Abstract:The uppermost Eocene Florissant Formation, Rocky Mountains, Colorado, has yielded numerous insect, vertebrate, and plant fossils. Three previous comprehensive palynological studies investigated sections of lacustrine deposits of the Florissant Formation and documented the response of plant communities to volcanic eruptive phases but overall found little change in plant composition throughout the investigated sections. These studies reported up to 150 pollen and spore phenotypes. In the present paper we used a … Show more
“…Ephedra pollen was represented by three species, following characters documented by Steeves and Barghoorn (1959;Plate I, 1;Plate II, 20-27;Plate V, 20-22). The two medium-sized forms we clearly identified were the first-and second-order branch-furrowed pollen of E. nevadensis and the smooth-furrowed pollen of E. torreyana (Davis, 2001;Bolinder et al, 2016;Bouchal et al, 2016). These were accompanied by a third species differentiated from above-mentioned by its small size and distinctive sculpture, short axis, and first-and second-order branched furrows (Plate I, 1; Plate II, 24; Plate V, 22).…”
Section: Comparison Of the Four Oligocene Florasmentioning
confidence: 69%
“…4 Axelrod's identifications accepted by Wolfe and Schorn (1990). These are tantalizing records of some importance because unequivocal pollen of this highly derived family (Asteraceae) was present as rare elements at Florissant (Wingate and Nichols, 2001;Bouchal et al, 2016) as well as at all four of these Oligocene sites but are not characteristic of earlier Cenozoic floras of the United States.…”
Section: Comparison Of the Four Oligocene Florasmentioning
confidence: 94%
“…The Florissant megafossil and pollen flora is extremely diverse and warm-temperate in character, including more than 100 taxa (MacGinitie, 1953 as modified by Manchester, 2001;Leopold and Clay-Poole, 2001;Bouchal, 2013;Bouchal et al, 2016;Zaborac-Reed and Leopold, 2016; Table 4). Rosaceae is the main family (eight genera).…”
New pollen data from four Oligocene floras in volcanic landscapes of Colo rado record important climatic shifts that reshaped the local flora and promoted the development of subarid vegetation types. We combined new pollen data with previous megafossil evidence to assess vegetation changes during the Eocene-Oligocene Transition (EOT). Pollen data are the basis for updating the list of flora identified at Creede. Local extinctions in response to lower sum mer rainfall abruptly removed many of the exotic woody taxa of eastern North American and Asian affinity. This loss was followed by the appearance of xeric shrubland taxa of the Ponderosa pinefir woodland and sagebrush flora that characterize the Colorado area today. Telltale genera appear and suggest an understory of shrubs such as Artemisia, Elaeagnus, Ribes, Ephedra, Jamesia, and Shepherdia. Poaceae are also present. Significantly, herbaceous taxa of the Asteraceae, Rosaceae, Cucurbitaceae, Euphorbiaceae, and Caryophyllaceae make their first appearances in the fossil record of Colorado here. The new Oligocene pollen data record a significant drop in summer rainfall and a climatic cooling at 33.8 Ma of several degrees that relates to the Oi1 glaciation in Antarctica. The particular taxa that continued after the EOT were a basis for estimating changes in soil moisture during this time. The condi tions in Colorado are reminiscent of Wolfe's "terminal Eocene event." This re markable shift precipitated the development of a local pollen and megafossil flora more "modern" in aspect (e.g., a larger proportion of extant local genera are present). The impressive floristic turnover was probably a response to the increasingly continental climate that embraced the area during the Oligocene.
“…Ephedra pollen was represented by three species, following characters documented by Steeves and Barghoorn (1959;Plate I, 1;Plate II, 20-27;Plate V, 20-22). The two medium-sized forms we clearly identified were the first-and second-order branch-furrowed pollen of E. nevadensis and the smooth-furrowed pollen of E. torreyana (Davis, 2001;Bolinder et al, 2016;Bouchal et al, 2016). These were accompanied by a third species differentiated from above-mentioned by its small size and distinctive sculpture, short axis, and first-and second-order branched furrows (Plate I, 1; Plate II, 24; Plate V, 22).…”
Section: Comparison Of the Four Oligocene Florasmentioning
confidence: 69%
“…4 Axelrod's identifications accepted by Wolfe and Schorn (1990). These are tantalizing records of some importance because unequivocal pollen of this highly derived family (Asteraceae) was present as rare elements at Florissant (Wingate and Nichols, 2001;Bouchal et al, 2016) as well as at all four of these Oligocene sites but are not characteristic of earlier Cenozoic floras of the United States.…”
Section: Comparison Of the Four Oligocene Florasmentioning
confidence: 94%
“…The Florissant megafossil and pollen flora is extremely diverse and warm-temperate in character, including more than 100 taxa (MacGinitie, 1953 as modified by Manchester, 2001;Leopold and Clay-Poole, 2001;Bouchal, 2013;Bouchal et al, 2016;Zaborac-Reed and Leopold, 2016; Table 4). Rosaceae is the main family (eight genera).…”
New pollen data from four Oligocene floras in volcanic landscapes of Colo rado record important climatic shifts that reshaped the local flora and promoted the development of subarid vegetation types. We combined new pollen data with previous megafossil evidence to assess vegetation changes during the Eocene-Oligocene Transition (EOT). Pollen data are the basis for updating the list of flora identified at Creede. Local extinctions in response to lower sum mer rainfall abruptly removed many of the exotic woody taxa of eastern North American and Asian affinity. This loss was followed by the appearance of xeric shrubland taxa of the Ponderosa pinefir woodland and sagebrush flora that characterize the Colorado area today. Telltale genera appear and suggest an understory of shrubs such as Artemisia, Elaeagnus, Ribes, Ephedra, Jamesia, and Shepherdia. Poaceae are also present. Significantly, herbaceous taxa of the Asteraceae, Rosaceae, Cucurbitaceae, Euphorbiaceae, and Caryophyllaceae make their first appearances in the fossil record of Colorado here. The new Oligocene pollen data record a significant drop in summer rainfall and a climatic cooling at 33.8 Ma of several degrees that relates to the Oi1 glaciation in Antarctica. The particular taxa that continued after the EOT were a basis for estimating changes in soil moisture during this time. The condi tions in Colorado are reminiscent of Wolfe's "terminal Eocene event." This re markable shift precipitated the development of a local pollen and megafossil flora more "modern" in aspect (e.g., a larger proportion of extant local genera are present). The impressive floristic turnover was probably a response to the increasingly continental climate that embraced the area during the Oligocene.
“…The earliest pollen records are from the Maastrichtian of Canada (Srivastava 1969) and the United States(Nichols 2002). From the Palaeogene, pollen of this family is more 146F.Grímsson et al often reported and is known from the Paleocene to Eocene of the United StatesBouchal et al 2016a), the Eocene of Central and East Asia(Wang & Zhao 1980;Hoorn et al 2012), and the Eocene of western Eurasia(Akkiraz et al 2006;Worobiec & Gedl 2018). From the Neogene onward Amaranthaceae pollen is very common in Eurasia (summarised byMuller 1981;Stuchlik et al 2009).…”
The continued investigation of the middle Miocene palynoflora from the Lavanttal Basin reveals numerous additional angiosperm taxa. The Myrtales to Ericales pollen record documented here comprises 46 different taxa belonging to (Rehderodendron) and Symplocaceae (Symplocos). Köppen signatures of potential modern analogues of the additional fossil woody elements confirm the hypothesis of a subtropical (Cfa, Cwa) climate at lower elevations and subsequent transition into a temperate climate with altitudinal succession (Cfa → Cfb/Dfa → Dfb; Cwa → Cwb → Dwbclimate). The fossil plants represent different vegetation units, from wetland lowlands to well-drained montane forests. Many of the fossil taxa have potential modern analogues that can be classified as nemoral and/or meridio-nemoral and/or semihumid-meridional vegetation elements. New is the recognition of oreotropical elements, which are direct indicators for a substantial altitudinal gradient.
“…Nevertheless, taxonomic control is typically poorer in LM than in SEM studies. As far as known, SEM studies of the same dispersed pollen flora reveal usually higher biodiversity and taxonomic resolution than LM studies (Grímsson & Zetter 2011; Grímsson et al 2011, 2015a, 2016; Bouchal et al 2016). Thus, it could be expected that a comprehensive SEM study of the dispersed pollen at Messel and Eckfeld would provide a large number of distinct taxa (genera, groups of genera).Figure 17.…”
The middle Eocene Messel and Eckfeld localities are renowned for their excellently preserved faunas and diverse floras. Here we describe for the first time pollen from insect-pollinated plants found in situ on well-preserved ancient bees using light and scanning electron microscopy. There have been 140 pollen types reported from Messel and 162 pollen types from Eckfeld. Here we document 23 pollen types, six from Messel and 18 from Eckfeld (one is shared). The taxa reported here are all pollinated by insects and mostly not recovered in the previously studied dispersed fossil pollen records. Typically, a single or two pollen types are found on each fossil bee specimen, the maximum number of distinct pollen types on a single individual is five. Only five of the 23 pollen types obtained are angiosperms of unknown affinity, the remainder cover a broad taxonomic range of angiosperm trees and include members of several major clades: monocots (1 pollen type), fabids (7), malvids (4), asterids (5) and other core eudicots (1). Seven types each can be assigned to individual genera or infrafamilial clades. Since bees visit only flowers in the relative vicinity of their habitat, the recovered pollen provides a unique insight into the autochthonous palaeo-flora. The coexistence of taxa such as Decodon, Elaeocarpus, Mortoniodendron and other Tilioideae, Mastixoideae, Olax, Pouteria and Nyssa confirms current views that diverse, thermophilic forests thrived at the Messel and Eckfeld localities, probably under a warm subtropical, fully humid climate. Our study calls for increased attention to pollen found in situ on pollen-harvesting insects such as bees, which can provide new insights on insect-pollinated plants and complement even detailed palaeo-palynological knowledge obtained mostly from pollen of wind-pollinated plants in the dispersed pollen record of sediments. In the case of Elaeocarpus, Mortoniodendron, Olax and Pouteria the pollen collected by the middle Eocene bees represent the earliest unambiguous records of their respective genera.
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