Eocene vegetation and ecosystem fluctuations inferred from a high-resolution phytolith record

Miller, Lauren A.; Smith, Selena Y.; Sheldon, Nathan D.; Strömberg, Caroline A.E.

doi:10.1130/b30548.1

Cited by 31 publications

(31 citation statements)

References 71 publications

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“…Inside the plant, Si is transported in the sap and deposited inside the cells, in the cell walls and in extracellular spaces of stems and leaves as micrometric hydrous amorphous silica particles called phytoliths. Upon plant decay, part of the phytolith production can be incorporated into soils or sediments and preserved for as long as millions of years (Alexandre et al, 2011;Miller et al, 2012;Strömberg et al, 2013). These fossil phytolith assemblages can be used for reconstructing past vegetation and climate conditions via their morphological and geochemical signatures (Piperno, 2006;Alexandre et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

et al. 2015

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Abstract. Phytoliths contain occluded organic compounds called phytC. Recently, phytC content, nature, origin, paleoenvironmental meaning and impact in the global C cycle have been the subject of increasing debate. Inconsistencies were fed by the scarcity of in situ characterizations of phytC in phytoliths. Here we reconstructed at high spatial resolution the 3-D structure of harvested grass short cell (GSC) phytoliths using 3-D X-ray microscopy. While this technique has been widely used for 3-D reconstruction of biological systems it has never been applied in high-resolution mode to silica particles. Simultaneously, we investigated the location of phytC using nanoscale secondary ion mass spectrometry (NanoSIMS). Our data evidenced that the silica structure contains micrometric internal cavities. These internal cavities were sometimes observed isolated from the outside. Their opening may be an original feature or may result from a beginning of dissolution of silica during the chemical extraction procedure, mimicking the progressive dissolution process that can happen in natural environments. The phytC that may originally occupy the cavities is thus susceptible to rapid oxidation. It was not detected by the NanoSIMS technique. However, another pool of phytC, continuously distributed in and protected by the silica structure, was observed. Its N / C ratio (0.27) is in agreement with the presence of amino acids. These findings constitute a basis to further characterize the origin, occlusion process, nature and accessibility of phytC, as a prerequisite for assessing its significance in the global C cycle.

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Section: Introductionmentioning

confidence: 99%

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

et al. 2015

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“…For example, Miller et al (2012) identified C 3 grass phytoliths in Montana by ~39 Ma (at THA in and found patchy but measurable amounts (up to 25%) of C 4 vegetation based on organic carbon isotopic ratios from paleosol and phytolith evidence, as well as a different C 3 grass phytolith assemblage than at the older site pointing to a shift in C 3 species composition. Taken together, these sites bracket the local evolution or spread of C 4 vegetation into southwestern Montana, and support previous ideas of a more complicated regional history for the spread of grasslands in general (Strömberg, 2005(Strömberg, , 2011, and the presence of significant amounts of C 4 plants prior to their global expansion to dominance in some regions (Fox and Koch, 2004;Edwards et al, 2010;Cotton et al, 2012).…”

Section: Accepted Manuscriptmentioning

confidence: 96%

“…Five of 12 samples were too poorly preserved for a quantitative count; these were instead analyzed qualitatively for absence or presence of key indicator phytoliths (Supplemental Table 2, 3). The remaining seven samples yielded, on average, 31.3 ± 3.3 (1σ) morphotypes (range: 26-36), significantly more than at older southwestern Montana sites (Miller et al, 2012, Middle Eocene: 19.6 ± 3.3 (1σ) morphotypes, range 14-25). MBJ has a lower diversity of total FI morphotypes and higher diversity of total GSSC compared to THA (total 26 FI morphotypes and 9 GSSC morphotypes vs. total 11 FI morphotypes and 23 GSSC morphotypes).…”

Section: Phytolithsmentioning

confidence: 98%

“…As a result, phytolith morphology can often be used to identify the original plant taxon or habitat it was produced in, providing a means for vegetation reconstructions in deep time (e.g., Strömberg, 2004Strömberg, , 2005Miller et al, 2012). Studies of phytolith production in modern plants and soils have helped identify characteristic morphotypes distinctive of plant taxa and functional groups (e.g., Piperno, 1985;Strömberg, 2003;Prychid et al, 2004;Chen and Smith, 2013), which can then be used in the identification of fossil phytoliths.…”

Section: Reconstructing Paleovegetationmentioning

confidence: 98%

“…see also Miller et al (2012) for details; Supplemental Table 2, 3) were excluded from analysis due to, among other things, uncertainty about the functional plant groups they represent (discussed in Strömberg, 2004;McInerney et al, 2011). Non-plant biogenic silica, including diatoms, sponge spicules, and chrysophyte cysts (DSCs), was also counted to provide information on hydrologic conditions (Piperno, 1988;Clarke, 2003).…”

Section: Phytolithsmentioning

confidence: 99%

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Regional-scale variability in the spread of grasslands in the late Miocene

Chen

Smith

Sheldon

et al. 2015

Palaeogeography, Palaeoclimatology, Palaeoecology

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Highlights• C 3 and C 4 plant abundances are reconstructed using phytoliths and δ 13 C org values • Penecontemporaneous sites from the same region show different temporal patterns • Expansion of C 4 in the Northern Rocky Mts. does not match the global pattern • Elevation places a primary control on C 4 abundance Abstract A new paleovegetation reconstruction based on both phytolith and paleosol carbon isotopic data is presented for the middle-late Miocene (11.2-9.5 Ma) of southwestern Montana. Both sources of data indicate an open-habitat, C 3 grassland ecosystem with a small C 4 component (<10%).However, while a penecontemporaneous record from further south within the same region indicated significant spatial and temporal variability in C 4 abundance, the new record indicates relatively little change either in space or in time. Because paleoclimatic conditions reconstructed at these two sites are the same, we hypothesize that other ecological factors controlled C 4 abundance across the region. The relative abundance of C 3 and C 4 plants in the Miocene is the same as in modern environments at both sites, suggesting that their distribution was likely established by the middle-late Miocene. This is consistent with the idea that paleoelevation was also similar, which agrees with independent constraints on the regional tectonic history. TheMontana records indicate a more limited distribution of C 4 vegetation than is observed in the Great Plains and elsewhere globally, as well as variable timing in the shift to C 4 dominance in ecosystems. Taken together, this local, regional, and global variability during a time of little or no climate change suggests that C 4 distribution and expansion was driven by local, rather than global, environmental factors.

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Building the monocot tree of death: Progress and challenges emerging from the macrofossil‐rich Zingiberales

Smith

Iles

Benedict

et al. 2018

American J of Botany

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Inclusion of eight fossil taxa expands the Zingiberales tree and helps explain the difficulty in resolving relationships. Inclusion of fossils was possible in part due to a large morphological data set built using nondestructive microcomputed tomography data. Collaboration between paleo- and neobotanists and technology such as microcomputed tomography will help to build the tree of death and ultimately improve our understanding of the evolutionary history of monocots.

show abstract

Eocene vegetation and ecosystem fluctuations inferred from a high-resolution phytolith record

Cited by 31 publications

References 71 publications

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

Regional-scale variability in the spread of grasslands in the late Miocene

Building the monocot tree of death: Progress and challenges emerging from the macrofossil‐rich Zingiberales

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