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African savanna elephants and their vegetation associations in the Cape Region, South Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants

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This study tests the association between opal phytoliths in dental calculus on modern, historic, and prehistoric specimens of Loxodonta africana (African savanna elephant) with their local and regional vegetation. The modern samples were obtained from dental remains from deceased animals at the Addo Elephant National Park (Eastern Cape Province) and the Pilanesberg National Park & Game Reserve (Northwest Province) in the Republic of South Africa. The historic and prehistoric specimens, presumed to be free-roaming elephants, were sampled from museum collections in the Eastern Cape and Western Cape Provinces. In addition to comparing phytolith assemblages in dental calculus with those of the main vegetation associations, this study assesses the phytolith assemblage differences between free-roaming and park elephants.
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African savanna elephants and their vegetation associations in the
Cape Region, South Africa: Opal phytoliths from dental calculus on
prehistoric, historic and reserve elephants
Carlos Cordova
a
,
*
, Graham Avery
b
,
c
a
Department of Geography, Oklahoma State University, Stillwater, OK, USA
b
Iziko South African Museum, Natural History Collections Department: Cenozoic Studies Section, Cape Town, South Africa
c
University of Cape Town, Archaeology Department, Cape Town, South Africa
article info
Article history:
Received 8 June 2016
Received in revised form
22 December 2016
Accepted 26 December 2016
Available online xxx
Keywords:
Phytoliths
African elephant
South Africa
Cape Region
Biomes
Paleoecology
abstract
This study tests the association between opal phytoliths in dental calculus on modern, historic, and
prehistoric specimens of Loxodonta africana (African savanna elephant) with their local and regional
vegetation. The modern samples were obtained from dental remains from deceased animals at the Addo
Elephant National Park (Eastern Cape Province) and the Pilanesberg National Park &Game Reserve
(Northwest Province) in the Republic of South Africa. The historic and prehistoric specimens, presumed
to be free-roaming elephants, were sampled from museum collections in the Eastern Cape and Western
Cape Provinces. In addition to comparing phytolith assemblages in dental calculus with those of the main
vegetation associations, this study assesses the phytolith assemblage differences between free-roaming
and park elephants.
The results show that: (1) the phytolith assemblages in dental calculus of park elephants show little
variation among individual specimens and close resemblance to phytolith assemblages of soils inside
their areas of connement; (2) the free-roaming specimens have a much higher diversity of phytolith
morphotypes than those in parks and reserves, exhibiting sometimes typical signatures of more than one
biome; (3) free-roaming Cape elephants from fynbos areas have signicant amounts of Restionaceae
phytoliths, which suggests that grazing on restios in grass-poor fynbos types was important; (4) short
saddles, typical of Chloridoideae grasses, are always the most abundant short-cell morphotypes in dental
samples, even in areas where other grass subfamilies dominate, and (5) with some limitations, the study
of phytoliths in herbivore dental calculus has a high, largely unexplored, potential in paleoecology and
conservation ecology.
©2017 Elsevier Ltd and INQUA. All rights reserved.
1. Introduction
Opal phytoliths are microscopic particles of amorphous silica
deposited in cellular and extra-cellular parts of plants by means of
absorbed silica in soluble state from underground water (Piperno,
2006). Eventually, silica becomes solid and resistant to organic
decay, being sometimes the only part of a plant surviving as fossils.
Most of these particles take the form of characteristic cells and
other parts of the plant, rendering these forms useful to identify
particular taxonomic groups of plants. The opal phytolith approach
has strong applications in archaeology, and their usefulness in
paleoecology has provided information on long-term vegetation
structure (e.g. Alexandre et al., 1997; Blinnikov, 2005; Golyeva,
2007; Bremond et al., 2008; Neumann et al., 2009; Cordova et al.,
2011), paleoclimates (e.g., Fredlund and Tieszen, 1994; Lu et al.,
2006, 2007), and denition of stages of plant-herbivore coevolu-
tion in deep geologic time (e.g., Str
omberg, 2004; Prasad et al.,
2005).
In general, opal phytoliths can provide paleo-vegetation infor-
mation including taxonomic details of C
3
and C
4
grasses (e.g., Twiss
et al., 1969; Fredlund and Tieszen, 1994), graminoids, and a number
of monocots and dicots (Runge, 1999; Piperno, 2006; Neumann
et al., 2009; Mercader et al., 2010), as well gymnosperms and
other groups of higher plants (e.g., Klein and Geis, 1978; Kondo and
*Corresponding author.
E-mail addresses: carlos.cordova@okstate.edu (C. Cordova), gavery@iziko.org.za
(G. Avery).
Contents lists available at ScienceDirect
Quaternary International
journal homepage: www.elsevier.com/locate/quaint
http://dx.doi.org/10.1016/j.quaint.2016.12.042
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Quaternary International xxx (2017) 1e23
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
Tsumida, 1978; Blinnikov, 2005). Opal phytoliths provide a poten-
tial alternative proxy for paleovegetation reconstruction particu-
larly in deposits where pollen grains are absent or do not preserve
(Scott, 2002). However, it is important to bear in mind that phy-
tolith records do not replace the type of information provided by
pollen analysis, since they both represent different aspects of
vegetation.
The research approach that uses opal phytoliths embedded in
dental calculus (i.e., tartar) can provide relevant information on
herbivore diets and their paleoenvironments. Unfortunately, this
approach is still in its infancy, limited mostly to tests that empha-
size its potential for paleodiet reconstruction (e.g., Armitage, 1975;
Middleton and Rovner, 1994; Gobetz and Bozarth, 2001), particu-
larly on specimens of extinct North American Pleistocene mega-
herbivores (Bozarth and Hofman, 1998; Gobetz and Bozarth,
2001; Scott-Cummings and Albert, 2007; Cordova and Agenb-
road, 2009). Nonetheless, the potential for its application to pre-
historic and modern herbivores can be tested in modern and
historical environments where fauna-vegetation relations are
known, and studies of modern phytolith assemblages exist. Thus,
the study presented here is an attempt to relate modern (reserve)
and free-roaming (prehistoric and historic) African elephants with
vegetation associations and biomes using phytoliths assemblages
from soils and from dental calculus of a number of specimens.
The Republic of South Africa contains nine different biomes
(Fig. 1a), and historical and archaeological evidence suggest that
elephants once roamed in all of them (Ebedes et al., 1995), although
not all of them are considered preferred elephant habitat (Boshoff
and Kerley, 2001). At present, however, elephants in the Republic
of South Africa are conned to parks and reserves (Fig. 1b). The
study presented here focuses mainly on the southern part of the
country, where reports of elephants and other megafauna go back
to the mid-1600s, when the Dutch established a colony near the
Cape of Good Hope and from where European settlement radiated
into the interior and along the coast (Fig. 2). Thus Dutch settlers and
explorers in the 17th and 18th century and later British settlers,
missionaries, and explorers of the 19th century produced historical
records all of which can be used to describe herds of elephants
being exterminated (Skead et al., 2007; Boshoff and Kerley, 2010).
Based on historical records, elephants in the Greater Cape region
existed in a mostly non-savanna environment, including various
vegetation types of fynbos, renosterveld, coastal succulent scrub,
forest, subtropical thicket, grassland, nama karoo and succulent
karoo (Fig. 1a), although not all of these environments sustained
elephants permanently (Boshoff and Kerley, 2001). The fact that the
so-called savanna elephant(i.e., Loxodonta africana var. africana)
adapted to non-savanna vegetation communities is an interesting
topic discussed by several authors (Carter, 1970; Ebedes et al., 1995;
Seydack et al., 2000; Boshoff and Kerley, 2001; Skead et al., 2007)
and part of the present research.
Furthermore, the fact that some habitats in the Cape region
provided permanent elephant habitats whereas others were only
seasonal (per Boshoff and Kerley, 2001), meant that specic
migration patterns would have existed. Some migratory routes
could be hypothesized using proxies such as stable isotopes or in
the case of this study through distinctive phytolith assemblages
associated with particular ora. Within this contextual framework,
the study presented here is a preliminary research project with the
following objectives: (1) assess dietary differences between free-
roaming and park elephants, (2) assess the diet of the savanna
elephant in non-savanna biomes of temperate southern Africa, and
(3) to assess the use of the opal phytoliths in dental calculus to
study prehistoric elephant-vegetation interactions. Objective 1 is
applied to the Addo Elephant National Park in the Eastern Cape
Province coastal region and the Pilanesberg National Park &Game
Reserve in the Northwest Province. Objectives 2 and 3 directs
attention to phytoliths in soil and dental calculus samples from a
broad area in the Cape Region (Focus area in Fig. 1a and b).
2. Background information
2.1. Study areas
The focus area of this study comprises the southern part of the
Western Cape and Eastern Cape Provinces south of latitude 32
S
(Fig. 1b). In general terms, this area constitutes the southern part of
the Greater Cape Floristic Region. Its physiography is dominated by
landforms resulting from the tectonic and erosional evolution of
Cape Fold structures and the African Escarpment (Partridge, 1998;
Maud, 2012). The Cape Fold structures form a series of mountain
systems parallel to the coast, which have created a series of interior
valleys connected by antecedent stream valleys. Some of the
mountain systems associated with the Cape Fold Belt include the
Cederberg, the Hottentots-Holland, the Outeniqua Mountains and
the Suurberg. The African Escarpment forms the edge of a plateau
in the west forming a series of mountains such as the Roggeveld-
berg, the Nuweveldberg and the Sneeuberg (Fig. 2). Towards the
east, the Escarpment is marked by the Drakensberg Mountains.
Other erosional remnants of the retreating African Escarpment
have formed minor mountain systems such as the Amathole
Mountains in the Eastern Cape.
Between the Cape Fold Mountains and the African Escarpment
lies a vast area of interior plains and lowlands drained by the
Gamka, Groote and Sundays Rivers. The lithology of the Cape Fold
Mountains includes sandstone and shale, with minor structures of
granites, quartzite, conglomerates, and limestone. The Escarpment
consists of even older rocks, mostly sedimentary, with a few of
volcanic origin. The coastal areas in the west and south are domi-
nated by plains and rolling hills of eolian sand, eolianites and al-
luvium of Late Cenozoic age.
The focus area of this study encompasses the southern part of
South Africa's winter rainfall zone (WRZ), an area dened by more
than the 60% in the winter months, the summer rainfall zone, with
less than 40% of winter rain, (SRZ), and the all-year rainfall zone
(ARZ), with between 40 and 60% of rain in winter (Fig. 1). The latter
includes an area with rains uniformly distributed throughout the
year on the south coast, and an area with two conspicuous rainfall
concentrations (i.e., bimodal) in winter and summer rainfall. The
K
oppen climate types in the focus area include the Cs (Mediterra-
nean) and Cf (temperate with rain all year) in the west and coastal
south, BS (semiarid) in the interior, and Cw (temperate with sum-
mer rains) in the east. Temperatures in the focus area are highly
modied by elevation, solar irradiation (dependent on cloud cover),
ocean temperatures, and locally, on slope orientation and exposure.
Areas of the south coast with frequent cloudy days tend to have less
extreme temperatures, while those in the dry interior exhibit a
wide range daily and seasonally. Winter snow is common at high
elevations, usually above 1000 m in the west and 1800 m in the
east.
Territories of seven of the nine biomes present in South Africa
are included in the focus area (Fig. 1). The fynbos biome, which
dominates the WRZ and parts of the ARZ, consists mainly of
shrubby vegetation, which in some cases can be dominated by
Proteaceae (proteoid fynbos), Ericaceae (ericoid fynbos), or Resti-
onaceae (restioid fynbos) (Campbell, 1986). Grasses are rare in most
fynbos types, except in types in the ARZ, where summer rainfall has
higher incidence, particularly on quartzite or shale substrate
(Rebelo et al., 2006). Most fynbos associations thrive on nutrient-
poor soils developed on sand, sandstone, granite, and limestone.
In contrast, renosterveld (a type of fynbos association) develops on
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e232
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
Fig. 1. Biomes of South Africa, indicating focus area and two studied parks (b), and parks and reserves with elephant populations in South Africa.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 3
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
nutrient-rich soils, like those developed on shale and occasionally
old ne-grained alluvium. Unlike the high diversity of species in the
other fynbos types, renosterveld is dominated by renosterbos
(Elytroppapus rhinocerotis), a bush of the Asteraceae family. Grasses
can be found in relatively high proportions in the grassy fynbos
types in the ARZ and in the renosterveld. Although C
3
and C
4
grasses can grow in fynbos vegetation, C
3
tends to be dominant,
particularly in areas with the highest percent of winter rainfall.
The succulent karoo occurs in the drier parts of the WRZ and
areas of the ARZ with relatively high winter rainfall. This biome is
characterized by succulent shrubs and herbs of the Asteraceae,
Mesembryanthemaceae, Aizoaceae, and Asphodeloideae families,
and other drought resistant plants. Together with fynbos, the suc-
culent karoo has one of the highest plant diversities and ende-
misms on the African continent (Van Wyck and Smith, 2001).
Grasses are rare in most succulent karoo types, and both C
3
and C
4
grasses occur depending on the proportions of winter and summer
rain.
The nama karoo is also dominated by drought tolerant shrubs
and scrub, particularly those of the Asteraceae family such as the
genera Pentzia and Felicia, and several succulents of the Crassula-
ceae and Aizoaceae family. In some parts, shrubs are widespread,
particularly Acacia karoo,Schotia afra, and Euclea undulata. Grasses
may dominate in areas with reduced grazing, particularly during
rainy years. Because this biome is in the SRZ, most grasses are C
4
,of
which the majority are in the drought-resistant Aristidodieae and
Chlroidoideae subfamilies.
The Albany Thicket, often referred to as subtropical thicket, is
dominated by a dense cover of thorny shrubs and succulents (e.g.
spekboom, Portulacaria afra). Other succulents such as euphorbias
and aloes dominate in some thicket types. Interestingly, the thicket
biome incorporates elements from the surrounding biomes, which
is why it is sometimes considered a transitional type of vegetation
and not a specic biome (Vlok et al., 2003; Hoare et al., 2006). The
subtropical thicket in general has few grasses due to the high
competition posed by dominant shrubs, although they are often
found in areas opened up by big herbivores (e.g., elephant, rhi-
noceros, and kudu) or by re (Lechmere-Oertel et al., 2005; Hoare
et al., 2006). Sometimes intense grazing and re pressure produces
more open vegetation, although with low species richness (Kerley
et al., 1995; Kerley and Landman, 2006). C
3
and C
4
grasses coexist
in most subtropical thicket types, but the C
4
grasses normally
dominate. Subtropical thicket is the typical vegetation of the Addo
Elephant National Park.
The Afrotemperate forest occupies a small area of the coast and
coastal mountains in the most humid part of the ARZ. Trees such as
Podocarpus latifolius,Afrocarpus falcatus,Ocotea bullata,Olea
capensis subsp. macrocarpa,Pterocelastrus tricuspidatus, and Rapa-
nea melanophloeos tend to be common throughout the forest.
Grasses are rare and the existing species are mainly C
3
; neverthe-
less, given the high incidence of summer rain C
4
grasses can be
common, particularly in open areas. Fynbos usually occurs in
clearings in the forest.
Grasslands and savannas occupy a relatively small proportion of
the focus area. The grassland biome is conned mainly to high el-
evations in the mountains in the east of the focus region. C
4
grasses
dominate, but C
3
species are not uncommon, particularly at higher
elevations. The savanna biome comprises only one type in the
eastern part of the region in the former Ciskei and the Albany
district around East London where communities of predominantly
C
4
grasses intersperse with shrubs, particularly Acacia natalitia.
2.2. The elephant reserves of this study
The Addo Elephant National Park (AENP), located in the focus
area of this research (Fig. 2), occupies the hills and terraces of the
Sundays River, the Zuurberg Mountains, and the dune cordon along
the coast. Total annual precipitation at the park is 450 mm
distributed throughout the year with October, November,
December, March and April as the ve wettest month accumulating
about half of the total for the year. Mean daily temperatures uc-
tuate between 28 and 17
C in February and 26- 6
C in July.
Although subtropical thicket vegetation occupies most of the park,
the Addo Elephant National Park includes Afromontane forest on
some protected slopes of the Zuurberg Mountains and Alexandria
sector of the park with grassy fynbos on the summits of the Zuur-
berg Mountains.
As indicated by the Dutch name (Zuur, or sour), most of the
grasses in this vegetation type correspond to the sour grasses,
namely the Panicoideae subfamily. Although C
4
grasses predomi-
nate (e.g., Themeda triandra,Trystachya leucothrix, and Eragrostis
curvula), C
3
grasses (e.g., Festuca costata,Merxmuellera stricta)are
not uncommon. Because grasses co-dominate with typical fynbos
plant families such as Proteaceae, Ericaceae, and Asteraceae, this
type of fynbos (Zuurberg quartzite and shale fynbos) is often
referred to as grassy fynbos (Rebelo et al., 2006; Esler et al., 2014).
Although the elephant fenced area has expanded, at the time of
this research (2008) it covered 103 km
2
(out of the 1640 km
2
of the
entire park). The fenced area covers only subtropical thicket, clas-
sied as Sundays Subtropical Thicket and the Coega Bontveld
Fig. 2. Expansion of European settlement of the Cape Colony until the early 1800s indicating main rivers, mountain ranges and neighboring indigenous groups. Compiled by the
author using dates by Guelke (1989).
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e234
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
(Hoare et al., 2006). The former, which occupies most of the area of
the elephants' distribution, comprises dense thickets mainly on
nutrient-poor soils. The Coega Bontveld has less dense islands of
thicket and more open secondary grasslands, mainly on richer soils,
and combinations of elements from succulent karroo, fynbos, and
grasslands (Hoare et al., 2006). The dominant species in both types
are succulents such as Portulacaria afra,Aloe ferox,A. africana and a
number of thorns such as Carissa bispinosa and Acacia natalitia, and
small trees and tall shrubs such as Schotia afra var. afra,Euclea
undulata, and Olea capensis, among others. Grasses in both vege-
tation types include C
4
(e.g., Aristida diffusa,Cynodon dactylon,
Eragrostis curvula,Panicum maximum,Heteropogon contortus, and
Themeda triandra) and C
3
grasses (e.g., Ehrharta calycina,Merx-
muellera disticha,Helichtotricon hirtulum,H. turgidulum, and Stipa
dregeana). However, the C
4
grasses are the most abundant
throughout the park.
The Pilanesberg National Park &Game Reserve (PNPGR) is
located in the Northwest Province in the region traditionally known
as the western Transvaal (Fig. 2). The reserve is located in an ancient
volcanic massif of intrusive and extrusive alkaline, silica-poor, and
potassium-sodium-rich rocks. Elevations range between 1100 and
1500 m, and mean latitude is S 25
14
0
40
00
. The climate is sub-
tropical, with an annual precipitation of 600e700 mm, most of
which falls between October and May. The average daily maximum
and minimum temperatures at the park uctuate between 32
C
and a18
C in January and 20
C and 2
C in July. The vegetation in
the reserve is broadly classied as bushveld savanna, and more
specically as the Pilanesberg Mountain Bushveld (Mucina and
Rutherford, 2006). The arboreal vegetation is dominated by
broadleaf trees with Combretum molle,C. apiculatum and C. zeyheri,
and Croton gratissimus, among others, and various tall shrubs
among which several Grewia species are important (Mucina and
Rutherford, 2006). The herbaceous vegetation shows the typical
bushveld dominance of C
4
grasses, of which the Panicoideae are the
most abundant ehence the name Sour Bushveld given by Acocks
(1988).
2.3. The historical range of elephants in the Cape Region
Unlike most other countries in Sub-Saharan Africa, the Republic
of South Africa has no herds of free-roaming elephants; all of them
are conned to parks and reserves (Blanc et al., 2007; Carruthers
et al., 2008)(Fig. 1b). The Kruger National Park, Tembe Elephant
Park, the Addo Elephant National Park, and the Knysna Forest (part
of the Garden Route National Park) are the only parks that harbor
local descendants of free-roaming elephants (Hall-Martin, 1992).
Other parks and reserves have elephants descended from in-
dividuals translocated from the Kruger National Park (Garaï et al.,
2004; Carruthers et al., 2008).
Historical records of elephants in the Cape Region date back to
the Portuguese seafarers in the late 15th and early 16th century, as
well as accounts of shipwreck survivors in subsequent centuries
(Carruthers et al., 2008). After the mid-17th century and the Dutch
settlement historical records of fauna begin to accumulate, though
still scarce and in some cases elusive (Skead et al., 2011). More
reliable records, however, are from the 18th century, mainly from
explorers, travelers, traders, and missionaries (Skead et al., 2007,
2011; Boshoff and Kerley, 2010). In the early 19th century the
extent of the Cape Colony, then under British control, encroached
the largest remaining herds into areas east of the Sundays River.
As the White colonization advanced from its focal point in Cape
Town in the 18th century (Fig. 2), a wave of extermination advanced
ahead of it. The killing of elephants for ivory, meat, conict with
farmers, and sport, decimated the populations and forced the sur-
vivors into isolated areas of dense vegetation of the Knysna Forest
and the Addo Bush, neither of which has soils suitable for crops.
Thus, by the beginning of the 20th century, these were the only
remaining areas with elephants.
Despite the killings, elephants ventured out of their hideouts in
forest or thicket to raid crops, resulting in even heavier responses
from local human populations, sometimes through systematic
shootings, as with the mass shooting of elephants by Major P.J.
Pretorius in the years 1919e1920, allegedly claiming 119 ele-
phants in the Addo Bush area alone, and 5 in the Knysna Fores
(Greig, 1982; Hoffman, 1993). Two of the specimens sampled for
the present study were elephant remains were the result of such
killings.
In the end, the elephant shootings failed to stop the raids on
crops while the public became increasingly angered at the mass
killings. As attempt to alleviate these problems was the creation of a
park to protect the Addo Bush elephants. Thus, the precursor of the
modern Addo Elephant National Park was established in 1931 with
a population of only 11 elephants (Carruthers et al., 2008). Since
then the population increased to 391 in 2006 necessitating
expansion of the park (Carruthers et al., 2008).
The elephant survivors in the Knysna Forest had a different fate.
Although the dense cover of Afrotemperate forest and the rugged
topography protected them, they still fell prey to humans. The main
problem for the elephants in the forest was that they were living in
an environment in which their diets and social relations were
severely negatively affected (Seydack et al., 2000; Carruthers et al.,
2008). Inevitably those elephants that were not shot began to die of
malnutrition.
Elephant populations in the forest proved difcult to track, but
estimates indicate numbers from 20 animals in 1908 to 10 in 1970
(Carter, 1970; Milewski, 2002b). By 1990 the population had fallen
to four individuals and by 2001 to three (Hall-Martin, 1992;
Carruthers et al., 2008). Attempts to reintroduce populations of
elephants in the 1990s failed and the native population of the forest
continued to decline (Milewski, 2002b). At the time of writing only
one female has been spotted in the forest (Lizette Moolman,
elephant ecologist at SANparks, personal communication).
The geographic range of the elephant in the southern Cape Re-
gion focus area of this study is known by historical records,
archaeological and paleontological nds, and indirect evidence
such as rubbing rocks and rock art compiled in maps by J.C. Skead
(Skead et al., 2007, 2011) and Carl Vernon (Ebedes et al., 1995)
(Fig. 3). Despite some differences these two maps of show a large
concentration of elephant localities on the eastern part of the study
area, including the AENP (Fig. 3 and b). In this high-concentration
area, Boshoff and Kerley (2001) found a strong association of
elephant localities with the presence of subtropical thicket, where
spekboom (Portulacaria afra) is purportedly one of the key foods.
Elsewhere, localities with prehistoric and historic elephant evi-
dence are concentrated along the oodplains of major rivers and
their tributaries, most notably the Gamtoos and the Gouritz rivers,
and in some coastal areas (Fig. 3). Outside the areas described above
the roaming of elephants was seasonal or occasional (Boshoff and
Kerley, 2001). One can infer that the optimal habitats existed in
the east of the study area and along oodplains, with marginal
habitats practically everywhere else.
3. The research framework
3.1. Elephants, vegetation, and opal phytoliths
The methodological framework devised for this study is based
on a hypothetical model that hypothesizes the relationship be-
tween elephants and their surrounding vegetation using opal
phytoliths trapped in dental calculus (Fig. 4). This should reect the
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 5
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
diversity of phytolith morphotypes and the presence of phytoliths
unique to a particular vegetation type or biome within the elephant
range or inside a park. The model also suggests that park and
reserve elephants should have a more limited range of opal phy-
toliths determined by the vegetation types within the boundaries
of their conned area (Fig. 4). In the present study, testing of this
model was done in two ways: rst comparing dental calculus
phytoliths with soil surface phytoliths in two parks: Pilanesberg
National Park &Game Reserve and Addo Elephant National Park
(Fig. 1b), and secondly, by comparing phytolith assemblages in
modern soil surfaces in various vegetation types in the focus region
(Fig. 5a) with the phytolith assemblages in the dental calculus of
free-roaming elephants in the same region (Fig. 5b).
3.2. Dental calculus samples
The dental calculus from the Pilanesberg National Park &Game
Reserve and the Addo Elephant National Park includes samples
from molars of dead elephants housed in the parks; in some,
characteristics as to age and gender were recorded (Table 1).
Although they constitute a small portion of the samples from each
park, they elucidate the vegetation choices that these herbivores
made in relation to what was available in the areas in which they
were conned.
It is known that elephants replace their molars every six or
seven years, having gone through six or seven sets of molars at the
end of adulthood. Although we acknowledge that differences could
exist, uncertainty with respect to the ontogenetic age of sampled
teeth and small sample sizes prohibited such an analysis. However,
that likely does not impact our ability to interpret plant availability
in a region, which is the primary focus of our study.
The dental calculus samples from historic and prehistoric ele-
phants include specimens housed in museums and private collec-
tions. Because they are mainly historic or prehistoric, pre-dating
the establishment of fenced parks and reserves, they are assumed
to represent free-roaming elephants. The metadata associated with
most specimens is often incomplete, but it helps place them in the
geographic and historical context (Tables 2 and 3). Among the free-
roaming specimens, the historic specimens, dating to the 1800s and
early 1900s are SMEH-1, SMEH-2, SMEH-3 and most probably STL-1
Specimens that may be proto-historic or prehistoric of Holocene
age are SMEH-1, SMEH-3, STB-1, and CDL-1 The prehistoric ele-
phants include specimens SME-1, SME-2, SME-3, which correspond
to samples from the Lower Paleolithic Elandsfontein site, dated
between 1 million and 600,000 years before the present (Klein
et al., 2007; Braun et al., 2013).
When possible their locations were mapped, although with
different levels of accuracy (Fig. 5b). Because the specimens of free-
roaming elephants are compared with those of the AENP, they have
been divided geographically, namely separating those to the east
and west of the AENP (Tables 2 and 3). To the east, samples were
more likely associated with the summer rainfall area and mostly in
vegetation types of the subtropical thicket and savanna (Table 2). To
the west, the studied specimens were in the winter rainfall region,
and in vegetation types of the fynbos, renosterveld, forest, and to a
certain degree subtropical thicket (Table 3).
Fig. 3. Localities with prehistoric and historic evidence of elephants after (a) J.C. Skead (Skead et al., 20 07, 2011) and (b) Carl Vernon (Ebedes et al., 1995).
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e236
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
3.3. Phytoliths in South Africa and the Cape Region
3.3.1. General and regional aspects
A study of dental calculus for paleoecological reconstruction
requires phytolith reference samples from individual species and
taxonomic groups of plants, as well as phytolith groups that char-
acterize the different vegetation types and biomes. Thus far in
Southern Africa grass phytoliths have been studied in relative detail
(Rossouw, 2010; Cordova and Scott, 2010; Cordova, 2013), although
some studies report phytoliths found in other graminoids such as
Cypearaceae and Restsionacecae (e.g., Cordova, 2013; Esteban et al.,
2016), and non-graminoids (e.g., Mercader et al., 2010).
Typically phytoliths are divided by the plant group that pro-
duces them and by morphotype. Thus, grass phytoliths are classi-
ed as short cells, elongates (or long cells), pointy (or trichomes),
and bulliforms (Fig. 6a). Of these, the short cells (i.e., GSSC) are the
ones used as diagnostic for taxonomic groups within the Poaceae
family. Other graminoids such as Restionaceae (restios) and
Cyperaceae (seges) have characteristic forms as well (Fig. 6b).
Non-graminoids produce different morphotypes (Fig. 6c) among
which the most common in Africa that globular (spherical) and
some facetates, which are typically produced by trees (Fig. 6c,
numbers 19e21). Other morphotypes are widely found in various
dicots, mostly woody plants (Fig. 6c., 18 and 22e25). For this study a
number of dicots were tested, but no specic morphotype was
found associated with a particular group. The tests on plant spec-
imens carried out through this study showed that globular mor-
photypes produced by Nuxia oribunda (Fig. 6c, 19) were
undistinguishable from those produced by Schotia afra; in other
cases many dicot plants produced amorphous types often referred
to as blocky morphotypes. Many plants tested for phytoliths in this
study did not produce opal phytoliths as was the case of most
succulents (e.g., Portulacaria afra,Aloe spp., and Sensieveira
hyacinthoides).
3.3.2. Graminoid phytoliths
Among the grass opal phytoliths (Fig. 6a) the short cells are the
most reliable for linking morphotypes with taxonomic groups at
the subfamily level. This serves as a means for differentiating the
two groups of photosynthetic pathways, C
3
and C
4
, used as proxies
for climate or soil moisture regime. They are often referred to as
grass silica short cells (GSSC) and are usually formed in leaves
(Rossouw, 2010), although other studies reported certain types in
inorescences and other parts (Novello and Barboni, 2015; Babot
et al., 2016). The classication of GSSC used in this study follows
closely the one previously published by Cordova and Scott (2010)
and Cordova (2013), but has been slightly modied and updated
for the present study (Fig. 7;Table 4). This classication is loosely
based on the nomenclature proposed by Madella et al. (2005) and
uses terms from Piperno (2006) and a number of other studies
(Fredlund and Tieszen, 1994; Alexandre et al., 1997; Barboni and
Bremond, 2009; Neumann et al., 2009; Rossouw, 2010).
As for the other graminoids, this study uses three categories:
Cyperaceae, Restionaceae and generic graminoid. Cyperaceae
include mainly the papillae and hats (Fig. 6b, 16 and 17). Restio-
naceae include several forms such as disks, some of which are at
or have papillae, boomerang-shaped and paddle-shaped elongates
that can resemble hockey sticks (Figs. 6b,and 10e15). Although
some phytoliths of Restionaceae deteriorate quickly in soils or
dental assemblages, they still retain certain characteristic forms
Fig. 4. Model of elephant roaming, vegetation types, biomes, and opal phytoliths.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 7
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
(Fig. 6b, 14 and 15). The generic graminoidcategory encompasses
types that may occur in more than one graminoid family (Poaceae,
Restionaceae, and Cyperaceae), usually some elongates and
papillae, and morphotypes that cannot be assigned to a specic
graminoid family due to deterioration.
3.3.3. Non-graminoid phytoliths
The non-graminoid phytoliths are not as well studied as those of
graminoids, but they have recently received attention in locations
in tropical Africa, where along with grass phytoliths they have
become an important proxy for climatic and environmental con-
ditions (Alexandre et al., 1995; Neumann et al., 2009). Those types
are directly associated with taxonomic groups such as the Acer-
aceae (palms) and several tropical plants found elsewhere in Africa,
but not present in the study area. Because no comprehensive
taxonomic study of dicot phytoliths exists in the study area, only
three basic groups are used here. One group includes globular types
(spherical) and the faceted and tree tracheids (Fig. 6c) because of
their strong relation with trees. In a separate category other groups
such as the polygons, facetates, blocky types, and unclassied
shapes have been amalgamated. To determine the relationship
between dicots and graminoids, the dicot/graminoid ratio was
used, although its accuracy has not been tested in this region.
4. Methods
4.1. Sampling dental calculus
The sampling methodology varied depending on the condition
and preservation of the tooth. In elephant molars calculus accu-
mulates at the level of the gums on both sides and on the posterior
portion of an erupted tooth. After tartar has been identied on the
tooth, the rst step is a removal of any varnish, if present. Acetone
dissolves most varnishes or solvents. A clean cotton swab was
soaked in solvent and applied carefully on the surfaces. Cotton -
bers do not contaminate the sample, since they do not produce
phytoliths. After removal of the varnish, if any, the tooth surface
was gently washed with distilled water. Finally, the surface of the
tooth was gently washed with distilled water from a squeeze bottle.
A small artist's paint brush was used to remove any sediment from
the surface during washing. Detergent was not used since it can
dissolve some organic particles attached to the tooth. After the
sampling surface was dry, dental tools were used to carefully
scratch the tartar off the tooth. A small watercolor paintbrush was
then used to sweep the tartar powder into a small sterile vial.
Fig. 5. The focus area of study. (a) Soil samples tested for phytolith assemblages and represented in Figs. 8 and 9; (b) approximate location of elephant specimens sampled for dental
calculus phytoliths (See Tables 1 and 2).
Table 1
Modern elephant specimens in parks.
Park Designation Materials
Pilanesberg National Park &
Game Reserve
PBE-1 Adult, approximately 30 y. o., one
molar
PBE-2 Sub-adult, approximately 15 y. o.,
one molar
PBE-3 Juvenile, approximately 5 y. o., one
molar
Addo Elephant
National Park
ADE-1 Young adult, 18e20 y.o., full
mandible molars
ADE-2 Adult, >30 y.o., upper molars
ADE-3 Adult, >30 y.o., lower molars
ADE-4 Adult, >30 y.o., lower molars
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e238
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
4.2. Sampling soil surface samples
Phytolith assemblages from soil surface samples were collected
to provide a regional and local background of phytoliths produced
by the regional and local vegetation. The regional soil surface
sample consists of 68 samples collected between 2008 and 2012
along several transects. Part of the data was originally published in
Cordova (2013), but more recent samples were taken as part of the
current study. The local soil surface samples were collected inside
the parks, two from the Pilanesberg National Park &Game Reserve
(labeled PB) and ve samples from the Addo Elephant National Park
(labeled ADDO). Metadata, percentages of data used in this study,
and raw counts are provided in the supplementary les S1 (regional
samples) and S2 (park samples).
At each sampling location, a four-by-four meter quadrat was
marked on the ground, where coordinates and elevation were
recorded. Then, cover percentages of plant groups were recorded.
Four or ve random pinches of surface soil were collected from the
ground within the quadrat and combined as a single sample for that
locality. For purposes of comparison with phytolith assemblages
from elephant dental calculus, the percent cover of vegetation is
summarized in Table 5.
4.3. Laboratory processing
The method used here for extracting phytoliths from herbivore
dental calculus takes elements from methodologies employed
before (i.e., Armitage, 1975; Gobetz and Bozarth, 2001; Scott-
Cummings and Albert, 2007; Cordova and Agenbroad, 2009). The
sample was transferred to a small dish and weighed. Then it was
transferred carefully into a 15-ml centrifuge tube. Then, 2e5mlof
35% HCl was added to the sample and the tube was shaken for
5 min using a vortex genie. Subsequently 2e5 ml of distilled water
was added and shaken for another 2 min. The tube was then lled
up with distilled water and centrifuged at 2800 rpm for 3 min. The
liquid was carefully decanted, and the test tubes lled up with
distilled water again, and centrifuged again. This operation (adding
water-centrifuge-decant) was repeated a further two times, or until
the pH of the solution was neutral.
A microscope slip was weighed in a high resolution balance (at
least 3 decimals). The sample was transferred from the tube to a
microscope coverslip using a pipette. The sample was evenly
distributed on the coverslip. Then the coverslip with sample was
placed on a hot plate at 50
C until water evaporated. After drying
any pieces of enamel were removed using ne tweezers under a
magnier. The coverslip with sample was weighed and the differ-
ence with the clean coverslip provided the sample's weight. Then, a
drop of Entellanmounting medium was placed on a 1 3cm
microscope slide and the coverslip was quickly placed, sample
down on the Entellan medium surface, allowing the still unsolidi-
ed medium to ow under the full area below the coverslip. When
the Entellan medium was fully dry and solid, after about six or
seven days, the slide was ready for microscope work.
4.4. Microscopy, counting, analysis, and presentation of data
Once the medium was dry, the sample was scanned under a
refraction microscope at 400. If necessary, particularly for
photography or study of details, magnication should be increased
to 1000in immersion oil. Normally, counts in soil samples are
relatively high (Tables S1 and S2), so that they can be represented in
percentages. However, phytolith counts in dental calculus, though
highly variable, are generally low (Table 6;Table S3). Therefore,
they are reported here as counts. Exceptions include samples of
modern elephants at the PNPGR and AENP, as well as some speci-
mens from the eastern part of the zone, namely those labeled EL,
AME, and ALE (Table 6), which in this study are also represented in
percentages.
Whether presented in percentages or in total counts, data in
graphs and tables are structured under two groups, graminoid and
Table 3
Free-roaming elephant specimens around and west of the Addo Elephant National Park.
Area Designation Finding location and
circumstances
Material Source/collection
South Coast SMEH-1 Knysna, killed by Pretorius Upper and lower molars SAM ZM-15884
SMEH-2 Addo Bush, 1920 (presumably killed by Pretorius) One molar SAM ZM-15737
SMEH-3 Schoenmakerskop dunes, Port Elizabeth area Upper and lower molars SAM ZM-33420
SMEH-4 Addo Bush, 1897 Upper and lower molars SAM ZM-02459
STL-1 Knysna One molar University of Stellenbosch, Animal
Science Department collection.
STB-1 Stilbaai dunes Two lower molars Stillbaai Museum display
Olifants River Valley (Citrusdal) CDE-1 Olifants River valley One molar Citrusdal Museum display
West Coast SME-1 One molar Iziko South African Museum
SME-2 One molar Iziko South African Museum
SME-3 One molar Iziko South African Museum
Table 2
Free-roaming elephant specimens east of the Addo Elephant National Park.
Area Designation Finding location Material Source/collection
Albany District-East London EL-1 Gonubi River mouth One molar Carl Vernon collection
EL-2 East London area One molar Carl Vernon collection
EL-3 East London area One molar Carl Vernon collection
ALE-1 Port Alfred area One molar Grahamstown, Albany Museum, #5063
AME-2 Trappe's Valley, Albany district One molar King Williams Town, Amathole Museum, AMSA/M 3274. Registered in 1925
AME-3 Amathole Mountains region One molar King Williams Town, Amathole Museum, MKM 10823
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 9
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
non-graminoid phytoliths. Graminoids include phytolith morpho-
types diagnostic of the Poaceae, Cyperaceae and Restionaceae
families and those morphotypes that for various reasons can fall
within the three families (i.e., generic non-graminoid). Poaceae
morphotypes are subdivided into short cells, elongates, pointy and
bulliforms (Fig. 6a). In turn, short cells are subdivided into the
groups that characterize the different C
3
and C
4
subfamilies (Fig. 7).
Cyperaceae and Restionaceae are divided into some of the basic
groups identied in Cordova (2013), which include papillae, hats,
disks, paddles and boomerang-shape morphotyes (Fig. 6b). The
non-graminoid group (quasi-equivalent with dicot phytoliths) is
summarized into three groups: globular (or spherical), woody plant
tracheids, facetates, and faveolates, and other including mainly
irregular, blocky types and others not associated with a particular
type (Fig. 6c).
5. Results
5.1. Soil samples in the focus area
The 68 soil surface samples taken from the seven biomes in the
focus area were used here both as a regional background for
vegetation and as a modern reference (Fig. 5a). They constitute
samples of 42 vegetation types distributed as follows: fynbos (28
types, of which 6 are renosterveld types), succulent karoo (3 types),
Afrotemperate forest (1 type), Albany thicket (6 types), nama karoo
(2 types), grassland (1 type), and savanna (1 type). The reason for
the high number of samples and types in the fynbos is because this
biome occupies most of the focus area (Fig. 1a) and has a high di-
versity of vegetation types (See Mucina and Rutherford, 2006).
The distribution of modern phytolith assemblages by biome
indicates variations in opal phytolith assemblage patterns as shown
Fig. 6. Selected phytolith morphotypes. All bars are 20
m
m long. (a) Poaceae phytoliths Short cells: 1, rondel; 2, trapeziform sinuate; 3, panicoid bilobate; 4, short saddle; 5,
aristidoid, long and narrow shank bilobate. Other: 6, elongate; 7, trichome; 8, cuneiform bulliform cell; and 9, parallepipedal bulliform cell. (b) Other graminoids, Restionaceae, 10
and 11; disks; 12, boomerang; 13; paddle 13 and 15 deteriorated disk and paddle from dental calculus (SME-2). Cyperaceae: 16, papilla; and 17.hat-shaped cell. (c) Dicots, f ¼fruit,
l¼leaf: 18, woody plant tracheid, Ocotea bullata (l); 19, decorated globular, Nuxia oribunda (l); 20 and 21, facetates, Pterocelastrus tricuspidatus (l) and Schotia afra (f), respectively;
22 and 23, polygons, Celtis africana (f,l) and Schyzophiton rautenii (l), respectively; 24; favelolate, Rapanea melanophloeos; and 25, psilate round blocky globular and ovates, Pter-
ocelastrus rautenii.
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
Fig. 7. Grass subfamilies and their corresponding diagnostic grass silica short cells (GSSC). Bars are 20
m
m long, unless otherwise indicated.
Table 4
GSSC used in this study. Designations and equivalents in other sources.
Morphotype groups Code Reference to other names (source at the bottom) Poaceae taxonomic group
Rondels and trapezoids 5-A, 5-N, 3-C, 3-F Conical
(1) (Q)
Rondels
(2) (G)
Trapeziform rondels
(3) (I)
Pyramidal
(1) (Q)
Pooidea, Danthonioideae and
Ehrhartoideae
Oblong trapezoid and crenates 4-C, 4-E, 4-K Long crenates
(1) (E)
Trapeziform polylobates &trapeziform sinuates
(2) (E)
Oblongs
(3) (I)
Pooideae and Danthonioideae
Trapezoid bilobates and reniforms 8-B, 8-C, 8-E
3-G; 8-E (including reniform variant)
Stipa-type
(1)
Bilobate Variant 2
(3) (I)
Trapeziform bilobates
(4)
Reniforms
(3) (I)
Danthonioideae, Pooideae and
Ehrhartoideae
Small, round bilobates 10 L
10Z
Bilobates Variant 3
(3) (1)
Bilobates Variant 2
(3) (I)
Other bilobates
(1) (I)
Ehrhartoideae, Danthonioideae &
Pooideae
Long, narrow bilobates 10A Bilobates variant-1
(3) (E)
Aristida (Aristidoideae)
Chloridoid saddles 9A
9B
Short saddles
(5) (E)
Saddles Variant 1
(3) (E)
A variant of chloridoid saddles
(6) (E)
Chloridoideae
Panicoid bilobates and crosses 10K, 10W
11A
Panicoid bilobates
(1)
BilobatesVariant-2
(3) (I)
Quadra-lobates
(2) (E)
Crosses
(3) (E)
Panicoideae
Phragmites-type saddle 9F Plateau saddles
(5) (E)
Typical of Phragmites
(Arundinoideae), but found in some
Danthonioideae and some
Stipagrostis (Aristidoideae)
Designation sources: (1) Fredlund and Tieszen (1994); (2) Madella et al. (2005); (3) Rossouw (2010); (4) Cordova (2011); (5) Lu and Liu (2003); (7) Piperno (2006, p. 31).
Degree of equivalence with designation source: (E) exact equivalent; (I) included as a sub-type in this variant or class; (G) general morphotype designation; (Q), quasi-
equivalent morphotype
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 11
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
by the diagram in Fig. 8. The most notable aspect is that the samples
from the fynbos biome have a percentages ranging from 60 to 80%
of Restionaceae along with smaller percentages (no higher than
10%) of morphotypes classied as Cyperaceae and generic grami-
noids (Fig. 8, left column). This is concordant with the fact that in
most fynbos types Restionaceae tend to dominate over grasses
(Cordova, 2013).
The non-graminoid to graminoid (NG/G) ratio curve (Fig. 8) does
not show a clear pattern through the different vegetation type
types. The highest values, in the order of 4e10, are in samples of
Albany Thicket (i.e., subtropical thicket). In contrast, the lowest NG/
G values are in grassland and savanna biome, where they are
usually less than 1. The forest samples, where one would expect a
high NG/G, have values no greater than 4. In fact, the NG/G values
are similar to those in the fynbos samples. Although there is high
variation of NG/G values in the fynbos, as expected, the lowest
(usually <1) are in the grassy fynbos.
The distribution of the sum of C
3
and C
4
diagnostic GSSC (grass
silica short cells) shows an interesting pattern along the different
rainfall regimes and biomes (Fig. 8). The C
3
diagnostic GSSC tend to
be more common in those biomes and vegetation types in the
winter and all-year rainfall zones, while the C
4
is common in the
summer rainfall zone. There is, however, no sharp correspondence
between C
3
and winter rain and C
4
and summer rain, except in
some samples of the Albany thicket. Nonetheless, those samples
deep in the summer rainfall, such as the nama karoo, grassland and
savanna have a predominance of C
4
diagnostic GSSC. At the other
extreme, the fynbos types have a relatively higher incidence of C
3
diagnostic GSSC than other biomes, except for the grassy fynbos
type, which is located in the all-year rainfall zone with a consid-
erably higher percentage of summer rain (see location of samples
117e120 on Fig. 5a).
Table 5
Information on the localities sampled at the Addo Elephant National Park.
Sample and location Percent area covered by different plant groups
55 meters
PB-1
Flat area within 500 m
from dam
Trees: none
Shrubs and small trees: none
Forbs and scrub: unidentied, 5%
Grasses:
Chloridoideae: Eragrostis sp (30%);
Panicoideae grasses: Panicum sp (25%) Cymbopogon sp (2%)
Barren: 38%
PB-2
Near water
Trees: none
Shrubs and small trees: Unidentied, 1%
Forbs: Unidentied, 2%
Grasses
Chloridoideae: Cynodon dactylon, 40%.
Panicoideae: Panicum sp. 5%
Unidentied: 5%
Barren: 47%
ADDO-1
Open area near entrance
Trees: None
Shrubs and small trees: Portulacaria afra (24%); other (2%)
Forbs and scrub: Pentzia (10%), undetermined geophyte (1%); undetermined succulent (8%)
Grasses:
Chloridoideae: Eragrostis spp. (30%)
Panicoideae: Panicum maximum (15%); Eustachys sp. (5%).
Barren: 5%
ADDO-2
Dense thicket area near entrance
Trees: none
Shrubs and small trees: Portulacaria afra, 40%; Azima tetracantha, 2%; Rhus sp., 20%
Forbs and scrub: Asparagus sp., 3%; Sensieveira hyacinthoides, 3%; other (1%).
Grasses:
Chloridoideae: Eragrostis spp., 1%.
Panicoideae: Panicum maximum, 5%.
Barren: 25%
ADDO-3
Discovery trail
Trees: none
Shrubs and small trees: Azima tetracantha, 3%; Cadaba aphylla, 3%; Euclea sp., 30%; Rhus, 5%; Portulacaria afra, 5%; Carissa bispinosa, 30%.
Forbs and scrub: Sensieveira hyacinthoides, 4%; Asteraceae herbs, 3%.
Grasses:
Pooideae: Stipa dregeana,5%
Panicoideae: Panicum maximum, 5%.
Barren: 7%
ADDO-4
Near water
Trees: Schotia afra,2%
Shrubs and small trees: Azima tetracantha, 4%; Carissa bispinosa, 4%; other unidentied, 15%.
Forbs and scrub: Pentzia, 3%; Sensieveira hyacinthoides, 1%; other unidentied, 3%
Grasses:
Chloridoideae: Cynodon dactylon,6%
Panicoidae: Panicum sp., 2%
Barren: 60%
ADDO-5
Zuurkop hilltop
Trees: none
Shrubs and small trees: Euclea undulata, 8%; Carissa bispinosa, 2%, Portulacaria afra, 5%; Syderoxylon inerme, 8%; other unidentied, 5%.
Forbs and scrub: Asteraceae, 4%; unidentied, 3%
Grasses:
Danthonioideae: Merxmuellera disticha, 10%
Chloridoideae: Eragrostis, 8%; Chloris sp., 10%
Panicoidae: Heteropogon contortus, 5%; Panicum sp., 3%; Themeda triandra, 15%
Barren: 17%
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e2312
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
In Fig. 9, the individual GSSC morphotypes are separated on the
basis of form and afliation with C
3
and C
4
subfamilies. There is no
particularly good indicator of rainfall regime or biome among the C
3
diagnostic GSSC morphotypes. As discussed by Cordova (2013) one
problem with the C
3
grass subfamilies, particularly Ehrhartoideae
and Danthonioideae, is that there is no consistent pattern of phy-
tolith morphology except for a few that are sometimes shared with
the Poaceae (e.g., rondels) and reniforms (Rossouw, 2010). However,
other morphotypes such as trapezoid bilobates and several long
(oblongs) are relatively diagnostic to most C
3
grasses (Rossouw,
2010; Cordova, 2013). It is necessary, however, to dedicate a more
focused study to the phytoliths of the three C
3
grass subfamilies.
The C
4
diagnostic morphotypes are dominated by the chloridoid
saddles (e.g., short saddles), the most common of the C
4
diagnostic
GSSC, shows a strong abundance in the summer rainfall zone. It
dominates in biomes such as the nama karoo and the Albany
Thicket. The Panicoideae diagnostic GSSC are present in all biomes,
except the succulent karoo, but they tend to be more consistent and
relatively abundant in the summer rainfall areas, particularly in the
samples from the grassland and savanna biomes. The
Aristidoideae-diagnostic GSSC appear only sporadically. They
characterize the presence of the genus Aristida, which in this part of
Southern Africa mainly indicates disturbance, often by overgrazing
(Gibbs-Russell et al., 1990).
5.2. Park and reserve elephants and their environment vegetation
The soil samples from the Pilanesberg National Park &Game
Reserve (PNPGR) were obtained from the area grazed and browsed
by elephants. The vegetation surrounding the samples includes an
approximately typical array of the vegetation inside the reserve
(Table 6). The phytolith assemblages show a dominance of grass
phytoliths. The GSSC show a dominance of C
4
grasses, particularly
those diagnostic to the Chloridoideae grass subfamily (Figs. 10 and
11). The non-graminoids are represented by a variety of forms,
including several of the typical tree-phytoliths such as the globular
and faveolated morphotypes (Fig. 7b).
The phytolith assemblages in the three sampled elephant den-
titions at the PNPGR show a distribution of phytoliths similar to
those in the soil samples (Figs. 10 and 11). Specimens PBE-2 and
PBE-3 show strikingly similar proportions among the phytolith
groups. Specimen PBE-3, presents a slightly different distribution,
with larger proportions of graminoids than non-graminoids. Dif-
ferences between the elephant and the soil samples exist mainly in
the distribution of long, pointy and bulliform grass phytoliths.
The phytolith assemblages from dental calculus at the AENP
tend to have much lower NG/G values (0.24e1.8) than those in the
soil samples (0.79e4.45) (Fig. 12a). In both groups the dental and
soil samples, the Chloridoideae-diagnostic GSSC dominate
(Fig. 12b), which is consistent with the abundance of Chloridoideae
(particularly Cynodon dactylon) in the modern vegetation in areas
grazed by elephants in the park (Table 5). Although C
3
grasses are
present in the sampled areas (Table 5) and overall in the Albany
Thicket vegetation type (Mucina and Rutherford, 2006), they are
practically absent in the dental calculus of the AENP elephants
(Fig. 13).
5.3. Free-roaming elephants in the research focus area
The dental calculus phytolith counts of the presumed free-
roaming specimens vary considerably by region as shown in the
counts (Figs. 14 and 15) and percentages (Fig. 16), which was ex-
pected since the samples originate from geographic areas with
different vegetation types (Fig. 5b). The most remarkable difference
exists in the graminoid morphotype groups, where those speci-
mens from geographic areas characterized by fynbos tend to have
Restionaceae and Cyperaceae phytoliths (Fig. 15).). Even in the
early-to-middle Pleistocene, fynbos vegetation occupied the same
areas it does today, as was suggested by isotopic and mesowear
studies on several herbivore remains at Elandsfontein (Luyt et al.,
2000; Kaiser and Franz-Odendaal, 2004; Stynder, 2009; Braun
et al., 2013).
Among the Poaceae phytoliths the differences in C
3
and C
4
diagnostic GSSC are noticeable. Those specimens collected from
Table 6
Total counts of phytoliths in the dental calculus samples studied. The asterisk (*) indicates the sets used in the analyses of this study. Park elephants (a) and free-roaming
elephants.
Sample Diagnostic GSSC (*) Non- diagnostic/
non-determined GSSC
Other graminoid(*) Non graminoid (*) Deteriorated and/or
non- determined
Total
a)
PBE-1 6 14 26 61 15 107
PBE-2 27 9 23 118 2 177
PBE-3 6 14 9 72 0 101
ADE-1 78 18 8 45 5 149
ADE-2 8 4 8 36 12 56
ADE-3 98 33 24 66 40 261
ADE-4 44 10 53 26 3 136
b)
EL-1 33 61 119 60 3 276
EL-2 28 30 76 50 3 187
EL-3 12 46 6 98 1 162
AME-2 108 105 100 38 10 361
AME-3 32 72 69 91 3 267
ALE-1 42 152 87 169 2 452
SMEH-1 4 5 6 37 3 55
SMEH-2 2 13 20 64 11 110
SMEH-3 1 1 10 18 4 33
SMEH-4 4 10 34 44 3 95
STB-1 0 2 6 25 4 37
STL-1 2 4 7 63 3 79
CD-1 3 15 9 16 2 73
SME-1 4 14 38 58 30 144
SME-2 2 15 8 41 14 80
SME-3 2 4 10 28 7 51
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 13
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
areas the winter and all-year rainfall regions, particularly the West
Coast, tend to have more C
3
than C
4
diagnostic GSSC, while those in
the east tend to have more C
4
diagnostic GSSC (Fig. 15). Nonethe-
less, this point is difcult to assert because of the relatively low
numbers of phytoliths counted in most dental calculus samples
(Table 6).
The samples from free-roaming elephants collected in the
Albany District and East London surprisingly produced large
numbers of phytoliths (Table 6). Therefore, they can be compared
with the relatively phytolith-rich samples of the AENP (Fig. 16).
Although there are differences in terms of percentages of short
cells, elongated, pointy and bulliforms, for the most part the
Fig. 8. Graminoid phytolith percentages (Poaceae, Cyperaceae, Restionaceae and generic graminoid) types and graminoid to non-graminod from modern surface soil samples
(Fig. 4a for location) arranged by biome and winter rainfall. The graph to the far left indicates the sum of diagnostic C
3
and C
4
GSSC percentages of the total number of grass short
cells.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e2314
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
proportions of non-graminoids and graminoids are similar be-
tween the free-roaming and park elephants (Fig. 6). The similarities
between the samples of park and free-roaming specimens are
perhaps the dominance of C
4
-diagnostic GSSC, and the lack of
Restionaceae phytoliths. The free-roaming elephants, however,
have more diversity of C
4
-diagnostic GSSC and a small but relatively
larger number of C
3
-diagnostic GSSC than their park counterparts
(Fig. 16).
6. Discussion
6.1. The testing of a model
The comparison of the dental calculus phytolith assemblages
between samples of the Albany District-East London Area (samples
EL-1, 2 &3, AME 2 &3, and ALE-1) and samples from the AENP (ADE
1, 2, 3 &4) (Fig. 16) can be used to test the model proposed for this
Fig. 9. Percentages of all GSSC distributed by their corresponding subfamily (See morphotypes on Fig. 6).
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 15
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
study (Fig. 4). The Albany District-East London Area samples
correspond to the free-roaming elephants, while the AENP samples
to the park elephants. Geographically both sample sets correspond
to the transition between the all-year and summer rainfall regimes,
and the area dominated by the subtropical thicket and patches of
adjacent savanna, forest, grassland nama karoo and fynbos). This
general area is singled out in the circle in Fig. 1a.
In both data sets, the phytolith assemblages look at rst very
similar (Fig. 16). The most important similarities between the two
data sets is high amount of short cells over other Poaceae phytoliths
(i.e., elongated, pointy, and bulliform), with only one exception
(ADE-4), and the predominance of C
4
-diagnostic GSSC in all sam-
ples (Fig. 16). Additionally, both datasets have relatively similar NG/
G ratios both mostly <1, with only two in each set >1 but <2
(Figs. 11a and 14).
However, some notable differences exists between the two
groups. First, the free-roaming elephant assemblages have higher
richness of phytolith groups than those of the AENP (see num-
ber of morphotypes presentcolumn in Fig. 14).Thedifferenceis
slight, with an average richness of 9 and 7.75 for the free-
roaming and AENP groups, respectively (Fig. 14). In parallel
with this difference, the assemblages from free-roaming speci-
mens have a higher variety of GSSC morphotypes (see number of
morphotypes present in Fi g. 15). The difference in is considerable,
with averages of 7.83 and 3.75 for free-roaming and park groups,
respectively. Another evident difference in the GSSC is the higher
number of panicoid bilobates and crosses in relation to chlor-
idoid saddles in the samples of the free-roaming group. This
could be because of their location deeper into the summer
rainfall area, where Panicoideae are more prominent (Cordova,
2013), but also because of the broad diversity of veld types for
grazing in their ranges.
Although the percentages of C
3
-diagnostic morphotypes are
considerably low in both groups (Fig. 16), the free-roaming ele-
phants group presents a higher variety of C
3
-related morphotypes
(Fig. 15). It is possible that the ample range of the free-roaming
elephants covers areas with more grass diversity. Interestingly,
however, the lack of Restionaceae phytoliths in the free-roaming
group suggests that the elephants probably did not roam in areas
of fynbos areas in the west. Instead, they may have grazed areas at
higher elevations where lower temperatures promote growth of C
3
grasses.
Despite the small number of samples, it is evident that the
modern elephants in the Addo Elephant National Park have less
rich phytolith assemblages than the free-roaming, historical ele-
phants of the same region, suggested in the diagram of Fig. 4.
Nonetheless, the invisibility of many plant species in the record
may be a problem. But because graminoids produce more distinc-
tive phytolith morphotypes, they could be used as the basis for
assessing richness among different regional sets of samples.
6.2. Opal phytoliths and the ecology of the Cape elephants
Although traditionally seen as a savanna species, Loxodonta
africana subsp. africana, is an adaptable herbivore that can subsist
in other African biomes with tropical, subtropical, desert, and
temperate vegetation (Blanc et al., 2007; Carruthers et al., 2008).
This can be seen in the number of historical elephant occurrences in
practically all the biomes of South Africa (Klein, 1983; Seydack et al.,
2000; Boshoff and Kerley, 2001; Skead et al., 2007). Although not all
the biomes are optimal habitat for elephants, many of the locations
where they were historically or archaeologically reported had
special vegetation characteristics that provided to their survival. In
the region of study many occurrences were associated with low
Fig. 10. Pilanesberg National Park Game Reserve phytoliths from teeth and surface soil sample. Counts.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e2316
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
areas (e.g., oodplains) where there was more water and vegetation
(Boshoff and Kerley, 2010). Other occurrences are often reported in
the Albany thicket and some of the coastal areas with succulent
shrubs highly palatable to elephants (Boshoff and Kerley, 2001).
The fynbos biome, despite having a number of historic and
prehistoric occurrences (Fig. 3), is one area considered marginal
within the elephant range (Boshoff and Kerley, 2001). But one
problem to study elephant interaction with fynbos is that there are
currently no parks with elephants in this part of South Africa,
where preferences for plant foods can be observed. Nonetheless,
based on the movements and tracking of Knysna elephants, it is
known that some elephants come out of the forest graze in the
opening areas with fynbos vegetation (Seydack et al., 2000;
Milewski, 2002a, 2002b). One study found that elephants
preferred a species of Leucadendron (a shrub of the Proteaceae
family) and Bobartia (a bulb of the Iridaceae family), and plants
grown after re, particularly grasses and grasslike [sic] plants
(Milewski, 2002b: 32). This suggests that Restionaceae, a grasslike
plant, could be eaten. But in another publication the same author
stated that observations on their fynbos plant preferences did not
include restios (Milewski, 2002a). This contrasts with the ndings
in our study, since several of the calculus samples from elephants
found the fynbos area produced Restionaceae phytoliths, including
sample SMEH-1 from the Knysna region (Table 1). Other samples
that produced Restionaceae phytoliths include the historic speci-
mens from the fynbos areas around Stilbaai (STB-1) and Port Eliz-
abeth (SMEH-4), one specimen from the pre-park Addo Bush
(SMEH-2), and the prehistoric specimens from Elandsfontein (SME-
1, 2 &3) (Table 3;Fig. 14).
Most fynbos types are poor in grasses (Rebelo et al., 2006), a
matter that is also reected in the phytolith assemblages in modern
surface soil samples from the fynbos region, in which not only the
Fig. 11. Pilanesberg National Park Game Reserve phyttoliths from teeth and surface soil samples. Percentages.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 17
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
number of Restionaceae phytoliths exceeds the number of Poaceae
phytoliths, but also the non-graminoid ratio is usually above 1.5
(Fig. 8). The presence of Restionaceae phytoliths in almost all the
dental calculus samples from the south and west coast (Fig. 14)
suggests that in their diets elephants in the fynbos areas may have
substituted grasses with restios.
6.3. The case of elephants in parks and reserves
The results of our study shows differences in the dental calculus
across vegetation areas and between free-roaming and modern
park elephants, emphasizing the potential for distinguishing
elephant habitats or changing ecologies through the study of diets.
In addition to direct observation, one frequent method used in
parks for monitoring elephant diets is through plant remains in
dung. In the AENP, a study of plant remains in elephant dung
showed that the summer and winter diets were dominated by
grasses and shrubs, respectively, and that the overall grass diet is
36e38% with the rest composed of forbs, succulents, and shrubs
(Paley and Kerley, 1998). Interestingly, that observation is not much
different than the composition of plant groups in the dental phy-
tolith assemblages of the four AENP specimens, in which the total
graminoid (i.e., mainly grass) vary between 40% and 45%of the total
number of phytoliths (Fig. 13). However, one has to account that
there are plants that are invisible in phytoliths, and that many non-
graminoids produce different amounts than grasses.
According to the plant remains in dung, the grass preferentially
consumed by the AENP elephants in the AENP dung is Cynodon
dactylon (Chloridoideae), which accounted for the 29% of all the
plant weight in the dung (Paley and Kerley, 1998,Table 1). In the
same tally, the other only grass reported is Panicum deustum with
3.4% of the total plant weight. The dominance of C. dactylon in the
dung corresponds with the predominance of chloridoid saddles in
the phytolith assemblages from dental calculus, which for the three
of the four specimens is 32%, 30%, and 24% (Fig. 16). In contrast, the
panicoid bilobates and crosses make up for 1.3% and 0.9% in only
two of the four specimens (Fig. 16). This comparison is suggestive of
the potential use of this technique for studying habitat preferences
of elephants in different sections of a park, or as shown here, be-
tween park elephants and their free-roaming ancestors.
6.4. Potentials and limitations for elephant diet reconstruction
The study of large herbivore paleodiets is an important aspect of
Quaternary paleoecological research because of the broad impli-
cations regarding changing climates, plant-herbivore relationships,
and even animal behavior. The most widely used method for
reconstructing dietary patterns on modern and past animal pop-
ulations is the application of stable isotopes on dental enamel and
other faunal remains. The stable isotopes of carbon provide a
general picture of diet, particularly distinguishing C
3
from C
4
plants
(Vogel et al., 1990; Van der Merwe et al., 1998; Cerling et al., 1999;
Fig. 12. Addo Elephant National Park. Phytoliths from teeth and surface soil samples. Counts.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e2318
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
Luyt et al., 2000; Hoppe, 2004; Radloff et al., 2010). In tropical
forests and savanna environments where the C
3
/C
4
division often
corresponds to the tree/grass division this method is greatly useful.
However, phytolith research on dental calculus can add informa-
tion to stable isotope studies by delineating the divisions between
the different C
4
grass subfamilies. Additionally, in temperate areas
it can also add information on the incidence of C
3
grasses.
One aspect to consider regarding the reconstruction of herbi-
vore paleodiets is that not all phytoliths embedded in dental cal-
culus originate from plants eaten by the animal. Although there are
no studies addressing this problem, one still has to assume that
while most phytoliths are incorporated in the plaque from plant
foods, some may also enter through indirect pathways such as soil
grit mastication and drinking water. But even if this is the case, the
signature of each vegetation type may be recorded as most phy-
toliths acquired via these other pathways are local to a particular
habitat.
Despite the potential contributions of dental calculus phytoliths
to conservation ecology and paleoecology, it is important to
acknowledge their limitations. First, not all plants produce diag-
nostic phytoliths (Piperno, 2006), which means that many plant
groups would be invisible in the record. Second, dental calculus
Fig. 13. Addo Elephant National Park. Phytoliths from teeth and surface soil samples. Percentages.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 19
Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
Fig. 14. Free roaming elephants and Addo Elephant NP (ADE) phytolith summaries. Counts.
Fig. 15. Free roaming elephants and Addo Elephant NP (ADE) GSSC. Counts.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e2320
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
may not preserve well in all environments, which may mean fewer
counts or no data at all. Third, the number of phytoliths could be
highly variable between samples, which can be a problem when
comparing cohort groups.
In this study, the best preservation and numbers were obtained
from the reserve elephants at the PNPGR and the AENP because
these are from animals that died recently, and in most cases the
specimens were kept protected from exposure to the elements.
Other well preserved material came from the specimens from the
Albany and East London area, which seem to have been well-
preserved since the time of the shooting of animals. Many of the
specimens date to more recent times, probably the 1800s (Carl
Vernon, personal communication). Nevertheless, some older
specimens do preserve well, as is the case of the samples from the
Pleistocene Elandsfontein elephants.
One possible approach to dental calculus samples with low
numbers of phytoliths can be overcome by combining cohort
samples from herds the same age from one particular site. In
paleontological sites where death traps exist, it is possible some-
times to look at individuals as a group, as is the case of data from
the Hot Springs Site in South Dakota, USA (Cordova and Agenbroad,
2009). In archaeology, kill sites often provide a number of animals
Fig. 16. Free roaming elephants and Addo Elephant NP (ADE) phytolith summaries and GSSC. Percentages.
C. Cordova, G. Avery / Quaternary International xxx (2017) 1e23 21
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Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
that can be grouped as a single sample. For example, the Elands-
fontein elephants could be grouped as one cohort if they were to be
compared with elephants of the same age in another site.
7. Conclusions
Despite the small number of samples and phytoliths in some
samples, the study of dental calculus phytoliths presented here
points to some preliminary information about elephant ecology in
the Cape Region of South Africa. First, phytolith assemblages in
dental calculus and permitted differentiation between elephant
species in the fynbos area from those of the subtropical thicket-
savanna-grassland-forest mosaic of the east. Second, the results
of this research show that free-roaming elephants grazed a wide
array of graminoids (C
3
and C
4
grasses, restios, and sedges). Third,
the results also showed that, as expected, park elephants have less
rich assemblages of phytoliths than the free-roaming specimens
collected in the same region. These results suggest that phytoliths
embedded in dental calculus constitute a valuable, yet unexplored
record of ecological information, particularly on the extent of the
species range and habitats.
Finally, the application of dental calculus phytoliths may yield
important components of diets when undertaken in tandem with
direct observations and other dietary studies (e.g., stable isotopes).
This approach can be applied to a range of herbivores recovered
from arcaheological and paleontological sites, whenever dental
calculus is preserved, as well as modern specimens. Although the
dental calculus approach was developed for studying elephant
paleoenvironnments (including paleodiets) of extinct herbivores it
could be applied to long-term studies of wildlife conservation.
Acknowledgments
We thank the SANParks for permission and support for work at
the Addo Elephant National Park; John Adendorf (AENP) and Nav-
ashni Govender (Kruger National Park) provided scientic assis-
tance and suggestions. Staff of the Pilanesberg National Park &
Game Reserve assisted with the sampling of soils and elephant
teeth at the reserve.
Staff at Iziko South African Museum are thanked for their sup-
port, in particular Denise Hamerton for help locating historic
specimens in the museum. We also thank the late Brian Mathiesen
of the local museum at Still Bay, and Juandr
e Kotz
e of the local
museum at Citrusdal.
Lizette Moolman (SANParks), Professor Graham Kerley and Dr
Andr
e Boshoff (Center for African Conservation Ecology, Nelson
Mandela Metropolitan University) are thanked for their comments
and support. Pierre Koekemoer assisted during eldwork. Finally,
we would like to thank the guest editors and the anonymous re-
viewers for their comments and suggestions.
This study was supported by grants from the National Endow-
ment for the Humanities (NEH-ACOR 2006-2007) via the American
Center for Oriental Research (Amman, Jordan), and grants from the
College of Arts and Sciences, Oklahoma State University (ASR Travel
FY 2008).
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.quaint.2016.12.042.
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Please cite this article in press as: Cordova, C., Avery, G., African savanna elephants and their vegetation associations in the Cape Region, South
Africa: Opal phytoliths from dental calculus on prehistoric, historic and reserve elephants, Quaternary International (2017), http://dx.doi.org/
10.1016/j.quaint.2016.12.042
... Dental calculus accumulation is progressive, thus diverse food micro-remains, including phytoliths, starch and pollen grains, spores, plant tissues, and non-dietary elements, such as sponge spicules, diatom frustules, soil debris, among others, can be preserved in its matrix (Middleton and Rovner, 1994;Henry and Piperno, 2008;Henry, 2012). These elements might resist the fossil diagenesis process, and can be retrieved from fossil specimens (Gobetz and Bozarth, 2001;Scott-Cummings and Albert, 2007;Cordova and Avery, 2017;Asevedo et al., 2012Asevedo et al., , 2020. Therefore, plant microfossils may provide unique and direct information regarding the potential dietary items consumed by the species in deep-time (Henry and Piperno, 2008;Henry, 2012;Strömberg et al., 2018). ...
... Nevertheless, phytoliths are more frequently reported in fossilized dental calculus of extinct mammals. They have been used to interpret feeding patterns of ungulates (Bozarth and Hofman, 1998;Gobetz and Bozarth, 2001;Strömberg et al., 2018), proboscideans (Gobetz andBozarth, 2000, 2001;Scott-Cummings and Albert, 2007;Asevedo et al., 2012Asevedo et al., , 2020Cordova and Avery, 2017;González-Guarda et al., 2018;Wu et al., 2018;Cammidge et al., 2020), and primates (Ciochon, 1990), including early hominins (Henry et al., 2011. ...
... The over-represented phytoliths in the M. patachonica dental calculus agrees with previous studies of herbivorous mammals, where phytoliths were widely identified supporting their dietary interpretations (Armitage, 1975;Middleton and Rovner, 1994;Gobetz and Bozarth, 2001;Cordova and Avery, 2017;González-Guarda et al., 2018;Strömberg et al., 2018). Phytoliths are opaline bodies (i.e., amorphous silica) produced by plants which absorb silica from the soil and accumulate it between and inside their cells and tissues (Piperno, 2006). ...
Article
Macrauchenia patachonica Oiwen, 1838 is a native and extinct Quaternary megamammal from South America. Although studies on macraucheniids started two centuries ago, when Darwin found their first fossils, M. patachonica paleobiology is still poorly understood. Dental calculus is an oral pathology that fossilizes and the analysis of its contents is a useful, simple, and low-cost method to access paleobiological information of fossil mammals. Here, the paleodiet of an adult M. patachonica from Buenos Aires province, Argentina, was assessed using quantitative and qualitative analyses of dental calculus content. The sample was chemically processed and many phytoliths, palynomorphs, sponge spike fragments, and diatom frustules were recovered. Both herbaceous phytoliths (49%) and eudicotyledons (35.4%) were well represented. These results support, for this individual, a mixed feeding habit, including consumption of C3 and C4 plants composed of tree/shrub plants and C3/C4 grasses, although C3 could have been more significant. Dental calculus provided direct evidence of paleodiet elements of an extinct South American native mammal for the first time, and such data might support broader paleoecological, paleoenvironmental, and evolutionary studies.
... Cyperaceae morphotypes include the typical achenes (i.e, hats) and papillae of Piperno (2006) and a number of other morphotypes (cf. Cordova and Scott, 2010;Cordova, 2013;Cordova and Avery, 2017;Esteban et al., 2017aEsteban et al., , 2017bMercader et al., 2010;Novello et al., 2018). Nonetheless, other plants including the Restionaceae (cf. ...
... Non-graminoid phytoliths include those most commonly referred to as woody plants such as globular, facetates, and woody-plant tracheids (cf. Esteban et al., 2017aEsteban et al., , 2017bCordova and Avery, 2017;Novello et al., 2018). As graminoids produce more morphotypes, the non-graminoid-tograminoid ratio is meant to represent the proportions of plants that do not belong to grass-like plants and in general, it provides an idea of closed shrub canopy versus open grassy spaces. ...
... The C 4 groups include the Chloridoideae types such as the short and double saddles (9A and 9B), typical Panicoideae types such as bilobates (10-K, 10-W) and crosses (11-A), and the Aristidoideae types (10-A and 9-M). Additionally, the tall, plateau saddle (9F) is included here as being one of the main components of Phragmites australis, although it is also reported in other grasses (Cordova, 2013;Cordova and Avery, 2017). ...
Article
A multi-proxy approach conducted on a sediment core from a small lake in the Cape Flats (Princessvlei, South Africa), supported by five AMS dates, reveals the paleoenvironments over the last 3900 years. Despite some gaps in the records, phytoliths, diatoms, δ¹⁸Odiatom, pollen, coprophilous fungus spores, microscopic charred particles (micro-charcoal), and burnt-grass phytoliths, indicate vegetation disturbances caused by climatic changes, anthropogenic influences, fire, and herbivore activity. Pollen spectra indicates a moist period (3600-2600 cal yr BP), which co-occurs with an increase in fires, possibly due to greater biomass fuel loads coupled with the moderate presence of large herbivores. Subsequently, a dry period (2600-1900 cal yr BP) saw a rapid increase of large herbivores probably congregating around the lake, a contention supported also by the occurrence of nutrient-rich waters. This dry period saw reduced fires and a decline of C3 grasses in favor of C4 grasses. The arrival of herders in the Cape after 2000 cal yr BP is not immediately apparent in the multiple records, except for minor vegetation changes and regional fires c. 1200–1400 cal yr BP. However, a more consistent presence of livestock in the immediate area of Princessvlei occurs only after c. 600 cal yr BP, when peak frequencies of coprophilous spores coincide with changes in vegetation composition and occurrence of more eutrophic waters in the lake. The introduction of exotic flora, fire suppression, and a reduction of herding activities, characterizes the period of European settlement (c. 300 BP to present).
... Major changes began when archaeologists started focusing on human dental calculus, which degrades more swiftly than its animal counterpart. The study of animal dental calculus expanded its use to other species (such as elephants and ancient mastodons), but continued to focus on phytoliths (Gobetz and Bozarth 2001;Cordova and Avery 2016). One of the first attempts to extend the use of calculus degradation into humans was in 1996 when Fox, Juan, and Albert modified Middleton and Rovner's dental wash methodology for use on Roman-Era human skeletons. ...
... One of the most recent and relevant studies in this review is Cordova and Avery's (2016) article on degrading the dental calculus on African Savannah Elephants. The authors use both modern and historic specimens and use a very different protocol than what is currently employed for human dental calculus. ...
... They found differences of diversity within the phytoliths which correlated with the elephants roaming patterns. They also noted that modern elephants in Addo Elephant National Park show less diversity of grass phytoliths than their historic counterparts which roamed the same area (Cordova and Avery 2016). This paper serves as an excellent example for this dissertation both because they are also focusing on herbivores as well as producing a unique methodology that strongly contrasts those currently used to degrade human dental calculus. ...
Thesis
Full-text available
Animal dental calculus is capable of storing valuable information about palaeodiet and palaeoecology. Despite this, it has been understudied in the past 20 years and its protocols have been surpassed in efficiency by efforts to degrade human dental calculus. Studies that focus on human dental calculus have been able to quickly degrade the calculus matrix and also render a greater variety of microfossils than contemporary studies in animal dental calculus. This dissertation begins by surveying how and why the methodologies to degrade dental calculus have altered over the years and then shift to creating its own. A large dental calculus sample taken from a Roman-era cattle mandible from the Whitefriars excavation is subdivided in order to test twelve deflocculation and degradation protocols. Each sample is manually viewed and photographed underneath a microscope and compared to one another in regard to degradation efficiency, microfossil quantity, and the quality of said microfossils. There were some errors in the mounting of the degraded calculus samples onto slides, but the results are promising. It appears that animal dental calculus degrades more quickly and thoroughly when submerged in higher strengths of hydrochloric acid (HCL) and/or is ground, despite initial hypothesizes that assumed it would react better to lower levels, similar to human dental calculus. Although this study was unable to produce more delicate microfossils such as starch granules or insect remains, it is difficult to know whether it is due to the protocol or an absence in the original material. This study was able to successfully degrade animal dental calculus and will serve to hopefully resume progress in a field whose methodology has stagnated.
... In the phytolith assemblage of 13.7-12.9 ka, the high incidence of non-graminoids (woody and shrubby vegetation), abundant Restionaceae and relatively low proportions of Poaceae imply a dominance of fynbos vegetation (Cordova, 2013;Cordova and Avery, 2017). Distinctively, the burnt grass phytoliths count is lower. ...
... This could be a type of grassy fynbos like the ones found farther east (cf. Rebelo et al., 2006) or the amplification of the renosterveld (Stoebe type), which normally has more grasses (Cordova, 2013;Cordova and Avery, 2017). However, given the incidence of Panicoideae, it is possible that increased summer rain prompted more lightning-initiated fires, as it currently occurs in areas of fynbos farther east, thus promoting the spread of grasses and the decline of Ericaceae and Thymeleaceae. ...
Article
To address long-standing questions concerning Southern Hemisphere climate dynamics and palaeoecological change in southern Africa, a Late Glacial-Holocene alluvial sediment sequence from the relatively dry interior year-round rainfall zone in South Africa was investigated. The study site borders the Fynbos biome and Succulent Karoo biome ecotone, and comprises a rare stratified sequence of sandy and organic-rich silt deposits, shown to span the last 14,000 years. A high resolution multi-proxy record of ecological change was derived using pollen, phytoliths and organic geochemical analyses. For the period 14–11 ka, significant valley aggradation occurred under relatively drier conditions, followed, during the early and middle Holocene, by alternating phases of humid and dry events with higher stream energy, slower accumulation or subtle seasonality changes. A transition from relatively humid to more arid conditions at 4–3 ka is identified and is consistent in timing with several interior year-round rainfall zone records. Results revealed alternations of fynbos and karroid elements and C3/C4 grasses throughout the last fourteen thousand years, but did not suggest large-scale biome shifts. The record joins a growing number of sites contributing to debate over the complex atmospheric-oceanic drivers of palaeoclimate in this region. These data broadly fit to the regional pattern for the southernmost interior of South Africa in showing alternating influences from the westerly winter rain systems in the early Holocene, with a greater contribution from subtropical summer rain system during the middle and later Holocene.
... Accumulation is progressive, thus diverse food micro-remains, including phytoliths, starch grains, pollen, spores, plant tissues, and non-dietary elements such as sponge spicules, diatom frustules, among others can be preserved in the matrix (Middleton and Rovner, 1994;Gobetz and Bozarth, 2001;Asevedo et al., 2012;Power et al., 2014). Even after fossilization, tartar, when present, may preserve elements that indicate what was ingested during a span of time when the tooth was used by the animal (Gobetz and Bozarth, 2001;Weber and Price, 2016;Cordova and Avery, 2017). ...
... Among the plant micro-remains that can be recovered from calculus in fossilized teeth, phytoliths have been widely used for diet reconstructions of herbivorous mammals. Fossil phytoliths in calculus have been used to interpret feeding patterns in ungulates (Bozarth and Hofman, 1998;Gobetz and Bozarth, 2001;Strömberg et al., 2018), primates (Henry, 2012) and also proboscideans Bozarth, 2000, 2001;Scott-Cummings and Albert, 2007;Cordova and Avery, 2017;González-Guarda et al., 2018). ...
... Plant microremains in dental calculus can provide direct information on feeding habits (Cordova and Avery, 2017) and a longterm dietary signal (Weyrich et al., 2017). The period involved in formation of dental calculus has not yet been established because the formation processes and their composition can be highly variable between and within individuals (Power et al., 2015). ...
Article
Stable isotopes are a powerful tool for reconstructing the past. However, environmental factors not previously considered can lead to misinterpretations. Our study presents a novel analysis of the feeding behavior of the megafauna that inhabited the Pilauco ecosystem in south-central Chile during the last glacial termination. We analyzed a suite of modern plant and animal samples from closed-canopy forests to establish an isotopic baseline with which to compare stable isotope results from fossil megafauna. Using the modern samples as a reference, the δ ¹³ C results from the Pilauco megafauna indicate feeding behaviors in forested areas. These results were then calibrated with dental calculus samples and coprolites, which suggest the coexistence of graze- and grass-dominated mixed-feeder diets. The δ ¹⁵ N values found in Pilauco megafauna are not consistent with modern reference data sets or with the low δ ¹⁵ N values of extinct proboscideans from other contemporaneous and nearby sites. Probably, the δ ¹⁵ N values of the Pilauco ecosystem were not primarily affected by climate, but rather by disturbance factors (e.g., grazing effect). Our results indicate that the Pilauco megafauna fed mainly on arboreal vegetation; however, non-isotopic proxies indicate that they were also eating open vegetation (e.g., herbs and grasses).
... Food ingestion is involved in the oral microbial flora formation which can lead to biofilm formation, dental plaque and calculi, as reported in humans and carnivores (Avila, Ojcius, & Yilmaz, 2009;Brealey, Leitão, Xu, Dalén, & Guschanski, 2019;Haberstroh et al., 1984;Harvey, Serfilippi, & Barnvos, 2015;Hyde et al., 2014;Strużycka, 2014;Wade, 2013). Similar dental disorders have also been reported in herbivorous mammals such as cattle (Bos Taurus) (Dent & Williams, 1984), sheep (Ovis aries) (Unmack & Rowles, 1963), pigs (Sus domesticus) (Andrews, 1973;Tucker & Widowski, 2009), miniature pigs (Weaver, 1964), elephants (Loxodonta africana) (Fagan et al., 2020;Cordova & Avery, 2017), lama (Lama glama), yak (Bos grunniens), and bennett's wallaby (Protemnodon rufogrisea) (Dent, 1979). ...
Article
Full-text available
Objective The present review aims to: a) describe the features that support tusks in extra-oral position, and b) represent distinctive features of tusks, which provide insights into tusks adaptation to ambient conditions. Design A comprehensive review of scientific literature relevant to tusks and comparable dental tissues was conducted. Results The oral cavity provides a desirable condition which is conducive to tooth health. Therefore, it remains questionable how the bare (exposed) tusks resist the extra-oral conditions. The common features among tusked mammals indicate that the structural (e.g. the peculiar dentinal alignment), cellular (e.g. low or lack of cell populations in the tusk), hormonal (e.g. androgens), and behavioral traits have impact on a tusk’s preservation and occurrence. Conclusions Understanding of bare mineralized structures, such as tusks and antlers, and their compatibility with different environments, can provide important insight into oral biology.
... African elephants are mixed feeders, with a selective and adaptive feeding regime that varies both spatially and seasonally from mostly woody browse to mostly grasses [13][14][15]. Fynbos shrublands are naturally lacking in both grass and tree elements, and recent investigations into opal phytoliths in dental calculus from historical free-roaming African elephants suggest that grazing on Restionaceae was important to the elephant diet in the CFR [16]. Recently, the burgeoning wildlife and tourism industry in the Western Cape has seen large herbivores such as the African elephant being reintroduced into newly created reserves in the CFR [17], with little information on how these animals are responding to this environment. ...
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Fynbos is a unique endemic vegetation type belonging to the Cape Floral Kingdom in the Western Cape Province of South Africa, representing the smallest of the six floral kingdoms in the world. Nowadays, only a few game reserves in this region support populations of African elephants (Loxodonta africana), and thus, little information exists regarding the suitability of the nutritionally poor Fynbos vegetation for these megaherbivores. Using already established non-invasive methods, the monitoring of individual body conditions and fecal glucocorticoid metabolite (fGCM) concentrations, as a measure of physiological stress, was performed to examine a herd of 13 elephants in a Western Cape Province Private Game Reserve, during two monitoring periods (April and June 2018), following a severe drought. The results indicate that overall median body condition scores (April and June: 3.0, range 2.0–3.0) and fGCM concentrations (April: 0.46 µg/g dry weight (DW), range 0.35–0.66 µg/g DW; June: 0.61 µg/g DW, range 0.22–1.06 µg/g DW) were comparable to those of other elephant populations previously studied utilizing the same techniques. These findings indicate that the individuals obtain sufficient nutrients from the surrounding Fynbos vegetation during the months monitored. However, a frequent assessment of body conditions and stress-associated fGCM concentrations in these animals would assist conservation management authorities and animal welfare practitioners in determining ways to manage this species in environments with comparably poorer nutritional vegetation.
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