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Abstract

To identify the phytolith signal of lacustrine environments, which are prone to preserving faunal remains in- cluding hominins, we analyzed the phytolith content of 46 grass and sedge species, and of 26 soil and mud samples. The samples were collected in Chad (Central Africa), in the Sudanian and Sahelian phytogeograph- ical zones, near temporary and permanent water-bodies (including Lake Chad) and in grass-dominated bi- omes on well-drained soils. Altogether, we observed and counted separately 80 different phytolith types, including 38 grass silica short cells (GSSCs). Phytolith type diversity and relative abundances were analyzed in the botanical specimens to improve the phytolith taxonomic resolution. For the Poaceae, we used a value- test analysis to identify significant cohorts of phytoliths to characterize aquatic, mesophytic, and xerophytic species. Our results show that the abundance of Cyperaceae in swampy areas may be deduced from the com- bined abundance of blocky and elongate phytolith types, but not by the typical silicified Papillae phytoliths, which were barely found preserved in the soil/mud. The abundance of aquatic Poaceae near water-bodies is inferred from the presence and abundance of a cohort of eight GSSC types (including notably several trapezi- form GSSCs within the bilobate, cross, and saddle categories), which averages 42% in the mud samples, but only 23% and 14% in the samples from the Sudanian and Sahelian zones, respectively. The characterization is unclear for mesophytic grasses, but obvious for xerophytic grasses whose abundance in the Sahelian grass- lands is inferred from the presence and abundance of a cohort of five GSSC types (mainly tabular saddles), which averages 50% in the soil samples from the arid Sahelian zone, and b19% in the more humid Sudanian and swamp samples. In conclusion, considering the full morphological diversity of grass silica short cell phy- toliths (rather than just the broad morphological categories) allows greater discrimination of the aquatic en- vironments. Such approach is therefore required for analyzing vegetation distribution at a local scale.

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... For example, epidermal cells have been calibrated to reconstruct leaf area index (LAI) (Dunn et al., 2015). Bulliform cells (i) from the leaves of Poaceae are used as a proxy of aridity (Bremond et al., 2008); • the woody dicotyledon category is composed of globular granulate (j) (Alexandre et al., 1997;Bremond et al., 2005a;Kondo et al., 1994;Scurfield et al., 1974), globular decorated (k) (Neumann et al., 2009;Novello et al., 2012;Piperno, 2006;Runge, 1999), sclereid (Mercader et al., 2000;Neumann et al., 2009;Runge, 1999), blocky faceted (l) (Mercader et al., 2009;Neumann et al., 2009;Runge, 1999) and blocky granulate morphotypes (Mercader et al., 2009); • the other family-specific morphotypes are composed of morphotypes that can be attributed to specific families. Papillae types (m) (Albert et al., 2006;Gu et al., 2008;Novello et al., 2012;Runge, 1999) are produced by Cyperaceae (Kondo et al., 1994) that mainly grow in wetlands. ...
... Bulliform cells (i) from the leaves of Poaceae are used as a proxy of aridity (Bremond et al., 2008); • the woody dicotyledon category is composed of globular granulate (j) (Alexandre et al., 1997;Bremond et al., 2005a;Kondo et al., 1994;Scurfield et al., 1974), globular decorated (k) (Neumann et al., 2009;Novello et al., 2012;Piperno, 2006;Runge, 1999), sclereid (Mercader et al., 2000;Neumann et al., 2009;Runge, 1999), blocky faceted (l) (Mercader et al., 2009;Neumann et al., 2009;Runge, 1999) and blocky granulate morphotypes (Mercader et al., 2009); • the other family-specific morphotypes are composed of morphotypes that can be attributed to specific families. Papillae types (m) (Albert et al., 2006;Gu et al., 2008;Novello et al., 2012;Runge, 1999) are produced by Cyperaceae (Kondo et al., 1994) that mainly grow in wetlands. The globular echinate morphotype (n) is produced by palms (Arecaceae) (Kondo et al., 1994;Runge, 1999). ...
... Other specific phytoliths can be attributed to rice, Maize or Marantaceae [see the exhaustive discussion in Piperno (2006)]; • non-diagnostic morphotypes (p) such as globular smooth, elongated or tabular and blocky types are sometimes attributed to specific vegetation types, such as closed environments. However, the diversity of shapes behind the generic terms makes it difficult to be exhaustive for this category (see Garnier et al., 2012;Novello et al., 2012;Runge, 1999). ...
... Fig. 8a), and the Chloridoideae subfamily is indicated by saddles (2% in MS1, 0.6% in MS5). Bulliform cells, generally produced by the leaves of grasses and sedges (Novello et al. 2012), are present, including cuneiform bulliform (0.8% in MS1) and parallelepipedal bulliform (0.3% in all samples apart from MS4) types. These bulliform phytoliths are scarce in these samples, but this does not exclude the presence of monocotyledonous leaves. ...
... These bulliform phytoliths are scarce in these samples, but this does not exclude the presence of monocotyledonous leaves. The formation of bulliform phytoliths, which is favourably influenced by environmental conditions such as high evapotranspiration rate (e.g. in moist habitats in arid regions; Bremond et al. 2005;Novello et al. 2012), may have not been common in this environmental context. Furthermore, bulliform cells silicify in a later stage of life of the plant (Moulia 1994), which could have been grazed before silicification in these cases. ...
... The silica skeletons found in this study are concentrated in samples MS2-3 and MS5. There are few skeletons with psilate and sinuate long cells (spanning from 11.8% in MS2-3 to 24.6% in MS4), usually attributed to the stems/ leaves of Poaceae (Lancelotti and Madella 2012;Madella 2007;Portillo and Albert 2011), where they are very abundant; however, they have also been seen in Poaceae inflorescences and in leaf/culm of Cyperaceae (Novello et al. 2012;Ryan 2011). Many skeletons consist of echinate long cells that, along with papillae, characterise inflorescences of Poaceae (e.g. ...
Article
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In recent years, ethnoarchaeological studies focusing on herbivore faecal remains within the soils, especially those from goat, sheep and cattle, have shown the importance of their study for identifying socio-economic activities. Thus, an accurate microstratigraphic examination of these deposits can provide us new insights into past land use, site formation processes, activity areas and intensity of use of space, mobility, domestic use of fuel, manuring, and foddering strategies. Mountain landscapes represent a relatively new terrain of investigation for geo-ethnoarchaeology. In this paper, we present a pilot project featuring an applied inter-disciplinary methodology that includes micromorphology, bulk stable isotope analysis (δ13C and δ15N), phytolith, pollen and non-pollen palynomorphs (NPPs) analyses. These were carried out on samples from three high-mountain (up to 1400 m a.s.l.) pastoral sites located at Monti Sibillini, in the Italian central Apennines. Results show that the presence of anthropic organic-rich deposits, even when poorly preserved, (1) allows for an accurate description of herbivore dung internal characteristics, (2) establishes precise microstratigraphy of anthropogenic deposits and husbandry practices related to intensity of use of space, and (3) gives accurate information about former vegetation and landscape use in the local area. Based on this exploratory ethnoarchaeological approach, we discuss the potential of micro-analyses of archaeological decayed or burnt livestock dung in a small set of samples collected during a initial survey for obtaining insights into the environment and husbandry practices from dung and goat stabling floors in a high-mountain context.
... Depuis les années 1990, des recherches développent des analogues phytolithariens modernes pour les différentes zones phytogéographiques du continent africain. Elles traitent soit du matériel botanique (Runge 1996a & b;Runge and Runge 1997 ;Vrydaghs et al. 2000 ;Fahmi 2008 ;Mercader et al. 2009 ;Eichorn et al. 2010 ;Novello et al. 2015), soit des échantillons de sols superficiels (Runge 1999 ;Barboni et al. 2007;Mercader et al 2011 ;Novello et al. 2012 ;Albert et al. 2015). Ces travaux portent soit sur l'identification d'assemblages caractéristiques de formations végétales (Runge 1999) ou l'identification de GSSCP caractéristiques de certains environnements (Barboni et Bremond 2009 ;Novello et al. 2012 ;Neuman et al. 2017). ...
... Elles traitent soit du matériel botanique (Runge 1996a & b;Runge and Runge 1997 ;Vrydaghs et al. 2000 ;Fahmi 2008 ;Mercader et al. 2009 ;Eichorn et al. 2010 ;Novello et al. 2015), soit des échantillons de sols superficiels (Runge 1999 ;Barboni et al. 2007;Mercader et al 2011 ;Novello et al. 2012 ;Albert et al. 2015). Ces travaux portent soit sur l'identification d'assemblages caractéristiques de formations végétales (Runge 1999) ou l'identification de GSSCP caractéristiques de certains environnements (Barboni et Bremond 2009 ;Novello et al. 2012 ;Neuman et al. 2017). Pour Barboni et al. (2007) et Neumann et al. (2017, l'essentiel de l'information écologique est bien capturé par certains types de GSSCP. ...
... Ppour une recension générale des divers indices, il est renvoyé àStromberg et al. 2018. Il s'agit donc pour nous de nous inquiéter de la présence (ou de l'absence) de certains types de phytolithes sans pour autant reconstituer une/des couverture(s) végétale, cet effort impliquant la prise en compte des fréquences relatives des phytolithes(Barboni et al. 2007 ;Barboni et Bremond 2009 ;Novello et al. 2012), approche qui ne peut s'appliquer aux échantillons de Rivière Denis.Barboni et al. (2007) repèrent 13 types de phytolithes récurrents dans 149 échantillons de sols superficiels d'Afrique de l'Ouest et de l'Est distribués en 10 zones phytogéographiques. Ils relèvent que les SPHEROID PSILATE, SPHEROID ORNATE et SPHEROID ECHINATE caractérisent les spectres de forêts, les SPHEROID ECHINATE paraissant plus spécifiquement associés à une mosaïque forêt semidécidue/savane incluse. ...
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The Rivière Denis archaeological site is located in Gabon close to the Atlantic Ocean and the Equator. The studied pottery indicates it is part of a series of pre-metallurgical sites located in southern Cameroon and Gabon. The integration of paleo-environmental evidence, of soil analysis and pottery typology enables the authors to suggest the “Neolithic” assemblage was deposited after ⁓3000 BP, perhaps predating the local Okala Group of ⁓2500-1900 BP chronology, but more sensibly being part of it. This coastal site would be associated to a very short list of settlements suggestive of a low-density early coastal wave of advance from southern Cameroon, starting before ⁓3000 BP, and extending later to the Kouilou river in the Congo Republic, reaching ⁓2300 BP the Congo River in the DRC. It thus bypassed the core of the Equatorial rain-forest and this before the forest contraction of the so-called “Late Holocene Rainforest Crisis”. We conclude by outlining “Neolithic” to Early Iron Age transitions from Cameroon to Angola documented by the latest studies published up to 2021. We argue these materialize a second wave of advance overlapping the first one, as suggested since 1991. It developed at the onset of the Early Iron Age between ⁓2200-2000 BP, expanding through the forests towards the Atlantic Ocean, completely changing the local material cultures of early villagers. Iron technology seems for the time being to have strung along this widespread movement and may have been associated to it. Lastly, our study further underlines the importance for open-air site excavations in the region to have more precise bioturbation studies carried out.
... For example, epidermal cells have been calibrated to reconstruct leaf area index (LAI) (Dunn et al., 2015). Bulliform cells (i) from the leaves of Poaceae are used as a proxy of aridity (Bremond et al., 2008); • the woody dicotyledon category is composed of globular granulate (j) (Alexandre et al., 1997;Bremond et al., 2005a;Kondo et al., 1994;Scurfield et al., 1974), globular decorated (k) (Neumann et al., 2009;Novello et al., 2012;Piperno, 2006;Runge, 1999), sclereid (Mercader et al., 2000;Neumann et al., 2009;Runge, 1999), blocky faceted (l) (Mercader et al., 2009;Neumann et al., 2009;Runge, 1999) and blocky granulate morphotypes (Mercader et al., 2009); • the other family-specific morphotypes are composed of morphotypes that can be attributed to specific families. Papillae types (m) (Albert et al., 2006;Gu et al., 2008;Novello et al., 2012;Runge, 1999) are produced by Cyperaceae (Kondo et al., 1994) that mainly grow in wetlands. ...
... Bulliform cells (i) from the leaves of Poaceae are used as a proxy of aridity (Bremond et al., 2008); • the woody dicotyledon category is composed of globular granulate (j) (Alexandre et al., 1997;Bremond et al., 2005a;Kondo et al., 1994;Scurfield et al., 1974), globular decorated (k) (Neumann et al., 2009;Novello et al., 2012;Piperno, 2006;Runge, 1999), sclereid (Mercader et al., 2000;Neumann et al., 2009;Runge, 1999), blocky faceted (l) (Mercader et al., 2009;Neumann et al., 2009;Runge, 1999) and blocky granulate morphotypes (Mercader et al., 2009); • the other family-specific morphotypes are composed of morphotypes that can be attributed to specific families. Papillae types (m) (Albert et al., 2006;Gu et al., 2008;Novello et al., 2012;Runge, 1999) are produced by Cyperaceae (Kondo et al., 1994) that mainly grow in wetlands. The globular echinate morphotype (n) is produced by palms (Arecaceae) (Kondo et al., 1994;Runge, 1999). ...
... Other specific phytoliths can be attributed to rice, Maize or Marantaceae [see the exhaustive discussion in Piperno (2006)]; • non-diagnostic morphotypes (p) such as globular smooth, elongated or tabular and blocky types are sometimes attributed to specific vegetation types, such as closed environments. However, the diversity of shapes behind the generic terms makes it difficult to be exhaustive for this category (see Garnier et al., 2012;Novello et al., 2012;Runge, 1999). ...
Article
The Earth has experienced large changes in global and regional climates over the past one million years. Understanding processes and feedbacks that control those past environmental changes is of great interest for better understanding the nature, direction and magnitude of current climate change, its effect on life, and on the physical, biological and chemical processes and ecosystem services important for human well-being. Microfossils from terrestrial plants – pollen, microcharcoal and phytoliths – preserved in terrestrial and marine sedimentary archives are particularly useful tools to document changes in vegetation, fire and land climate. They are well-preserved in a variety of depositional environments and provide quantitative reconstructions of past land cover and climate. Those microfossil data are widely available from public archives, and their spatial coverage includes almost all regions on Earth, including both high and low latitudes and altitudes. Here, we (i) review the laboratory procedures used to extract those microfossils from sediment for microscopic observations and the qualitative and quantitative information they provide, (ii) highlight the importance of regional and global databases for large-scale syntheses of environmental changes, and (iii) review the application of terrestrial plant microfossil records in palaeoclimatology and palaeoecology using key examples from specific regions and past periods.
... Iridaceae), eudicots and gymnosperms (e.g. Bamford et al. 2006;Novello et al. 2012;An 2016;Esteban et al. 2017a;Murungi 2017). These morphotypes, and mostly in their parallelepiped form, have been traditionally associated with the presence of wood and bark from trees and shrubs. ...
... In South Africa, Esteban et al. (2017aEsteban et al. ( , 2017b and Novello et al. (2018) observed that blocky morphologies were among the most common phytolith morphotypes in eudicot plants and shrubby vegetation from the Cape Floristic Region. Nevertheless, blocky morphologies have also being found in monocotyledonous plants, in grasses and related them to bulliform cells (Novello et al. 2012), in sedges (Novello et al. 2012;Murungi 2017) and perhaps also related to bulliform cells, and in monocotyledonous geophytes (Esteban et al. 2017a). Here, we conducted a correlation measurement (Spearman's) between blocky morphotypes and grass phytoliths (i.e. ...
... In South Africa, Esteban et al. (2017aEsteban et al. ( , 2017b and Novello et al. (2018) observed that blocky morphologies were among the most common phytolith morphotypes in eudicot plants and shrubby vegetation from the Cape Floristic Region. Nevertheless, blocky morphologies have also being found in monocotyledonous plants, in grasses and related them to bulliform cells (Novello et al. 2012), in sedges (Novello et al. 2012;Murungi 2017) and perhaps also related to bulliform cells, and in monocotyledonous geophytes (Esteban et al. 2017a). Here, we conducted a correlation measurement (Spearman's) between blocky morphotypes and grass phytoliths (i.e. ...
Article
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The interior regions of South Africa have had less attention devoted to archaeological research than coastal regions, and palaeoenvironmental studies are also more limited. As such, little is known about the interaction between human behaviours and past environments in these semi-arid regions. Here, we present an archaeobotanical and mineralogical study from the Middle Stone Age site of Mwulu’s Cave, Limpopo Province. Our study shows the importance of using taphonomical approaches prior to interpreting archaeobotanical assemblages, while provides with novel information on the plants used by ancient inhabitants of Mwulu’s. The grass phytolith composition is of environmental significance, where a shift from C4 Panicoideae to C3 grasses is observed in the last occupation event. This tentatively suggests a shift in rainfall regime, from summer rainfall conditions to an increase in winter rain, during Marine Isotope Stage 5b in the Polokwane region, or a decrease in rainfall seasonality. Although we are unable to chronostratigraphically associate this change in the plant composition, our study adds evidence in support of previous propositions for an expansion of the winter rainfall zone into the interior regions of South Africa.
... Phytogenic silica is released into soils after litter decomposes and discharges both amorphous silica and phytoliths. This process creates a synchronous phytolith record of the plant communities that grew in the soil (Piperno & Becker, 1996;Kerns, Moore & Hart, 2001;Clarke, 2003;Piperno, 2006;Thorn, 2006;Honaine, Zucol & Osterrieth, 2009;Morris, Ryel & West, 2010;Mercader et al., 2011;Novello et al., 2012;Novello et al., 2018;Blinnikov, Bagent & Reyerson, 2013;An, Lu & Chu, 2015;Watling et al., 2016;Esteban et al., 2017;Fick & Evett, 2018). ...
... Two system, polarizing microscopes (Olympus BX51, Motic BA410E) allowed us to confirm the opal silica's isotropy and tally phytoliths at 400x, following the International Code for Phytolith Nomenclature 1.0 to name and describe specimens (Madella, Alexandré & Ball, 2005), with exceptions duly noted. Geographically pertinent reference collections and published soil phytolith assemblages were consulted (Albert, Bamford & Cabanes, 2006;Albert, Bamford & Esteban, 2015;Bamford, Albert & Cabanes, 2006;Fahmy, 2008;Mercader et al., 2009;Mercader et al., 2010;Mercader et al., 2011;Barboni & Bremond, 2009;Eichhorn, Neumann & Garnier, 2010;Novello et al., 2012;Collura & Neumann, 2017;Neumann et al., 2017). Full datasets with individual counts for each morphotype are available at the Federated Research Data Repository (DOI https://dx.doi.org/10.20383/101.0122). ...
... We classified discrete phytolith shapes in four large groups (woody dicot, grass short cells, generic Poaceae, and rare) and 17 classes that encompass 76 types. The woody dicot group totalled the blocky class (Mercader et al., 2009;Novello et al., 2012;Collura & Neumann, 2017), cylindrical types from bark (Mercader et al., 2009), varied globular phytoliths (Runge, 1999;Mercader et al., 2009), tabular types from woody dicots (Mercader et al., 2009;Collura & Neumann, 2017), clavates (Mercader et al., 2009), and sclereid phytoliths (Collura & Neumann, 2017). Phytoliths from Poaceae short cells were subdivided in three classes: lobate (Fahmy, 2008;Neumann et al., 2017), rondels (Mercader et al., 2010;Novello et al., 2012;Neumann et al., 2017) and chloridoid saddles (Twiss, Suess & Smith, 1969;Mercader et al., 2010). ...
Article
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This article studies soil and plant phytoliths from the Eastern Serengeti Plains, specifically the Acacia-Commiphora mosaics from Oldupai Gorge, Tanzania, as present-day analogue for the environment that was contemporaneous with the emergence of the genus Homo . We investigate whether phytolith assemblages from recent soil surfaces reflect plant community structure and composition with fidelity. The materials included 35 topsoil samples and 29 plant species (20 genera, 15 families). Phytoliths were extracted from both soil and botanical samples. Quantification aimed at discovering relationships amongst the soil and plant phytoliths relative distributions through Chi–square independence tests, establishing the statistical significance of the relationship between categorical variables within the two populations. Soil assemblages form a spectrum, or cohort of co-ocurring phytolith classes, that will allow identifying environments similar to those in the Acacia - Commiphora ecozone in the fossil record.
... A small number of three-lobed crosses were also found (2%). The saddles are generally of the symmetric type, and often tending towards rondel type, hence referred to as saddle-rondel after Novello et al. (2012). The rondels are sometimes conical, sometimes keeled and cylindrical reinform, as described and illustrated by Novello et al. (2012). ...
... The saddles are generally of the symmetric type, and often tending towards rondel type, hence referred to as saddle-rondel after Novello et al. (2012). The rondels are sometimes conical, sometimes keeled and cylindrical reinform, as described and illustrated by Novello et al. (2012). The longcells are clearly dominated by the bulliform cuneiform type (82%), with occasional hair cells, hair bases and elongated types. ...
... Thus, the saddle phytoliths found in our sample should stem from other sources than C 4 grasses. Considering the particular combination of morphological forms found in the Motala sample (rondel, trapeziform, saddle) it closely resembles the characteristics of the phytolith composition in reeds of Phragmites australis, a species which is highly productive in terms of phytoliths (Liu et al., 2015;Novello et al., 2012). Also the saddle morphotype appear in Phragmites sp., although being from the Arundinoideae rather than the Chloridoideae subfamily (Ramsey et al., 2016). ...
Article
We analysed microfossil remains in human dental calculus sampled from an individual of the Mesolithic burials at Strandvägen, Motala, central Sweden. The analysis was targeted on phytoliths, diatoms and fungal spores. The composition of the phytolith assemblage suggests that plant micro-fossils found in the dental calculus partially stem from reeds of Phragmites. This suggests that the studied individual was consuming and/or manipulating reeds with his teeth. Spherical fungal spores were abundant in the calculus, possibly indicating weak health status, although it cannot be excluded that they originate from natural long-term accumulations. The diatom composition in the dental calculus was dominated by Cyclotella distinguenda, a species which is strongly linked to waters of the nearby Lake Vättern. This suggests that the studied individual primarily used water, and/or aquatic flora/fauna, from Lake Vättern.
... Distinctive grass phytoliths are important for independently assessing grazing pressure from changes in taxonomic composition (e.g., Breman, 2010;Finné et al., 2010;Lejju et al., 2005;Novello et al., 2012). Phytoliths or 'plant stones' (e.g. Figure 1.5), form as resistant silica casts within grass leaf and inflorescences when silicates are taken up from soils (Piperno, 2006). ...
... Grass subfamilies indicated by phytoliths are important for interpreting climate-vegetation relationships used for reporting about aridity and grass sward heights (Barboni and Bremond, 2009;Bremond et al., 2005;Bremond, Alexandre, Peyron, et al., 2008). Productive wetland margins are demarcated by C3 Pooideae and Arundinoideae subfamilies (Aleman et al., 2014;Kotze and O'Connor, 2000;Novello et al., 2012;Tieszen et al., 1979;Vesey-Fitzgerald, 1963. Importantly, dryland C4 grasses represented by Chloridoideae and Panicoideae represent increased drought/grazing and fires, respectively. ...
... Positive responses between drought and grazing (Illius and O'Connor, 1999;Milchunas et al., 1988), and aridity and shortgrasses (Coughenour, 1985;McNaughton, 1984;Veldhuis et al., 2014), also compound problems. This suggests the aridity index based on the ratio of Chloridoideae shortgrasses to Panicoideae tallgrasses (Bremond et al., 2005;Novello et al., 2012) is for dry and wet conditions and is not reliable ...
Thesis
Rainfall, fire, and grazing all control changes in vegetation and soil in grassland and savanna ecosystems. In these ecosystems, wetlands are key resource areas because they keep moisture and collect nutrients that support grass production. The grass production supports high grazer densities in landscapes, especially during dry climatic periods. The equilibrium idea suggests that, at high densities, herbivores reduce grass production and damage soils. In contrast, the disequilibrium idea argues that unreliable rainfall and frequent droughts lower herbivore densities to levels rendering their effects negligible. Thus, grass production and grazer densities rarely stabilise. However, nonequilibrium theories suggest the relevance of both ideas in natural systems. Spatial and temporal scales used for looking at landscapes and the resilience of persistent soil and grass states control which idea wins. In turn, stability of vegetation states is related to traits of grass biomass including palatability, flammability, and tolerance to drought. At long timescales, we remain uncertain about how grass production in landscapes are affected by indigenous herbivores, and those managed with fires by pastoralists for livestock. In this thesis, I test nonequilibrium dynamics with stability domains of grass biomass, i.e., centres of stable vegetation states (tallgrass versus shortgrass), to assess the resilience of contrasting key resource areas. Long-term sediment proxy data offer the opportunity for assessing vegetation and soil dynamics over many centuries.
... Due to their siliceous structure, phytoliths are resistant to oxidation and are well preserved in such tropical environment deposits (Alexandre et al., 1997;Madella and Lancelotti, 2012;Piperno, 2006;Watling et al., 2016). They also allow good monitoring of herbaceous environments thanks to the morphotype diversity of Cyperaceae and Poaceae (Twiss et al., 1969;Fredlund and Tieszen, 1994;Lu and Liu, 2003;Strömberg, 2004;Iriarte and Paz, 2009;Novello et al., 2012). Moreover, unlike pollen, phytoliths are a good local bioindicator of plant formations (Madella and Lancelotti, 2012;Piperno, 2006). ...
... We, therefore, chose to create species complexes for trees (62 nomens associated with woody dicotyledons). Phytoliths are, however, a good tool for characterizing monocotyledon families, such as Arecaceae, Cyperaceae, Commelinaceae, Musaceae, and Poaceae (Piperno, 2006;Honaine et al., 2009;Eichhorn et al., 2010;Novello et al., 2012;Chen and Smith, 2013). With some families, it is sometimes possible to determine the genus or species. ...
... The grass short-cell phytoliths (GSCPs) are divided into three main morphotypes: the lobate, saddle and rondel shapes. These three classes of phytoliths represent a great diversity of shapes and can be divided into numerous sub-variants (Mulholland, 1989;Piperno and Pearsall, 1998;Barboni and Bremond, 2009;Novello et al., 2012;Neumann et al., 2017). Barboni and Bremond (2009) suggest that the multiplication of sub-variants reduces the effects of taxonomic redundancy within the subfamilies of Poaceae. ...
Article
Phytoliths, unlike pollen and charcoal, are frequently conserved in sediments in the Maya lowlands but are rarely used as paleoenvironmental proxies. To better interpret and reconstruct paleoecological signatures and changes, it is necessary to provide current analog of fossil assemblages. To do so, we selected six modern ecosystems and differentiated them by their soil phytolith assemblages in the ancient Maya city of Naachtun (northern Petén, Guatemala). We studied the plant communities and relative phytoliths frequencies in surface soils on 4 north–south vegetation transect, composed of 43 quadrats. These transects cross forests and savannahs in low swampy areas North and South of the site, and hill forest in its center, where the city was built. Quadrats were statistically compared using multivariate analyses (CA). Six types of plant communities were characterized by their phytolith assemblages, as well as on the presence of siliceous bioindicators such as diatoms and sponges. The D/P and LU indexes developed for these assemblages allow us to provide a precise signature of the current vegetation cover, and identify the presence of undergrowth in forest areas, or forest edges in savannah areas. This first modern phytolith reference for the Maya area will contribute to the development of paleoecological reconstructions for this zone.
... Because BILOBATE can be found in taxa from across the Poaceae, its taxonomic use depends on a priori knowledge of local grass communities (e.g., Alexandre et al., 1997;Barboni et al., 1999Barboni et al., , 2007, a more finely divided BILOBATE morphospace (e.g., Lu and Liu 2003;Strömberg, 2005;Fahmy 2008;Novello et al., 2012;Neumann et al., 2017), or both. ...
... CRENATE, on the other hand, have an overall rectangular shape in IPS view, with less well-defined castulae (Mulholland, 1989). POLYLOBATE has mainly been used to indicate grasses in the Panicoideae and other (C3/C4) PACMAD taxa (e.g., Mulholland, 1989, Barboni et al., 2007Novello et al., 2012). ...
... Taxonomic occurrence: CROSS has been described from the Panicoideae and other PACMAD grasses, as well as from the Bambusoideae and Oryzoideae (Twiss et al., 1969;Piperno and Pearsall, 1998;Strömberg, 2003;Prasad et al., 2005Prasad et al., , 2011Fahmy, 2008;Barboni and Bremond, 2009;Novello et al., 2012;Neumann et al., 2017). ...
... D/P 2 = 0.01-1) overlap with those observed at Palo Verde. Finally, in Chad (Novello et al. 2012) D/P indices (recalculated from reported values to D/P 1 , D/ P 2 = 0-1.3) from grass-dominated vegetation types (i.e., woodlands, edaphic grassland mosaics, wooded grasslands, and deciduous bushlands) overlap with those recorded in many of Palo Verde quadrats (e.g., Q15, Q16, Q17, Q20, Q21, Q22, and Q25). ...
... The overlap between D/P values of PV dry forest and these African grass-dominated ecosystems (Barboni et al. 2007;Bremond et al. 2005aBremond et al. , 2005bNovello et al. 2012) does not allow us to differentiate these vegetation types based on the D/P index. However, floristic differences between these ecosystems should nonetheless be reflected in phytolith assemblages. ...
... Indeed, despite the limited taxonomic information from GSSCP assemblages provided in many of these studies, broad compositional trends indicate major distinctions between these assemblages and Palo Verde samples. Among arboreal markers, SPHEROID ORNATE are more abundant in the African phytolith assemblages (Barboni et al. 2007;Bremond et al. 2005aBremond et al. , 2005bNovello et al. 2012) than in the PV dry forest (see also further discussion of the comparison between D/P index and FI-t ratio in section 4.5). Furthermore, Palo Verde and the African GSSCP assemblages with overlapping D/P indices differ in term of relative abundance of different GSSCP classes. ...
Article
To improve paleoenvironmental reconstruction based on fossil phytoliths, it is vital to establish modern calibrations that explicitly consider important functional aspects of vegetation, such as structure, composition, diversity, and spatial heterogeneity. No such studies currently exist for Central-and South America. To begin to solve this problem, we address two questions: 1) do phytolith assemblages reflect the overall differences in structure, composition , and diversity between rainforest and dry forest? and 2) do phytolith assemblages from lateral transects capture variation in structure and composition typical of these vegetation types? At La Selva (rainforest) and Palo Verde (dry forest) biological stations (Costa Rica), we collected soil phytolith samples from, respectively, fourteen and eleven quadrats along vegetation transects. Along each transect, we measured gradients in canopy openness (LAI), elevation, and moisture. Statistical analyses were used to characterize and compare vegetation structure, composition, and diversity to soil phytolith assemblage composition, and to test for correlation with environmental gradients at each site. The two sites were then compared using multivariate statistical methods. Results indicate that rainforest and dry forest vegetation can be distinguished by analyzing multiple phytolith samples collected within sites. Within each vegetation type, the comparison of phytolith assemblages along transects allows reconstruction of important structural (canopy openness and patchiness) and compositional (dominant plant functional types) aspects of the vegetation. Thus, the analysis of phytolith samples collected along temporally constrained stratigraphic levels is a viable and vital tool for inferring heterogeneity in canopy cover and gross vegetation composition in the deep-time fossil record.
... A total of 168 samples (SOM Table S2) were selected from 10 published modern phytolith datasets compiled from eastern and western Africa (Alexandre et al., 1997;Barboni et al., 1999;Runge, 1999;Bremond et al., 2005a;Bremond et al., 2005b;Bremond et al., 2008;Garnier et al., 2012;Novello et al., 2012;Arráiz et al., 2017;Barboni et al., 2019) to assess the relationship between D/P • values and tree cover, and the relative abundances of palm (Arecaceae), woody dicotyledonous (trees), and GSSC (grass; Poaceae) phytoliths (A:D:P) with vegetation formation in the form of a ternary plot. To accomplish this, each modern D/P • and A:D:P sample was assigned to a basic vegetation formation type and woody canopy cover based on White (1983) as follows: swamp (open), shrubland (open), bushland (> 40% short woody cover) grassland (0-10% tree cover), wooded grassland (10-40% tree cover), woodland (40-80% tree cover), forest (80-100% tree cover). ...
... Our observations agree with the Cabanes and Shahack-Gross (2015) conclusion that under conditions of partial dissolution, bulliforms may be overrepresented. However, Novello et al. (2012) showed that surface soil samples in a swamp dominated by reeds (Typha) and grasses (Vossia, Phragmites) produced a phytolith assemblage with <1% GSSCs, and 99% bulliform, elongates, and trichomes. Thus, the absence or rarity of GSSC phytoliths is not always an indicator of dissolution, especially if bulliforms are well preserved. ...
Article
As part of the Hominin Sites and Paleolakes Drilling Project (HSPDP), phytoliths, pollen, and microcharcoal were examined from the 228 m (3.29 to 2.56 Ma) Baringo-Tugen Hills-Barsemoi drill core (BTB13). A total of 652 samples were collected at ~10 to 32 cm intervals, corresponding to sub-millennial to millennial scale temporal resolution. Microcharcoal was well-preserved throughout the core and often peaked in abundance ~5 kyr before and after insolation peaks. Phytolith preservation varied between excellent to total dissolution in alternating intervals throughout the core. Pollen was rarely preserved. These combined datasets indicate that prior to ~3.1 Ma, woody cover fluctuated between open savanna (< 40% cover), woodland (40–80% cover), and forest (> 80% cover) at typically precessional (19–23 kyr) periodicities. During the mid-Piacenzian Warm Period (MPWP; 3.26–3.01 Ma), intervals with exceptionally high microcharcoal abundance suggest that regional turnover from wooded to open habitats was driven in part by fire. After ~3.1 Ma, low-elevation woody cover likely never exceeded 40%, with oscillations between mesic tall-grass vs. xeric short-grass savanna at precessional periodicities. Mesic C4 tall-grass (Panicoideae) peaked in abundance during insolation maxima, whereas xeric C4 short-grass (Chloridoideae) peaked during insolation minima. The onset of Northern Hemisphere glaciation (NHG) at ~2.75 Ma coincided with the appearance of deep lake phases and increases in grass density and fire frequency. Spectral analysis and intervals with well-preserved phytoliths indicate that precession and interhemispheric insolation gradients influenced vegetation via their effects on equatorial precipitation and fire. This study fills a crucial gap in Pliocene vegetation reconstructions from the East African Rift Valley and its associated hominin localities. It also provides orbitally resolved regional vegetation data useful in paleodata–model comparisons for the onset of the MPWP (which is often used as an analog for future warming) and NHG.
... As well as creating reference collections of modern plants, researchers also analyze the phytolith assemblages from surface soils underlying known vegetation to provide analogues with which to compare paleoecological assemblages (e.g. Fredlund and Tieszen, 1994;Alexandre et al., 1997;Runge, 1999;Fernández Honaine et al., 2006;Iriarte and Paz, 2009;Mercader et al., 2011;Novello et al., 2012) This approach often illuminates important issues of over-and under-representation of certain taxon, whether due to different phytolith production patterns or the differential preservation of specific morphotypes in soils. ...
... Anatomical studies have long reported the presence of bulliforms in the Cyperaceae family (Beal, 1886), but it is rare for these phytoliths to be directly extracted from plant tissue. An exception to this is the study of Novello et al. (2012), which documented a range of bulliform types, including those with both cuneiform and hexagonal characteristics, in African Cyperaceae species. ...
Article
Phytolith reference collections of plants and surface soils are a critical part of studies that use these microbotanical remains for archaeological and paleoecological reconstruction. In the archaeologically-rich region of the Upper Madeira river in Rondônia, Brazil, phytolith analysis is being applied in both on- and off-site contexts in order to shed light on human-environment interactions over a period that extends almost the entire Holocene. The present study brings together data on phytolith production patterns among 90 native species, representing 36 plant families, as well as 56 surface soil samples taken from underneath 11 monitored forest plots. Our discussion focuses on the comparison between the surface soil phytolith records and the above-ground floristic inventories, scrutinized considering the plant reference collection results. We found that the phytoliths of several species which produce diagnostic or potentially-diagnostic morphotypes were under-represented in the surface soils, including several understory herbs. While the phytolith assemblages from three forest types (palm, sororoca and dense forest) presented considerable overlap, in accordance with similarities in the floristic inventories, bamboo forest and different types of campinaranas were able to be distinguished based on their phytolith signatures.
... Grass bulliform phytoliths Pan_I type is potentially not differentiable from the above mentioned blocky phytoliths. A vaguely cuneiform phytolith type was observed in Cyperaceae (Novello et al. 2012). It (Blo-5) resembles Pan_II type defined in this study judging from the image provided. ...
... In a study of modern soil phytolith assemblages in western Africa, fan-shaped index (Fs) (%), fan-shaped vs. sum of characteristic phytoliths, was found to be increasing toward the more arid regions (Bremond et al. 2005). However, the same trend was not observed from the soils in Chad, central Africa (Novello et al. 2012). How a cuneiform phytolith type was defined is likely the main cause of this inconsistency. ...
Article
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Background: Grass phytoliths are the most common phytoliths in sediments; recognizing grass phytolith types is important when using phytoliths as a tool to reconstruct paleoenvironments. Grass bulliform cells may be silicified to large size parallelepipedal or cuneiform shaped phytoliths, which were often regarded as of no taxonomic value. However, studies in eastern Asia had identified several forms of grass bulliform phytoliths, including rice bulliform phytolith, a phytolith type frequently used to track the history of rice domestication. Identification with a higher level of taxonomic resolution is possible, yet a systematic investigation on morphology of Poaceae bulliform phytoliths is lacking. We aimed at providing a morphological description of bulliform phytoliths of Poaceae from Taiwan based on morphometric measurements in anatomical aspect. The results are important references for paleo-ecological studies. Result: The morphology of grass bulliform phytoliths is usually consistent within a subfamily; the end profile is relatively rectangular in Panicoideae and Micrairoideae, whereas cuneiform to nearly circular in Oryzoideae, Bambusoideae, Arundinoideae, and Chloridoideae. Bulliform phytoliths were seldom observed in Pooideae. Certain morphotypes are limited to plants growing in specific environments. For example, large, thin, and pointed bulliform phytoliths are associated with wet habitat; Chloridoideae types are mostly from C4 plants occupying open arid places. Conclusion: Grass bulliform phytoliths can be identified at least to the subfamily level, and several forms were distinguished within large subfamilies. Previously un-reported silicified cell types, i.e., arm cells and fusoids, and two special trichome phytolith types associated with bulliform phytoliths, were described. Morphometric methods were great tools for delimiting morphotypes; with refined morphological classification the association between forms and habit/habitats was revealed. The knowledge provides new ways to interpret phytolith assemblage data, and it is especially useful when the sediments are enriched in large blocky phytoliths.
... Phytoliths accumulate as a component of the topsoil when plant tissues decay, and the definition of the preservation status of phytoliths in topsoil can help determine which types of phytoliths can be used to represent woody plants in warm temperate humid zones in paleovegetation reconstruction (Blinnikov, 2005;Novello et al., 2012Novello et al., , 2018Gao et al., 2019). In addition, phytoliths produced by the aboveground plant community which have accumulated in the topsoil for many years are a modern analog for phytolith data from stratigraphic profiles. ...
... Many phytolith indexes have been proposed or modified to determine the aboveground plants. For example, the Iph index (aridity index) was shown to be able to distinguish tall grassland and short drought-adapted grassland (Novello et al., 2012); and the D/P index (the ratio of tree phytoliths to Poaceae phytoliths) is commonly used as a proxy for characterizing the openness of the community (Alexandre et al., 1997). The B/BC index has been proposed to distinguish broad-leaved forest and coniferous forest in the studied region, and it can be applied to paleovegetation reconstruction in warm temperate forest areas. ...
Article
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Studies of the morphotypes, production and preservation of phytoliths in soils provide a theoretical basis for paleovegetation reconstruction. However, there is a lack of systematic studies of the phytoliths of woody plants in the warm temperate humid zones, which greatly limits the application of phytoliths in paleovegetation reconstruction in this environmental context. In this study we analyzed the phytoliths of 211 plant samples (81 leaf samples, 73 branch samples, 57 bark samples) and 30 topsoil samples from the warm temperate humid zones of China. The results demonstrate that while most of the leaf samples contained phytoliths, only a few of the branch and bark samples did so. In terms of phytolith concentration, the sample types were ordered as follows: leaf samples > bark samples > branch samples. In this study the phytoliths in woody plants were classified into 7 categories and 21 sub-categories, and the results of detrended correspondence analysis (DCA) showed that elongate dentate and blocky morphotypes were closely associated with Picea; elongate cavate and margin-cuneiform morphotypes were closely associated with Larix; acute bulbosus and hair base morphotypes were associated with Morus, Broussonetia and Diospyros; and elongate psilate, elongate attenuate, and sclereid morphotypes were associated with Quercus, but these types are not unique to Quercus. The topsoil woody phytolith assemblages contained four types of broad-leaved phytolith (tabular, tabular sinuate, sclereid, epidermal phytolith), and three types of coniferous phytolith (blocky, elongate dentate, elongate tabular). The ratio of the total of broad-leaved phytoliths to the sum of broad-leaved phytoliths and coniferous phytoliths is useful for discriminating broad-leaved forest from coniferous forest. Overall, the results confirm the usefulness of phytoliths as indicators of woody plants in the warm temperature humid region in China, and they demonstrate the potential of woody phytolith assemblages for paleovegetation reconstruction.
... The archaeological recovery and identification of phytoliths enables reconstructions of human use of plants and local vegetation composition during site formation. Since the 1990s, phytoliths have been increasingly used in African archaeology as environmental proxies and in reconstructions of human use of plants (for example, Barboni et al. 1999;Mercader et al. 2000Mercader et al. , 2010Mercader et al. , 2011Fahmy and Magnavita 2006;Barboni and Bremond 2009;Neumann et al. 2009Neumann et al. , 2017Eichhorn et al. 2010;Radomski and Neumann 2011;Wadley et al. 2011Wadley et al. , 2020Novello et al. 2012;Madella et al. 2014Madella et al. , 2016Novello and Barboni 2015;Collura and Neumann 2017;Esteban et al. 2017;Murungi 2017;Murungi et al. 2017;Out and Madella 2017;Ryan 2018). ...
... Phytolith types are classified and described according to the International Code for Phytolith Nomenclature (ICPN 1.0 and 2.0) (Madella et al. 2005;Neumann et al. 2019). Short cell phytoliths (Fig. 4) were classified using previously published African grass Bilobate, Saddle, Rondel and Cross morphologies (Fahmy 2008;Mercader et al. 2010;Radomski and Neumann 2011;Novello et al. 2012;Novello and Barboni 2015;Neumann et al. 2017). Elongate classifications also followed common descriptions for projections along the lateral margins (clavate, dentate, entire and sinuate) (Madella et al. 2005;Piperno 2006;Ball et al. 2009) (Fig. 4). ...
Article
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Throughout northern Africa, evidence for an intensification of wild grass gathering is reflected in Holocene archaeological contexts. However, both the recovery of macrobotanical assemblages and the specificity of their taxonomic classification are heavily influenced by food processing and post-depositional conditions. In contrast, inflorescence phytoliths provide high levels of taxonomic specificity and preserve well in most archaeological contexts. This study analyses the in situ morphology of inflorescence phytoliths from modern specimens of nine wild C4 grass species commonly observed in ethnographic studies and recovered in seed assemblages from archaeological contexts across northern Africa. Morphological differences in Interdigitate phytoliths within the fertile florets of six Paniceae species enabled differentiation between them. The morphological parameters established in this study provide an additional resource for archaeological and palaeoecological analyses using phytoliths, which demonstrates the effectiveness of applying this method to African wild grass species.
... Morphological description and classification were based on phytolith shape and size based on the International Codes for Phytolith Nomenclature (ICPN) (Madella et al. 2005), while additional literature was consulted for specific taxa. Grass short cell phytoliths (GSCPs) assignments were based largely on the following studies Bremond et al. 2008;Esteban et al. 2016;Mercader et al. 2010;Neumann et al. 2009;Novello et al. 2012;Piperno 2006;Rossouw 2009;Strömberg 2004;Twiss 1992;Twiss et al. 1969), Woody (tree and shrub) (Albert and Weiner 2001;Mercader et al. 2009;Neumann et al. 2009;Piperno 2006;Runge 1999;Strömberg 2004) and Palm phytoliths (Figures 4b) (Albert et al. 2009;Ashley et al. 2010b;Neumann et al. 2009), Cyperaceae morphotypes (Honaine et al. 2006;Ollendorf 1992;Piperno 2006;Strömberg 2004), while the non-diagnostic types (trichomes, bulliforms, elongates) followed (Albert and Weiner 2001;Mercader et al. 2009;Neumann et al. 2009;Piperno 2006;Runge 1999;Strömberg 2004) (see Table 1). ...
... • Parallelepipedal bulliform cells. Madella et al. 2005;Neumann et al. 2009;Novello et al., 2012. Palm trees ...
... Similarly, the occurrence of plateaued saddle-like morphotypes ( Fig. 9: 18, 26), which are today produced in abundance in the genus Phragmites (Piperno and Pearsall, 1998), may point to the presence of C 3 PACMADs in the Arundinoideae. However, it cannot be ruled out that they instead derive from Chloridoideae as plateaued saddle-like GSSCP have been reported from a few species within this subfamily (Neumann et al., 2017;Novello et al., 2012). Moreover, the occurrences of various bilobate and cross types typical of various PACMAD grasses ( Fig. 9: 21 , 27, 28, 29) likely indicate the presence of the Panicoideae subfamily at Mush. ...
Article
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Miocene paleoecology of East Africa has implications for human origins and understanding the vicariant legacy forests found today on either side of the East African Rift. Fossil leaves preserved in 21.73 million year old lacustrine sediments from the Mush Valley, Ethiopia, provide a unique opportunity to investigate forest composition and dominance-diversity patterns at an ecological scale. We classified and analyzed 2427 leaves in total from two to three quarries within each of six stratigraphic levels, spanning 7 m of section; we estimate each quarry census represents one to three centuries, and 50–60 kyrs separate the oldest and youngest levels. Pollen, phytolith, and compound-specific organic geochemical data were also collected in a detailed stratigraphic context to provide independent, integrated lines of evidence for landscape evolution and lacustrine paleoecology of the system that preserves the macrofossils. Forty-nine leaf morphotypes were documented, and Legume 1 dominated all samples. Nonmetric multidimensional scaling, Jaccard similarity analyses, and diversity and evenness indices demonstrate a degree of change comparable to community ecology dynamics, likely illustrating a dynamic stable state in forest vegetation surrounding the lake. Taxonomic assessments of leaves, phytoliths, and pollen are consistent with a closed canopy forest with limited palm diversity. A high abundance of des-A ring triterpenoid molecules (diagenetic products formed by microbial degradation under anoxic conditions) and very negative δ¹³C values (<−45‰) of several hopanoid compounds point to anoxic conditions at the lake bottom, consistent with exquisite fossil preservation. The proportion of mid-chain n-alkanes is low, signifying relatively few submerged plants, but increases up-section, which signals shallowing of the paleolake. The Mush Valley locality is unique in Africa with regard to its very early Miocene age and the abundance and quality of organic remains. This densely forested landscape in an upland volcanic region of the Ethiopian Plateau showed resilience amid volcanic eruptions and had botanical affinities with species found today in West, Central, and eastern Africa.
... Trapezoid morphotypes are also known from Panicoideae from other studies (Dickau et al. 2013;MorcoteRíos et al. 2015). Further research is required to investigate whether this type in the studied species also includes rondels (also known from Panicoideae: Barboni & Bremond 2009;Novello et al. 2012;Neumann et al. 2017). ...
Chapter
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The last decades have seen a steep rise in attention in Eurasian archaeology for the millets Panicum miliaceum and Setaria italica. While various identification criteria are available for finds of these taxa in the archaeological record, these mostly concern remains of the flowering part of the plant. Methods to differentiate other plant remains are scarce. To make a contribution towards filling this gap, this study aims to explore the variation of phytolith short cells in leaves of P. miliaceum and S. italica. The study included five modern-day populations of each species, two plants per population, two leaves per plant, and two samples per leaf, of which material was prepared by dry-ashing. Six categories of short cells were distinguished: bilobates, complex bilobates, intercostal morphotype phytoliths, crosses, polylobates and trapezoids. Statistical analyses show that the percentage of these short cell categories differs significantly between the two studied taxa, and between populations. While the study of the morphotypes will benefit from more detailed study, these results provide a direction for the development of new identification criteria.
... Specifically, phytolith analysis has been widely used in paleovegetation reconstructions, such as monitoring shifts in forest-grassland boundaries, vegetation succession, and changes in alpine timberlines (Barboni et al., 2007;Ákos, 2013;Coe et al., 2013;Dickau et al., 2013;Song et al., 2016;Li et al., 2017;Novello et al., 2017). However, it has been observed that soil phytoliths are subject to preservation bias, and they can be dissolved from archaeological and sedimentary records under alkaline conditions, or due to mechanical abrasion, and partially dissolved phytoliths will more easily break into fragments (Fraysse et al., 2009;Tsartsidou et al., 2009;Cabanes et al., 2011;Novello et al., 2012;Albert et al., 2015;Prentice and Webb, 2016). In addition, under the influences of wind, surface runoff, and human activity, soil phytoliths can be horizontally migrated (Wallis, 2001;Farmer et al., 2005;Esteban et al., 2017;Bremond et al., 2017), and phytoliths maybe also translocated beneath the soil surface due to various taphonomic events (Osterrieth et al., 2009;Golyeva and Svirida, 2017). ...
Article
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Phytoliths are a reliable paleovegetation proxy and have made an important contribution to paleoclimatic studies. However, little is known about the depositional processes affecting soil phytoliths, which limits their use for paleoclimate and paleovegetation reconstructions. Here, we present the results of a study of the vertical translocation characteristics of phytoliths in 40 natural soil profiles in Northeast China. The results show that phytolith concentration decreases within the humic horizon of the soil profiles and that ∼22% of the phytoliths are translocated below the surface of the studied soils. In addition, we find that the translocation rate of phytoliths varies markedly with phytolith type and that phytolith size and aspect ratio also have a significant effect. Phytoliths with length >30 μm and with aspect ratio >2 and those with length <20 μm and aspect ratio <2 are preferentially translocated compared to those with length >25 μm and aspect ratio <2. Our results demonstrate that differential translocation of phytoliths within soil profiles should be considered when using soil phytoliths for paleoclimate and paleovegetation reconstruction.
... While both fields use both methods, most sedge studies that analyze phytolith in situ have come from botanists that seek to resolve taxonomic relationships in Cyperaceae while those that extract phytoliths from sedges (ex situ studies) have come from paleobotanists, paleoecologists and archeologists who create modern references to aid the identification of sedges in paleoflora and reconstruction of paleovegetation (Piperno, 1989;Ollendorf, 1992;Bamford et al., 2006;Fernández Honaine et al., 2009;Novello et al., 2012;Watling and Iriarte, 2013). For purposes of the discussion, we separate the two fields by referring to the former as botanical studies and the latter as paleobotanical studies. ...
Article
This paper comprises two complementary parts. Firstly, phytolith morphology results from 17 species in 8 genera (Cyperus, Eleocharis, Fuirena, “Mariscus,” “Pycreus,” “Schoenoxiphium,” Scirpoides and Scleria) that were drawn from phytolith analysis of 36 sedge species from 13 genera are presented for their importance in the taxonomically problematic Cyperaceae. Secondly, we provide a synthesis aimed at bridging the current disconnect between phytolith analyses in paleobotanical studies and botanical studies which also seem to recognize plant silica differently. We found that results which were thought to be novel for paleobotanical studies have already been documented by taxonomists. To this end, commonly used terms such as “Cyperus/Kyllinga-type” and “Scirpus-type” in paleobotanical studies are not consistent with sedge taxonomy and need to be revised to adapt to new sedge classifications. We present supporting phytolith morphology evidence. We report likely the first known evidence of the presence of the Carex-type phytolith morphotype in the African genus “Schoenoxiphium.” Among others, our phytolith data support the generic classification of Scleria and provides tentative support for the recent suggested close relationship between Fuirena and Eleocharis by molecular studies. Although this study is limited in scope and the fact that the presence of the same unique morphotype in different taxa does not necessarily imply that they are closely related since they may exhibit homoplasy, our data are a preliminary step on how phytolith morphology may contribute to understanding relationships in Cyperaceae, a character that has long been used by taxonomists.
... La identificació i caracterització del conjunt de fitòlits es va fer a partir de la seva comparació amb els resultats de la nostra col·lecció de referència de plantes i sòls moderns (Esteban, 2016;, 2017b, 2017c), així com amb estudis previs de la zona de Sud-àfrica (Rossouw, 2009;Cordova i Scott, 2010;Cordova, 2013;Novello [et al.], 2018;Murungi, 2017), altres regions geogràfiques (Albert i Weiner, 2001;Bamford [et al.], 2006;Tsartsidou [et al.], 2007;Mercader [et al.], 2009;Novello [et al.], 2012;Collura i Neumann, 2017;Albert [et al.], 2016 -disponible a www.phytcore.org) i literatura estàndard (Mulholland i Rapp, 1992;Piperno, 1988Piperno, , 2006Twiss [et al.], 1969). ...
Article
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A través de l’estudi de fitòlits (microrestes minerals d’origen vegetal)| la nostra investigació ha detectat diferents patrons i estratègies d’explotació de recursos vegetals per part de poblacions d’humans moderns que van habitar a la costa sud de Sud-àfrica| on es localitza la vegetació extratropical de més diversitat i endemisme| la Gran Regió Floral Capense| durant l’anomenada Middle Stone Age africana| i que de ben segur que va influenciar en el desenvolupament d’un comportament humà modern.
... In paleoecological studies, phytolith assemblages (phytolith descriptions at species level include all morphotypes and their relative frequency, which together characterize specific phytolith assemblages) are used as ancient vegetation markers, taking advantage of the high quantity of phytoliths (more specifically, grass silica short cells -GSSCs) produced by grasses and the different morphotypes produced in different grass families, which can be used to infer ancient ecological conditions (Twiss, 1992). For example, Novello et al. (2012) performed analyses in 37 species in Lake Chad to identify the phytolith signal for aquatic, mesophytic, and xerophytic grasses, distinguishing aquatic vegetation zones from non-aquatic grasslands and woodlands, aiming at reconstructing hominine paleoenvironments in the area. ...
Article
Phytoliths are silica casts of plant cells, created within and between living tissues across almost all plant clades. Because they are abundant, durable and distinctive, phytoliths are used to deduce historic vegetation patterns and human uses across the fields of archeology, paleoethnobotany, paleoecology, and historical ecology, particularly at sites where preservation of larger plant-derived samples is poor. Nonetheless, phytolith research has recently contributed to advances in biogeochemical cycling and carbon sequestration. Although much progress has been made over the past few decades, some basic methodological concerns in phytolith systematics and Si cycling still hamper the overall development of this emerging field of science. Here, we first review basic scenarios of phytolith studies across different disciplines of science and then advocate interdisciplinary phytolith research to overcome the challenges of phytolith systematics, inform the representation of Si and C cycling in biogeochemical models, and improve the utility of phytoliths as proxies in archeology and paleontology.
... Low DWT values indicate humid conditions. During 7,500e3,000 cal yr BP, Pooideae reached a minimum and xeromorphic-adapted types-bulliform cells (Novello et al., 2012) reached maximum values, suggesting that warm-dry conditions occurred in the peatland during the mid-Holocene. The age-depth model indicated that the regional sedimentation rate had a declining trend since 7,500 cal yr BP, which might be influenced by the dry conditions and slightly decreased Asian monsoon (Fig. 2). ...
Article
Quantitative reconstructions of the depth to water table (DWT) of ombrotrophic (rain-fed) peatlands are important for understanding the palaeohydrological responses of peatlands to past climate changes. This understanding can provide insights into projecting peatlands future variability and evolution. However, the postglacial DWT reconstruction of peatlands in China is challenging due to complications of the atmospheric circulation system, the scarcity of hydrological proxies, and the site-specific nature of hydrological signals. Here we present a postglacial quantitative DWT reconstruction based on the analysis of fossil phytoliths from the Dajiuhu Peatland, central China. The reconstructions were based on a phytolith-DWT calibration model using a weighted averaging partial least-squares regression analysis of peatland topsoil calibration datasets. Three shallow DWT (wet) periods at 13,000–11,500 cal yr BP, 9,600–7,500 cal yr BP, and 3,000 cal yr BP-present, and two extended deep DWT (dry) periods at 11,500–9600 cal yr BP and at 7,500–3,000 cal yr BP are found based on the cluster analysis of phytolith assemblages and reconstructed DWT changes. These five documented hydrological periods are consistent with regional precipitation reconstructions from independent records in the middle Yangtze Valley (MYV). We interpret these changes as mostly reflecting changes in ENSO at various timescales. An amplified ENSO forced a southward Western Pacific Subtropical High and caused the persistence of the Meiyu Front in the mid-lower Yangtze Valley, consistent with the intense rainfall periods in our study region. Our results indicate that phytolith records are a reliable and sensitive proxy for the calibration of water table models and the quantitatively palaeo-DWT reconstruction of peatlands and reveal a remarkable link between the local hydrological variations and the coupled atmospheric-oceanic circulation, which is significant for the prediction of future hydrological changes in the Asian monsoon region under the background of global warming.
... Wetlands exhibit a phytolith signal indistinguishable from that of grasslands most likely also because our dataset was restricted to main phytolith categories. Novello et al. (2012) showed that distinguishing trapeziform grass silica short cell phytoliths within the bilobate, cross, and saddle categories could improve the identification of wetland grasses. Unfortunately, such distinction was not considered by all the authors who contributed to the African phytolith dataset presented here. ...
Article
Hominins evolved in Africa during a period of overall regional cooling, drying and increasingly variable climate. Despite prevailing regional aridity since the mid-Miocene, data show that early hominins Sahelanthropus tchadensis, Orrorin tugenensis, and Ardipithecus ramidus lived in environments made of mosaics of grasslands, mixed grasslands, woodlands, and forests, where wooded habitats were maintained by edaphic rather than regional (climatic) humidity. Groundwater systems (springs, seeps, shallow aquifers) and surface water (rivers, lakes), locally create wetter and more wooded environments in addition to that supported by precipitation alone. However, edaphically sustained woodlands are rare to missing in most published paleoeclogical interpretations of hominin archeological sites. To explore the importance of groundwater to the record of hominins in Africa, we provide newly acquired field data from spring sites in the Awash Valley, Ethiopia, and Lake Eyasi-Lake Manyara region, Tanzania, and re-evaluate published data from the Ardipithecus-bearing Aramis Member, Ethiopia. Results show that 1) in arid Eastern Africa, a wide variety of microhabitats such as groundwater-fed wetlands, Hyphaene palm woodlands, Phoenix reclinata palm woodlands, and structurally complex and species-rich forest patches exist due to local variability of geologic, topographic and hydrologic conditions. 2) These microhabitats carry some characteristic pollen and phytolith signals, that may be easily masked by the signal of surrounding grass-dominated shrublands and grasslands. 3) The Aramis Member (Awash Valley, Ethiopia), which is to date, the best documented paleo-groundwater ecosystem, is not a riparian habitat. It is one of > 50 examples (within 22 geographically distinct areas) in Africa and the Middle East where evidence of groundwater systems co-exist with hominin and/or archeological remains. Springs are commonly localized features of limited area within a landscape, but provide ecological continuity through time and diverse microhabitats, some of which may be densely forested. At the local scale, springs create microclimates, distinctive vegetation, and increase soil nutrients, species richness, structural complexity, and provide habitat for animals. At the landscape scale, they represent hydro-refugia favoring increased connectivity among animals and allowing migrations during dry periods. We conclude that in the East African Rift where low, highly seasonal rainfall and high evaporative demand limit vegetation growth in many areas, groundwater-fed zones create diverse microhabitats and play a major role in ecosystem functioning. It is likely that, within a context of increasing aridity and expansion of grass-dominated open habitats during the Mio-Pliocene, early hominins and many other animals viewed edaphically sustained woodlands as attractive habitats.
... Five phytolith indices were used in this study including the water stress (Fs) index (after Bremond et al., 2005b); two grass phytolith indices, the climatic (Ic) (Barboni et al., 2007;Bremond et al., 2008;Twiss, 1992) and the aridity (Iph) (Alexandre et al., 1997;Diester-Haass et al., 1973;Novello et al., 2012) indices; the tree cover density (D/Pº) index ( (Bremond et al., 2005a); and the fynbos (Fy) index (Esteban et al., 2017a). ...
Article
The Cape south coast presents some of the world's most significant early modern human sites preserving evidence for complex human behaviour during the Middle Stone Age (MSA), and it is centrally located in the megadiverse Greater Cape Floristic Region. The extinct Palaeo-Agulhas Plain (PAP) once abutted this region, forming an important habitat for the subsistence strategies of past hunter-gatherers during the MSA. Here, we use phytoliths — amorphous silica particles that formed in cells of plants — extracted from archaeological deposits of two sites at Pinnacle Point (PP; cave 13B [PP13B] and site 5–6 [PP5-6]) to investigate the interactions between environments and hunter-gatherer foraging strategies along the Cape south coast during Marine Isotope Stage (MIS) 6 to MIS 3. To do this, we developed an analytical approach built on a modern plant and soil reference collection for using phytoliths from archaeological deposits for palaeoenvironmental reconstructions. In the latter phases of MIS 6, phytoliths indicate shrubby vegetation, possibly limestone fynbos, which might have occurred in inland landscapes, and this was the area preferred for plant foraging practices by the inhabitants of PP13B. During MIS 4, phytoliths at PP5-6 indicate the presence thicket and riparian vegetation on the rocky cliffs and the exposed PAP, along with some type of fynbos vegetation above the actual coastal cliffs. During interglacials MIS 5(c-e) and MIS 3 when the PAP was less exposed, the phytolith record points towards a mosaic of habitats with fynbos and thicket/forest, but also a constant presence of vegetation with high grass content dominated by a mix of both C 3 and C 4 species. Our data suggests a continuous inland regional mosaic of habitats with fynbos, thicket/forest and grassy vegetation that persisted during the glacial-interglacial periods. The changes observed in the phytolith record might be indicative of changes in plant foraging preferences along with slight vegetation movements in accordance with climate changes and sea level fluctuations.
... However, the full potential of this new source of data on grass distribution through time has not been realized due to the lack of a GSSCP classification methodology that is objective, repeatable and accurate while allowing for the estimation of classification error rates. Current methods for classifying GSSCP include traditional approaches, which entail visual comparison with a reference set (Twiss et al., 1969;Piperno, 1988;Mulholland & Rapp 1992;Gallego & Distel, 2004;Novello et al., 2012;Neumann et al., 2019) and, more recently, quantitative approaches using 2D outlines, shape descriptors and/or linear measurements (Liu et al., 2016;Cai & Ge, 2017). Although good classification results have been achieved using these methods, each has limitations. ...
Article
Rationale: Fossil grass silica short cell phytoliths (GSSCP) have been used to reconstruct the biogeography of Poaceae, untangle crop domestication history, and detect past vegetation shifts. These inferences depend on accurately identifying the clade to which the fossils belong. Patterns of GSSCP shape and size variation across the family have not been established and current classification methods are subjective or based on a two-dimensional view that ignores important 3D shape variation. Methods: Focusing on Poaceae subfamilies Anomochlooideae, Pharoideae, Pueliodieae, Bambusoideae, and Oryzoideae we observed in-situ GSSCP to establish their orientation and imaged isolated GSSCP using confocal microscopy to produce three-dimensional models. 3D geometric morphometrics was used to analyze GSSCP shape and size. Classification models were applied to GSSCP from Eocene sediments from Nebraska, USA and Anatolia, Turkey. Key Results: There were significant shape differences between nearly all recognized GSSCP morphotypes and between clades with shared morphotypes. Most of the Eocene GSSCP were classified as woody bamboos with some distinctive Nebraska GSSCP classified as herbaceous bamboos. Main conclusion: 3D morphometrics hold great promise for GSSCP classification. It accounts for the complete GSSCP shape, automates size measurements, and accommodates the complete range of morphotypes within a single analytical framework. Key Words: Microfossils, phytoliths, Poaceae, machine learning, paleobotany, paleoecology, archaeology.
... Fragmentation et dissolution affectent surtout les formes présentant des zones de fragilité ou les ornementations les plus délicates [130,133,136,144], ainsi que les particules les plus faiblement silicifiées ou celles dont l'opale contient une proportion importante d'impuretés [130,136]. Les phytolithes issus du bois des dicotylédones, produits en quantités réduites, sont parmi les plus résistants [127,136] avec les cellules bulliformes foliaires et les cellules allongées lisses des graminées [133,136] ; les cellules courtes des graminées et les phytolithes de palmier, produits au contraire grandes quantités, semblent plus sensibles aux agents taphonomiques, alors que les formes produites par les cypéracées, les cellules longues ornementées et les papilles issues des glumes des graminées sont les plus facilement altérées [133,136,[144][145][146]. Dans les conditions les plus courantes, le feu n'a que peu d'impact sur les phytolithes dont la morphologie reste intacte jusqu'à 800°C [147]. ...
... (1) Grass silica short cell phytoliths (GSSC). Grass silica short cells (GSSC) are phytolith morphologies characteristic of Poaceae (Aleman et al., 2014;Novello et al., 2012). Although some phytolith morphologies cannot indicate the species of a plant, phytoliths from grass silica short cells are generally distinguishable at the subfamily level, and thus have a certain level of taxonomic significance . ...
Article
Microcharcoal in soils and sediments is an ideal proxy for studying fire activity. Phytoliths in soils and sediments record the environmental conditions in which the phytoliths were formed by plants. However, our understanding of the relationships between fire activity, plant communities, and the preservation of microcharcoal and phytoliths in soils and sediments remains limited. In this study, we collected soils and sediments across a gradient of burned and unburned forest in southwest China, and analyzed the microcharcoals and phytoliths in these samples to understand the relationships between these microfossils (ratios of microcharcoal to phytolith particles (Ch/Ph)), fire activity, and vegetation cover. We show that the Ch/Ph ratios recorded fire activity and were significantly different across the gradient of burned to unburned forest. The highest and lowest ratios (0.25 and 0.01) were found in burned forest (Bs1) and unburned forest samples (Us2), respectively. The ratios gradually decreased with increasing distance from the fire. This study suggests the ratio (Ch/Ph) to be a useful proxy for studying fire activity and/or history using soils and sediments.
... Bulliform cells are involved in rolling and unrolling of the leaves, a mechanism that protects the leaf from overheating and dehydration by reducing the transpiring surface and minimizing light exposure and water transpiration in unfavourable conditions (Clarke, 1986;Moulia, 1994). Studies on plant samples showed that abundance of bulliform phytoliths sensitively responds to the plant leaves dehydration induced by aridity (Issaharou-Matchi et al., 2016;Sangster & Parry, 1969, 1971 or excessive evaporation (Novello et al., 2012), but palaeo-climate responses and impacts on peatland water loss of bulliform cells remain unclear. ...
Article
Peatland ecosystem processes are strongly influenced by hydrology linked to climate change. However, how transpiration, as major water loss pathway in closed peatland, responds to climate change and then regulates ecosystem water balance that remains poorly understood. Here, we reported an 18,000-year fossil phytolith record from an herbaceous community-dominated mountain peatland in central China to reconstruct climate changes and vegetation evolution and reveal the interactions between regional climate changes and peatland ecosystem. The abundance of bulliform phytoliths—a silicified type of cells that regulate the movements of plant leaves to reduce light exposure and transpiration rate—shows close correlations with the Holocene climate variations with higher bulliform abundance in response to warm-dry climate (11,500-9,600 cal yr BP; 7,500-3,000 cal yr BP) and lower values associated with cold-wet climate (13,000-11,500 cal yr BP; 3,000 cal yr BP-present). Spectral analysis reveals that bulliform abundance and reconstructed climate vary with a major ∼1000-year periodicity during the Holocene, suggesting a possible causal relationship to solar activity. A high bulliform abundance and warm-dry climate correspond with enhanced solar activity, and vice versa. We interpret that the resultant leaf water deficit resulted from greater light interception, high temperature and drought promoted the production of bulliform cells to fold leaf for water conservation, which is an effective protective mechanism of peatland grasses from the environmental stress. These results expand our understanding of how grass-dominated peatland plant water regulation recorded by bulliform phytoliths responds to solar radiation and local hydroclimate during geological period.
... Pooideae is the largest Poaceae subfamily, with almost 4000 species, most of them adapted to open areas experiencing frost (Bouchenak-Khelladdi et al., 2010;Edwards and Smith, 2010;Soreng et al., 2017;Schubert et al., 2019a, b). While considerable effort has been made to refine the categorization of phytolith shape variation within subfamilies Panicoideae, Chloridoideae, Bambusoideae and Oryzoideae (Lu and Liu 2003;Fahmy, 2008;Novello et al., 2012;Cai and Ge, 2017;Neumann et al., 2017;Gallaher et al., 2020), phytolith shape variation in Pooideae is largely unexplored, with only a handful of studies touching on this area, such as investigations of Stipatype phytoliths (Mullholand, 1989;Gallego and Distel, 2004;Silantyeva et al., 2018). ...
Article
Background and aims Grass silica short cell (GSSC) phytoliths appear to be the most reliable source of fossil evidence for tracking the evolutionary history and paleoecology of grasses. In recent years, modern techniques that quantitatively assess phytolith shape variation have widened opportunities for the classification of grass fossil phytoliths. However, phylogenetic, ecological and intraindividual variability patterns in phytolith shape remain largely unexplored. Methods The full range of intraindividual phytolith shape variation (3650 2D outlines) from 73 extant grass species, 48 genera, 18 tribes, and 8 subfamilies (particularly Pooideae) was analysed using geometric morphometric analysis based on semilandmarks spanning phytolith outlines. Key results 2D phytolith shape is mainly driven by deep-time diversification of grass subfamilies. There is distinct phytolith shape variation in early-diverging lineages of Pooideae (Meliceae, Stipeae). The amount of intraindividual variation in phytolith shape varies among species resulting in a remarkable pattern across grass phylogeny. Conclusions The phylogenetic pattern in phytolith shape was successfully revealed by applying geometric morphometrics to 2D phytolith shape outlines, strengthening the potential of phytoliths to track the evolutionary history and paleoecology of grasses. Geometric morphometrics of 2D phytolith shape is an excellent tool for analysis requiring large numbers of phytolith outlines, making it useful for quantitative palaeoecological reconstruction.
... Among paleobotanical sources of evidence, phytoliths stand out for providing information that is relevant for reconstructing the spread of open, grass-dominated habitats (Strömberg et al., 2018). Specifically, phytolith assemblages have been shown to reliably reflect the composition and dominance of grass communities in past vegetation on local to regional scales, as demonstrated by a body of modern analog work for example, Barboni et al. (2007); Iriarte and Paz (2009);Novello et al. (2012); Strömberg (2020, 2021). We therefore limited our compilation of paleovegetation data to phytolith studies and use these to define the OHT. ...
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The shift from denser forests to open, grass‐dominated vegetation in west‐central North America between 26 and 15 million years ago is a major ecological transition with no clear driving force. This open habitat transition (OHT) is considered by some to be evidence for drier summers, more seasonal precipitation, or a cooler climate, but others have proposed that wetter conditions and/or warming initiated the OHT. Here, we use published (n = 2,065) and new (n = 173) oxygen isotope measurements (δ¹⁸O) in authigenic clays and soil carbonates to test the hypothesis that the OHT is linked to increasing wintertime aridity. Oxygen isotope ratios in meteoric water (δ¹⁸Op) vary seasonally, and clays and carbonates often form at different times of the year. Therefore, a change in precipitation seasonality can be recorded differently in each mineral. We find that oxygen isotope ratios of clay minerals increase across the OHT while carbonate oxygen isotope ratios show no change or decrease. This result cannot be explained solely by changes in global temperature or a shift to drier summers. Instead, it is consistent with a decrease in winter precipitation that increases annual mean δ¹⁸Op (and clay δ¹⁸O) but has a smaller or negligible effect on soil carbonates that primarily form in warmer months. We suggest that forest communities in west‐central North America were adapted to a wet‐winter precipitation regime for most of the Cenozoic, and they subsequently struggled to meet water demands when winters became drier, resulting in the observed open habitat expansion.
... Production of silica in plants is highly dependent on (1) the nature of plant tissues, e.g., seeds, husks and leaves (Li et al., 2013); (2) ecology, e.g., drought and water availability and evapotranspiration (Hattori et al., 2005;Piperno 2006); and (3) phylogenetic identity of the plant (Hodson et al., 2005;Piperno 2006). Studies have also suggested that silica intake and precipitation in the form of phytoliths increases substantially in Poaceae growing under arid/semiarid ecological conditions (Epstein, 1994;Bremond et al., 2005;Novello, et al., 2012;Issaharou-Matchi et al., 2016). Results from such studies thus usually document a general trend in the vegetation communities among which the Poaceae are located, and the predominant environmental conditions (soil, water, and temperature) that preside over their existence. ...
Article
Investigating the taphonomy of phytoliths at open-air archaeological sites is essential for reconstructing past land cover and assessing the plant resources available to hominins, particularly when other indicators (e.g., pollen) are scarce. Here we analyse phytolith abundance and diversity encountered in distinct ‘reservoirs’ at and around the Palaeolithic site of Attirampakkam, South India: (1) in the present-day vegetation (database of 134 species), generating on that basis a fine classification of species-specific phytolith morphotypes; (2) in the topsoil (surface); and (3) at greater soil depths above the archaeological layers (subsurface). We then compare the data to results previously obtained from the deeper underlying archaeological layers. Comparison of the assemblages retrieved from the different reservoirs shows that morphotypes most likely to get carried over from the living plants to the oldest fossil specimens were subsets of herbaceous taxa (Poaceae and Cyperaceae) and a few woody monocotyledons (Arecaceae). The high fidelity of these taxa ranks them among the most reliable for conducting palaeoenvironmental studies at this site, and perhaps more widely in southern India. Provided those taxonomically traceable, non-redundant and non-multiple morphotypes are prioritised over herbaceous dicotyledons and most woody taxa, inferences about environmental conditions and changes at the time of hominin occupation during the Pleistocene can be made with a fair margin of confidence.
... phytcore.org; Albert et al. 2016;Bamford et al. 2006;Barboni et al. 1999;Barboni and Bremond 2009;Collura and Neumann 2017;Mercader et al. 2009;Novello et al. 2012). Additionally, standard literature (Bozarth 1992;Mulholland and Rapp Jr. 1992;Piperno 2006;Twiss et al. 1969) was accessed. ...
Article
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Umhlatuzana rockshelter has an occupation sequence spanning the last 70,000 years. It is one of the few sites with deposits covering the Middle to Later Stone Age transition (~40,000–30,000 years BP) in southern Africa. Comprehending the site’s depositional history and occupation sequence is thus important for the broader understanding of the development of Homo sapiens’ behavior. The rockshelter was first excavated in the 1980s by Jonathan Kaplan. He suggested that the integrity of the late Middle Stone Age and Later Stone Age sediments was compromised by large-scale sediment movement. In 2018, we initiated a high-resolution geoarchaeological study of the site to clarify the site formation processes. Here, we present the results of the excavation and propose a revised stratigraphic division of the Pleistocene sequence based on field observations, sedimentological (particle size) analyses, and cluster analysis. The taphonomy of the site is assessed through phytolith and geochemical (pH, loss on ignition, stable carbon isotope) analyses. The results indicate a consistent sedimentological environment characterized by in situ weathering. The analysis of the piece-plotted finds demonstrates semihorizontal layering of archaeologically dense zones and more sterile ones. There was no indication of large-scale postdepositional sediment movement. We show that the low-density archaeological horizons in the upper part of the Pleistocene sequence are best explained by the changing patterns of sedimentation rate.
... Because most samples had low phytolith abundances, phytoliths >5 m in diameter in each sample were counted and classified with aim of attaining a minimum of 200 grass short silica cells (GSSCs) to acquire a statistically robust dataset. Identification and classification of phytoliths largely followed the International Code of Phytoliths Nomenclature (51) with refined GSSCs classification based on (52)(53)(54) and with further consultation of other published studies (28,50,(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66)(67)(68)(69)(70). Phytolith data interpretation was based on two approaches. ...
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Although climate change is considered to have been a large-scale driver of African human evolution, landscape scale shifts in ecological resources that may have shaped novel hominin adaptations are rarely investigated. We use well-dated, high-resolution, drill-core datasets to understand ecological dynamics associated with a major adaptive transition in the archeological record ~24 km from the coring site. Outcrops preserve evidence of the replacement of Acheulean by Middle Stone Age (MSA) technological, cognitive, and social innovations between 500 and 300 thousand years (ka) ago, contemporaneous with large-scale taxonomic and adaptive turnover in mammal herbivores. Beginning ~400 ka ago, tectonic, hydrological, and ecological changes combined to disrupt a relatively stable resource base, prompting fluctuations of increasing magnitude in freshwater availability, grassland communities, and woody plant cover. Interaction of these factors offers a resource-oriented hypothesis for the evolutionary success of MSA adaptations, which likely contributed to the ecological flexibility typical of Homo sapiens foragers.
... Moreover, phytoliths are especially useful in open environments as they help to determine the composition of the grass cover layer. Numerous studies conducted on African modern analogues have demonstrated the possibility of distinguishing several grass sub-families and thus to extract information on palaeoecological conditions in fossil assemblages [39][40][41][42][43]. Methods of phytolith extraction and analysis are those in Neumann et al. (2009) [37] and Garnier et al. (2013) [38]. ...
Article
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The end of the Palaeolithic represents one of the least-known periods in the history of western Africa, both in terms of its chronology and the identification of cultural assemblages entities based on the typo-technical analyses of its industries. In this context, the site of Fatandi V offers new data to discuss the cultural pattern during the Late Stone Age in western Africa. Stratigraphic, taphonomical and sedimentological analyses show the succession of three sedimentary units. Several concentrations with rich lithic material were recognized. An in situ occupation, composed of bladelets, segments, and bladelet and flake cores, is confirmed while others concentrations of lithic materials have been more or less disturbed by erosion and pedogenic post-depositional processes. The sequence is well-dated from 12 convergent OSL dates. Thanks to the dating of the stratigraphic units and an OSL date from the layer (11,300-9,200 BCE [13.3-11.2 ka at 68%, 14.3-10.3 ka at 95%]), the artefacts are dated to the end of Pleistocene or Early Holocene. Palaeoenvironmental data suggest that the settlement took place within a mosaic environment and more precisely at the transition between the open landscape of savanna on the glacis and the plateau, and the increasingly densely-wooded alluvial corridor. These humid areas must have been particularly attractive during the dry season by virtue of their rich resources (raw materials, water, trees, and bushes). The Fatandi V site constitutes the first stratified site of the Pleistocene/Holocene boundary in Senegal with both precise geochronological and palaeoenvironmental data. It complements perfectly the data already obtained in Mali and in the rest of western Africa, and thus constitutes a reference point for this period. In any case, the assemblage of Fatandi V, with its bladelets and segments and in the absence of ceramics and grinding material, fits with a cultural group using exclusively geometric armatures which strongly PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.
... This agrees with the results obtained by Cabanes et al. (2011), where they analyzed the degradation of these morphotypes in wheat and found that modern inflorescence wheat phytolith assemblages were more unstable than those from leaves/stems. These results reinforce those findings that indicate that the absence of some morphotypes in fossil records may be related to dissolution or degradation process more than to the absence of the organ or the species (Iriarte and Paz, 2009;Novello et al., 2012;De Rito et al., 2018). ...
Article
Phytoliths represent an important fraction of soil's components and they are incorporated through different agents. One of the sources of phytoliths to soils and sediments is dung. In particular, in agroecosystems, the incorporation of phytoliths from dung may be of importance, since pastures (grasses) belong to one of the highest producer families. The main objective of this work was to compare the content and state of phytoliths in rumen and dung samples from cows in relation to the phytoliths produced in the forage plants eaten. Secondly, we analyzed if phytolith assemblages differed between dung collected in different pastures in Pampean region, Argentina. Phytoliths from rumen and dung samples from five fistulated cows were compared with the main forage species eaten (Festuca arundinacea). Also, dung of three different pastures (two naturals and one controlled) were compared. Phytoliths of plants and dung were extracted by a calcination technique, while rumen samples were treated with hydrogen peroxide. In rumen and dung samples, the morphologies derived from Festuca arundinacea plants had different stages of degradation: the acute bulbosus and the papillate were the most degraded, while the rondels remained with little wear. A high percentage of phytoliths remained unidentified, probably due to their degradation state. Through phytolith morphometric analysis, it was possible to identify that the principal organ eaten by cows was the inflorescence. The dung belonging from different pastures was differentiated by their phytolith content, although the unidentified morphotypes predominated. Dung allow the incorporation of new morphologies and a high amount of degraded phytoliths to soils, modifying its permanent stock of phytoliths.
... The smallest sized debris, which is usually abundant in knapping activities (e.g., de la Torre et al., 2018), was likely washed away by water activity or disaggregated due to immersion in water over a long duration as the groundwater at Ravin Blanc I has often been high. Nevertheless, despite these wet and carbonated conditions, the site revealed an exceptional preservation of the phytoliths, especially regarding the high proportion of sedge morphotypes which are usually not well preserved in soils Novello et al., 2012). Moreover, Cabanes et al. (2011) suggest that the best indication of a wellpreserved assemblage is the presence of abundant hairs, papillae and decorated long cells, which are rather well represented in the Ravin Blanc I samples. ...
Article
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The Ravin Blanc I archaeological occurrence, dated to MIS 5, provides unprecedented data on the Middle Stone Age (MSA) of West Africa since well-contextualized archaeological sites pre-dating MIS 4/3 are extremely rare for this region. The combined approach on geomorphology, phytolith analysis, and OSL date estimations offers a solid framework for the MSA industry comprised in the Ravin Blanc I sedimentary sequence. The paleoenvironmental reconstruction further emphasizes on the local effects of the global increase in moisture characterizing the beginning of the Upper Pleistocene as well as the later shift to more arid conditions. The lithic industry, comprised in the lower part of the sequence and dated to MIS 5e, shows core reduction sequences among which Levallois methods are minor, as well as an original tool-kit composition, among which pieces with single wide abrupt notches, side-scrapers made by inverse retouch, and a few large crudely shaped bifacial tools. The Ravin Blanc I assemblage has neither a chronologically equivalent site to serve comparisons nor a clear techno-typological correspondent in West Africa. However, the industry represents an early MSA technology that could either retain influences from the southern West African ‘Sangoan’ or show reminiscences of the preceding local Acheulean. A larger-scale assessment of behavioral dynamics at work at the transition period between the Middle to Upper Pleistocene is discussed in view of integrating this new site to the global perception of this important period in the MSA evolutionary trajectories.
... Other Poaceae phytoliths identified are BULLIFORM FLABELLATE (fan type), and ACUTE BULBOSUS, produced in the leaves of graminoid plants. Bulliforms are specialized large epidermal cells that occur in the upper surface of leaves (adaxial leaf blade) of Poaceae (Metcalfe, 1960), but also in other monocots such as sedges (Andrejko and Cohen, 1984;Novello et al., 2012). They facilitate leaf rolling or folding when plant water availability decreases. ...
Article
For five decades Olduvai Gorge has been a key site to reconstruct and understand the relationship between environmental and landscape conditions and use of affordances by early African hominin populations. Following the first Olduvai Gorge Coring project (OGCP) during 2014, a multiproxy microbiological analysis, which includes phytoliths, pollen, diatoms, sponge spicules and chrysophyte cysts, was undertaken on samples collected from various borehole cores. The aim of the study is to better understand palaeoenvironmental and palaeovegetation conditions and changes through time and their relationship to hominin presence and evolution. This study details the first palaeobotanical and palaeoenvironmental study of Borehole 2A at Olduvai Gorge. It represents the as yet oldest known sedimentary sequence in the Olduvai Basin for a portion of the pre-Bed I Naibor Soit Formation; this is a unit that is not accessible in any natural exposures in Olduvai Gorge, and has only recently been encountered by drilling. Here we present the results from a particularly phytolith-prone portion between ~2.09 Ma and 2.12 Ma. Phytolith results indicate a savannah environment dominated by grasses, where Poaceae were a key component and where the C3 Pooideae grasses were mostly dominant, alternating with C4 grasses. Oscillations between grass subfamilies, C3 Pooideae, C4 Chloridoideae, and C4 Panicoideae to lesser degrees, indicate five substantial climatic shifts, varying between more humid and arid conditions. Associated with phytoliths, freshwater indicators such as diatoms, sponge spicules and chrysophyte cysts were also identified, suggesting the presence of wetlands in the lake catchment area. Pollen is extremely rare in the sediments but when present, comprises fungal spores and Poaceae pollen, thus supporting the wetland and grassland reconstructions, respectively. These results offer for the first time, a whole picture of the palaeovegetation and associated palaeoenvironments for this pre-Bed I period. Together with previous results from other areas and chronological periods, they improve our understanding of the evolution and adaptation of early hominins and their close relationship to the surrounding landscape.
... chloridoid grasses, we did note that saddle short cells are predominately the "squat" or square saddle type typical of chloridoid grasses, not the "trapeziform saddle" or "plateaued saddles" distinctive of Phragmites sp. reeds ( Fig. 4G; Gu et al., 2008;Novello et al., 2012;Ollendorf et al., 1988;Piperno and Pearsall, 1998). Therefore, the chloridoid short cells in dung-rich samples most likely derive from expected sources such as weedy species growing along disturbed agricultural field edges and from wild grasses growing on the hillsides surrounding the Khani Masi plain. ...
Article
Understanding everyday agro-pastoral practice is critical for reconstructing the formation and maintenance of ancient societies. The ancient Near East (Southwest Asia) has one of the longest histories of agro-pastoral practice and one of the richest textual datasets anywhere on the globe. Yet, our knowledge of local, day-to-day agro-pastoral management strategies remains conjectural in many regions of Southwest Asia during the Bronze Age (late 4th–2nd millennium BCE). In this study we used phytoliths, dung spherulites, and Fourier Transform Infrared (FTIR) spectroscopy to identify and examine dung-rich sediments from Khani Masi, a mid-second millennium BCE Kassite site located in the Kurdish Region of Iraq. While micro-remain and geochemical approaches have not yet been widely applied in Mesopotamia (Ancient Iraq), they have the potential to shed light on the production systems supporting its Bronze Age cities, states, and empires. Our aim was to investigate (1) the range of local pastoral management strategies, (2) the degree of integration between agricultural and pastoral practice, and (3) the presence of signals related to the local ecology, seasonality, and environmental change and continuity. Phytolith results indicate that sheep-goat herds were primarily free grazed on wild grasses. The dominance of wild grass inflorescences, a potentially strong seasonality indicator, may suggest transhumant pastoralism. However, further evidence, including occasional foddering with cereal chaff, a diverse range of crop types, and significant accumulation of burnt dung within the site, collectively suggests a closely linked local agro-pastoral subsistence economy. This study provides much-needed empirical botanical data as well as productive insights for future application of phytolith studies in the Mesopotamian region, and sheds new light on agro-pastoral practice in the Zagros foothills during the second millennium BCE Kassite period.
... Phytolith nomenclature followed Madella et al. (2005), with exceptions. Supporting keys from pertinent African regions were consulted (e.g., Runge, 1999;Fahmy, 2008;Albert et al., 2009Albert et al., , 2015aBarboni and Bremond, 2009;Neumann et al., 2009Neumann et al., , 2017Eichhorn et al., 2010;Novello et al., 2012;Collura and Neumann, 2017). It is generally accepted that phytolith-based environmental reconstruction resolves vegetation type, community, and habitat change over time (Strömberg et al., 2018). ...
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The rock shelter site of Mumba in northern Tanzania plays a pivotal role in the overall study of the late Pleistocene archaeology of East Africa with an emphasis on the Middle to Later Stone Age transition. We used phytolith analysis to reconstruct general plant habitat physiognomy around the site from the onset of the late Pleistocene to recent times, tallying 4246 individual phytoliths from 19 archaeological samples. Statistical analysis explored phytolith richness, diversity, dominance, and evenness, along with principal components to compare phytolith distributions over the site's sequence with known plant habitats today. Generally, the phytolith record of Mumba signifies paleoenvironments with analogs in the Somalia-Masai bushland and grassland, as well as Zambezian woodlands.
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The rise of grasses using C4 photosynthesis and dominating grasslands during the latest Cenozoic is one of the most dramatic events in Earth's history. A growing body of geological records adds more details to this process, such as the study of fossil phytoliths. Phytolith data make it possible to track major grass lineages over time, and distinguish which kind of C4 grasses rise to dominate in a particular region. If the environmental niches of this kind of C4 grass are well studied, the corresponding environmental controls and driving mechanisms could be identified. Here, we combine geospatial data and climate data from two public archives to produce a database of ~12 million collections spanning ~6000 species of grasses with corresponding climate data to explore the quantitative relationship between the major grass lineages (subfamilies) and climate at global and regional scales. Our results show that the 10 °C isotherm of mean annual temperature is the transitional boundary of Pooideae and Panicoideae/Chloridoideae distribution in North America and East Asia; the 400 mm isohyet of summer precipitation is the transitional boundary of Panicoideae and Chloridoideae distribution in North America and South Africa. However, the detailed environmental niches of certain grass lineages vary from region to region and are controlled by regional climate, topography and local species. Based on these data, the reanalysis of phytolith data since the Neogene reveals a distinct evolutionary history of grassland ecosystems. The onset of modern like grassland happened in the early Miocene in both North America and East Asia, those original grasslands were most likely dominated by C3 Pooideae with minor Panicoideae (C4) and few Chloridoideae (C4); C4 expansion on both continents was based on substantial heterogeneity in vegetation, with similar aridity in climate as a possible driver, but with different timings and results: the rise of Chloridoideae in North America at 8–5 Ma and the rise of Panicoideae in East Asia at ~11 Ma. We suggest that synchronous changes in Asian monsoon precipitation and temperature are responsible for the rise of Panicoidaeae in East Asia, whereas the combination of warm and semiarid climates is responsible for the rise of Chloridoideae in North America. We emphasize the importance of regional environmental control on the evolution and distribution of the major grass lineages and offer a database that could be used to reconstruct palaeoclimate by phytoliths in different regions.
Article
To assess the impacts of increasing human disturbance, wetland degradation, and biodiversity loss, and to determine the main environmental factors affecting the spatial distribution of phytoliths in Nanjishan Nature Reserve, phytoliths from 17 topsoil samples and a sediment core sample were analyzed. Yellow-brown, silty, and gray-black clays were the main sedimentary constituents, and the total organic carbon content decreased with increasing depth. Lakes Zhanbei, Chang, and Sanniwan were located in an alluvial delta and characterized by intensive human activity and grass communities of Triarrhena lutarioriparia and Zizania latifolia, whereas Lakes Shangbeijia, Beishen, Nanshen and Baisha were characterized by a lower degree of disturbance and grass communities of T. lutarioriparia and Phragmites australis. A total of 11,942 phytoliths (4248 in topsoil and 7694 in core sediment) were isolated from 46 samples and 19 distinct morphological types were identified. Vesicular cells constituted 42%–51% of all samples, short cells 24%–32%, and elongate types 15%–26%. The phytolith assemblages at Lakes Zhanbei, Chang, and Sanniwan were mainly composed of fans, rectangles, points and elongates. While Lake Shangbeijia, Beishen, Nanshen and Baisha were dominated by fans, saddles and elongates. Based on phytolith analysis, we found that the typical communities in the study area were significantly degraded from 1986 to 2003. Sediment cores dated by ²¹⁰Pb showed that the main plant communities were transformed from Carex and T. lutarioriparia to Z. latifolia, T. lutarioriparia and P. australis.
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The Poaceae family produces diagnostic phytoliths commonly called Grass Silica Short Cell Phytoliths (GSSCP), of which shapes and sizes are very distinguishable from those produced by other plant families. Grass Silica Short Cell Phytoliths are usually classified into four main categories: the rondels, bilobates, crosses, and saddles. Among them, the bilobates have in common a general "dumbbell" shape consisting of two lobes inter-connected by a shank. They represent the dominant morphotypes observed in the leaf tissues of many Panicoideae grass species. Besides, they tend to often be related to this subfamily in the fossil record, especially when they occur in large amounts. Several studies based on modern African grasses have however demonstrated that bilobates were also abundantly produced by a few members of the Aristidoideae, Chloridoideae, and Oryzoideae grass subfamilies which, like Panicoideae, are today mainly distributed in tropical low-altitude areas. The relationship between bilobates and Panicoideae is thus not so direct in the tropics. As a result, it can lead to significant misinterpretations when applied to paleoenvironmental and archaeological surveys. This study investigates variations in the size of bilobate phytoliths in 15 African grass species, including eight Panicoideae, three Aristidoideae, two Chloridoideae, and two Oryzoideae, with the intention to explore new alternatives for refining their identification in the past deposits of tropical Africa. Different statistical analyses (Principal Component Analysis, Mann–Whitney tests, decisional trees) applied to the previous dataset allowed testing whether: (i) bilobate length and width significantly vary between grass species; (ii) these variations (if so) have the potential to be used as taxonomical and/or ecological proxies. Our analyses confirm that bilobate length is significant in discriminating dry-adapted Aristidoideae and Chloridoideae species from the other sub-families. In particular, a bilobate base longer than 25 μm is almost exclusively observed for Aristidoideae and Chloridoideae, which is in agreement with previous studies. Although subject to less variations, the length/width of bilobate shanks and the average length of their lobes appear significantly useful to refine grass taxonomical identification and discriminate < 120 cm-high grasses from taller grasses. Yet, it seems that the key towards a robust identification of bilobate phytoliths involves considering the size parameters.
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Grass silica short cell (GSSC) phytoliths appear to be the most reliable source of fossil evidence for tracking the evolutionary history and paleoecology of grasses. In recent years, modern techniques have been used to quantitatively assess phytolith shape variation. This progress has widened opportunities with respect to the classification of grass fossil phytoliths. However, phylogenetic, ecological and intraindividual variability patterns in phytolith shape remain largely unexplored. The full range of intraindividual phytolith shape variation (3650 2D outlines) from 73 extant grass species, 48 genera, 18 tribes, and 8 subfamilies (with special attention paid to Pooideae) was analysed using the geometric morphometric analysis based on the semilandmarks spanning phytolith outlines. Although we showed that 2D phytolith shape is mainly driven by deep-time diversification of grass subfamilies, a closer look uncovered distinct phytolith shape variation in early-diverging lineages of Pooideae. The phylogenetic pattern in phytolith shape was successfully revealed by applying geometric morphometrics to 2D phytolith shape outlines. This finding strengthens the potential of phytoliths to track the evolutionary history and paleoecology of grasses. Moreover, geometric morphometrics of 2D phytolith shape proved to be an excellent tool for analysis requiring large sums of phytolith outlines, making it useful for quantitative palaeoecological reconstruction.
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The Chaco Region is the third biogeographic and morpho-structural territory of South America after the Amazon and Cerrado savannahs. This region is one of the few areas in the world where the transition from the tropics to temperate zones does not consist of a desert but of semi-arid woodlands and savannahs. The modern biodiversity patterns of the region were severely affected by the climatic and environmental changes that occurred during the Quaternary. Remains of an extinct megamammal Neosclerocalyptus sp. (Upper Pleistocene) and charred fossil woods inside of sedimentary nodules, was recently discovered in Chaco Argentina. The aim of paper is the paleoenvironmental reconstruction of quaternary sedimentation in the western Chaco through the taxonomic identification of charred woods and siliceous microfossils analysis. Twenty-three charcoal fragments related to Anacardiaceae, Apocynaceae, Fabaceae, Rhamnaceae and Malvaceae were identified. The phytolith analysis showed that Poaceae elements were the most abundant compared to the other herbaceous and non-herbaceous elements, along with algae and sponge microfossils. Eco-anatomic features of the charcoals and the microfossil remains suggest that environment and climate conditions existed in the area during the Upper Pleistocene were similar to the current one. Finally, the results reveal the presence of natural wildfires during the Quaternary in the region.
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The Chaco Region is the third biogeographic and morpho-structural territory of South America after the Amazon and Cerrado savannahs. This Region is one of the few areas in the world where the transition from the tropics to temperate zones does not consist of a desert but of semi-arid woodlands and savannahs. The modern biodiversity patterns of the region were severely affected by the climatic and environmental changes that occurred during the Quaternary. Remains of an extinct megamammal Neosclerocalyptus sp. (Upper Pleistocene) and charred fossil woods inside of sedimentary nodules, was recently discovered in Chaco Argentina. The aim of paper is the paleoenvironmental reconstruction of quaternary sedimentation in the western Chaco through the taxonomic identification of charred woods and siliceous microfossils analysis. Twenty-three charcoal fragments related to Anacardiaceae, Apocynaceae, Fabaceae, Rhamnaceae and Malvaceae were identified. The phytolith analysis showed that Poaceae elements were the most abundant compared to the other herbaceous and non-herbaceous elements, along with algae and sponge microfossils. Eco-anatomic features of the charcoals and the microfossil remains suggest that environment and climate conditions existed in the area during the Upper Pleistocene were similar to the current one. Finally, the results reveal the presence of natural wildfires during the Quaternary in the region.
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Mwanganda's Village (MGD) and Bruce (BRU) are two open-air site complexes in northern Malawi with deposits dating to between 15 and 58 thousand years ago (ka) and containing Middle Stone Age (MSA) lithic assemblages. The sites have been known since 1966 and 1965, respectively, but lacked chronometric and site formation data necessary for their interpretation. The area hosts a rich stone artifact record, eroding from and found within alluvial fan deposits exhibiting poor preservation of organic materials. Although this generally limits opportunities for site-based environmental reconstructions, MGD and BRU are located at the distal margins of the alluvial fan, where lacustrine lagoonal deposits were overprinted by a calcrete paleosol. This has created locally improved organic preservation and allowed us to obtain ecological data from pollen, phytoliths, and pedogenic carbonates, producing a regional- to site-scale environmental context for periods of site use and abandonment. Here, we integrate the ecological data into a detailed site formation history, based on field observations and micromorphology, supplemented by cathodoluminescence microscopy and μ-XRF. By comparing local, on-site environmental proxies with more regional indicators, we can better evaluate how MSA hunter-gatherers made decisions about the use of resources across the landscape. Our data indicate that while tree cover similar to modern miombo woodland and evergreen gallery forest prevailed at most times, MSA hunter-gatherers chose more locally open environments for activities that resulted in a lithic artifact record at multiple locations between 51 and 15 ka.
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Seven Romanian halophyte species were histo-anatomical investigated: Bolboschoenus maritimus (L.) Palla ssp. compactus (Hoffm.) Dobrow, Carex distans L., Carex vulpina L. (Cyperaceae family), Juncus gerardi Loisel. (Juncaceae), Agrostis stolonifera L., Alopecurus arundinaceus Poir. and Puccinellia distans (L.) Parl. ssp. limosa (Schur) Jáv (Poaceae). These species have been classified by the authors of the present study as "amphibious" halophytes, related to the field observations and anatomical considerations. All the analyzed taxa present bulliform cells at the foliar epidermis level. Despite the fact that there are different interpretations regarding the bulliform cells role and functional significance, we correlate these structures with the ecological factors, salinity and, respectively, drought conditions.
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Descriptive “keys”, including definitions and explanatory diagrams, are given for the standardization and simplification of anatomical descriptions of the epidermides of grass leaf blades as seen in surface view. About 340 characters of the epidermis are included with ample room for expansion. Notes on variation and taxonomic importance of the characters are also included.
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Chad is a key region for understanding early hominid geographic expansion in relation to late Miocene and Pliocene environmental changes, owing to its location 2500 km west from the Rift Valley and to the occurrence of sites ranging in age from about 6 to 3 Ma, some of which yield fossil hominids. To reconstruct changes in herbivore paleodiet and therefore changes in the paleoenvironment, we measured the carbon and oxygen isotope composition of 80 tooth-enamel samples from three time horizons for nine families of Perissodactyla, Proboscidea, and Artiodactyla. The absence of significant alteration of in vivo isotopic signatures can be determined for carbon, thus allowing paleodietary and paleoenvironmental interpretations to be made. While the results generally confirm previous dietary hypotheses, mostly based on relative crown height, there are some notable surprises. The main discrepancies are found among low-crowned proboscideans (e.g., Anancus) and high-crowned rhinocerotids (Ceratotherium). Both species were more opportunistic feeders than it is usually believed. This result confirms that ancient feeding ecology cannot always be inferred from dental morphology or extant relatives. There is an increase in the average carbon isotope composition of tooth enamel from the oldest unit to the youngest, suggesting that the environment became richer in C4 plants with time. In turn, more C4 plants indicate an opening of the plant cover during this period. This increase in carbon isotope composition is also recorded within genera such as Nyanzachoerus, Ceratotherium, and Hexaprotodon, indicating a change from a C3-dominated to a C4-dominated diet over time. It appears that, unlike other middle Pliocene hominid sites in eastern and southern Africa, this part of Chad was characterized by very open conditions and that savanna-like grasslands were already dominant when hominids were present in the area.
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A peat-sequence covering the last 16 ka (16 000 cal. yr BP) from Braamhoek wetland, eastern South Africa, was analysed in terms of phytolith and diatom composition. The fossil peat was rich in phytoliths, while diatoms were less prominent, probably as a result of degradation during wetland plant growth associated with silica uptake. With this study we present the first continuous phytolith and diatom record from South Africa covering the Late Pleistocene and Holocene period. The phytolith assemblages indicate a clear dominance of C3-grasses within the wetland throughout the sequence. The fossil diatom record infer changes in past moisture conditions. Unlike the modern wetland, which is dominated by benthic and aerophilic diatoms, the Late Pleistocene—early Holocene wetland favoured growth of planktonic species. Abundance of planktonic diatoms suggests three main phases when water depth was deeper than today; at c.13.6 ka, 11.3 ka and 10.4—10.0 ka. These indications of past fluctuations in humidity mostly provide confirmation of previously published indications of pollen, charcoal fragments and isotopes in the same core, but the siliceous microfossil data also help to refine the paleo-environmental interpretation of the sequence.
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Chad is a key region for understanding early hominid evolution and the related environmental changes of the Late Miocene. We present an extensive study of the freshwater ichthyofauna associated with Toumai, the oldest hominid known so far, at site 266 of the Late Miocene fossiliferous area of Toros-Menalla, northern Chad. Fish diversity was found to be relatively high and included at least 20 species: Polypteriformes, Polypteridae (Polypterus sp.); Osteoglossiformes, Osteoglossidae (cf. Heterotis niloticus), Mormyriformes, Gymnarchidae (cf. Gymnarchus niloticus); Cypriniformes, Cyprinidae (cf. Labeo sp.); Characiformes, Alestidae (Hydrocynus sp., Alestes/Brycinus sp., Sindacharax sp., cf. Sindacharax sp. or Bunocharax sp.); Siluriformes Claroteidae (Clarotes sp., Auchenoglanis soye), Clariidae (two Clarias sp.), Mochokidae (two Synodontis sp.), and two Siluriformes indet.; Perciformes incertae sedis (Semlikiichthys darsao), Latidae (Lates niloticus); Tetraodontiformes Tetraodontidae (two Tetraodon sp.). Among the fossil taxa three belong to extinct genera, four to fossil species of extant genera, and two species (Semlikiichthys darsao and Auchenoglanis soye) are only known from Toros-Menalla. The Tetraodon from TM 266 is the oldest known in continental Africa. After estimating the taphonomic bias, we propose a reconstruction of the fossilised aquatic environment.This corresponds to a stream or a lake with open waters, vegetated bank and a flooding regime. © 2010 E. Schweizerbart'sche Verkgsbuchhandlung, Stuttgart, Germany.
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The concentrations of atmospheric cosmogenic 10 Be normalized to the solubilized fraction of its stable isotope 9 Be have been measured in the authigenic phase leached from silicated continental sediments deposited since the upper Miocene in the northern Chad Basin. This method is validated by the systematic congruence with the biochronological estimations based on the fossil mammal evolutive degree of faunal assemblages. The fifty-five authigenic 10 Be/ 9 Be ages obtained along 12 logs distributed along two West–East cross sections that encompass best representative Mio-Pliocene outcrops including paleontological sites show a systematic stratigraphic decrease when considering all studied sedimentary facies extending from the Pleistocene up to 8 Ma and allow performing geologic correlations otherwise impossible in the studied area. The resulting global sequence evidences and temporally specifies the succession of the main paleoenvironments that have developed in this region since the Miocene. Under the special conditions encountered in the northern Chad Basin, this study demonstrates that the authigenic 10 Be/ 9 Be ratio may be used as a dating tool of continental sedimentary deposits from 1 to 8 Ma. The half-life of 10 Be theoretically allowing dating up to 14 Ma, it may have fundamental implications on important field research such as paleoclimatology and, through the dating of fossiliferous deposits in paleontology and paleoanthropology.
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A mandible and first upper premolar discovered in North Chad by the Franco-Chadian Paleoanthropological Project demonstrate for the first time the presence of an australopithecine west of the Rift Valley. The Chad hominid presents a combination of primitive and derived characters which distinguishes it from all other early hominid taxa and which suggests that this new species represents a clade independent since 4 Ma or more.
Chapter
Sedge cone phytoliths appear to be morphologically distinct from those of other families. As a result, these phytoliths from Cyperaceae may be of taxonomic importance and may be useful to archaeologists and paleoecologists. This study is a compilation of information regarding sedge phytoliths from widely separated geographic areas. Included here are previously published descriptions along with newly interpreted material. It is hoped that all the data presented will be of use in the future development of a classification scheme for phytoliths of Cyperaceae.
Chapter
Classifications of grass silica-bodies are constructed for various purposes ranging from botany to archaeology. Specific organizational details vary with the experience of the phytolith analyst and the condition of the material to be classified. The first step in classification of disaggregated phytoliths, however, must be consistent identification of types based on characteristics that survive burial, ie, morphology. The defined types then need to be correlated with plant taxa at as low a level as possible. This paper presents a standard terminology for classification of silica phytoliths, focusing on grass silica-bodies. Morphology forms the basis of the organization, although it is correlated to anatomical origin where possible. Grass silica-bodies exhibit three general geometric shapes; eight types are defined based on outline of the base. In addition, basic three-dimensional structures are defined. The classification presents standardized definitions of the “classic” grass phytolith shapes reported in the literature.
Article
The formation of discrete ‘tablets’ of hydrated silica in the bulliform cells of the leaf blade was followed over a 16-day period in three species of the Gramineae representing different habitats. Seedlings of Oryza sativa (rice) and Cynodon dactylon (Bermuda Grass) were cultured under growth-cabinet conditions at levels of 50 and 500 ppm dissolved silica (SiO2) in the nutrient solution. In addition, bulliform deposition was studied in mature tiller leaves of Sieglingia decumbens (Heath Grass). Attached leaves, as well as those excised from the culm, were used. Initial stages of tablet formation were observed by the 2-day harvest in the central and basal zones of the fully expanded seedling blades. Deposition did not occur at a stage when bulliform turgor changes might influence blade evolvement. At the 16-day harvest, deposition was heaviest in the tip zone, and decreased progressively towards the base of the blade. In addition, proportionately higher tablet counts (P = 0.05) generally were absent from the leaves grown at the higher silica level. This indicated a limited availability of deposition sites. These results are discussed in relation to (i) cellular maturation; (ii) internal leaf anatomy; (iii) leaf expansion; (iv) a basipetal senescence gradient within the leaf blade. Certain of these are considered to be possible limiting factors to silica deposition in the grass leaf.
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Despite the wide range of research that has involved phytolith analysis, including studies of palaeosols and palaeovegetation, palaeoenvironmental reconstruction, and archaeological interpretation, examples of applications to the systematic identification of modern plants are scarce, and are not applied rigorously. The present study suggests that phytolith analysis may be useful for identification of certain grasses unidentified or misidentified in the field. Leaf samples of Arundo donax and Phragmites communis, giant reedgrasses important to past and present societies in the eastern Mediterranean, are distinguished through phytolith analysis and serve as new examples of the potential use of phytoliths in systematic botany.
Article
Eighty of the 150 or so grass species occurring in Britain have been subjected to controlled wet oxidation to facilitate the study of the opaline silica bodies in their silica cells proper, and in cells which are less consistently silicified. The various types of bodies are classified, figured, and described so as to make clear their true three-dimensional shapes, their sizes, relative abundances, and positions relative to other structures in the leaf, noting differences of silica pattern particularly between sheath and blade and between adaxial and abaxial surfaces. The deposition of silica is discussed in relation to suggested functions. Possible causes of differences in the silica pattern sometimes observed between leaves of the same species are considered.
Article
The analysis of fifty modern phytolith assemblages demonstrates the practicality of opal-phytolith analysis as a surrogate for pollen analysis in the North American Great Plains. The fifteen native grassland sites used in the study span both the east-west moisture and north-south temperature gradients of the central North American grasslands. Multiple soil samples analysed from each grassland site measure within-site variability and provide evidence of how assemblages are formed. Soil assemblages strongly reflect regional grassland composition rather than local vegetation. Five factors contribute to assemblage formation: decay-in-place, fire, eolian transport, herbivory and fluvial/colluvial deposition. Soil assemblages should be interpreted as the end result of these processes integrated over long time periods. The correspondence of assemblages to local conditions controlled by landscape position (e.g. upland v. lowland) is less important than the regional correspondence but is detectable and predictable. Data presented here will provide a basis for interpretation of fossil assemblages from late Quaternary paleosols in the North American Great Plains.