is true of the Duchesnean, identified by Wood et al. (1941) as the youngest Eocene LMA. The Duchesnean LMA has either been questioned, abandoned, subdivided or defended. Here, I defend the validity of the Duchesnean...

    • 5. MAMMALIAN RANGE ZONES IN THE CHADRONIAN WHITE RIVER FORMATION AT FLAGSTAFF RIM, WYOMING
      (pp. 106-115)
      Robert J. Emry

      The White River Formation at Flagstaff Rim in central Wyoming was recognized as a potentially very important section for developing a Chadronian mammalian biostratigraphy (Emry, 1973) that might be useful for resolving time intervals within the Chadronian NALMA. Its potential derives from several attributes that are not all present in a single continuous section elsewhere: it is thick compared to most Chadronian sections, is abundantly fossiliferous through much of its extent, appears to represent much of Chadronian time, and has a series of volcanic ash beds for which radiometric ages had been determined (Evernden et al., 1964). These same characteristics...

    • 6. EOCENE-OLIGOCENE CLIMATIC CHANGE IN NORTH AMERICA: THE WHITE RIVER FORMATION NEAR DOUGLAS, EAST-CENTRAL WYOMING
      (pp. 116-130)
      Emmett Evanoff, Donald R. Prothero and R. H. Lander

      The White River Group, a fine-grained volcaniclastic sequence in the western United States, records faunal, depositional, and paleoclimatic changes across the Eocene/Oligocene boundary. It contains the most complete late Eocene and early Oligocene vertebrate record in North America, and somewhat less well known invertebrate, sedimentologic, and volcaniclastic records. The White River Group is an unconformity-bounded nonmarine sequence(sensuHanneman, 1988, 1989) that extends across the northern Great Plains and central Rocky Mountains (Figure 6.1). It is treated as a formation in Colorado, Wyoming, and North Dakota, but is considered a group in Nebraska and South Dakota, where it includes the...

  7. PART II: CLIMATIC EVENTS
    • 7. EVIDENCE FROM THE ANTARCTIC CONTINENTAL MARGIN OF LATE PALEOGENE ICE SHEETS: A MANIFESTATION OF PLATE REORGANIZATION AND SYNCHRONOUS CHANGES IN ATMOSPHERIC CIRCULATION OVER THE EMERGING SOUTHERN OCEAN?
      (pp. 131-159)
      Louis R. Bartek, Lisa Cirbus Sloan, John B. Anderson and Malcolm I. Ross

      The onset of extreme glacial conditions in Antarctica and the ensuing glacial history of the continent have been the objects of controversy for a number of years. The controversy arises from the fragmented nature of the available data bases. Ninety-seven percent of the continent is shrouded in ice, so researchers are often faced with disjointed bits of information that are available in only one part of the continent (or ocean basin) and that frequently represent only a small segment of the stratigraphic record from that geographic area. Another factor that has contributed to the controversy is the variety of data...

    • 8. MIDDLE EOCENE TO OLIGOCENE STABLE ISOTOPES, CLIMATE, AND DEEP-WATER HISTORY: THE TERMINAL EOCENE EVENT?
      (pp. 160-177)
      Kenneth G. Miller

      First introduced by Wolfe (1978), the concept of the “Terminal Eocene Event” has been used to describe climatic, faunal, and sedimentological changes in the marine and terrestrial realms which occurred near the end of the Eocene (Van Couvering et al., 1981). The synchrony and causal relationships among these events are still debatable. The nature and timing of the middle Eocene-Oligocene biotic and climatic changes are significant in view of impact-related extinctions because this is one of the predicted periodic mass extinctions (Raup and Sepkoski, 1982). In contrast to the biotic synthesis of Raup and Sepkoski (1982), more detailed stratigraphic studies...

    • 9. LATE EOCENE AND EARLY OLIGOCENE IN SOUTHERN AUSTRALIA: LOCAL NERITIC SIGNALS OF GLOBAL OCEANIC CHANGES
      (pp. 178-201)
      Brian McGowran, Graham Moss and Amanda Beecroft

      The increased scrutiny of “mass extinctions” and of other events in the stratigraphic record has enforced a much more detailed and quantified plotting of the fossil record itself than was deemed necessary until quite recently. Apart from tracing the iridium-enriched layer and associated phenomena at the Mesozoic/Cenozoic boundary, most of that scrutiny has been invested in oceanic sections. And for good reason: the microfossil record is richer; control is better with hydraulic piston cores; correlation and age determination are tighter in the presence of magnetostratigraphy and of diverse oceanic microplanktonic assemblages.

      There is not a great amount of modern research...

    • 10. PALEOGENE CLIMATIC EVOLUTION: A CLIMATE MODEL INVESTIGATION OF THE INFLUENCE OF CONTINENTAL ELEVATION AND SEA-SURFACETEMPERATURE UPON CONTINENTAL CLIMATE
      (pp. 202-217)
      Lisa Cirbus Sloan and Eric J. Barron

      The Paleogene was a time during which global climate underwent great transitions. In an extreme sense, the transition can be represented by the change from the “globally warm” late Cretaceous to the glaciated Pleistocene. In between these extremes a general cooling took place (e.g., Savin, 1977, 1982). According to a variety of sources from the marine record, a key time of change in this long-term transition was during the Eocene and Oligocene (Savin, 1977; Keller, 1983; Keigwin and Corliss, 1986; Oberhansli and Hsü, 1986; Shackleton, 1986; Boersma et al., 1987; Rea et al., 1990). There is also evidence of large...

  8. PART III: THE MARINE RECORD
    • 11. EOCENE-OLIGOCENE FAUNAL TURNOVER IN PLANKTIC FORAMINIFERA, AND ANTARCTIC GLACIATION
      (pp. 218-244)
      Gerta Keller, Norman MacLeod and Enriqueta Barrera

      Contrary to some previous reports, the so-called Eocene-Oligocene (E/O) mass extinction among planktic foraminifera was not centered at this boundary, but rather was part of a longterm trend that began during the middle Eocene and continued into the late Oligocene (Steineck, 1971; Keller, 1983a,b, 1985, 1986; Corliss et al., 1984; Molina et al., 1988), an interval spanning over 14 m.y. Within this interval, accelerated faunal turnovers can be recognized near the middle/late Eocene and early/late Oligocene boundaries. These faunal turnovers include the successive extinction of tropical and subtropical faunas and their replacement by cool and temperate assemblages of species (Kennett,...

    • 12. MIDDLE EOCENE - LATE OLIGOCENE BATHYAL BENTHIC FORAMINIFERA (WEDDELL SEA): FAUNAL CHANGES AND IMPLICATIONS FOR OCEAN CIRCULATION
      (pp. 245-271)
      Ellen Thomas

      Dramatic climate changes occurred in the Cenozoic, especially from middle Eocene through early Oligocene (e.g., Shackleton and Kennett, 1975; Kennett and Shackleton, 1976; Kennett, 1977; Savin, 1977; Shackleton and Boersma, 1981; Mercer, 1983; Shackleton, 1986; Miller et al., 1987a; Kennett and Barker, 1990; Thomas, 1989,1990a; Webb, 1990; Barron et al., 1991; Zachos et al., 1991, Wise et al., 1991). Deep waters in the world’s oceans and surface waters at high latitudes cooled strongly after the very warm early Eocene: early Eocene surface water temperatures at high latitudes were estimated to have been about 15-17°C (Stott et al., 1990). At some...

    • 13. LATE PALEOGENE CALCAREOUS NANNOPLANKTON EVOLUTION: A TALE OF CLIMATIC DETERIORATION
      (pp. 272-309)
      Marie-Pierre Aubry

      Calcareous nannofossils are calcific particles representative of the Phylum Haptophyta (Margulis and Schwartz, 1988) in the Kingdom Protoctista (Copeland, 1956). The coccolithophorids which belong to the order Prymnesiida (Hibberd and Leedale, 1985) constitute a major component of the modern phytoplankton and have probably maintained this position since the Jurassic (see Tappan and Loeblich, 1971; Berger, 1976). The calcareous nannoplankton are particularly sensitive indicators of oceanographic/climatic changes which have occurred during the last 150 million years. For instance, changes in their biogeographic patterns have been established on a broad scale allowing the delineation of trends in temperature during the Cenozoic (e.g.,...

    • 14. MIDDLE EOCENE THROUGH EARLY MIOCENE DIATOM FLORAL TURNOVER
      (pp. 310-326)
      Jack G. Baldauf

      Numerous studies have examined diatoms present in Paleogene and lower Neogene sediments. These include studies by Baldauf and Monjanel (1989), Benda (1972), Cleve-Euler (1941), Fenner (1976, 1977, 1981, 1984a, 1984b, 1985, 1986), Fourtanier (in press), Gombos (1977, 1982, 1983, 1984, and 1987), Gombos and Ciesielski (1983), Grunow (1866), Heiberg (1863), Kanaya (1957), Schrader and Fenner (1976), and Schulz (1927), among others. The majority of these studies document the diatom assemblage from stratigraphic sequences or individual samples for specific biostratigraphic or taxonomic purposes. Few studies have addressed the evolutionary response of the Paleogene and early Neogene diatom flora to changing oceanographic...

    • 15. LATE PALEOGENE DINOFLAGELLATE CYSTS WITH SPECIAL REFERENCE TO THE EOCENE/OLIGOCENE BOUNDARY
      (pp. 327-340)
      Henk Brinkhuis

      The number of detailed reports on Paleogene dinoflagellate cyst assemblages have increased progressively during the last decades, stimulated by their application to oil and gas exploration. The accumulation of knowledge on their qualitative distribution now allows detailed stratigraphic correlations, especially in former marginal marine areas. Well over 400 species have been recognized in the late Eocene, an all-time high in the geologic record of dinoflagellate cysts (Williams and Bujak, 1977a). Despite the successful application of dinoflagellate cysts in Eocene and Oligocene biostratigraphy, only a few attempts have been made to integrate these microfossils in multidisciplinary research aimed at specific problems,...

    • 16. THE PATTERNS AND CAUSES OF MOLLUSCAN EXTINCTION ACROSS THE EOCENE/OLIGOCENE BOUNDARY
      (pp. 341-348)
      Thor Hansen

      Although not in the “first tier” of extinctions in terms of magnitude, the Eocene—Oligocene extinction affected a broad range of organisms including planktonic foraminifera and benthic molluscs in the marine realm. Several prominent Eocene molluscan genera and subgenera that were geographically wide-spread and resilient through earlier changes in temperature and shoreline position, disappear at or near the Eocene/Oligocene boundary. These taxa include the bivalvesYoldia (Calorhadia), Venericardia (Venericor), Pachecoa,and the gastropodsCalyptraphorous, Pseudoliva,andLapparia. Athleta,a prominent Eocene gastropod, became extinct in North America but continued into the Oligocene in Europe (Dockery, 1984). Study of the Eocene/Oligocene...

    • 17. EVOLUTION OF PALEOGENE ECHINOIDS: A GLOBAL AND REGIONAL VIEW
      (pp. 349-367)
      Michael L. McKinney, Kenneth J. McNamara, Burchard D. Carter and Stephen K. Donovan

      Echinoids provide much information about biotic and climatic evolution in the early Cenozoic. The evolutionary patterns of the group itself are of great interest because echinoids underwent a profound evolutionary radiation, from less than 200 known species in the Paleocene to well over 1000 species in the Eocene. They were then greatly decimated by the events toward the end of the Eocene and well into the Oligocene. Numerous orders within the Echinoidea show distinct trends as biotic interactions occurred, such as the rise of clypeasteroids at the expense of the cassiduloids. In addition, echinoids provide excellent independent clues to the...

    • 18. CETACEAN EVOLUTION AND EOCENE/OLIGOCENE ENVIRONMENTS
      (pp. 368-381)
      R. Ewan Fordyce

      Marine mammal history starts in the Eocene, long after the demise of large marine reptiles at the end of the Cretaceous. Two main groups, the Cetacea (whales, dolphins, porpoises), and Sirenia (dugongs, manatees and relatives) dominate the Eocene to Oligocene interval, although other taxa are known. This review concentrates on the evolutionary history of Cetacea and the possible role of environmental changes in their evolution.

      The oldest whale-like animal is of uncertain early to middle Eocene age; other Cetacea provide evidence of a Lutetian and later radiation of the rather conservative archaeocetes. The Oligocene saw rapid evolution amongst Cetacea, with...

  9. PART IV: THE TERRESTRIAL RECORD
    • 19. PALEOSOLS AND CHANGES IN CLIMATE AND VEGETATION ACROSS THE EOCENE/OLIGOCENE BOUNDARY
      (pp. 382-398)
      Gregory J. Retallack

      The demonstration by Dokuchaev (1883) that soil types such as the Russian Chernozem (or Mollisols in modern terminology) were similar over many different kinds of parent rocks marked the liberation of soil science as a discipline, independent of geology and agronomy. In this example and others gathered by this pioneering Soviet school of soil geography (Glinka, 1931), climate and vegetation were seen as more important factors in determining the nature of soils, than parent material, topographic setting or time for formation. These other factors are known to be significant, even limiting in certain cases, so that each factor must be...

    • 20. LOW-BIOMASS VEGETATION IN THE OLIGOCENE?
      (pp. 399-420)
      Estella B. Leopold, Gengwu Liu and Scott Clay-Poole

      Compelling evidence from paleosols and fossil root traces in the Oligocene deposits of the South Dakota Badlands documents the spacing of trees through time; indications are that the late Eocene forest stands were characterized by trees spaced rather closely together, while early Oligocene vegetation had widely spaced trees as in a savanna, and trees may have become eliminated in the final phases of the Oligocene by a drying climate. The extensive work of Retallack (1982, 1983, 1988) in the Badlands deposits documents the trend toward arid soil types and toward smaller root diameters during the Oligocene. Such climates and vegetation...

    • 21. CLIMATIC, FLORISTIC, AND VEGETATIONAL CHANGES NEAR THE EOCENE/OLIGOCENE BOUNDARY IN NORTH AMERICA
      (pp. 421-436)
      Jack A. Wolfe

      The climatic deterioration near the Eocene/Oligocene boundary was the single most important global climatic event that occurred between events near the Cretaceous/Tertiary boundary and the glaciation of the late Pliocene. Although the deterioration is recognized in marine environments, the effects of the deterioration were more marked in nonmarine environments, from which the deterioration was also first inferred.

      MacGinitie (1953) was the first to suggest that a major, abrupt climatic deterioration might have occurred in the Oligocene. He discussed the stratigraphic evidence that placed the Goshen (now considered of earliest Oligocene age) and Bridge Creek floras (now considered of late early...

    • 22. VEGETATIONAL AND FLORISTIC CHANGES AROUND THE EOCENE/OLIGOCENE BOUNDARY IN WESTERN AND CENTRAL EUROPE
      (pp. 437-450)
      Margaret E. Collinson

      A critical assessment of vegetational change around the Eocene/Oligocene boundary requires two major sources of evidence. Firstly a complete, or more or less complete, sequence of strata through this interval or, alternatively, a series of isolated exposures with good local correlation. Secondly these strata should contain plant macrofossils and microfossils in comparable depositional settings or in settings where the differential taphonomic bias can be reliably assessed. In practice very few geological circumstances combine these features to provide ideal information. Around the Eocene/Oligocene boundary in Europe the situation is particularly problematic. Areas which yield diverse plant macrofossils (e.g. Germany and Czechoslovakia)...

    • 23. WESTERN NORTH AMERICAN REPTILE AND AMPHIBIAN RECORD ACROSS THE EOCENE/OLIGOCENE BOUNDARY AND ITS CLIMATIC IMPLICATIONS
      (pp. 451-463)
      J. Howard Hutchison

      The Eocene-Oligocene interval marks a dramatic transformation and modernization of the non-marine herpetofauna of western North America, a modernization substantially achieved by the end of the Oligocene. The record of amphibian and reptile diversity (richness) across the interval of the Eocene/Oligocene boundary is only adequately represented in the western part of North America, west of the Mississippi River and from southern Canada to northern Mexico, specifically along the southern and eastern slopes of the Rocky Mountain province south to the Big Bend region of Texas. The eastern non-marine faunas, especially during the Eocene-Oligocene interval, are very poorly known and are...

    • 24. MAMMALIAN FAUNAS IN NORTH AMERICA OF BRIDGERIAN TO EARLY ARIKAREEAN “AGES” (EOCENE AND OLIGOCENE)
      (pp. 464-493)
      Richard K. Stucky

      Fossil mammals from the middle Eocene through Oligocene (~50 to 24 million years ago, Ma) are well represented in the geological record of North America. A number of sedimentary basins and regions preserve thick sequences of strata of these ages with fossil mammals, especially in the Western Interior (central Rocky Mountains and Great Plains) and coastal southern California. New data and more refined biostratigraphies and chronologies now allow an updated assessment of the patterns of mammalian diversification and faunal change (Prothero, 1985, 1989; Krishtalka et al., 1987; Emry et al., 1987; Tedford et al., 1987; Aubry et al., 1988; Emry,...

    • 25. BRITISH MAMMALIAN PALEOCOMMUNITIES ACROSS THE EOCENE-OLIGOCENE TRANSITION AND THEIR ENVIRONMENTAL IMPLICATIONS
      (pp. 494-515)
      J.J. Hooker

      This paper investigates the changes in diversity and ecological composition of mammal faunas in southern England from the late middle Eocene to the early Oligocene. It puts forward available evidence for the dating of these changes in terms of the global time scale. It then attempts to relate them to southern European faunas of the same age and to major contemporaneous events like changes in climate and in land and sea distribution.

      Because of a long sequence of superposed mammaliferous deposits, southern England is a key area for tracing the changes in diversity and ecological composition, which mirror and interrelate...

    • 26. EVOLUTION OF MAMMALIAN FAUNAS IN EUROPE DURING THE EOCENE AND OLIGOCENE
      (pp. 516-528)
      Serge Legendre and Jean-Louis Hartenberger

      During the two last decades, our knowledge of Paleogene mammalian faunas has increased, but data are still expected for the late Cretaceous and Paleocene history of mammals in Europe. In contrast, major progress and results have been obtained for the periods following the Paleocene. Eocene and Oligocene faunas are now well documented.

      Thus, the overview proposed here does not concern the Paleocene, but will focus on Eocene and Oligocene mammalian evolution and faunal changes in western Europe. Tempo, patterns and processes in evolutionary changes in mammalian faunas are studied using different methods:

      —origination/extinction analysis and cohort analysis using survivorship...

    • 27. THE CHINESE OLIGOCENE: A PRELIMINARY REVIEW OF MAMMALIAN LOCALITIES AND LOCAL FAUNAS
      (pp. 529-547)
      Banyue Wang

      The study of the Oligocene mammals of China began in 1922, when the Third Asiatic Expedition led by R. C. Andrews made the first discovery of Tertiary mammals from Houldjin beds near Iren Dabasu, Nei Mongol (Inner Mongolia), China. The beds were considered to be Oligocene by Osborn one year later. Very soon some other Oligocene localities, such as Ulan Gochu, Baron Sog and Urtyn Obo were discovered. At about the same time, exploring along the middle reach of the Yellow River, P. Teilhard de Chardin and E. Licent found Oligocene mammals near Saint Jacques, Nei Mongol. From the 1930s...

    • 28. THE EOCENE-OLIGOCENE TRANSITION IN CONTINENTAL AFRICA
      (pp. 548-566)
      D. Tab Rasmussen, Thomas M. Bown and Elwyn L. Simons

      The Eocene and Oligocene fossil record of African terrestrial mammals is regrettably sparse. Knowledge of the mammalian fauna has been based almost exclusively on fossils from several localities in one region, the Fayum Depression, Egypt. Fossiliferous rocks there have generally been viewed as spanning a time period from about the middle Eocene to the middle Oligocene. Even as knowledge of the Fayum fauna and geology has grown, it has proven difficult to establish precise biostratigraphic correlations between the Fayum fauna and those elsewhere. Correlation of Eocene and Oligocene Afro-Arabian vertebrates with non-African fossil assemblages has been a long-standing problem for...

  10. INDEX
    (pp. 567-568)