Preface; List of contributors; 1. Notes toward a history of vertebrate paleontology at Gran Barranca; Part I. Geology: 2. Physical stratigraphy of the Sarmiento Formation (middle Eocene - lower Miocene) at Gran Barranca, central Patagonia; 3. Paleomagnetism and magnetostratigraphy of the Sarmiento Formation (Eocene-Miocene) at Gran Barranca, Chubut, Argentina; 4. A geochronology for the Sarmiento Formation at Gran Barranca; Part II. Systematic Palaeontology: 5. Middle Eocene - Oligocene gastropods of the Sarmiento Formation, central Patagonia; 6. Middle Tertiary marsupials from central Patagonia (early Oligocene of Gran Barranca): understanding South America's Grande Coupure; 7. Middle Eocene - Early Miocene Dasypodidae (Xenarthra) of southern South America: biostratigraphy and palaeoecology; 8. The 'Condylarth' Didolodontidae from Gran Barranca: history of the bunodont South American mammals until the Eocene-Oligocene transition; 9. The Notohippidae (Mammalia, Notoungulata) from Gran Barranca: preliminary considerations; 10. Rodent-like notoungulates (Typotheria) from Gran Barranca, Chubut Province, Argentina: phylogeny and systematics; 11. The Leontiniidae (Mammalia, Notoungulata) from the Sarmiento Formation at Gran Barranca, Chubut Province, Argentina; 12. Colhuehuapian Astrapotheriidae (Mammalia) from Gran Barranca south of Lake Colhue Huapi; 13. The rodents from La Cantera and the early evolution of caviomorphs in South America; 14. Colhuehuapian rodents from Gran Barranca and other Patagonian localities: the state of the art; 15. A new primate from the early Miocene of Gran Barranca, Chubut Province, Argentina: paleoecological implications; 16. Bats (Mammalia: Chiroptera) from Gran Barranca (early Miocene, Colhuehuapian), Chubut Province, Argentina; Part III. Patterns of Evolution and Environmental Change: 17. The Mustersan age at Gran Barranca: a review; 18. A new mammal fauna at the top of the Gran Barranca sequence and its biochronological significance; 19. Loessic and fluvial sedimentation in Sarmiento Formation pyroclastics,middle Cenozoic of central Patagonia; 20. Paleosols of the Middle Cenozoic Sarmiento Formation, central Patagonia; 21. Ichnofacies analysis of the Sarmiento Formation (middle Eocene-early Miocene) at Gran Barranca, central Patagonia; 22. Phytolith studies in Gran Barranca (central Patagonia, Argentina), the middle-late Eocene; 23. Stable isotopes of fossil teeth and bones at Gran Barranca as a monitor of climate change and tectonics; 24. Hypsodonty and body size in rodent like notoungulates; Part IV. Regional Applications: 25. Vegetation during the Eocene-Miocene interval in central Patagonia: a context of mammal evolution; 26. Paleogene climatic and biotic events in the terrestrial record of the Antarctic Peninsula: an overview; 27. Mid-Cenozoic palaeoclimatic and palaeoceanographic trends in the southwestern Atlantic basins, a dinoflagellate view; 28. Divisaderan land mammal age or local fauna?; Part V. Summary: 29. Gran Barranca: a twenty-three million year record of Middle-Cenozoic faunal evolution in Patagonia; Index.