ORIGINAL PAPER Paleogene Land Mammal Faunas of South America; a Response to Global Climatic Changes and Indigenous Floral Diversity Michael O. Woodburne & Francisco J. Goin & Mariano Bond & Alfredo A. Carlini & Javier N. Gelfo & Guillermo M. López & A. Iglesias & Ana N. Zimicz Published online: 3 February 2013 # Springer Science+Business Media New York 2013 Abstract An appraisal of Paleogene floral and land mam- mal faunal dynamics in South America suggests that both biotic elements responded at rate and extent generally com- parable to that portrayed by the global climate pattern of the interval. A major difference in the South American record is the initial as well as subsequent much greater diversity of both Neotropical and Austral floras relative to North American counterparts. Conversely, the concurrent mammal faunas in South America did not match, much less exceed, the diversity seen to the north. It appears unlikely that this difference is solely due to the virtual absence of immigrants subsequent to the initial dispersal of mammals to South America, and cannot be explained solely by the different collecting histories of the two regions. Possible roles played by non-mammalian vertebrates in niche exploitation remain to be explored. The Paleogene floras of Patagonia and Chile show a cli- matic pattern that approximates that of North America, with an increase in both Mean Annual Temperature (MAT) and Mean Annual Precipitation (MAP) from the Paleocene into the Early Eocene Climatic Optimum (EECO), although the Paleocene-Eocene Thermal Maximum (PETM) is not recog- nized in the available data set. Post-EECO temperatures de- clined in both regions, but more so in the north than the south, which also retained a higher rate of precipitation. The South American Paleogene mammal faunas devel- oped gradual, but distinct, changes in composition and di- versity as the EECO was approached, but actually declined somewhat during its peak, contrary to the record in North America. At about 40 Ma, a post-EECO decline was recov- ered in both hemispheres, but the South American record achieved its greatest diversity then, rather than at the peak of the EECO as in the north. This post-EECO faunal turnover apparently was a response to the changing conditions when global climate was deteriorating toward the Oligocene. Under the progressively more temperate to seasonally arid conditions in South America, this turnover reflected a major change from the more archaic, and more tropical to subtropical-adapted mammals, to the beginning of the ulti- mately modern South American fauna, achieved completely by the Eocene-Oligocene transition. Interestingly, hypso- donty was achieved by South American cursorial mammals about 15–20 m.y. earlier than in North America. In addition to being composed of essentially different groups of mam- mals, those of the South American continent seem to have responded to the climatic changes associated with the ECCO M. O. Woodburne (*) Department of Geology, Museum of Northern Arizona, Flagstaff, AZ, USA e-mail: mikew@npgcable.com F. J. Goin :M. Bond :A. A. Carlini : J. N. Gelfo :G. M. López : A. N. Zimicz División Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, CONICET, Argentina, (B1900FWA), La Plata, Argentina A. Iglesias División Paleobotánica, Museo de La Plata, Paseo del Bosque s/n, CONICET, Argentina, (B1900FWA), La Plata, Argentina G. M. López División Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, (B1900FWA), La Plata, Argentina J Mammal Evol (2014) 21:1–73 DOI 10.1007/s10914-012-9222-1 and subsequent conditions in a pattern that was initially comparable to, but subsequently different from, their North American counterparts. Keywords South America . Biotic change . Evolution . Paleontology . Early Cenozoic Introduction The Paleogene Period witnessed major global changes in climate and ocean temperatures (Zachos et al. 2001), with the Early Eocene Climatic Optimum (EECO) having been the warmest interval of the Cenozoic Era and a very low thermal gradient between the poles and the equator (Keating-Bitonti et al. 2011). This report investigates the evolution of land mammal faunas of South America in terms of the paleoclimatic setting of that interval based on terres- trial floras. The project began as part of an appraisal of Paleocene and Eocene floral and land mammal biotic pat- terns during a time of global temperature fluctuation, cul- minating in the EECO and its aftermath. The project first focused on the record in North America (Woodburne et al. 2009a, b), and detailed numerous changes in faunal diver- sity and composition in response to a number of fluctuations in the plant record response to the ebb and flow of subtrop- ical, tropical, and more arid conditions. The plants and land mammals of South America are and were substantially different from their North American counterparts. As regards the Paleogene plants, and although much effort has been taken to compare plant species be- tween both hemispheres in recent years, only one taxon (the menispermacean podocarp Palaeoluna; Herrera et al. 2011) was found in common between North and South America. In contrast, several plant families recognized in the fossil record of southern South America are shared, both as fossil and recent taxa, with the Australasian region. Examples are Araucariaceae, Podocarpaceae, Proteaceae, Nothofagaceae, as well as Eocene records of the genera Papuacedrus, Gymnostoma, and Ecualyptus (Zamaloa et al. 2006; González et al. 2007; Wilf et al. 2009; Gandolfo et al. 2011). All of these records suggest a strong southern Gondwana floral belt during the Late Cretaceous and early Paleogene (Iglesias et al. 2011), distinct from floras in the northern part of South America (e.g., Crisci et al. 1991; Moreira-Muñoz 2007). For the mammals, the two hemispheres experienced dra- matically different evolutionary histories, and were provided with substantially different groups of mammals. As summa- rized in Woodburne et al. (2009a, b), North American Paleogene therian mammals had a long history that extend- ed well into the Cretaceous, and developed a relatively complex pattern of endemic evolution energized by immigrations from elsewhere in Holarctica, as well as by climate changes. In addition to a relatively small component of metatherians, the North American biota enjoyed a diver- sity of small-sized insectivorous to omnivorous mammals (‘insectivores,’ primates) as well as a variety of non-therian multituberculates. Larger-sized mammals included a host of placental carnivorans as well as the various and diverse ungulates. In the Late Cretaceous, South America began with its own component of non-therian mammals. These were most- ly comprised of dryolestoids, but also included ‘tricono- donts,’ ‘symmetrodonts,’ substantially specialized gondwanatheres, and a single multituberculate (Kielan- Jaworowska et al. 2007; Rougier et al. 2009a). In the early Paleocene, first metatherian, and then placental mammals, were introduced via as yet undocumented immigration events that likely began in the Late Cretaceous, at least for metatherians (Pascual and Ortiz-Jaureguizar 1991, 1992; Case et al. 2005). As far as is known, no other small-sized insectivorous to omnivorous, or even carnivorous eutherian mammals accompanied the first metatherians. The first pla- cental mammals were mostly kollpaniine ‘condylarths’ and a few other archaic groups, such as pantodonts. The net effect was that therian mammals of South America began the Paleogene with a set of taxa that was substantially less diverse both phyletically and ecologically-adaptively than seen in North America. How this unique group of mammals reacted to the same global temperature changes as seen in North America is the focus of the present study. Cenozoic South American mammalian dynamics have been the subject of research since Ameghino’s contributions in the late XIX Century (see Patterson and Pascual 1972; Pascual 1996; and literature cited therein). In recent deca- des, the contributions by Rosendo Pascual and Edgardo Ortiz-Jaureguizar (Pascual 2006; Pascual and Ortiz- Jaureguizar 1990, 2007; Ortiz-Jaureguizar and Cladera 2006) stand out, with North and South American Late Cretaceous-Paleocene mammalian faunas having been com- pared by Ortiz-Jaureguizar and Pascual (1989) and Pascual and Ortiz-Jaureguizar (1992). The following presentation benefitted from these and many other outstanding publications. Our presentation is organized in three parts. The first documents and summarizes the paleofloral record of South America from the Late Cretaceous to early Oligocene in order to set the vegetational and climatic context in which the evolution of the mammalian faunas can be viewed. The first mammalian section sets out the fundamental chrono- logic, geographic, and taxonomic data by which the indi- vidual SALMAs can be recognized and characterized, with information on their ecological structure. The second mam- malian section integrates the first two sections in order to place the faunal succession and its structural changes into a 2 J Mammal Evol (2014) 21:1–73 climatic and ecological framework. The final portion of the treatment summarizes that synthesis and compares it to the patterns seen in coeval record of North America. The Appenedix documents the bases for the ages of the SALMAs. Methods Definitions and Abbreviations brachydont A descriptor of the height of crown above the roots in mammalian teeth generally referred to as being low-crowned. Damuth and Janis (2011) and Janis (1988) utilized an index based on the m3 height/width of <1.7 to define brachydont. CIE Carbon Isotope Excursion; sharp decrease in δ13C recorded at the beginning of the Sparnacian Stage/Age and the Wasatchian NALMA (Thiry et al. 2006); CIE lasted about 113,000 years, with a recovery interval of about 83,000 years (Murphy et al. 2010). EECO Early Eocene Climatic Optimum (Fig. 1; see text). This signifies the interval that experienced the highest mean ocean temperature of the Cenozoic Era (Wolfe 1978; Zachos et al. 2001, 2008). It began about 53 Ma and persisted to about 50 Ma (Tsukui and Clyde 2012) and occurred in the context of the overall relatively warm conditions that characterized the early Cenozoic from the Paleocene to about medial Eocene. euhypsodont A term used by Mones (1982) for hypselodont of Damuth and Janis (2011) and Janis (1988). FAD First Appearance Datum; first stratigraphic occurrence of a taxon, considered to have been synchronous over a specified geographic region (Woodburne 1996). GPTS Geomagnetic Polarity Time Scale (Gradstein et al. 2004). hypsodont A descriptor of the height of crown above the roots in mammalian teeth generally referred to as being high-crowned. Damuth and Janis (2011) and Janis (1988) utilized an index based on the m3 height/width of 3.5–5.0 to define hypsodont. hypselodont Teeth in mammals that are not only hypsodont but also ever-growing (Janis 1988; Damuth and Janis 2011), with an hypsodonty index >5.01. k.y. A segment of geologic time one thousand years in duration or the age of an event (e.g., ten thousand years ago), without reference to a point or set of points on the radioisotopic time scale. LAD Last Appearance Datum; last stratigraphic occurrence of a taxon, considered to have been synchronous over a specified geographic region (Woodburne 1996). Ma Megannum. One million years in the radioisotopic time scale (e.g., 10 Ma refers to the ten million year point on the time scale). MAP Mean Annual Precipitation (as inferred from paleobotanical leaf margin data; Wilf et al. 1998). MAT Mean Annual Temperature (as inferred from paleobotanical leaf margin data). MECO Mid-Eocene Climatic Optimum; a hyperthermal warming event at about 41.6 Ma (Zachos et al. 2008; Figueirido et al. 2012). MPBE Mid-Paleocene Biotic Event; biotic response to the short-term hyperthermal pulse at the latest Selandian or the be- ginning of the Thanetian, ca 58.7 Ma (Bernaola et al. 2007). Westerhold et al. (2011) referred to the thermal event as the Early Late Paleocene Event (ELPE) and considered its age as about 58.2 Ma (Fig. 1). m.y. A segment of geologic time one million years in duration or the age of an event (e.g., ten million years ago) without reference to a point or a set of points on the radioisotopic time scale. NALMA North American Land Mammal Age (Woodburne 2004a); an interval of time based on mammalian biochronology. Tiffanian, Clarkforkian, Wasatchian, Bridgerian, and Uintan NALMAs are discussed in this report (see Fig. 1). NPHP North Patagonian High Plateau (Aragón et al. 2011). PETM Paleocene-Eocene Thermal Maximum; short-term hyperthermal pulse of global warming at the Paleocene-Eocene boundary (Zachos et al. 2008; McInerney J Mammal Evol (2014) 21:1–73 3 and Wing 2011). This is the earliest Eocene hyperthermal event, calibrated at 56.33 Ma (Westerhold et al. 2009). It had a duration of 120–220 k.y. (Murphy et al. 2010), with an initial pulse of about 10 k.y., during which global sea surface temperatures rose 5–9 °C. protohypsodont A term used by Mones (1982) for hypsodont of Damuth and Janis (2011) and Janis (1988). SALMA South American Land Mammal Age; comparable to NALMA; see Pascual et al. (1965), Simpson (1971), Patterson and Pascual (1972), Marshall et al. (1983). The classification of non-therians follows Kielan- Jaworowska et al. (2004). Metatherian classification follows Goin et al. (2012a), while that for eutherian mammals fol- lows Gelfo et al. (2009: table S1). Floral Terms Vegetation classification follows Graham (1999); natural life zones are from Holdridge (1967); information on mod- ern plants is taken from Heywood (1993) Tropical Forest (paratropical to tropical): MAT ca. 25 °C; subhumid, MAP ca 165 cm/year; little seasonality; growth rings absent to weak; broad-leaved evergreen, single-tiered, open canopy vegetation; leaves mostly entire-margined; thick textured; few drip tips. Tropical rain forest: mean temperature of coldest month not below ca. 18 °C; MAT above 25 °C; MAP above 165 cm/year; no pronounced dry season; broad leaved, evergreen, multistratal; drip tips, lianas (high-climbing woody vines), and buttressing common (supporting of trees or vines by each other); leaves sclerophyllous, mostly mesophyllous (megaphyllous in substratum), entire-margined leaves majority (above 75 %). Subtropical rain forest (= paratropical of authors): may expe- rience some frost; MAT 20–25 °C; no extended dry season; precipitation may be seasonal; floristically like tropical rain forest, mostly broad-leaved evergreens with a few deciduous plants; woody lianas diverse; buttressing present; mostly entire-margined leaves (57–75 %). Subtropical forest: frost present but not severe; MAT be- tween 13 °C and 18 °C; mean of coldest month between 0 °C and 18 °C; more seasonal rainfall; sclerophylls abundant; few lianas; no buttressing; mostly broad- leaved evergreen forest with some conifers; entire- margined leaves 39–55 %. Megathermal rain forest: Such a forest requires a minimum mean monthly temperature above 18 °C, an annual precipitation above 200 cm, and a dry season in which no more than 4 months have less than 10 cm of rainfall per month (Morley 2000). Notophyllous broad-leaved evergreen forest (ecotonal; oak- laurel forest of eastern Asia): mean of coldest month about 1 °C; MAT about 13 °C; some broad-leaved deciduous trees present; conifers not common; woody climbers abundant; buttressing absent; sclerophyllous; no drip tips; entire-margined leaves 40 %–60 %. Cool-temperate forest: temperatures fall below 0 °C for several months (mean coldest month between −3 °C and 2 °C); pronounced seasonality in climate; MAT between 6 °C and 12 °C; broad-leaved deciduous for- est, with conifers; broad-leaved evergreens present but not dominant; entire-margined leaves about 30–38 %. Megathermal: MAT above 20 °C. Mesothermal: MAT between 20 °C and 13 °C. Microthermal: MAT less than 13 °C. Modern counterparts of plant families and other groups referred to in the text are from Stevens (2007) and Heywood (1993). Biogeographic Terminology Biogeographic classification and terminology follows Morrone (2002, 2006). Neotropical Region– Effectively all of South America east of the Andes and north of Patagonia and adjacent Chile, from the latitude of Buenos Aires northwestward to about latitude 28°S. It forms part of the Holotropical Kingdon (sensu Morrone 2002), together with tropical Africa and southern Asia. Andean Region– Patagonia and adjacent Chile, from the latitude of Bahia Blanca (38°S) northwestward to about latitude 28°S. It forms part of the Austral Kingdom (sensu Morrone 2002) together with Antarctica, the Cape region, and the Australiasian Region. Australasian Region– Australia, New Zealand, New Guinea, and neighboring islands in the Pacific Ocean. Mammalian Ecological Categories Ecological categories after Woodburne et al. (2009b). Herbivore: utilizing plant resources including both high energy and low energy herbaceous foliage. Insectivore: utilizing high energy insect or arthropod resources. 4 J Mammal Evol (2014) 21:1–73 Hypercarnivore: utilizing exclusively high-energy verte- brate resources. Carnivore: diet dominated by high-energy vertebrate resour- ces but may include other high-energy resources (insects, invertebrates). Omnivore: diet dominated by high-energy fruits, seeds, and insects but may also utilize other invertebrates as well as high-energy vertebrate resources. Small size: less than 1 kg of body mass. Medium size: 1 to 10 kg. Large size: greater than 10 kg. Long-term Climatic Trends and Transient Hyperthermal Events The general climatic pattern of the early Cenozoic Era has been updated recently (Zachos et al. 2008, 2010; Westerhold et al. 2011) from previous analyses (e.g., Zachos et al. 2001). The Paleogene Period witnessed the most important long-term warming trend of the Cenozoic. As indicated in Fig. 1, the warmer global climates began in the early Paleocene and achieved their maximum development during the EECO, with subsequent cooling toward the onset of the Icehouse World at the beginning of the Oligocene. Several short-term hyperthermal pulses (on the order of a few tens of k.y.) were superimposed on this pattern, with the most impressive being the PETM at the Paleocene-Eocene boundary. Other hyperthermal pulses have yet to be shown as global in extent. Unfortunately the South American land mammal record appears to not preserve the PETM, but the MPBE, if global, may be generally correlative with the Carodnia Zone, and the Itaboraian to Tinguirirican mam- mals could reflect the warm to cooler climates indicated on Fig. 1. Based on the sharp drop in temperatures and associ- ated impact on indigenous floras, mammal faunas of Tinguirirican and Deseadan age could be expected to show a biofacies that was comparable between them and also different from those of previous intervals. Mammalian Biochrons This report employs an updated chronology of fossil mammal-bearing successions in North and South America (Fig. 1) not only in terms of the Cenozoic time scales presented in Gradstein et al. (2004), but also with respect to advances made subsequent to compilations for North America (Woodburne 2004b; Woodburne et al. 2009b) and South America (Flynn and Swisher 1995; Pascual et al. 1996). It is convenient to utilize the Paleogene and Neogene time scales presented in Gradstein et al. (2004) as a template in which to accomplish these aims. North America The North American Land Mammal Ages (NALMA) follow Woodburne (2004b) and Woodburne et al. (2009b), but with adjustments made relative to the Luterbacher et al. (2004) time scale. South America Historically, the main sequence of Paleogene mammal faunas in South America (Fig. 1) was documented in the Golfo San Jorge Basin of Patagonia (Fig. 2a), as summarized by Bond et al. (1995) and Pascual and Ortiz-Jaureguizar (2007). Beginning about 1990, fossil-bearing sequences in Bolivia, Brazil, Chile, Perú, and Colombia have made important con- tributions to our understanding of South American Paleogene biochronology and counterparts of some of them (Itaboraian, Tinguirirican) have been recognized in Patagonia as well (Roth 1903; Gayet et al. 1991; Sempere et al. 1997; Marshall et al. 1997; Croft et al. 2008b). The incorporation of the Tiupampan (early Paleocene) and Peligran (medial Paleocene) SALMAs (Ortiz-Jaureguizar and Pascual 1989; Bonaparte et al. 1993) and the reconsideration of the Casamayoran SALMA from its conventional early Eocene age to the late Eocene (Kay et al. 1999) were the first major temporal revisions of the conventional SALMA bio- chronological scale (Fig. 1). This was followed by the addition of a new early Oligocene Tinguirirican SALMA (Flynn et al. 2002, 2003), a new earliest Paleocene Grenier Farm metather- ian record (Goin et al. 2006a), a new early Eocene Paso del Sapo fauna (Tejedor et al. 2009), and a reinterpretation of the age of the Divisaderan assemblage (López 2010). These are fully discussed in Appendix I. Floral Background Late Cretaceous Floras and Climate in South America The global floral record indicates that angiosperms progres- sively overtook gymnosperms as the dominant plant group during the Late Cretaceous. In Patagonia, angiosperms diver- sifed from the middle Albian, ca 105 Ma (Archangelsky et al. 2009; Quattrocchio et al. 2011). In the Austral Basin (6, Fig. 2a), Iglesias et al. (2007c) discussed the Mata Amarilla flora derived from a littoral coastal plain of Cenomanian age (ca 96 Ma; Varela et al. 2012). Abundant megafossils demon- strated an important diversification of angiosperm shrubs and small trees, along with a canopy of podocarp and araucarian forests with a rich understory of ferns. Cupressaceae s.l. reflect very wet conditions, and widespread fungi, including J Mammal Evol (2014) 21:1–73 5 epiphyllous forms, may indicate tropical conditions of high temperatures and humidity. Similar inferences were made based on analyses in the Mata Amarilla Formation where Varela (2011) recognized paleosols that reflected a MAT of about 20 °C (subtropical) and MAP above 100 cm, but with markedly seasonal rainfall. This is the oldest record of an angiosperm-dominated flora in southwest Gondwana. Other angiosperm-dominated floras of Cenomanian-Coniacian age include Portezuelo flora in the Neuquén Basin and the Bajo Barreal Formation in the San Jorge Basin (Archangelsky et al. 2009). Angiosperm pollen are an important part of the record from the Campanian onward (Prámparo et al. 2007). During the Early Cretaceous (to the Albian), several fossil records of xerophilic plants (Ephedraceae, Gnetaceae, Cheirolepidiaceae, some conifers, and a few small-leafed angiosperms) infer a large area with dry con- ditions in equatorial and tropical South American regions, which extended from northern Brazil Crato Formation to central Argentina La Cantera Formation (Mohr et al. 2006; Sucerquia and Jaramillo 2007; Kunzmann et al. 2009; Prámparo 2005; Puebla 2010), and isolated northern wetter areas from those in the far south. Later Cretaceous and Paleocene elements of this tropical dry area could have continued the isolation of wet floras in the north from those of southern South America (Iglesias et al. 2011). Maastrichtian and early Paleocene (Danian) marine trans- gressions flooded most Patagonian areas, including the Salado, Colorado, Neuquén, and Golfo San Jorge basins, as well as the Austral and Malvinas basins in the south (Malumián and Náñez 2011: Fig. 1). This figure (Fig. 2a) also shows the extent of marine transgressions elsewhere in South America, with a narrow zone on the eastern margin of the proto-Andes on the western side of the continent. A number of minor marginal re-entrants along the eastern Brazilian coastline are not shown. Both in Patagonia and elsewhere in South America, it appears that the positive areas still were of relatively low relief and elevation, except for elements of the proto-Andes, which generally experienced a strong episode of tectonic activity in the preceding Campanian (Viramonte et al. 1999; Jaillard et al. 2008; Vallejo et al. 2009), although the ranges were not high enough to interfere with circulation patterns, or to produce a rain shadow, as characterizes the modern Andes (Folguera et al. 2011). Representative Maastrichtian and Danian units in the Neuquén Basin, southern Mendoza and La Pampa provin- ces, include the Loncoche, Jagüel, and Roca formations (columns 1–3, Fig. 3), and the Pedro Luro Formation in the Colorado Basin to the east (Fig. 2a). In addition, the Allen and Los Alamitos formations of Río Negro Province (Colorado Basin) are important nonmarine units (columns 3, 4, Fig. 3), as are the Chubut Province Chubut Group, the La Colonia Formation, and the estuarine and littoral Lefipán and Salamanca formations in the northwestern and central parts of the Golfo San Jorge Basin to the south (Malumián and Náñez 2011; Fig. 2a; columns 5 and 7, Fig. 3). Angiosperms exhibit a progressive diversification through the Late Cretaceous and become abundant in the Paleogene (Prámparo et al. 2007; Archangelsky et al. 2009). Cretaceous floras are strongly represented by the Proteaceae (rain forest Gondwanan elements), Nothofagaceae (southern beech), Myrtaceae (Eucalyptus family), Ulmaceae (elms), and Bombacacoideae (baobab tropical family) (Prámparo et al. 2007). Nothofagus is represented by pollen grains in the Jagüel Formation (3, Fig. 2a) in Río Negro Province (medial Maastrichtian according to Prámparo et al. (2007), but the first well-identified macrofossils of Nothofagaceae in Patagonia are from the early Danian Palacio de los Loros flora (3* [* indicates star symbol], Fig. 2b), with leaves as large as those found in present-day tropical New Guinea (Iglesias et al. 2007a). Well established pollen records and leaves having more temperate-like sizes in this family are recorded subsequently in the late Eocene of southernmost Patagonia. Cúneo et al. (2007) discussed new Late Cretaceous meg- afossil floras from the Lefipán Formation, Chubut Province, Argentina (4, Fig. 2a; Figs. 3, 4, 5, 6, 7, and 8), and noted that a suite from the lower part of the formation is a diverse assemblage composed of angiosperms (including aquatic Nelumbo leaves and fruits) and conifers. A suite from the upper part of the formation is represented by extremely diverse angiosperms (about 70 species), as well as mono- cots, conifers, and ferns. The leafy flora suggests a warm climate. Previously, Baldoni and Askin (1993) indicated that the 35 angiosperm and minor gymnosperm pollen species from this unit probably represent a shrubby angiosperm- fernland vegetation with patchy wooded areas in a warm temperate, possibly subtropical, climate. The somewhat cooler, more temperate, setting as compared with other Late Cretaceous floras may reflect the presence of the adja- cent highlands noted by Scasso et al. (2012). To the east, Gandolfo and Cúneo (2005) discussed then- new Nelumbo (lotus) fossils from the Campanian- Maastrichtian La Colonia Formation (5, Fig. 2a; Figs. 3, 4 and 8), and indicated that today this group is typically found in subtropical to tropical aquatic settings. These La Colonia lotuses were associated with aquatic ferns as well as other angiosperms and gymnosperms, and may represent a wet lowland area (wetland) where a diverse mammal fauna also was present (Pascual et al. 2000; Albino 2000; Gasparini and De La Fuente 2000). As suggested in Figs. 3 and 4, the Fig. 1 Paleogene Time Scale, showing the North American and South American Land Mammal ages. Age, Epoch, Stage and Polarity Chrons follow Luterbacher et al. (2004). Arikareean biochrons after Albright et al. (2008). Chronology of NALMAs and SALMAs is discussed in the text. The Global Temperature curve is after Zachos et al. (2001) � 6 J Mammal Evol (2014) 21:1–73 J Mammal Evol (2014) 21:1–73 7 La Colonia flora likely was about the same age as that from the Lefipán Formation. As indicated in Fig. 8, plant species diversity is still not known from the La Colonia site. The Late Cretaceous floras of South America reviewed here reflect a variety of subtropical to tropical aquatic to woodland conditions and a diversity of gymnosperm and angiosperm plants as well as ferns, cycads, and conifers. Ottone (2007) examined Late Cretaceous palm pollen and trunks from the Colipilli Group, Neuquén Province (2, Fig. 2a), and noted that these and the associated trunks of diverse cycads there and in Río Negro Province (Artabe et al. 2004) indicated a frost-free, warm, and humid climate for this region at that time (75–65 Ma). This is comparable to the conditions inferred from the other floras reviewed above, although the growth rings in the Colipilli tree trunks suggest a seasonal climate. Farther north in South America, Correa et al. (2010) reported on the late Maastrichtian (ca 68 Ma) Rhamnaceae (buckthorns) from the Guaduas Formation of Colombia (7, Fig. 2a), that lived under aMATof 22.1±3.4 °C and aMAP of Fig. 2 Paleogeographic maps of South America showing the plant and mammal localities discussed in the text. a Maastrichtian transgressions for the South American continent, with emphasis on Patagonia, with named basins, Argentine provinces, and details of formation units. After Malumián and Náñez (2011: fig. 3). The dark pattern shows the major transgressions; most of the continental platform also was inundated. Crosses show positive areas. Localities discussed in the text are: 1, Los Alamitos and Allen Formation sites, Rio Negro Province; 2, Colipilli Group sites, Neuquen Province; 3, Jäguel Formation sites, La Pampa Province; 4, Lefipán Formation sites, Chubut Province; 5, La Colonia Formation sites, Chubut Province; 6, Mata Amarilla Formation (middle Cenomanian) and Calafate Formation (Maastrichtian), Santa Cruz Province. b Danian transgressions and Paleocene localities. After Malumián (1999: fig. 1) and Malumián and Náñez (2011). The major transgression is located in Venezuela. The other incursions in Patagonia are partly shallow marine. Plants*: (1*) Cerrejón flora; early Paleocene; Guajira, northern Colombia; (2*) Flora Formation flora, late Paleocene; Bolivia; (3*) Palacio de los Loros flora, early Paleocene, Chubut Province. The Ormaechea Petrified Forest is about 30 km. NE of this point; (4*) Szlápelis Petrified Forest, early Paleocene, Salamanca Formation, Chubut Province; (5*) Ameghino Petrified Forest, early Paleocene, Salamanca Formation, Chubut Province; (6*) Estancia Laguna Manantiales, Salamanca Formation, Santa Cruz Province; (7*) Las Violetas Flora, Salamanca Formation; (8*) Puerto Viser and Bajo Palangana petrified forests, middle Paleocene, Peñas Coloradas Formation; (9*) Ligorio Márquez Flora, latest Paleocene, Chile; (10*) Pedro Luro Formation, core drill, Buenos Aires Province; (11*) Maíz Gordo Formation, Paleocene, Salta Province; (17*) Cerro Bororó Flora, early Danian, correlated to Salamanca Formation; (18) paleosols with calcretes, Queguay Formation, Paleocene, Uruguay. Mammals: (12) Tiupampa, Santa Lucía Formation, Cochabamba Department, Bolivia; Tiupampan SALMA, early Paleocene; (13) Grenier Farm, Lefipán Fm, Chubut Province; earliest Paleocene); (14) Punta Peligro, Hansen Member, Salamanca Formation, Chubut Province; Peligran SALMA, middle Paleocene; (15) Cerro Redondo (lowermost levels, Hansen Member, Salamanca Formation, Peligran SALMA, middle Paleocene; lower levels, Peñas Coloradas Fm, Carodnia Faunal Zone, late Paleocene; upper levels, Ernestokokenia Faunal Zone, Riochican SALMA, early Eocene; (16) Bajo Palangana, Chubut Province; lower fossiliferous level, Peñas Coloradas Formation, Carodnia Faunal Zone, middle Paleocene. c. Middle Eocene transgressions and Eocene localities. After Malumián (1999: fig. 2). Plants*: (17*) Piñalerita flora; early Eocene; Colombia; (18*) Laguna del Hunco flora, early Eocene, Chubut Province; (19*) Pampa de Jones flora; early Eocene, Neuquen Province; (20*) Confluencia flora, middle Eocene, Neuquen Province; (21*) Río Pichileufú flora; middle Eocene, Río Negro Province; (22*) Río Turbio Flora, late Eocene, Santa Cruz Province; (23*) Sloggett Formation, latest Eocene, Tierra del Fuego Province; (24*) Estancia La Sara well, late Eocene, Tierra del Fuego Province; (25*) Lota Coronel and Caleta Cocholgüe floras, early Eocene, Chile; (26*) Quinamávida Flora, early Eocene, Chile. Mammals: (27) Bajo Palangana, Chubut Province, upper fossiliferous level, Koluel Kaike Formation, Ernestokokenia Faunal Zone, Riochican SALMA, early Eocene; (28) Las Flores fauna, and Peñas Coloradas flora, Las Flores Fm, Chubut Province; Itaboraian SALMA, early Eocene; (29) Itaboraí Quarry, Itaboraí Formation, Niteroi State, Brazil; Itaboraian SALMA, early Eocene; (30) Las Flores locality, Las Flores Fm, Chubut Province; Itaboraian SALMA, early Eocene; (31) Cañadón Hondo, Las Flores Fm, Chubut Province; Itaboraian SALMA, early Eocene; (32) Gran Barranca, Koluel Kaike Formation, Ernestokokenia Faunal Zone, Riochican SALMA, early Eocene; (33) Laguna Fría and La Barda mammal localities and Laguna del Hunco flora, near Paso del Sapo Volcanic-Pyroclastic Complex of Middle Chubut River, Chubut, Province, middle Eocene; (34) La Meseta Fauna, Seymour (Marambio) Island, Antarctic Peninsula; (35) Cerro Pan de Azúcar (basal sandstones, ?Río Chico Group; but see Tejedor et al. 2009); (36) Cañadón Vaca, Sarmiento Formation, Chubut Province; Vacan Subage, middle Eocene; (37) Gran Barranca, type “Barrancan” levels, Gran Barranca Member, Sarmiento Formation, Chubut Province; Barrancan Subage, middle Eocene; (38) Several localities in Salta and Jujuy provinces, Lumbrera Fm, ?Barrancan Subage, middle Eocene; (39) Divisadero Largo, Divisadero Largo Formation, Mendoza Province; middle Eocene); (40) Gran Hondonada, Sarmiento Formation, Chubut Province, Mustersan SALMA, middle Eocene; (41) Gran Barranca, El Rosado levels, Sarmiento Formation, Chubut Province, Mustersan SALMA, middle Eocene; (42) Antofagasta de la Sierra, Geste Formation, Catamarca Province, Mustersan SALMA, middle Eocene; (43) Paso del Cuello, Fray Bentos Fm, Santa Lucía Basin, Canelones Department, Uruguay, Deseadan SALMA, late Oligocene; (44) Santa Rosa, ?Yahuarango Formation, Ucayali Department, Perú, ?Eocene-?early Oligocene, likely Mustersan); (45*) San Pedro Formation, Valdivia Basin, Chile; middle Eocene flora; (46) Santa Bárbara subgroup-equivalent beds of Río Loro Formation, Tucuman Province, Argentina, ?early-middle Paleocene; (47) Laguna Umayo faunal sites, Puno Department, Peru, ?Itaboraian. d. Early Oligocene transgressions and Oligocene mammal sites. After Malumián (1999: fig. 4). Plants*: (45*) Sloggett Formation, Tierra del Fuego Province, latest Eocene - early Oligocene; (46*) Estancia La Sara well, Tierra del Fuego Province, Oligocene; (47*) Río Guillermo, Santa Cruz Province, early Oligocene; (48*) Río Leona, Santa Cruz Province, early Oligocene; (49*) Monte León Formation, Santa Cruz Province, latest Oligocene - early Miocene; (50*) Río Foyel, Río Negro Province, latest Oligocene - early Miocene; (51*) Loreto Formation, southern Chile, latest Eocene.Mammals: (52) Termas del Flaco, Abanico Formation, Upper Tinguiririca Valley, central Chile; Tinguirirican SALMA, early Oligocene; (53) Gran Barranca, La Cancha locality, Vera Member, Sarmiento Fm, Chubut Province, Tinguirirican SALMA, early Oligocene; (54) Gran Barranca, La Cantera locality, Unit 3, Upper Puesto Almendra Member, Sarmiento Formation, Chubut Province, early Oligocene; (55) La Flecha, Sarmiento Formation, Santa Cruz Province, Deseadan SALMA, late Oligocene; (56) Cabeza Blanca, Sarmiento Formation, Chubut Province, Deseadan SALMA, late Oligocene; (57) Rancho Verde area, Fray Bentos Formation, Canelones Department, Uruguay, Deseadan SALMA, late Oligocene); (58) Quebrada Fiera, Agua de la Piedra Formation, Mendoza Province, Deseadan SALMA, late Oligocene; (59) Taubaté, Tremembé Formation, Sao Paulo Basin, Brazil, Deseadan SALMA, late Oligocene; (60) Salla-Luribay and Lacayani localities, Salla Beds, La Paz Department, Bolivia, Deseadan SALMA, late Oligocene); (61) Gran Salitral Formation and flora, La Pampa Province, early Eocene. Base maps used here were based on ones obtained from http://d-maps.com/index.php?lang=es � 8 J Mammal Evol (2014) 21:1–73 http://d-maps.com/index.php?lang=es J Mammal Evol (2014) 21:1–73 9 240 cm, but otherwise did not discuss the floral diversity there. Consistent with the MAT and MAP, the group is typically found in hot to warm tropical to subtropical lowlands. Paleogene Floras and Climate in South America Figure 2b shows the distribution of Paleocene sedimentary basins in South America. As for the Cretaceous, the most extensive such record is found in Patagonia, with the Maracaibo Basin of Venezuela having a landward southwest- erly extension to the Eastern Cordillera region (ECC) of Colombia. Other districts in western Amazonia reflect erosion from elevated parts of the proto-Andes, as discussed by Mann et al. (2006) and Escalona and Mann (2011) regarding the geohistorical development of northern South America, with emphasis on the Maracaibo Basin in western Venezuela and adjacent districts both east and west. Parra et al. (2010) pro- vided a tectonic context for adjacent Colombia; Hungerbühler et al. (2002) and Vallejo et al. (2009) for Ecuador; Contreras et al. (1996) and Jaillard et al. (2005, 2008) for Perú; McQuarrie et al. (2005), Horton (2005), and Garzione et al. (2006) for Bolivia; Mpodozis et al. (2005) and Arriagada et al. (2006a, b) for Chile; Carrapa et al. (2005) and Deeken et al. (2006) for northwestern Argentina; and Nullo and Combina (2011) for Patagonia in southern Argentina. Cúneo et al. (2007) proposed that the pattern of plant extinction and recovery in South America during and sub- sequent to the K-Pg interval was comparable to that seen in North America, with a major early Paleocene renovation. But, as shown on Figs. 4 and 8, and discussed further below, Patagonian Paleocene floras apparently achieved renewed diversity well in advance of their North American counter- parts, as recorded by the 62 Ma age, diversity and renovated composition reported by Iglesias et al. (2007a, b) for the Palacio de los Loros flora in the Salamanca Formation of Patagonia (3*, Fig. 2B; Figs. 4, 5 and 8). Figure 8 indicates that the Palacio de los Loros flora is represented by at least 40 species per fossil outcrop (as a minimum number), Fig. 3 Late Cretaceous to Paleocene stratigraphic units with palyno- floras and fossil land mammals. References: 1. southern Mendoza Province after Parras et al. (1998), Casadio et al. (2005). 2. southern La Pampa Province, after Massabie (1995). 3. northern Río Negro Province, after Rougier et al. (2009a). CT = Cerro Tortuga mammal site. 4. Los Alamitos, southeastern Río Negro Province, after Bonaparte (1987), Spalletti et al. (1999). LA = Los Alamitos mammal site. 5. Paso del Sapo, NW Chubut Province, after Ruiz (2006). GF = Grenier Farm mammal site. 6. La Colonia, northern Chubut Province, after Pascual et al. (2000). LC = La Colonia mammal site. 7. Golfo San Jorge Basin, SE Chubut Province, after Andreis et al. (1975); Iglesias et al. (2007a); Riccardi (1988) for the age of the Bajo Barreal Formation 8. Golfo San Jorge Basin, NE Santa Cruz Province, after Hechem and Strelkov (2002, Mesozoic), Malumián (1999, Cenozoic); Riccardi (1988) for the age of the Chubut Group and formations 10 J Mammal Evol (2014) 21:1–73 whereas temporally comparable floras in North America have only about 30. Subsequently, the floral diversity in South America increased dramatically to 186 species in the early Eocene Laguna del Hunco flora, as compared to about 50 in North American suites, in which case the Paleocene recovery of Patagonian floras would have been outstandingly greater than recorded in North America (Iglesias et al. 2007a). The following discussion is directed at an appraisal of the paleoclimatic setting for Paleocene and Eocene land mammals derived from a consideration of contem- poraneous paleofloras in South America, with especial focus on those of Patagonia where the record of both groups is best developed, although the Neotropical pale- ofloras are also assessed as representing the basic floral background for the continent. In addition to floral diversity, it has proven useful to compare floras regarding the MAT and MAP inferred from their foliar morphology. Recently, Little et al. (2010) have raised questions regarding the methodology commonly used in deriving such estimates, although Spicer and Yang (2010) have offered reasons in support of MAT and MAP calculations. Whereas the record for such analyses in North America is represented by a relatively large number of fossil floras in a well- developed chronologic framework (Woodburne et al. 2009a, b), and therefore might be internally consistent (Little et al. 2010), this is not yet the case in South America. As shown in Fig. 8, the three Patagonian floras that have been assessed regarding MAT and MAP occur within a span of about 20 m.y. (Palacio de los Loros, ca 62 Ma; Laguna del Hunco, ca 52 Ma; Río Pichileufú, ca 47 Ma), and provide only a general framework of cli- mate change during this time. Fortunately others, from Chile (Quinamávida, Concepción-Arauco, and Caleta Cocholgüe) and more northern Argentina (Gran Salitral), help fill in the pattern. Whereas these estimates are helpful, further consideration of the important South American floras can be realized by invoking a more general characterization, such as tropical, humid, and the like, without reliance on MAT and MAP values. In fact, MAP derived from fossil leaves should be treated as a minimum value for a paleoflora (Wilf et al. 1998), and precise taxonomic identifications at the generic and spe- cific levels should be taken as yielding better precipita- tion estimates, as based on modern relatives (Wilf et al. 2009). Neotropics The discussion begins with the Neotropical record in that floras there were already well developed in the early Paleocene, and form a background to which more southern floras may be compared. The concept of the Neotropical Region used here follows Morrone (2002, 2006), which included most of Central and South Fig. 4 Chart of SALMAs, deep ocean temperatures, MAT, MAP and South American floras discussed in the text. Ocean temperatures after Zachos et al. (2001). G in SALMA column refers to Grenier Farm site. KK1-KK3 are Koluel-Kaike Fm. paleosols after Krause et al. (2010). Rio Pichileufú and Laguna del Hunco floras after Wilf et al. (2005); Palacio de los Loros flora after Iglesias et al. (2007a) J Mammal Evol (2014) 21:1–73 11 America, with the exception of its southernmost part (the Andean Region, including Patagonia and the south- ern Andes), as well as a narrow strip of the Andean Range up to the low latitudes of Colombia. This strip is regarded by Morrone (2006) as a transitional zone of mixed biotas between both regions. Jaramillo et al. (2006) noted that the South American Neotropics have the highest plant diversity in the world. Their study is based on a high-resolution pollen and core record from Paleogene to early Neogene of Colombia and western Venezuela that shows tropical plant diversity generally following long-term global climatic changes. The data are derived from well cores in which the sediments range from Campanian (80 Ma) to medial Miocene (16 Ma) and encompass fluvial to coastal plain environments. As indicated in Fig. 8, the pattern of standing diver- sity is considered to have been relatively low in the early Paleocene (about 200 morphospecies). This is followed by an increase to about 300 morphospecies in the late Paleocene, and a drop at the end of that time (to about 250 morphospecies). Diversity then steadily increased during the Eocene toward a mid- Eocene peak (nearly 350 morphospecies). Diversity then declined during the middle and late Eocene, with a sharp drop at the Eocene - Oligocene boundary. 64 Ma 62.6 + 5 Ma sharp change in lithology normal polarity reversed polarity normal polarity reversed polarity = unconformity 12 11 9 5 2 1 57.8 _ 6 Ma reversed polarity reversed polarity Peligran SALMA ? ? ?? Carodnia zone ?? Kibenikhoria zone ?? ?? Ernestokokenia zone Palacio de los Loros Flora 61.7 _ 0.2 Ma Rancho Grande Flora Ormaechea Petrified Forest 50 m ? LITHOSTRATIGRAPHIC UNITS COLUMN "Patagonian" Gr. Monte Leon Fm. San Julian Fm. Sarmiento Gr. Casamayor Fm. Koluel Kaike Fm. Las Flores Fm. Penas Coloradas Fm.~ Rio Chico Gr. Salamanca "Fm." Hansen Mb. (= "Banco Negro inf." "Banco Verde" "Fragmentosa" "Glauconitico" Chubut Gr. + + (incl. Las Violetas Fm.) ca 62 Ma 59 Ma 51 Ma 45 Ma 71 Ma numerical ages after Legaretta and Uliana (1994) This paper 54 Ma 61.9 - 63.8 Maforaminiferal zone P1C H an se n M em be r Penas Coloradas Flora ~ Fig. 5 Paleogene stratigraphic units of the Golfo San Jorge Basin, Patagonia, after Bond et al. (1995). The magnetostratigraphic profile given in Marshall et al. (1981: fig. 2) is shown in relation to uncon- formities shown or inferred from the indicated lithologic relationships. Legarreta and Uliana (1994: fig. 3) inferred numerical ages for these units based on an interpretation of the sea level fluctuation history for these strata. In that example, the base of the Salamanca Formation was interpreted as 71 Ma, rather than 64 Ma as shown here (right hand numbers). The unconformity 2 at the base of the Banco Verde (sedi- ment-filled fissures) was interpreted as 63 Ma; the top of the Hansen Mbr. (vitreous tuff) dated at 62.6 Ma (between unconformities 2 and 5, after Andreis, 1977). This is now considered as 62 Ma after Iglesias et al. (2007a). The Palacio de los Loros Flora date is after Iglesias et al. (2007a) as is the 57.8 ± 6 Ma age near unconformity 9. The forami- niferal zone P1C age (61.9–63.8 Ma) is after Luterbacher et al. (2004). The base of the Peñas Coloradas Formation was interpreted as 60 Ma (unconformity 5; about 59 Ma here); the basal conglomeratic sandstone of the Koluel Kaike Formation was interpreted as 57 Ma (unconformity 11; about 51 Ma here; see text); the base of the Casamayor Formation is interpreted as 55 Ma (unconformity 12; about 45 Ma here) 12 J Mammal Evol (2014) 21:1–73 Jaramillo et al. (2006: fig. 2a) also showed a stable diversity during the Oligocene, with a slight fall toward the early Miocene. Overall, the Paleocene flora was of generally low diversity; the early to mid-Eocene flora was more diverse; that of the later Eocene and Oligocene was less diverse but more so than in the Paleocene. During the same Paleogene interval, Jaramillo et al. (2006) indicated that extinction rates were relatively uni- form, with a moderate increase in the late Paleocene and during the Eocene-Oligocene transition. Origination rates generally decreased slightly over the entire interval, but showed a somewhat higher rate that mirrored extinctions in the late Paleocene and early Eocene. Originations continued to decline in the later Eocene and Oligocene, comparable to extinctions. This is consistent with the overall diversity decrease seen in this part of the time scale (Fig. 8). Jaramillo et al. (2006) also showed a relatively strong floral turnover at the end of the Paleocene, as well as at the beginning of the Oligocene Oi-1 glaciation. Overall, the pattern of palynological diversity followed the gen- eral increase in global temperature from the early Paleocene to the EECO, although the floral pattern is slightly offset from (later than) the temperature trend (Fig. 8). The long drop in temperature from the EECO to the early Oligocene also is generally paralleled by a somewhat later and more gradual pattern of diminished floral diversity in the Neotropics, including the sharp drop in both temperature and floral diversity at the Eocene-Oligocene boundary. Whereas change in global temperature appears to have been the major factor reflected in the floral diver- sity pattern, it also is possible that there was an areal component (Jaramillo et al. 2006). In that context, glob- al warming likely also expanded the area that experi- enced increased temperatures, as well as precipitation (Jaramillo and Dilcher 2000; Jaramillo 2002), with a positive effect on speciation. As indicated by Wilf et al. (2005), the northern Patagonian Laguna del Hunco (18*, Fig. 2c) and Río Pichileufú floras (21*, Figs. 2c and 8) were very diverse and located in a wet and warm tropical region. It is possible that the greater areal extent of wet tropical conditions provided an enlarged platform for speciation, and contributed to diversity increases into the middle Eocene. Subsequent cooling would not only have promoted a decline in plant diver- sity in and of itself, but the areal restriction of tropical conditions likely was an important factor, as well. A late Paleocene megafossil flora (ca 58 Ma) is known from the Cerrejón Formation (1*, Figs. 2b and 8) of Guajira, northern Colombia (Jaramillo et al. 2007; Doria et al. 2008; Herrera et al. 2008, 2011; Gómez- Navarro et al. 2009; Wing et al. 2010). It contains a Fig. 6 Stratigraphic relationships of Upper Cretaceous and Paleogene strata in the Golfo San Jorge Basin of Patagonia (Fig. 2A). Geological sections at Cerro Solo, Cerro Abigarrado, Gran Barranca, Cañadon Hondo, and Punta Peligro after Feruglio (1949) and Raigemborn et al. (2010). The sequence at Cerro Redondo is from Simpson (1935) with the approximate locations for normal magnetic intervals after Marshall et al. (1981). The strata of the Peñas Coloradas Formation and that part of the Las Flores Formation below the normal magnetozone in unit J are of reversed polarity. Strata of unit K and the lower part of unit L in the Koluel Kaike Formation also are of reversed polarity. The D mammal horizon reflects the location of the Peligran SALMA. The H mammal horizon represents the location of the Carodnia Zone. The Upper Mammals horizon M is the location of the Ernestokokenia Faunal Zone J Mammal Evol (2014) 21:1–73 13 diverse suite of tropical palms and legumes reflective of coastal river and mangrove swamp-lake environments. Doria et al. (2008) indicated that Neotropical rain for- ests have a unique combination of high plant species diversity, a distinct floristic composition, and a multi- story forest structure. Wing et al. (2010) noted that the diversity and relative abundance of Cerrejón plant fam- ilies are similar to those of modern Neotropical rain forests. At about 58 Ma, the Cerrejón Formation plants are the oldest Neotropical megafossil flora yet recov- ered, both in terms of its geography as well as its floral characteristics. The Late Cretaceous Guaduas Formation flora of Colombia may obtain this position when more fully described. Cerrejón plants include leaves of 46 non-monocot angiosperms, 13 monocots, five ferns, and one conifer, Fig. 7 Stratigraphic and geochronologic distribution of elements of the Sarmiento Formation in the Gran Barranca, with ranges of indi- cated SALMAs, after Ré et al. (2010a: fig. 4.1). Changes relative to Ré et al. (2010a: fig. 4.1) include adding SALMA intervals, locating the Ar/Ar arrowheads to the age indicated by the basalts they repre- sent in upper unit 3 of the Upper Puesto Almendra Member; lowering the age of the “La Cantera” fauna to agree with the text; insert the “El Nuevo” fauna and D2 disconformity as indicated; adding an arrow relative to the “El Rosado” Tuff to indicate its chronologic location; adding the VRS Tuff at its chronological location; revising the basal contact of the Sarmiento Formation to agree with the discussion in the text. The numerical ages for the Koluel Kaike Formation are as in the text, modified from Krause et al. (2010). The Cañadón Vaca sequence is indicated to illustrate the age and faunal content of the Sarmiento Formation at that location in contrast to the Gran Barranca (after Cifelli 1985), and to demonstrate the extent of the unconformable contact between the Sarmiento and Koluel Kaike formations at Gran Barranca 14 J Mammal Evol (2014) 21:1–73 along with 33 kinds of compressed fruits and seeds. This suggests a diversity of at least 65 taxa, but that figure likely is conservative. The Cerrejón flora plots along the line that represents a conservative estimate of Paleocene Patagonian taxonomic diversity on Fig. 8 but, with likely greater ultimate diversity, it seems to poten- tially reflect the coeval pollen diversity pulse for floras from the same area in Colombia. The most abundant and diverse plant orders are: Araceae (6–7 leaf types), Arecaceae (2 leaf, 3 fruit); Fabaceae (5–7 leaves; 7 fruit); Lauraceae (2 leaf); Malvaceae (2–4 leaf); Menispermaceae (4 leaves, 11 fruits); and Zingiberales (2 leaf). Sub-familial level taxa include Montrichardia (Neotropical aquatic aroid monocot), Stephania (Australian menisperma- ceaean liana), Palaeoluna (fossil Menispermaceae), and two palms: Euterpeinae and the hydrophylous Nypa. Four rare ferns are the pantropical, floating-aquatic Salvinia; an Old World tropical swamp climber Stenochlaena; the cosmo- politan Lygodium; and the pantropical freshwater man- grove swamp fern, Acrostichum. The Menispermaceae is a pantropical angiosperm family, with its predominantly climbing habit indicating that the multistory structure of tropical rain forests had been established by the time of the Cerrejón flora (Doria et al. 2008; Herrera et al. 2011). Early members of this family (Palaeoluna) reflected trans-Caribbean Paleocene connections between Colombia and Wyoming, in North America. The Cerrejón genus, Stephania, is a possible precursor of modern Australian members (Herrera et al. 2011), but this dispersal scenario is hindered by the lack of infor- mation regarding fossil occurrences of the group in India and southeastern Asia, as well as Australia. Modern Araceae (aroids, including the arum lily; Heywood 1993) are one of the most diverse monocoty- ledenous plant families, and are most diverse in the modern tropics. The group ranges from the Late Cretaceous (Campanian) of Holarctica as well as the Maastrichtian of India and South America, the early Paleogene of Holarctica and northern South America, to the Recent. Wing et al. (2010) calculated that MAT was about 28 °C (tropical), comparable to that estimated from large-bodied fossil snakes from the same unit (32°–33 °C; Head et al. 2009: fig. 8). Subsequently, MATs about 30 °C likely were experienced by the Neotropics in the early Eocene when global climates increased substantially. The Cerrejón MAP Fig. 8 Chart of Paleogene oceanic temperatures, MAT and MAP of North American and selected South American megafloras, taxonomic diversity of North American megafossil plants and Neotropical pollen, as well as North American and South American mammals. Global time scale after Luterbacher et al. (2004); deep sea ocean temperatures after Zachos et al. (2001), North American MAT and MAP record after Woodburne et al. (2009a). MAT and MAP record for South American megafossil floras after Wilf et al. (2005), Iglesias et al. (2007a), and Hinojosa et al. (2006). Taxonomic diversity: Colombian pollen from Jaramillo et al. (2007). North American floras after Wing (1998) and Wing et al. (1995); South American floras from Wilf et al. 2005; Iglesias et al. (2007a). Mammal diversity for North America after Woodburne et al. (2009b). South America, this paper. Note that al- though the diversity pattern for Colombian pollen physically crosses that for North American floras, the numerical scale higher in the figure indicates that at the beginning of the Paleocene, Colombian pollen represented about 175 taxa as compared to about 20 for North Amer- ican megafloras. Megafloral diversity for the Correjón flora likely exceeded that indicated by the dashed line for Patagonian floras. Heavy dashed line indicates MAT and MAP for South American Austral Region floras as distinct from the Tropical Region Cerrejón flora J Mammal Evol (2014) 21:1–73 15 likely was at least 324 cm (Fig. 8; considered an underesti- mate), and plant morphology is compatible with that value and those above. With respect to other Paleocene South American floras, the Cerrejón floral diversity appears to be significantly greater than that of the Patagonian Palacio de los Loros flora from the Paleocene (ca 62 Ma), but only 80 % of that seen in modern tropical litter samples and 60 % of the highly diverse Paleocene Castle Rock Flora of Colorado, in North America. Wing et al. (2010) also indicated that PIE values (a measure of taxon evenness) are not different from those of modern tropical forest litter, the Palacio de los Loros flora, or Castle Rock, but are strongly higher than those of most Paleocene-Eocene North American sites. This continues to reflect the greater floral diversity of South American Paleogene floras as compared to those from North America. Cerrejón pollen samples (Jaramillo et al. 2007) show mean rarified richness about 66 % of that seen in Quaternary Amazonian samples; mean evenness is 85 % of that of Quaternary tropical forest samples. Insect preda- tion was 50 % of specimens seen; greater than mid latitude Paleocene floras, but is comparable to that of modern Neotropical forests. Overall, the Cerrejón flora shows that the basic plant components characteristic of modern Neotropical floras were present in the late Paleocene, with somewhat reduced levels of insect herbivory and lesser plant leaf and pollen diversity than at present. In that context both the megafossil and pollen data reinforce the interpretation that Neotropical floras were well established as such by the Paleocene in South America. As discussed below, coeval floras from Patagonia were more like their Neotropical counterparts than obtains as the present time, but still of a subtropical character. The Bolivian Flora Formation (Vajda-Santiváñez 1999) is considered to be Danian age (Vajda-Santiváñez and McLoughlin 2005). The flora (2*, Fig. 2b) consists almost entirely of angiosperm pollen grains, in which those of Aquillapollenites are conspicuously absent. Vajda- Santiváñez and McLoughlin (2005) reported on an exten- sive record of the fern, Azolla, from this and the underlying Eslabón Formation (Maastrichtian). The Flora Formation is largely lacustrine in origin. The microspore assemblages, and particularly the abundant pollen of palms, as well as ferns, are suggestive of a tropical, warm and humid, climate. The above data suggest that the basic character, structure, and framework of diversity of Neotropical floras was strongly under way by the Paleocene in northern South America and, although the episodically rising Andes cer- tainly influenced the floras in those regions, the overall character and climatic setting of Neotropical floras was maintained to the present day. Andean Region As indicated in Biogeographical terminology (above), this refers to the austral part of South America: Patagonia and Chile south of about 38°S. As shown in Fig. 2a–d, most Patagonian fossil localities were found in lowland coastal areas with fluvial, lacustrine, and swamp environments. The Paleocene and Eocene floral climatic conditions in the Andean region are presently best represented by paleofloras found in the Golfo San Jorge Basin in eastern Patagonia and adjacent areas. The floras and associated mineralogical data suggest that early Paleocene climate reflected warm temper- ate conditions dominated by podocarpacean and auraucar- iacean trees, with many angiosperms of warm-temperate affinity. These included many types of palms (including the mangrove, Nypa), along with Myrtaceae (Eucalyptus family), Pandanaceae (mangrove trees), and Olacaceae (Anacolosa). Groups of Gondwanan affinity include the Proteaceae (trees), Cuoniaceae (subantarctic shrubs and trees), and Elaeocarpaceae (tropical trees), along with a few northern elements such as Ulmaceae (elms) (Petriella 1972; Archangelsky 1973; Palazzesi and Barreda 2007). Based on clay mineralogy of paleosols, an episode of in- creased seasonality is recorded in the late Paleocene. Thus, the Paleocene-Eocene transition changed from a warm- temperate and humid climate with seasonal precipitation to a wetter subtropical climate with year-around rainfall (Raigemborn et al. 2009). Subsequently, this relatively uni- form early and middle Eocene climate led to cooler and drier conditions in the late Eocene and early Oligocene (Barreda and Palazzesi 2007). From then until the middle Miocene, it appears that semi-arid to arid conditions generally dominat- ed northern Chile (Pinto et al. 2004; Le Roux 2012). In addition, studies on lacustrine sediments in the Potosi Basin of Bolivia (Rouchy et al. 1993) indicate that the area was situated in the intertropical convergence zone during the Paleocene, where arid conditions prevailed after a more humid interval in the Maastrichtian (Le Roux 2012). These conditions appear to coincide with the generally arid region postulated to intervene between the more tropical conditions found in the Neotropical and Austral regions during the Late Cretaceous and Paleogene (Iglesias et al. 2011). The more tropical and wetter conditions would have been found north of the Guiana Shield and south of Paraguay on Fig. 2a and b. Intervening areas would have been more arid, but data are scarce. A number of floral samples have been obtained from the mostly marine to estuarine Salamanca Formation of late Danian age (Fig. 3); many of the Salamanca floras cannot be distinguished chronologically, but they show paleobio- geographic differences within the basin. The Ameghino Petrified Forest, located in the northwestern part of the Golfo San Jorge Basin (5*, Fig. 2b), was dominated by 16 J Mammal Evol (2014) 21:1–73 evergreen coniferous forests, with angiosperms and diverse palms also present. Conifers (Podocarpoxylon mazonii) are estimated to have been 17–29 m tall, and show regular growth rings indicative of a yearly regular (not seasonal) climate (Brea et al. 2011). This would be consistent with the warm off-shore sea water temperatures recorded in the up- permost Cretaceous-lowermost Danian Bustamante Member of the lower part of the Salamanca Formation (Andreis et al. 1975). The Cerro Bororó flora (17*, Fig. 2b) is also preserved in a similarly northwestern part of the basin, in the Bororó Formation, considered (Scafati et al. 2009) as contemporane- ous with the Salamanca Formation. The flora consists of spores and pollen of bryophytes, ferns, and angiosperms, including Nypa (mangrove palm; as well as other palms), Araceae (aroids), Sparganiaceae/Typhaceae (bulrush, cattails) that, together with fossil wood of the Rhyzophoraceae (man- grove trees), Elaeocarpaceae (clinodendrons), Cunoniaceae (lightwood), as well as Cycadales (cycads), indicate a lowland mangrove-swamp environment in the vicinity of a marine embayment (Petriella 1972; Scafati et al. 2009). The Sparganiaceae, Nypa palms, the extreme diversity in palm pollen, and the presence of other thermophilous taxa also indicate a warm, humid, subtropical-tropical climate for this region. Salamanca Formation floras also are recorded in the Victor Szlápelis Petrified Forest, and the Ormaechea Petrified Forest (3* and 4*, Fig. 2b). In the former (Brea et al. 2005), podocarp tree trunks are >1 m in diameter, which, along with associated angiosperms, show growth rings that indicate a warm-temperate, humid, seasonal climate. The setting evokes a flora likely similar to that of present-day southeastern Brazil, with savannas in a subtropical, humid climate with markedly seasonal rains. The presence of palms also suggests winter temperatures above 10 °C. This is consistent with the presence of crocodilians in these Salamanca beds at the same latitude, but farther east along the present coast. Pollen from the Estancia Laguna Manantiales are found somewhat farther south (6*, Fig. 2b), in Santa Cruz Province, but still within southern part of the Golfo San Jorge Gulf. The floras are from the southernmost outcrops of the Banco Negro Inferior (Zamaloa and Andreis 1995), and on that basis they are here considered to be stratigraph- ically comparable to the Palacio de los Loros Flora (PL, Fig. 4). In addition to a minor component of ferns, podocarp gymnosperms are next most abundant group. Angiosperm pollen predominates over all others in both abundance and diversity. Nevertheless, the flora is sparsely documented. As elsewhere, the material was deposited in fresh water to swampy environments. The Palacio de los Loros flora, southern Chubut Province (3*, Fig. 2b; Figs. 4 and 5) was recovered (Iglesias et al. 2007a) from the Salamanca Formation of about middle Paleocene age (ca 62 Ma, about equivalent to the Danian/ Selandian boundary; Fig. 1). The Salamanca Formation unconformably overlies (column 7, Fig. 3) the Bajo Barreal Formation (Chubut Group; Riccardi 1988; Data Repository in Iglesias et al. 2007a), and is unconformably overlain by the continental Río Chico Formation (Fig. 3). Based on Iglesias et al. (2007a), the Palacio de los Loros flora correlates as shown in Figs. 4, 5, and 8, and is about coeval with the Peligran SALMA, as also noted by Iglesias et al. (2007a, Data Repository) and Raigemborn et al. (2010). The Palacio de los Loros assemblage is diverse and richly populated taxonomically. The 36 angiosperm leaf species correspond to a large-leafed Nothofagus (southern beech), Menispermaceae (moonseed), Akaniaceae (also known in the Australian rain forest as well as in the early Eocene of Patagonia (Romero and Hickey 1976), Lauraceae (laurels), Urticaceae (nettles), Fabaceae (being one of the oldest records of this legume family), Sapindaceae (litchee), palmate-lobed Malvaceae, and Rosaceaae. The presence of the oldest record of Fabaceae (legume family) is notorious for this site (Brea et al. 2008a), and a new rich food source for animals. Conifers also are associated with the angio- sperms, which are represented by flowers, fruits, and seeds as well as leaves. The conifers include Auracariaceae (cone scales) and Podocarpaceae (leaves and cones), along with at least two species of fern, including Lygodium. Taxa such as Nothofagus, Akania, and the conifers indicate a Gondwanan affinity. Furthermore, the leaf diversity of angiosperms re- covered at the single Palacio de los Loros floral site exceeds the diversity known in most other comparable floras in the world, with the exception of those from wet tropical cli- mates. Yet, the diversity may be still higher due to the extremely conservative leaf taxonomy employed (Wilf et al. 2005). Leaf analysis suggests that the flora lived under a MATof about 14 °C (subtropical), with a MAP of at least 115 cm/ year in the absence of an Andean rain shadow. Brea et al. (2008a) considered the Palacio de los Loros to have been a mesothermal flora that reflected a warm temperate climate and strongly seasonal precipitation. The associated remains of thermophilic palms found throughout the exposures are compatible with this climatic setting, as is the presence of alligatorid reptiles (Bona 2005). The large-sized Nothofagus leaves are indicative of warm, humid conditions (Iglesias et al. 2011), and a frost-free climate also is supported by modern podocarps inhabiting only high-rainfall environ- ments and Akania living today only in eastern Australian tropical rain forests. Analysis of alpha diversity of angiosperm leaves shows that the Palacio de los Loros flora (Fig. 8; see PL under Taxonomic Diversity); greatly exceeds the diversity of J Mammal Evol (2014) 21:1–73 17 contemporaneous floras in North America on the one hand, but is less diverse than Patagonian floras of Eocene age (heavy dashed line, Fig. 8). Still, Wilf et al. (2005) consid- ered the Palacio de los Loros diversity to be conservative and that the actual figure approached the diversity seen at Laguna del Hunco. The relative, but not yet fully estab- lished, diversity pattern (increasing with younger geologic age) is comparable to the situation seen in North America (Fig. 8). At the same time, there is a sharp break in taxo- nomic continuity from the Paleocene to the Eocene floras in Patagonia suggesting that a number of turnover events took place in the interim. Notably, the Paleocene Patagonian floras show a much greater continuity with those of Late Cretaceous age than is the case for North America. The cause of this earlier diversity is not known, but its effect continued subsequently in South American floras up to the present time. The late Paleocene floras from the Peñas Coloradas and Las Flores formations of the Golfo San Jorge Gulf Basin (8*, Fig. 2b) are represented by phytoliths in addition to fossil wood and other plant remains (Raigemborn et al. 2009). The Peñas Coloradas flora (Figs. 4, 5, and 8) is composed of podocarp conifers and angiosperms. The latter are represented by the Cunoniaceae (trees and shrubs), along with the Styracaceae (modern tropical trees, silverbell, snowbell), Chrysobalanceae (tropical and subtropical trees), and Araliaceae (tropical - temperate ivy and other shrubs). The herbaceous component appears to be represented main- ly by the Zingiberales (ginger family) and the Poaceae (grasses). Such plants populated mixed temperate to sub- tropical forests that lived under warm and humid conditions. Associated clay mineralogy indicates a strongly seasonal climate for this late Paleocene flora. A late Paleocene flora of a more western and potentially higher elevation location is represented by the Ligorio Márquez flora of eastern central Chile (9*, Fig. 2b), about 300 km southwest of the Peñas Coloradas Formation, and almost immediately west of the Chile - Argentina border at 46°45’S. As discussed by Suárez et al. (2000), the Ligorio Márquez Formation unconformably overlies the Flamencos Tuffs of Lower Cretaceous age [128±3 Ma; 125±3 Ma; 123 ±3 Ma], and is overlain unconformably by ?early or mid- late Eocene basalts or the coeval San José Formation. The unconformably overlying basalts have been dated via K-Ar at 47.6±0.78 Ma (Yabe et al. 2006) based on feldspar crystals in the basalt. Whole-rock ages from sites to the north yielded an age of 57±1–44±5 Ma (Suárez et al. 2000); these authors also obtained a whole rock age of 41.6±1.4 Ma from a site immediately above the the Ligorio Márquez Formation Whether or not there are two basalt units above the the Ligorio Márquez remains to be determined (Yabe et al. 2006). In any case, the basalts provide an upper limit for the Ligorio Márquez flora, which is likely to be of late Paleocene or possibly earliest Eocene age. The pulse in MAT and MAP (Fig. 8) could be compat- ible with correlation to the PETM. Plant remains obtained from near the middle of the unit in its measured section (44 m, but stratigraphically incomplete), include Podocarpaceae (Podocarpus inopinatus), eight spe- cies of Lauraceae, and one of the Melastomataceae (Troncoso et al. 2002). The diversity of the Lauraceae is best compared with the late Paleocene Concepción-Arauco paleoflora, which indicates a wet subtropical setting (also Gayó et al. 2005). The flora is consistent with a late Paleocene age for the Ligorio Márquez Formation. A small pollen sample of Nothofagidites was taken from near the top the unit, which would imply a cooler climate than suggested by the macro- flora, although this could be accounted for by relating it to a short cool interval that apparently is recorded in the early late Paleocene, about 61 Ma (Dingle et al. 1998; Dingle and Lavelle 1998), as suggested by Suárez et al. (2000). In addition, Zachos et al. (2001) showed short-lived cool epi- sodes just before and after the PETM, one somewhat youn- ger than 56 Ma, and the other at about 54 Ma, which also could fit the temporal intervals discussed here. Alternatively, Iglesias et al. (2007a) indicated that Paleocene leaf records of Nothofagaceae can be associated with warm-temperate for- ests. Hinojosa et al. (2006) interpreted the Ligorio Márquez flora as indicating subtropical, frost-free, and humid conditions, with a MAP of 155 cm and MAT of 23 °C. Peppe et al. (2011), however, considered these analyses to be overestimated. From the preceding discussion, it appears that the Paleocene floras of Patagonia were largely preserved in lowland, coastal, settings. They were generally dominated by podocarp and araucarian conifer forests that lived under warm, humid, and at least subtropical climates; in lowlands typically of mangrove swamps and woodlands. Some of the floras record a seasonal climate, but others do not. As indicated in Fig. 4, the Eocene floral record in Patagonia begins with the Pampa de Jones flora, discussed further below. In the Golfo San Jorge Basin, the Las Flores Formation, located about 40 km NE of 3* (Fig. 2b), contains a range of phytoliths, wood, and other materials comparable to that of the Peñas Coloradas. Associated fossil mammals indicate an Itaboraian age for the Las Flores (Raigemborn et al. 2009; Oliveira and Goin 2011, and literature cited there- in; Fig. 4). In the lower part of the unit, palm (Arecaceae) phytoliths are abundant, along with those of Mimosoideae (Acacia-like), Chrysobalanaceae (Coco plum), and Lauraceae, characteristic of tropical to subtropical lowland forests, along with a grass understory (see also Brea et al. 2008b). This is one of the earliest occurrences of grasses (but not grasslands) in South America (Brea et al. 2008b; Prasad et al. 2005, indicated a Late Cretaceous record, as well). Cione et al. (2011) reported on a ceratodontid lungfish 18 J Mammal Evol (2014) 21:1–73 tooth plate from the lower Las Flores Formation, compatible with the indicated climatic setting. In the upper part of the Las Flores Formation, palms and herbaceous forms decrease, to be replaced by more arboreal elements: Magnoliaceae, Annonaceae (tropical trees, shrubs), Burseraceae (tropical trees and shrubs; frankin- sence), and Boraginaceae (herbs, shrubs, trees). The herba- ceous component is represented by the tropical Zingeberales (wetland monocots) and Poaceae (grasses). As indicated by their geologic setting (Raigemborn et al. 2009), these Golfo San Jorge Basin sites are fundamentally coastal lowland records, and reflect humid subtropical to tropical conditions. The coastal lowland record continues with the late early Eocene lateritized Koluel Kaike Formation (Krause et al. 2010) of Riochican age (Fig. 5). The sequence is about 50 m thick and displays a succession of five major pedotypes. The lower, strongly lateritized, units reflect humid megathermal conditions (subtropical) with MAP of 120–130 cm and MAT of 150C. Stratigraphically higher parts of the forma- tion are less strongly lateritized, and indicate sub-humid and mesic-megathermal conditions with a MAP of about 100 cm and MAT of ca 12 °C. The highest few meters of the unit show cooler and more arid conditions with MAP and MAT of about 60–70 cm and 10 °C, respectively. The sequence is interpreted to range in age from about 54 Ma at the base to about 42 Ma at the top, with the cooler conditions beginning at about 40 m and 45 Ma, and the drier period beginning at about 50 m and 42 Ma (Krause et al. 2010: fig. 10). Under this chronologic scenario, the overall pattern is considered to closely resemble that of global ocean temperature (Zachos et al. 2001; see Figs. 4 and 8). In Fig. 4 the base of the Koluel-Kaike section (KK1) is correlated as about 51 Ma, instead of 54 Ma because the underlying Las Flores Formation is considered to be of Itaboraian age. Similarly, the upper parts of the section (KK2, KK3) are considered as about 48 Ma because the overlying Sarmiento Formation contains fossil mammals of “Vacan” and “Barrancan” age. [Note that these and other mammal biochrons that are not formally designated as SALMAs are bracketed by “..”] These potential revisions in age of KK1-KK3 still comply with warmer and cooler parts, respectively, of the ocean temperature profile in Figs. 4 and 8. In any case, the inter- pretations of Krause et al. (2010) result in the 50-m thick Koluel Kaike Formation having a duration of nearly 10 m.y., a distinctly greater interval than the other, but comparably thick, Las Flores and Peña Coloradas forma- tions of the Río Chico Group. The geochemical analyses point to a climatic change from effectively subtropical at the base of the Koluel-Kaike Formation to a cooler and more arid setting at its top. The early Eocene Pampa de Jones (19*, Fig. 2c) and the middle Eocene Río Pichileufú sites (21*, Fig. 2c) represent more western examples of Patagonian Eocene floras, that likely also reflect somewhat higher elevations. The Pampa de Jones flora has been recovered from the lower part of the Huitrera Formation (Wilf et al. 2010), dated at 54.25± 0.45 Ma. Melendi et al. (2003) described the taxa as having constituted a podocarp cool-temperate rain forest, with gym- nosperms having dominated (32 %–46 %) over angiosperms (23 %–33 %) and pteridophytes/bryophytes (3 %–4.5 %), in association (Wilf et al. (2010) with a pipid frog, Llankibatrachus truebae, as well as insects. As shown on Fig. 2c, the Pampa de Jones is slightly farther north than other early Eocene Patagonian floras. The activity generated by the Pilcaniyeu volcanic belt and initial uplift of the North Patagonian High Plateau (NPHP, Fig. 2c) (Aragón et al. 2011) also likely contributed to the elevation of these cool- temperate rain forest sites. The Laguna del Hunco flora (18*, Fig. 2c) was originally recorded by Berry (1925). It is now known to occur in Tufolitas Laguna del Hunco tuffaceous mudstones and sand- stones related to the activity of the Pilcaniyeu volcanic belt, and to contain megafossil plants in addition to fish, insects, caddis-fly cases, and pipid frogs (Wilf et al. 2005). The flora is very diverse. Radioisotopic dates obtained from the se- quence center on 52.13±0.32 (Wilf et al. 2003), and mag- netic polarity data indicate that most samples fall within chron C23n.2n, and coeval with the Early Eocene Climatic Optimum (Figs. 4 and 8). Wilf et al. (2005) showed that the Laguna del Hunco flora is composed of conifers, a cycad, a Ginkgo, three monocots (including palms) and seven ferns. In addition, angiosperms are very diverse and include Proteaceae, Myrtaceae (eucalypts), Cunoniaceae, Lauraceae (laurels), Akaniaceae, Sapindaceae (litchee), Sterculiaceae, and Fabaceae (legumes), as well as many other families (Zamaloa et al. 2006). Zamaloa et al. (2006) added three species of Gymnostoma (Casuarinaceae), the genus also being known from the Recent of Malesia, Fiji, New Caledonia, and north- eastern Australia. Gandolfo et al. (2011) recorded the pres- ence of Eucalyptus at this site, indicating a setting marginal to the main rain forest in this volcanically disturbed caldera lake context. The sample represents the only and oldest non- Australian occurrence of the genus. Of the 30 most abundant species, thermophilic families are strongly represented, in- cluding Myrtaceae (eucalypts), Sapindaceae, Fabaceae, Lauraceae, and Araucariaceae (conifers), and it is apparent that diversity would increase with further collecting. At present, the diversity of the Laguna del Hunco flora (186 species; Fig. 8) is comparable to, or greater than, the most diverse Eocene floras of North America. As summarized by Zamaloa et al. (2006), megafossil Casuarinaceae are known from the Paleogene and Neogene of Australia and Miocene of New Zealand as well as the Eocene of Patagonia. Fossil pollen pertaining to this group extends the Patagonian record from early Paleocene J Mammal Evol (2014) 21:1–73 19 to Eocene, and such pollen also has been recorded from Paleogene deposits of Australia and the Antarctic Peninsula (as well as from younger rocks in other Gondwanan loca- tions). The Casuarinaceae thus provide a Gondwanan scope for Patagonian floras, as does the genus, Eucalyptus. Both are notable for their absence in the Río Pichileufú flora (ca 47 Ma; see below), so it is likely that both groups were extinct by then in South America, in contrast to Australasia. Paleoclimatic reconstruction for the Laguna del Hunco flora suggests that it was neither warm nor humid enough to qualify as a tropical rain forest, although Wilf et al. (2005) noted that it showed Neotropical affinities. The effect of a maritime setting to the west (Fig. 2c) narrowed the potential range of temperature and precluded frost. MAT is estimated to have been about 17 °C (subtropical), and a minimum MAP about 110 cm/year, with the latter incompatible with an elevated Andes at this time. Wilf et al. (2005) interpreted the climate as having been moist and equable. As indicated above, the present values may have been conservative, and likely approached those of more tropical character (arrows on Fig. 8), although the potential ecological and elevational influence of the Pilcaniyeu volcanism and the rising North Patagonian High Plateau (NPHP) should be considered. Wilf et al. (2009) noted that the presence of the rain forest podocarp Papuacedrus in the flora indicates a minimum MAP of 400 cm/year. These new estimates invigorate a completely new idea regarding the availability of water and thus forest type in the Eocene of Patagonia, such that MAP and MAT values would have reached those found today in the warm temperate rain forests of New Guinea. In central Chile, early Eocene floras are known from the Lota Coronel-Arauco and Caleta Cocholgüe (*25, Fig. 2c), and Quinamávida floras (26*, Fig. 2c; Fig. 8). These floras demonstrate warm, humid, subtropical conditions (Troncoso 1992; Gayó et al. 2005). Based on multiple regression analyses of the macroflora, Hinojosa et al. (2006) obtained MAT and MAP estimates of 203 cm/year and 22 °C for Lota Coronel-Arauco, and 260 cm/year and 19–26 °C for Caleta Cocholgüe. Comparable estimates for Quinamávida (Fig. 8) are 91 cm/year and ~18 °C (Hinojosa 2005). Peppe et al. (2011) considered these figures to be over estimated, how- ever, consistent with more subtropical conditions. From the preceding discussion, it appears that the Paleocene and early Eocene floras of Patagonia were largely preserved in lowland coastal settings, although Patagonian early Eocene floras attest to variations in climatic setting, with more cool-temperate elements at perhaps somewhat higher elevations contemporaneous with those of wetter and more subtropical character in lowland area, and season- ally more arid settings found locally (Gran Salitral; below). The floras were generally dominated by podocarp and araucarian conifer forests that lived under warm, humid, and at least subtropical climates, typically in mangrove swamp woodlands, likely at elevations below 1200 m (Quattrocchio et al. 2011). Angiosperms also were diverse and recorded the oldest legumes and bamboo-like grasses (Brea et al. 2008b). Early Eocene Papuacedrus, Gymnostoma, Akania, Eucalyptus, and several conifers (González et al. 2007; Zamaloa et al. 2006; Wilf et al. 2009; Gandolfo et al. 2011) reflected an old Gondwanan influence that was al- ready present between Australia and South America via Antarctica in the Late Cretaceous. The Ligorio Márquez flora of Chile likely recorded a short-lived cool pulse at about 56 Ma (possibly coeval with the PETM), and the Peñas Coloradas flora may be another example of that or, at least, of a locally more seasonal climate. The Chilean sample, as well as that from Pampa de Jones (cool-temper- ate), also may reflect its somewhat higher elevation as compared to most of the other floral sites. Overall, the diversity of these floras was notable from the outset, in strong contrast to North American analogs. In the Chaco-Paraná Basin, Uruguay (18, Fig. 2b), evap- orate beds in the Mariano Boedo and Laguna Paiva forma- tions suggest at least temporarily arid conditions during the early Paleocene (Padula and Minggram 1968). A change in climate from temperate to humid at the base of the sequence to hot and dry in the upper part is suggested by del Papa (2006). In the same basin, the development of a paleosol in the Maíz Gordo Formation also indicates an overall aridifi- cation and decrease in seasonality leading up to the Thanetian-Ypresian warm interval. However, the basal in- terval of the middle Eocene Lumbrera Formation of the Salta Basin, Argentina (38, Fig. 2c) to the north, reflects the deposition of permanent sandy fluviatile systems and the presence of a perennial fresh-water lake indicative of more humid conditions (Le Roux 2012). The middle Eocene Río Pichileufú flora (21*, Fig. 2c; Figs. 4 and 8) was recovered (Berry 1938) from sites near Bariloche, Río Negro Province, Argentina. As summarized in Wilf et al. (2005), the flora was obtained from volcanic lacustrine deposits of the Ventana Formation. Preliminary analysis of collections indicates that megafossils of flowers, fruits, seeds, and leaves are preserved, as well as remains of ants and frogs. The Río Pichileufú flora is the most diverse assemblage known from Cenozoic deposits in Austral South America. Tuff beds directly associated with the fossil sites yielded a mean age of 47.46±0.05 Ma for the flora. The Río Pichileufú flora indicates that the diversity of the early assemblages continued into the medial Eocene. Wilf et al. (2005) showed that this later flora is as diverse (180+ species) as the extremely differentiated Laguna del Hunco Flora of Patagonia (Fig. 8). Whereas some aspects of diver- sity at Laguna del Hunco appear to be related to distance from shoreline for a given fossil site, this does not seem to apply to the Río Pichileufú flora. Collectively, these floras are the most diverse assemblages known from Cenozoic 20 J Mammal Evol (2014) 21:1–73 deposits in South America as well as the entire Southern Hemisphere. The Río Pichileufú contains the oldest record of the Asteraceae (sunflowers) based on a complete inflo- rescence (Barreda et al. 2010), although dominance of this group begins in the Oligocene. Río Pichileufú MAT is suggested as having been about 19 °C, somewhat higher than at Laguna del Hunco, and somewhat out of line with the proposed global increase in temperature based on oceanic data (Zachos et al. 2001; Fig. 8). Minimum MAP was suggested as having been between 200–250 cm (Wilf et al. 2005; Barreda et al. 2010). The presence of Papuacedrus (rain forest podocarp) in both floras points to an underestimation of MAP, and suggests the presence of a large area in western Patagonia that supported floras similar to the modern subtropical or montane tropical rain forests (Wilf et al. 2009). Other than Rio Pichileufú, Barreda and Palazzesi (2007) summarized the Patagonian floras of middle to late Eocene age. The sites, which are mostly in southern Patagonia, include Confluencia (20*, Fig. 2c), and Río Turbio (22*, Fig. 2c), but also include Loreto in Chile (51*, Fig. 2d; Terada et al. 2006; Otero et al. 2012). The continued pres- ence of Nothofagus forests in these floras is compatible with the concurrent occurrence of other groups of micro- to mesothermal aspect, such as podocarp and araucarian coni- fers of Gondwanan heritage, as well as Cunoniaceae and Proteaceae, gunneracean herbs, and caryophyllacean carna- tions. Associated megathermal elements include laurels, Tiliaceae-Bombacaceae (tropical balsa, jute), Malpighiaceae (tropical climbers), Sapindaceae (tropical trees, lianas), Rubiaceae (gardenia shrubs), and Aquifoliaceae (holly). These floral elements suggest that in general a mesothermal setting was beginning a transition to cooler and drier climates, with an increase in seasonality indicated by the presence of marked growth rings in nothofagacean wood at Río Turbio to the south. This climatic change would be compatible with locally similar indications in some of the early Eocene floras. Megathermal conditions likely persisted in coastal regions. Tófalo and Morrás (2009) studied paleosols in continen- tal deposits of the Chaco-Paraná Basin, Uruguay (18, Fig. 2b). These indicate important climatic changes during the Late Cretaceous and Cenozoic. Paleocene palustrine carbonates of the Queguay Formation are associated with phreatic calcretes that indicate a seasonally-contrasted, semi-arid climate that might coincide with the Santonian- Danian cooling interval (Le Roux 2012). In the early Eocene Asencio Formation of the Chaco-Paraná Basin, fluvial deposits contain ultisols that developed under a warm and humid climate, and were indurated after periods of intense aridity marked by the development of ferricretes. Middle Eocene units of the San Pedro Formation in the Valdivia Basin (45*, Fig. 2c; Elgueta et al. 2000) contain fossil floras with Sabal ochseniusi, Tetracera ellipitica, and Bennettia grosseserrata, together with abundant conifers, which suggest a subtropical climate, possibly coinciding with the Lutetian warming (Le Roux 2012). Megathermal elements appear to have been absent in the later parts of the Eocene and early Oligocene in Patagonia (Barreda and Palazzesi 2007). Late Eocene – earliest Oligocene sites include the Sloggett Formation, Tierra del Fuego Province, Argentina (Panti et al. 2007; 45*, Fig. 2d), Estancia La Sara Well (Menéndez and Caccavari 1975; 46*, Fig. 2d), and Loreto, Chile (Otero et al. 2012; 51*, Fig. 2d). Early Oligocene floras are found in the Río Guillermo (47*, Fig. 2d) and Río Leona (48*, Fig. 2d) formations of Patagonia. In the latest Eocene to early Oligocene, the relatively homogeneous forests were composed of Nothofagus, podocarps and araucarian conifers, as well as cunoniaceaean angiosperms that are now well represented in tropical to subtropical and drier climates in the Americas, Australasia, and southern Africa (Heywood 1993). Understorys would have been composed of ferns and herbs. All wood described from the Río Leona flora resembles extant species that today inhabit the Patagonian Andean forest (Pujana 2009). Overall the flora of this time interval reflects high rainfall in a cool-temperate climate. Oligocene coal seams higher in the San Pedro Formation also contain an association ofMicrothyriaceae and Cyathidites patagonicus spores, together with pollen of Araucariacites australis, Nothofagus cinta, and Podocarpities species, imply- ing a forest environment of high to very high humidity and a cold to temperate climate similar to present-day conditions in southern Chile (Palma-Heldt and Alfaro 1982; Le Roux and Elgueta 2000). Late Oligocene floral sites are rare (Barreda and Palazzesi 2007, 2010; 49*, 50*, Fig. 2d), but have been dominated by forests of Nothofagus, podocarp and araucarian conifers, southern beech, an understory of abundant ferns, along with persistently megathermal lowland elements in the north that include palms (Arecaceae), tropical climbers (Malpighiaceae), gardenia shrubs (Rubiaceae), and largely tropical trees and lianas (Combretacea, Sapindaceae). Shoreline elements in- clude the first Asteraceae (sunflowers), and Convolvulaceae (morning glory), associated with Poaceae (grasses), Chenopodiaceae (sugar beet), and Ephedraceae (Mormon tea), a seasonally drier climate indicator. Climates overall were cool-temperate and humid. Apparently the climate rebounded somewhat from the initial Oligocene cooling in the late Oligocene warm interval (LOW) with a new south- ward dispersal of megathermal elements in Patagonia. Although as noted by some eastern floras, such as the Río Foyel (50*, Fig. 2d) Patagonian Subantarctic Floras were well established, and reach sea level in southern Chile (Terada et al. 2006) in the Loreto Formation (*51, Fig. 2d). Arid conditions during the Oligocene are indicated by gypsiferous units in the Salar de Antofalla region of the J Mammal Evol (2014) 21:1–73 21 Salta Basin (Adelmann 2001; Carrapa et al. 2005), which might coincide with Chattian warming (Le Roux 2012). The Oligocene – lower Miocene Fray Bentos Formation of the Chaco-Paraná Basin is composed of loess that was deposited under semi-arid conditions, with paleosols and pedogenic tubular calcretes also indicating a seasonal, semi-arid, climate (Tófalo and Morrás 2009). Discussion Based on the above summary, it appears that both North and South American Paleogene floras responded generally sim- ilarly to the global temperature pattern, but that the southern floras were considerably more diverse than their northern counterparts, with the possible exception of the Castle Rock flora of Colorado. The available data indicate that the Neotropical region had achieved its basic floral and ecolog- ical structure from the Paleocene, if not earlier, and that coeval floras from Patagonia were nearly as diverse and lived in nearly tropical conditions, as well, until about the middle Eocene. Under the conventions of Morley (2000), the Patagonian fossil sites could occur within the Southern Megathermal rain forest, but Wilf et al. (2005) noted that these Patagonian forests lived under conditions cooler and drier (but still quite moist) than expected for rain forests. To the north, in La Pampa Province, the early Eocene Gran Salitral Formation (61, Fig. 2d) is a lacustrine sequence that records seasonally semiarid conditions with MAT above 20 °C (about 24 °C; Melchor et al. 2002), in contrast to about 17 °C–19 °C for those in Patagonia (but note above comments on the likely conservative calcula- tions for the Patagonian floras). As indicated in Fig. 8, the Gran Salitral Formation is estimated at about 52 Ma old (early Eocene; Melchor et al. 2002). In this regard, Wilf et al. (2005) suggested that the Patagonian forest setting remained exceptionally diverse during the 4.5 m.y. between the Laguna del Hunco and Río Pichileufú floras, demonstrating a floral/climatic coherence in Patagonia through at least 52–47 Ma, with a cooler setting to the south and one of more seasonal aridity to the north. During this time, a corridor along the eastern margin of South America likely connected the Patagonian with Neotropical regions to the north (Wilf et al. 2005: 637) comparable to the modern situation (Morley 2000), with implications for the climatic setting of the nearly contempo- raneous Itaboraian fauna of Brazil (29, Fig. 2c) and the Australasian region via Antarctica to the south (Iglesias et al. 2011). The Patagonian floras contain significant numbers of genera with disjunct distributions in the Neotropics and Australasia that may be Eocene relicts (Davis et al. 1997; Villagrán and Hinojosa 1997). Barreda and Palazzesi (2007) proposed a rain forest- dominated setting in the Paleocene and early Eocene, but pointed out the presence of certain taxa indicative of a local presence of more arid-adapted shrubs and low trees. Cool- temperate Nothofagus is first recorded from the early Eocene and, with other more mesothermal elements, shows the begin- ning of at least locally cooler environments in Patagonia. Pulses of cooler or more seasonal conditions also are suggested by the Ligorio Márquez flora (late Paleocene) of Chile, and even by the early Paleocene Victor Szlápelis flora and the later Paleocene Peñas Coloradas flora of the San Jorge Golfo area. Grasses (Poaceae) are also recorded in the early Eocene (Brea et al. 2008b; Raigemborn et al. 2009), although grasslands are not represented until the late Oligocene (Barreda and Palazzesi 2007), and local seasonal aridity is recorded in central Argentina by the early EoceneGran Salitral biota and paleosols. The record in the later middle Eocene into the Oligocene is consistent with the global drop in temperatures after the EECO, including the development of more open areas with grasses, which continue into the late Oligocene. Nothofagus forests expand, with persisting cooler conditions. More mesothermal groups such as Juglandaceae (hickory) and Aquifoliaceae (holly), Tiliaceae (jute), Bombacaceae (balsa), and Sapindaceae (lianas) became extinct at the end of the Paleogene in Patagonia (Barreda and Palazzesi 2007). In the late Oligocene, the southward dispersal of Neotropical elements (such as palms, Rubiaceae, and Combretaceae) reflects a return of warmer climates, and the addition of xerophytic and halophytic shrubs and herbs (Convolvulaceae, Asteraceae, Poaceae, Chenopodiaceae, Ephedraceae) reflects the beginning of modern-aspect floras (Barreda and Palazzesi 2007). The Land Mammal Record Alamitan As background, the Late Cretaceous Alamitan SALMA is based on the mammals of the Los Alamitos Formation, Río Negro Province, Argentina (1, Fig. 2a; 4, Fig. 3; see also Pascual and Ortiz-Jaureguizar 2007). The Alamitan is considered to be of Campanian-Maastrichtian (Bonaparte 1986) or Maastrichtian age (Pascual et al. 2000; Rougier et al. 2009a, b). The Alamitan SALMA contains 17 genera (Table 1), all pertaining to non-tribosphenic groups that include an austroconodontid ‘triconodont,’ a ‘symme- trodont,’ 12 dryolestoids, and a sudamericid as well as a ferugliotheriid gondwanathere (Pascual and Ortiz- Jaureguizar 2007; Rougier et al. 2009a). Based on a speci- men from the La Colonia Formation, Pascual et al. (2000) referred Reigitherium bunodontum to the Docodonta, but later Rougier et al. (2009a) argued in favor of its dryolestoid affinities. Finally, a single multituberculate was recorded (Kielan-Jaworowska et al. 2007). 22 J Mammal Evol (2014) 21:1–73 T ab le 1 S ou th A m er ic an P al eo ge ne M am m al F au na s B io ch ro n A la . T iu . P el . C ar . It ab . R io . S ap . V ac . B ar . M us . T in g. D es . R em ar ks S up er fa m ili al ta xo n F am ily G en us M ul tit ub er cu la ta 1 0 0 0 0 0 0 0 0 0 0 0 L a C ol on ia ;K ie la n- Ja w or ow sk a et al .( 20 07 ) T ri co ni do nt a A us tr oc on od on tid ae A us tr ot ri co no do n 1 0 0 0 0 0 0 0 0 0 0 0 "S ym m et ro do nt a" B on de si id ae B on de si us 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te (1 99 0) D ry ol es to id ea P ar au ng ul at um 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te (1 99 0) D ry ol es tid ae G ro eb er ith er iu m 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te (1 98 6) L eo na rd us 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te (1 99 0) M es un gu la tid ae M es un gu la tu m 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te an d S or ia (1 98 5) C ol on ia th er iu m 1 0 0 0 0 0 0 0 0 0 0 0 R ou gi er et al . (2 00 9b ) P el ig ro th er iid ae P el ig ro th er iu m 0 0 1 0 0 0 0 0 0 0 0 0 R ou gi er et al . (2 00 9b ) R eg ith er iid ae R ei gi th er iu m 1 0 0 0 0 0 0 0 0 0 0 0 R ou gi er et al . (2 00 9b ) B ra nd on iid ae B ra nd on ia 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te (1 99 0) C as am ig ue lid ae C as am ig ue lia 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te (1 99 0) A la m at he ri um 1 0 0 0 0 0 0 0 0 0 0 0 R ou ge ri th er iu m 1 0 0 0 0 0 0 0 0 0 0 0 B on ap ar te (1 99 0) B ar be re ni id ae B ar be re ni a 1 0 0 0 0 0 0 0 0 0 0 0 R ou gi er et al . (2 00 9a ) Q ui ro ga th er iu m 1 0 0 0 0 0 0 0 0 0 0 0 R ou gi er et al . (2 00 9a ) G on dw an at he ri a S ud am er ic id ae Su da m er ic a 0 0 1 0 0 0 0 0 0 0 0 0 S ci lla to -Y an e a