The Neogene transition from C3 to C4 grasslands in North America: Assemblage analysis of fossil phytoliths

Paleobiology

Volumn 37, Issue 1, 2011, Pages 50-71

  Strömberg, Caroline A E ^a   McInerney, Francesca A ^b,c  

^a UNIVERSITY OF WASHINGTON   (United States)

^b UNIVERSITY OF CHICAGO   (United States)

^c NORTHWESTERN UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ABUNDANCE; ARIDITY; CARBON ISOTOPE; ENVIRONMENTAL CHANGE; FOSSIL RECORD; GRASSLAND; HERBIVORY; MIOCENE; PALEOBOTANY; PALEOENVIRONMENT; PALEOSOL; PHOTOSYNTHESIS; PHYTOLITH; PLIOCENE; RANGE EXPANSION; SEASONALITY; STABLE ISOTOPE; TAXONOMY; TOOTH; TROPICAL REGION;

GREAT PLAINS;

POACEAE; UNGULATA; ZANCLEA;

EID: 78650916720     PISSN: 00948373     EISSN: None     Source Type: Journal    
DOI: 10.1666/09067.1     Document Type: Article

References (149)

1. Alexandre, A., J.-D. Meunier, A.-M. Lezine, A. Vincens, and D. Schwartz. 1997. Phytoliths: indicators of grassland dynamics during the late Holocene in intertropical Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 136:213-229.
2. Barboni, D., L. Bremond, and R. Bonnefille. 2007. Comparative study of modern phytolith assemblages from inter-tropical Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 246:454-470.
3. Behrensmeyer, A. K., J. Quade, T. E. Cerling, J. Kappelman, I. A. Khan, P. Copeland, L. Roe, J. Hicks, P. Stubblefield, B. J. Willis, and C. Latorre. 2007. The structure and rate of late Miocene expansion of C4 plants: evidence from lateral variation in stable isotopes in paleosols of the Siwalik Group, northern Pakistan. Geological Society of America Bulletin 119:1486-1505.
4. Björkman, O. 1971. Comparative photosynthetic CO2 exchange in higher plants. Pp. 18-32 in M. D. Hatch, C. B. Osmond, and R. O. Slatyer, eds. Photosynthesis and photorespiration. Wiley, New York.
5. Blinnikov, M. S. 2005. Phytoliths in plants and soils of the interior Pacific Northwest, USA. Review of Palaeobotany and Palynology 135:71-98.
6. Boellstorff, J. B. 1978. Chronology of some late Cenozoic deposits from the central United States and the Ice Ages. Transactions of the Nebraska Academy of Sciences 6:35-49.
7. Bond, W. J., F. I. Woodward, and G. F. Midgley. 2005. The global distribution of ecosystems in a world without fire. New Phytologist 165:525-538.
8. Bouchenak-Khelladi, Y., N. Salamin, V. Savolainen, F. Forest, M. van der Bank, M. W. Chase, and T. R. Hodkinson. 2008. Large multigene phylogenetic trees of the grasses (Poaceae): progress towards complete tribal and generic level sampling. Molecular Phylogenetics and Evolution 47:488-505.
9. Bouchenak-Khelladi, Y., G. A. Verboom, T. R. Hodkinson, N. Salamin, O. Francois, G. N. Chonghaile, and V. Savolainen. 2009. The origins and diversification of C4 grasses and savanna adapted ungulates. Global Change Biology 15:2397-2417.
10. Bozarth, S. R. 1992. Classification of opal phytoliths formed in selected dicotyledons native to the Great Plains. Pp. 193-214 in G. J. Rapp and S. C. Mulholland, eds. Phytolith systematics: emerging issues. Plenum, New York.
11. Bremond, L., A. Alexandre, C. Hély, and J. Guiot. 2005a. A phytolith index as a proxy of tree cover density in tropical areas: calibration with Leaf Area Index along a forest-savanna transect in southeastern Cameroon. Global and Planetary Change 45:277-293.
12. Bremond, L., A. Alexandre, O. Peyron, and J. Guiot. 2005b. Grass water stress estimated from phytoliths in West Africa. Journal of Biogeography 32:311-327.
13. Brown, D. A. 1984. Prospects and limits of a phytolith key for grasses in the Central United States. Journal of Archaeological Science 11:345-368.
14. Buol, S. W., R. J. Southard, R. C. Graham, and P. A. McDaniel. 2003. Soil genesis and classification 5th ed. University of Iowa Press, Ames.
15. Cabido, M., E. Pons, J. J. Cantero, J. P. Lewis, and A. Anton. 2007. Photosynthetic pathway variation among C4 grasses along a precipitation gradient in Argentina. Journal of Biogeography 35:131-140.
16. Carnelli, A. L., J.-P. Theurillat, and M. Madella. 2004. Phytolith types and type-frequencies in subalpine-alpine plant species of the European Alps. Review of Palaeobotany and Palynology 129:39-65.
17. Cerling, T. E., J. M. Harris, B. J. MacFadden, M. G. Leakey, J. Quade, V. Eisenmann, and J. R. Ehleringer. 1997. Global vegetation change through the Miocene/Pliocene boundary. Nature 389:153-158.
18. Cerling, T. E., J. R. Ehleringer, and J. M. Harris. 1998. Carbon dioxide starvation, the development of C4 ecosystems, and mammalian evolution. Philosophical Transactions of the Royal Society of London B 353: 159-171.
19. Christin, P.-A., G. Besnard, E. Samaritani, M. R. Duvall, T. R. Hodkinson, V. Savolainen, and N. Salamin. 2008. Oligocene CO2 decline promoted C4 photosynthesis in grasses. Current Biology 18:37-43.
20. Clements, F. E., J. E. Weaver, and H. C. Hanson. 1929. Plant competition: an analysis of community functions. Carnegie Institution, Washington D.C.
21. Crowley, T. J., and G. R. North. 1991. Paleoclimatology. Oxford University Press, New York.
22. Damuth, J. D., M. Fortelius, P. Andrews, C. Badgley, E. A. Hadley, S. Hixon, C. M. Janis, R. H. Madden, K. Reed, J. M. Smith, J. M. Theodor, J. A. van Dam, B. Van Valkenburgh, and L. Werdelin. 2002. Reconstructing mean annual precipitation based on mammalian dental morphology and local species richness. Journal of Vertebrate Paleontology 22(Suppl. to No. 3):48A.
23. Dettman, D. L., M. J. Kohn, J. Quade, F. J. Ryerson, T. P. Ojha, and S. Hamidullah. 2001. Seasonal stable isotope evidence for a strong Asian monsoon throughout the past 10.7 m.y. Geology 29:31-34.
24. Diffendal, R. F., Jr. 1990. The Sidney Gravel and Kimball Formation, supposed parts of the Ogallala Group (Neogene), are not objectively mappable units. Pp. 23-38 in T. C. Gustavson, ed. Geologic framework and regional hydrology: Upper Cenozoic Blackwater Draw and Ogallala formations, Great Plains. Texas Bureau of Economic Geology, University of Texas, Austin.
25. -. 1995. Geology of the Ogallala-High Plains Regional Aquifer System in Nebraska. Pp. 61-75 in R. F. Diffendal Jr. and C. F. Flowerday, eds. Geologic field trips in Nebraska and adjacent parts of Kansas and South Dakota. Conservation and Survey Division, Univerisity of Nebraska, Lincoln.
26. Diffendal, R. F., Jr., R. K. Pabian, and J. R. Thomasson. 1996. Geologic history of Ash Hollow State Historical Park, Nebraska. Conservation and Survey Division, University of Nebraska, Lincoln.
27. Dugas, D. P., and G. J. Retallack. 1993. Middle Miocene fossil grasses from Fort Ternan, Kenya. Journal of Paleontology 67:113-128.
28. Duvall, M., J. I. Davis, L. G. Clark, D. H. Goldman, and J. G. Sánchez-Ken. 2007. Phylogeny of the grasses (Poaceae) revisited. Aliso 23:237-247.
29. Edwards, E. J., and C. J. Still. 2008. Climate, phylogeny, and the ecological distribution of C4 grasses. Ecology Letters 11:266-276.
30. Edwards, E. J., and S. A. Smith. 2010. Phylogenetic analyses reveal the shady history of C4 grasses. Proceedings of the National Academy of Sciences USA 107:2532-2537.
31. Edwards, E. J., C. P. Osborne, C. A. E. Strömberg, S. A. Smith, and C4 Grasses Consortium. 2010. The origins of C4 grasslands: integrating evolutionary and ecosystem science. Science 328:587-591.
32. Ehleringer, J. R. 1978. Implications of quantum yield differences on distributions of C3 and C4 grasses. Oecologia 31:255-267.
33. Ehleringer, J. R., R. F. Sage, L. B. Flanagan, and R. W. Pearcy. 1991. Climate change and the evolution of C4 photosynthesis. Trends in Ecology and Evolution 6:95-99.
34. Epstein, H. E., W. K. Lauenroth, I. C. Burke, and D. P. Coffin. 1997. Productivity patterns of C3 and C4 functional types in the U.S. Great Plains. Ecology 78:722-731.
35. Fortelius, M., J. T. Eronen, J. Jernvall, L. Liu, D. Pushkina, J. Rinne, A. Tesakov, I. A. Vislobokova, Z. Zhang, and L. Zhou. 2002. Fossil mammals resolve regional patterns of Eurasian climate change during 20 million years. Evolutionary Ecology Research 4:1005-1016.
36. Fortelius, M., J. Eronen, L. P. Liu, D. Pushkina, A. Tesakov, I. Vislobokova, and Z. Q. Zhang. 2003. Continental-scale hypsodonty patterns, climatic paleobiogeography and dispersal of Eurasian Neogene large mammal herbivores. in J. W. F. Reumer and W. Wessels, eds. Distribution and migration of Tertiary mammals in Eurasia. A volume in honour of Hans de Bruijn. Deinsea 10:1-11.
37. Fox, D. L., and P. L. Koch. 2003. Tertiary history of C4 biomass in the Great Plains, USA. Geology 31:809-812.
38. -. 2004. Carbon and oxygen isotope variability in Neogene paleosol carbonates: constraints on the evolution of the C4- grasslands of the Great Plains, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 207:305-329.
39. Fredlund, G. G., and L. L. Tieszen. 1994. Modern phytolith assemblages from the North American Great Plains. Journal of Biogeography 21:321-335.
40. -. 1997. Calibrating grass phytolith assemblages in climatic terms: application to late Pleistocene assemblages from Kansas and Nebraska. Palaeogeography, Palaeoclimatology, Palaeoecology 136:199-211.
41. Gardner, L. R., R. F. Diffendal Jr., and D. F. Williams. 1992. Stable isotope composition of calcareous paleosols and ground-water cements from the Ogallala Group (Neogene), western Nebraska. Contributions to Geology, University of Wyoming 29:97-109.
42. Gibson, D. J. 2009. Grasses and grassland ecology. Oxford University Press, Oxford.
43. GPWG (Grass Phylogeny Working Group). 2001. Phylogeny and subfamilial classification of the grasses (Poaceae). Annals of the Missouri Botanical Garden 88:373-457.
44. Hartley, W. 1973. Studies on the origin, evolution, and distribution of the Gramineae. V. The subfamily Festucoideae. Australian Journal of Botany 21:201-234.
45. Hattersley, P. W. 1983. The distribution of C3-grass and C4- grasses in Australia in relation to climate. Oecologia 57:113-128.
46. Hattersley, P. W., and L. Watson. 1992. Diversification of photosynthesis. Pp. 38-11 in G. P. Chapman, ed. Grass evolution and domestication. Cambridge University Press, Cambridge.
47. Herring, J. R. 1985. Charcoal fluxes into sediments of the North Pacific Ocean: the Cenozoic record of burning. Pp. 419-442 in E. T. Sundquist and W. S. Broecker, eds. The carbon cycle and atmospheric CO2: natural variations Archean to present. American Geophysical Union, Washington, D.C.
48. Huang, Y., S. C. Clemens, Y. Wang, and W. L. Prell. 2007. Largescale hydrological change drove the late Miocene C4 plant expansion in the Himalayan foreland and Arabian Peninsula. Geology 35:531-534.
49. Hutchison, J. H. 1982. Turtle, crocodilian and champsosaur diversity changes in the Cenozoic of the north-central region of western United States. Palaeogeography, Palaeoclimatology, Palaeoecology 37:149-164.
50. ICPN Working Group (M. Madella, A. Alexandre, and T. B. Ball) 2005. International code for phytolith nomenclature 1.0. Annals of Botany 96:253-260.
51. Jacobs, B. F., J. D. Kingston, and L. L. Jacobs. 1999. The origin of grass-dominated ecosystems. Annals of the Missouri Botanical Garden 86:590-643.
52. Janis, C. M. 1993. Tertiary mammal evolution in the context of changing climates, vegetation, and tectonic events. Annual Review of Ecology and Systematics 24:467-500.
53. Janis, C. M., K. M. Scott, and L. L. Jacobs. 1998. Evolution of Tertiary mammals in North America. 1. Terrestrial carnivores, ungulates and ungulatelike mammals. Cambridge University Press, Cambridge.
54. Janis, C. M., J. Damuth, and J. M. Theodor. 2000. Miocene ungulates and terrestrial primary productivity: where have all the browsers gone? Proceedings of the National Academy of Sciences USA 97:237-261.
55. -. 2002. The origins and evolution of the North American grassland biome: the story from the hoofed mammals. Palaeogeography, Palaeoclimatology, Palaeoecology 177:183-198.
56. -. 2004. The species richness of Miocene browsers, and implications for habitat type and primary productivity in the North American grassland biome. Palaeogeography, Palaeoclimatology, Palaeoecology 207:371-398.
57. Jia, G., P. Peng, Q. Zhao, and Z. Jian. 2003. Changes in terrestrial ecosystem since 30 Ma in East Asia: stable isotope from black carbon in the South China Sea. Geology 31:1093-1096.
58. Kealhofer, L. 1996. The human environment during the terminal Pleistocene and Holocene in northeastern Thailand: phytolith evidence from Lake Kumphawapi. Asian Perspectives 35:229-254.
59. Kealhofer, L., and D. Piperno. 1998. Opal phytoliths in Southeastern Asian Flora. Smithsonian Contributions to Botany 88:1-39.
60. Keeley, J. E., and P. W. Rundel. 2003. Evolution of CAM and C4 carbon-concentrating mechanisms. International Journal of Plant Sciences 164(3 Suppl.):S55-S77.
61. -. 2005. Fire and the Miocene expansion of C4 grasslands. Ecology Letters 8:683-690.
62. Kelly, E. F. 1989. A study of the influence of climate and vegetation on the stable isotope chemistry of soils in grassland ecosystems of the Great Plains. Ph.D dissertation. University of California, Berkeley.
63. Kennett, J. P. 1995. A review of polar climatic evolution during the Neogene, based on the marine sediment record. Pp. 49-64 in E. S. Vrba, G. H. Denton, T. C. Partridge, and L. H. Burckle, eds. Paleoclimate and evolution, with emphasis on human origins. Yale University Press, New Haven, Conn.
64. Kingston, J. D., B. D. Marino, and A. Hill. 1994. Isotopic evidence for Neogene Hominid paleoenvironments in the Kenya Rift Valley. Science 264:955-959.
65. Kondo, R., C. Childs, and I. Atkinson. 1994. Opal phytoliths of New Zealand. Manaaki Whenua, Canterbury, New Zealand.
66. Kucera, C. L. 1981. Grasslands and fire. Pp. 90-111 in H. A. Mooney, T. M. Bonnicksen, N. L. Christensen, J. E. Lotan, and W. A. Reiners, eds. Fire regimes and ecosystem properties. U.S. Department of Agriculture, Forest Service, Washington, D.C.
67. Kürschner, W. M. 1997. The anatomical diversity of recent and fossil leaves of the durmast oak (Quercus petraea Lieblein/Q. pseudocastanea Goeppert)-implications for their use as biosensors of palaeoatmospheric CO2 levels. Palaeogeography, Palaeoclimatology, Palaeoecology 96:1-30.
68. Kürschner, W. M., Z. Kvaček, and D. Dilcher. 2008. The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of terrestrial ecosystems. Proceedings of the National Academy of Sciences USA 105:449-453.
69. Levin, N. E. 2004. Isotopic evidence for Plio-Pleistocene environmental change at Gona, Ethiopia. Earth and Planetary Science Letters 219:93-110.
70. MacFadden, B. J., T. E. Cerling, and J. Prado. 1996. Cenozoic terrestrial ecosystem evolution in Argentina: evidence from carbon isotopes of fossil mammal teeth. Palaios 11:319-327.
71. Madella, M., M. K. Jones, P. Echlin, A. Powers-Jones, and M. Moore. 2009. Plant water availability and analytical microscopy of phytoliths: Implications for ancient irrigation in arid zones. Quaternary International 193:32-40.
72. Martin, R. A., J. G. Honey, P. Peláez-Campomanes, H. T. Goodwin, J. A. Baskin, and R. J. Zakrzewski. 2002. Blancan lagomorphs and rodents of the Deer Park assemblages, Meade County, Kansas. Journal of Paleontology 76: 1072-1090.
73. Martin, R. A., P. Peláez-Campomanes, J. G. Honey, D. L. Fox, R. J. Zakrzewski, L. B. Albright, E. H. Lindsay, N. D. Opdyke, and H. T. Goodwin. 2008. Rodent community change at the Pliocene-Pleistocene transition in southwestern Kansas and identification of the Microtus immigration event on the Central Great Plains. Palaeogeography, Palaeoclimatology, Palaeoecology 267:196-207.
74. McClaran, M. P., and M. Umlauf. 2000. Desert grassland dynamics estimated from carbon isotopes in grass phytoliths and soil organic matter. Journal of Vegetation Science 11:71-76.
75. McInerney, F. A., C. A. E. Strömberg, and J. W. C. White. 2011. The Neogene transition from C3 to C4 grasslands in North America: stable carbon isotope ratios of fossil phytoliths. Paleobiology 37:23-49 (this volume).
76. Morgan, M. E., J. D. Kingston, and B. D. Marino. 1994. Carbon isotopic evidence for the emergence of C4 plants in the Neogene from Pakistan and Kenya. Nature 367:162-165.
77. Morley, R. J., and K. Richards. 1993. Gramineae cuticle: a key indicator of Late Cenozoic climatic change in the Niger Delta. Review of Palaeobotany and Palynology 77:119-127.
78. Mulholland, S. C. 1989. Phytolith shape frequencies in North Dakota grasses: a comparison to general patterns. Journal of Archaeological Science 16:489-511.
79. Nambudiri, E. M. V., W. D. Tidwell, B. N. Smith, and N. P. Hebbert. 1978. A C4 plant from the Pliocene. Nature 276:816-817.
80. Nelson, D. M., F. S. Hu, J. Mikucki, J. Tian, and A. Pearson. 2007. Carbon isotopic analysis of individual pollen grains from C3 and C4 grasses using a spooling wire microcombustion interface. Geochimica et Cosmochimica Acta 71:4005-4014.
81. Osborne, C. P. 2008. Atmosphere, ecology and evolution: what drove the Miocene expansion of C4 grasslands? Journal of Ecology 96:35-45.
82. Osborne, C. P., and D. J. Beerling. 2006. Nature's green revolution: the remarkable evolutionary rise of C4 plants. Philosophical Transactions of the Royal Society of London B 361:173-194.
83. Pagani, M., K. H. Freeman, and M. A. Arthur. 1999. Late Miocene atmospheric CO2 concentrations and the expansion of C4 grasses. Science 285:876-879.
84. Parry, D. W., and F. Smithson. 1966. Opal silica in the inflorescences of some British grasses and cereals. Annals of Botany 30:525-538.
85. Paruelo, J. M., E. G. Jobbágy, O. E. Sala, W. K. Lauenroth, and I. C. Burke. 1998. Functional and structural convergence of temperate grassland and shrubland ecosystems. Ecological Applications 8:194-206.
86. Paruelo, J. M., and W. K. Lauenroth. 1996. Relative abundance of plant functional types in grasslands and shrublands of North America. Ecological Applications 6:1212-1224.
87. Passey, B. H., T. E. Cerling, M. E. Perkins, M. R. Voorhies, J. M. Harris, and S. T. Tucker. 2002. Environmental change in the Great Plains: an isotopic record from fossil horses. Journal of Geology 110:123-140.
88. Passey, B. H., L. K. Ayliffe, A. Kaakinen, J. T. Eronen, Z. Q. Zhang, T. E. Cerling, and M. Fortelius. 2009. Strengthened East Asian summer monsoons during a period of high-latitude warmth? Isotopic evidence from Mio-Pliocene fossil mammals and soil carbonates from northern China. Earth and Planetary Science Letters 277:443-452.
89. Pearson, P. N., and M. R. Palmer. 1999. Middle Eocene seawater pH and atmospheric carbon dioxide concentrations. Science 284:1824-1826.
90. Piperno, D. R. 1988. Phytolith analysis, an archaeological and geological perspective. Academic Press, San Diego.
91. -. 1993. Phytolith and charcoal records from deep lake cores in the American tropics. Pp. 58-71 in D. M. Pearsall and D. R. Piperno, eds. Current research in phytolith analysis: applications in archaeology and paleoecology. University Museum of Archaeology and Anthropology, University of Pennsylvania, Philadelphia.
92. -. 2006. Phytoliths: a comprehensive guide for archaeologists and paleoecologists. AltaMira, New York.
93. Piperno, D. R., and D. M. Pearsall. 1998. The silica bodies of tropical American grasses: morphology, taxonomy, and implications for grass systematics and fossil phytolith identification. Smithsonian Contributions to Botany 85:1-40.
94. Postek, M. T. 1981. The occurrence of silica in the leaves of Magnolia grandiflora L. Botanical Gazette 142:124-134.
95. Prasad, V., C. A. E. Strömberg, H. Alimohammadian, and A. Sahni. 2005. Dinosaur coprolites and the early evolution of grasses and grazers. Science 310:1177-1180.
96. Punyasena, S. W., G. Eshel, and J. C. McElwain. 2008. The influence of climate on the spatial patterning of Neotropical plant families. Journal of Biogeography 35:117-130.
97. Quade, J., and T. E. Cerling. 1995. Expansion of C4 grasses in the late Miocene of northern Pakistan: Evidence from stable isotopes in paleosols. Palaeogeography, Palaeoclimatology, Palaeoecology 115:91-116. (Pubitemid 26450770)
98. Quade, J., T. E. Cerling, and J. R. Bowman. 1989. Development of Asian monsoon revealed by marked ecological shift during the latest Miocene in northern Pakistan. Nature 342:163-164.
99. Retallack, G. J. 1983. Late Eocene and Oligocene paleosols from Badlands National Park, South Dakota. Geological Society of America Special Paper 193:1-82.
100. -. 1997. Neogene expansion of the North American prairie. Palaios 12:380-390.
101. -. 2001. Cenozoic expansion of grasslands and climatic cooling. Journal of Geology 109:407-426.
102. -. 2007. Cenozoic paleoclimate on land in North America. Journal of Geology 115:271-294.
103. Royer, D. L. 2006. CO2-forced climate thresholds during the Phanerozoic. Geochimica Cosmochimica Acta 70:5665-5675.
104. Royer, D. L., C. P. Osborne, and D. J. Beerling. 2002. High CO2 increases the freezing sensitivity of plants: Implications for paleoclimatic reconstructions from fossil floras. Geology 30:963-966.
105. Runge, F. 1996. Opal Phytolithe in Pflantzen aus dem humiden und semi-ariden Osten Afrikas und ihre Bedeutung fur die Klima- und Vegetationsgeschichte. Botanische Jahrbuch Syst. 118:303-363.
106. -. 2001. Evidence for land use history by opal phytolith analysis: examples from the central African tropics (eastern Kivu, D. R. Congo). Pp. 73-85 in J. D. Meunier and F. Colin, eds. Phytoliths: applications in Earth sciences and human history. A.A. Balkema Publishers, Lisse, Netherlands.
107. Sage, R. F. 2004. The evolution of C4 photosynthesis. New Phytologist 161:341-370.
108. Sakai, A., and W. Larcher. 1987. Frost survival of plants: Responses and adaptation to freezing stress. Springer, Berlin.
109. Sánchez-Ken, J. G., L. G. Clark, E. A. Kellogg, and E. E. Kay. 2007. Reinstatement and emendation of subfamily Micrairoideae (Poaceae). Systematic Botany 32:71-80.
110. Sankaran, M., N. P. Hanan, R. J. Scholes, J. Ratnam, D. J. Augustine, B. S. Cade, J. Gignoux, S. I. Higgins, X. Le Roux, F. Ludwig, A. Ardo, F. Banyikwa, A. Bronn, G. Bucini, K. K. Caylor, M. B. Coughenour, A. Diouf, W. Ekaya, C. J. Feral, E. C. February, P. G. H. Frost, P. Hiernaux, H. Hrabar, K. L. Metzger, H. H. T. Prins, S. Ringrose, W. Sea, J. Tews, J. Worden, and N. Zambatis. 2005. Determinants of woody cover in African savannas. Nature 438:846-849.
111. Sankaran, M., J. Ratnam, and N. Hanan. 2007. Woody cover in African savannas: the role of resources, fire and herbivory. Global Ecology and Biogeography 2007:1-10.
112. Ségalen, L., J. A. Lee-Thorp, and T. E. Cerling. 2007. Timing of C4 grass expansion across sub-Saharan Africa. Journal of Human Evolution 53:549-559.
113. Sepulchre, P., G. Ramstein, F. Fluteau, M. Schuster, J. J. Tier, and M. Brunet. 2006. Tectonic uplift and eastern African aridification. Science 313:1419-1423.
114. Simon, J. L. 1997. Resampling: the new statistics. Duxbury, Belmont, Calif.
115. Skinner, M. F., and C. W. Hibbard. 1972. Early Pleistocene preglacial and glacial rocks and faunas of North-Central Nebraska. Bulletin of the American Museum of Natural History 148:1-148.
116. Still, C. J., J. A. Berry, G. J. Collatz, and R. S. DeFries. 2003. Global distribution of C3 and C4 vegetation: carbon cycle implications. Global Biogeochemical Cycles 17:1-6.
117. Strömberg, C. A. E. 2002. The origin and spread of grassdominated ecosystems in the Late Tertiary of North America: preliminary results concerning the evolution of hypsodonty. Palaeogeography, Palaeoclimatology, Palaeoecology 177:59-75.
118. -. 2003. The origin and spread of grass-dominated ecosystems during the Tertiary of North America and how it relates to the evolution of hypsodonty in equids. Ph.D. dissertation. University of California, Berkeley.
119. -. 2004. Using phytolith assemblages to reconstruct the origin and spread of grass-dominated habitats in the Great Plains during the late Eocene to early Miocene. Palaeogeography, Palaeoclimatology, Palaeoecology 207:239-275.
120. -. 2005. Decoupled taxonomic radiation and ecological expansion of open-habitat grasses in the Cenozoic of North America. Proceedings of the National Academy of Sciences USA 102:11980-11984.
121. -. 2006. The evolution of hypsodonty in equids: testing a hypothesis of adaptation. Paleobiology 32:236-258.
122. -. 2009. Methodological concerns for analysis of phytolith assemblages: does count size matter? Quaternary International 193:124-140.
123. Strömberg, C. A. E., L. Werdelin, E. M. Friis, and G. Saraç. 2007. The spread of grass-dominated habitats in Turkey and surrounding areas during the Cenozoic: phytolith evidence. Palaeogeography, Palaeoclimatology, Palaeoecology 250: 18-49.
124. Taub, D. R. 2001. Climate and the U.S. distribution of C4 grass subfamilies and decarboxylation variants of C4 photosynthesis. American Journal of Botany 87:1211-1215.
125. Thomasson, J. R. 1979. Late Cenozoic grasses and other Angiosperms from Kansas, Nebraska and Colorado: biostratigraphy and relationships to living taxa. Kansas Geological Survey Bulletin 218:1-68.
126. -. 1984. Miocene grass (Gramineae: Arundinoideae) leaves showing external micromorphological and internal anatomical features. Botanical Gazette 145:204-209.
127. -. 1985. Miocene fossil grasses: possible adaptation in reproductive bracts (lemma and palea). Annals of the Missouri Botanical Garden 72:843-851.
128. -. 1987. Fossil grasses: 1820-1986 and beyond. Pp. 159-167 in T. R. Soderstrom, K. W. Hilu, C. S. Campbell, and M. E. Barkworth, eds. Grass systematics and evolution. Smithsonian Institution Press, Washington, D.C.
129. -. 1990. Fossil plants from the Late Miocene Ogallala Formation of central North America: possible paleoenvironmental and biostratigraphic significance. Pp. 99-114 in T. C. Gustavson, ed. Geologic framework and regional hydrology: Upper Cenozoic Blackwater Draw and Ogallala Formations, Great Plains. Bureau of Economic Geology. University of Texas at Austin, Austin.
130. Thomasson, J. R., M. E. Nelson, and R. J. Zakrzewski. 1986. A fossil grass (Gramineae; Chloridoideae) from the Miocene with Kranz anatomy. Science 233:876-878.
131. Thompson, R. S. 1991. Pliocene environments and climates in the western United States. Quaternary Science Reviews 10:115-132.
132. Thorn, V. C. 2004. Phytoliths from subantarctic Campbell Island: plant production and soil surface spectra. Review of Palaeobotany and Palynology 132:37-59.
133. Tidwell, W. D., and E. M. V. Nambudiri. 1989. Thomlinsonia thomassonii, gen, et sp. nov., a permineralized grass from the upper Miocene Ricardo Formation, California. Review of Palaeobotany and Palynology 60:165-177.
134. Tieszen, L. L., B. C. Reed, N. B. Bliss, B. K. Wylie, and D. D. DeJong. 1997. NDVI, C3 and C4 production, and distributions in Great Plains grassland land cover classes. Ecological Applications 7:59-78.
135. Tipple, B. J., and M. Pagani. 2007. The early origins of terrestrial C4 photosynthesis. Annual Review of Ecology, Evolution and Systematics 35:435-461.
136. Tripati, A. K., C. D. Roberts, and R. A. Eagle. 2009. Coupling of CO2 and ice sheet stability over major climate transitions of the last 20 million years. Science 326:1394-1397.
137. Twiss, P. C., E. Suess, and R. M. Smith. 1969. Morphological classification of grass phytoliths. Soil Science Society of America, Proceedings 33:109-115.
138. Vicentini, A., J. C. Barber, S. S. Aliscioni, L. M. Giussani, and E. A. Kellogg. 2008. The age of the grasses and clusters of origins of C4 photosynthesis. Global Change Biology 14:2963-2977.
139. Voorhies, M. R. 1977. Fossil Moles of late Hemphillian age from northeastern Nebraska. Transactions of the Nebraska Academy of Sciences 4:129-137.
140. -. 1990. Vertebrate biostratigraphy of the Ogallala Group in Nebraska. Pp. 115-151 in T. C. Gustavson, ed. Geologic framework and regional hydrology: Uppor Cenozoic Blackwater Draw and Ogallala Formations, Great Plains. Bureau of Economic Geology, University of Texas, Austin.
141. Vrba, E. S. 1993. Mammal Evolution in the African Neogene and a new look at the Great American Interchange. Pp. 393-432 in P. Goldblatt, ed. Biological relationships between Africa and South America. Yale Univeristy Press, New Haven, Conn.
142. Wallis, L. A. 2003. An overview of leaf phytolith production patterns in selected northwest Australian flora. Review of Palaeobotany and Palynology 125:201-248.
143. Wang, Y., T. E. Cerling, B. J. MacFadden, and J. D. Bryant. 1994. Fossil horses and carbon isotopes: new evidence for Cenozoic dietary, habitat, and ecosystem changes in North America. Palaeogeography, Palaeoclimatology, Palaeoecology 107:269-280.
144. Watson, L., and M. J. Dallwitz. 1992 onward. Grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. http://delta-intkey. com/.
145. Webb, T., III, T. J. Crowley, B. Frenzel, A.-K. Gliemeroth, J. Jouzel, L. Labeyrie, I. C. Prentice, D. Rind, W. F. Ruddiman, M. Sarnthein, and A. Zwick. 1993. Group report: paleoclimate data as analogs for understanding future global changes. Pp. 51-71 in J. A. Eddy and H. Oeschger, eds. Global changes in the perspective of the past. Wiley, New York.
146. Wing, S. L., and D. R. Greenwood. 1995. Eocene continental climates and latitudinal temperature gradients. Geology 23:1044-1048.
147. Woodburne, M. O., ed. 2004. Late Cretaceous and Cenozoic mammals of North America: biostratigraphy and geochronology. Columbia University Press, New York.
148. Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups. 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292:686-693.
149. Zubakov, V. A., and I. I. Borzenkova. 1988. Pliocene paleoclimates: past climates as possible analogs of mid-twenty-first century climate. Palaeogeography, Palaeoclimatology, Palaeoecology 65:35-49.