Article

High prevalence of enamel hypoplasia in an Early Pliocene giraffid (Sivatherium Hendeyi) from South Africa

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Abstract

Almost two thousand mandibular teeth of the short-necked giraffid, Sivatherium hendeyi, from Lange-baanweg, South Africa, were examined for dental pathologies. Enamel hypoplasia is present in 0 to 34 percent of deciduous teeth and 40 to 75 percent of permanent teeth. No linear enamel hypoplasias were found in the deciduous teeth, while 20 to 35 percent of the permanent teeth have this defect. The linear defects at the base of the first molar are thought to relate to stress associated with weaning. The defects in the later erupting permanent teeth are, however, widely distributed over tooth crowns. Several linear defects are present on some teeth suggesting that these stress episodes were periodic. We propose that poor environmental conditions, possibly seasonal nutritional stress, are responsible for the observed enamel hypoplasia in the permanent dentition of S. hendeyi. This study provides new insight into the current understanding of the paleoenvironment at Langebaanweg, South Africa.

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... EH has been used as a marker of physiological stress (Mead 1999) and environmental stress (Roohi et al. 2015) faced by extinct rhinocerotids. According to Franz-Odendaal et al. (2004), linear enamel hypoplasia (LEH) is a type of EH that can provide a unique perspective into vegetational and environmental conditions present during an extinct animal's life. All these descriptions indicate that LEH can be a good source to trace out the ecology of the Middle Miocene Siwalik rhinocerotids. ...
... Along with the described Brachypotherium (family Rhinocerotidae) specimens, the dental remains of the other families, i.e., Bovidae, Giraffidae, and Suidae, from the Middle Miocene Siwaliks of Pakistan are also used for current comparative EH analysis. For enamel hypoplasia analysis, the classification and methodologies used by Mead (1999), Franz-Odendaal et al. (2004), Roohi et al. (2015), and Ahmad et al. ...
... EH marks are not found on most of the analyzed specimens from the Middle Miocene Siwaliks of Pakistan (see Electronic supplementary material). So, as EH can be a proxy for ecological stress (Franz-Odendaal et al. 2004), current EH results also indicate the stability of the Middle Miocene Siwalik ecosystems for prehistoric mammals. The current comparative EH results have traced out that rhinocerotid samples have the least occurrence of EH among the other analyzed mammalian taxa (Fig. 8) that indicates that the Middle Miocene Siwalik habitats are most suitable for the rhinocerotids as compared to other mammals specially ungulates. ...
Chapter
New dental remains of rhinoceros species have been discovered from the Middle Miocene deposits of the Siwaliks of Pakistan. The specimens have been identified as Brachypotherium perimense and Brachypotherium fatehjangense based on their comparative morphometric analysis. The hypsodonty and thick enamel of the studied samples are the indicators of the presence of grazing community feeding on coarse grasses during Middle Miocene times in the Siwalik region. This newly discovered dental material adds up additional information about the Middle Miocene faunal composition of family Rhinocerotidae that can play role in tracing out the community structure during this epoch in the Asian region. The ecological implications of the Brachypotherium genus towards the changing Middle Miocene climatic condition on the basis of enamel hypoplasia is also discussed in this article.
... EH has been used as a marker of physiological stress (Mead 1999) and environmental stress (Roohi et al. 2015) faced by extinct rhinocerotids. According to Franz-Odendaal et al. (2004), linear enamel hypoplasia (LEH) is a type of EH that can provide a unique perspective into vegetational and environmental conditions present during an extinct animal's life. All these descriptions indicate that LEH can be a good source to trace out the ecology of the Middle Miocene Siwalik rhinocerotids. ...
... Along with the described Brachypotherium (family Rhinocerotidae) specimens, the dental remains of the other families, i.e., Bovidae, Giraffidae, and Suidae, from the Middle Miocene Siwaliks of Pakistan are also used for current comparative EH analysis. For enamel hypoplasia analysis, the classification and methodologies used by Mead (1999), Franz-Odendaal et al. (2004), Roohi et al. (2015), and Ahmad et al. ...
... EH marks are not found on most of the analyzed specimens from the Middle Miocene Siwaliks of Pakistan (see Electronic supplementary material). So, as EH can be a proxy for ecological stress (Franz-Odendaal et al. 2004), current EH results also indicate the stability of the Middle Miocene Siwalik ecosystems for prehistoric mammals. The current comparative EH results have traced out that rhinocerotid samples have the least occurrence of EH among the other analyzed mammalian taxa (Fig. 8) that indicates that the Middle Miocene Siwalik habitats are most suitable for the rhinocerotids as compared to other mammals specially ungulates. ...
Article
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Newly discovered rhinocerotid remains from the Middle Miocene (14.2–11.2 Ma) of the Siwaliks of Pakistan are described in this paper, adding new data to the existing rhinocerotid fossil record from the Siwalik region. The specimens are identified as belonging to a teleoceratine genus Brachypotherium on the basis of morphometric comparison with the previously known rhinocerotid specimens from the Siwaliks as well as other biogeographic regions. The article provides additional information on the systematics through the dental morphological comparison of the genus Brachypotherium and in particular of Brachypotherium perimense and Brachypotherium fatehjangense. The data indicate an increased teeth size and dental morphological variations in B. perimense by changing environment from the Middle to Late Miocene and morphological differences in B. fatehjangense from B. brachypus. Also, an attempt has been made to clarify the dental morphological differences among different Middle Miocene rhinocerotid species of the Siwaliks. The hypsodonty and thick enamel of the studied samples indicates the presence of grazing communities feeding on coarse grasses during the Middle Miocene of the Siwaliks. The ecological implications of the genus Brachypotherium toward the changing Middle Miocene climatic conditions on the basis of stable isotope and enamel hypoplasia analyses are also discussed. The results of these proxies indicate that the Brachypotherium perimense preferred woodland and ponds, while B. fatehjangense lived in a more forested environment with river system. The transitional pattern of the Middle Miocene Siwaliks of Pakistan from dry to more precipitation and humidity might had some more ecological pressure on B. fatehjangense than on B. perimense.
... The studies about EH in extinct and extant species of ungulates have been carried out by different researchers in order to trace out the environmental conditions these species faced during their developmental and growth period (Franz-Odendaal, 2004;Franz-Odendaal et al., ...
... Fig. 1. A, hypothetical tooth demonstrating the process of enamel formation (Goodman and Rose, 1990;Franz-Odendaal et al., 2004); B, diagrammatic representation of giraffid molar. The vertical arrow indicates the direction of crown development (addition of enamel) from tip to base. ...
... In case EH was an inherited disorder in extinct giraffids, than the animal having inherited EH should have all teeth showing signs of EH (Stewart and Poole, 1982;Franz-Odendaal et al., 2004). In this study occurrence of EH was observed in six out of seven jaw fragments. ...
Article
Full-text available
Studies on dental enamel hypoplasia have been used by different paleontologists as stress indicator in evaluation of palaeo-environments. The present study involves the analysis of enamel hypoplasia in seven extinct giraffid species to determine and compare stress periods during the early Miocene to Pleistocene ages of the Siwaliks of Pakistan. Enamel hypoplasia is a tooth malady which is caused by the deficiency of food/nutrients. The feeding deficiency is directly linked to the physiological or environmental stress. In this study occurrence of enamel hypoplasia in giraffids has been observed in species of all time intervals between 18.3-0.6 Ma except the time 11.2-9.0 (late Miocene) that has no giraffids with this dental defect. The comparative percentage for occurrence of enamel hypoplasia in giraffids of these Siwalik deposits is early Miocene-early middle Miocene (29%), middle Miocene (20%), late Miocene-early Pliocene (15%), early Pliocene-late Pliocene (26%) and late Pliocene-early Pleistocene (10%). Prevalence of enamel hypoplasia indicates the existence of stress episodes and percentage displays the comparative intensity of these stresses in the Neogene and Quaternary period of the Siwalik region. These stress episodes are due to the climatic, vegetational, ecological and faunal changes during these time spans. These early Miocene to Pleistocene stress events may have played a key role in evolution and speciation of the Siwalik fauna especially the mammals.
... Ameloblasts (enamel forming cells) are highly sensitive so their formation can be depleted by the stresses faced by an animal during its tooth development. The enamel is the hardest tissue of the body with no remolding in it so marks of EH once formed on tooth enamel will persist forever even if the affected tooth had been fossilized (Goodman and Rose, 1990;Franz-Odendaal et al., 2004). Keeping in view all these facts EH has been used by different researchers as a credible stress marker for different extinct mammalian groups i.e. ...
... Keeping in view all these facts EH has been used by different researchers as a credible stress marker for different extinct mammalian groups i.e. Pleistocene hominids (Molnar and Molnar, 1985), Pleistocene Neanderthals (Trinkaus, 2018), early Miocene primates (Lukacs, 2001), early Pliocene grazers and browsers (Franz-Odendaal et al., 2003), Pliocene giraffids (Franz-Odendaal et al., 2004), Miocene rhinocerotids (Mead, 1999;Böhmer and Rössner, 2018), Siwalik rhinocerotids (Roohi et al., 2015), Siwalik giraffids (Ahmad et al., 2018). There is no report about occurrence of EH in any extinct tragulid species from the Neogene or Quaternary deposits globally even though these are ecologically significant ungulates. ...
... There can be different etiologies for these types of EH i.e. birth trauma, metabolic and nutritional disorders, infections, exposures to toxic chemicals (Seow, 1991), rickets (Nikiforuk and Fraser, 1981), low birth weight (Slayton et al., 2001), poor health status of the mother (Armelagos et al., 2009), nutritional conditions of an area (El Najjar et al., 1978;Ogilvie et al., 1989), general physiological stress (Guatelli-Steinberg et al., 2004), weaning stress (Mead, 1999), post weaning stress Abbreviations PUPC, Punjab University Paleontological Collection; T7, The 7 th tragulid specimen specifically collected for current LEH analysis. (Moggi-Cecchi et al., 1994), nutritional and/or environmental stress (Franz-Odendaal et al., 2004). In the types of enamel hypoplasia, LEH is the most common type and its marks can macroscopically be observed on the enamel of living as well as fossilized dental remains. ...
Article
Full-text available
The present paper is the first ever report on occurrence of enamel hypoplasia in extinct tragulids. The dental defect, enamel hypoplasia is caused by suppressed function of enamel forming cells called ameloblasts. It is used as a reliable stress marker in different extinct mammalian taxa to trace out the level of ecological stress faced by these animals during their life histories. We have studied this defect in three extinct Siwalik tragulid species including; Dorcabune anthracotherioides, Dorcatherium majus and Dorcatherium minus. To assess habitat stability for the Neogene tragulids, dental remains from the middle Miocene-early Pliocene, ca. 13.5-4.0 Ma outcrops of the Siwalik of Pakistan were analyzed for the occurrence of linear enamel hypoplasia. According to our results there was a lower occurrence of enamel hypoplasia (13%) in the tragulid fossils from the middle Miocene outcrops (13.5-11.2 Ma) as compared to the late Miocene to the early Pliocene (11.2-4.0 Ma) tragulid remains (48%) which is statistically significant (p<0.05). The middle Miocene in the Siwaliks is hypothesized to have had warm and humid climatic conditions with dominance of dense forests whereas in the late Miocene to the early Pliocene there was a shift in the ecological conditions, with grasslands expanding at the expense of forests and woodlands and the climate gradually becoming less warm and humid. The current enamel hypoplasia results indicate that warm and humid dense forests were the preferred habitats for extinct tragulids present during the middle Miocene in the Siwaliks.
... Small horizontal linear pits and horizontal linear grooves are known as linear enamel hypoplasia. Linear defects have been associated with different systemic stressors (e.g., weaning, parturition, nutritional stress, and illness) at the time of tooth formation (Franz-Odendaal 2004;Franz-Odendaal et al. 2004). Some researchers consider that the width and depth of linear enamel hypoplasia correspond, respectively, to the duration of the stress episode and its severity (Goodman et al. 1980;Suckling 1989). ...
... These observations support the contention that similar tooth defects identified in the specimens that we assessed via direct observation corresponded to enamel hypoplasia. Only clearly defined, deep grooves were classified as enamel hypoplasia, following previous studies (e.g., Goodman and Rose 1990;Franz-Odendaal et al. 2004). ...
... Systemic and infectious diseases, severe fevers, premature births, parturition, weaning, parasite infestation, and intoxication with fluoride are some of the stressors linked to the development of enamel hypoplasia in mammals (Shearer et al. 1978;Shupe and Olson 1983;Skinner and Hung 1986;Suckling et al. 1986Suckling et al. , 1988Miles and Grigson 1990;Kierdorf et al. 1993Kierdorf et al. , 2000Kierdorf et al. , 2004Hillson 1996Hillson , 2005Larsen 1997;Dobney and Ervynck 2000). Inferring which stressor potentially caused enamel hypoplasia in a given individual cannot be accomplished without additional lines of evidence, such as knowledge of the diet and life history of the species under study (e.g., Dobney and Ervynck 2000;Franz-Odendaal et al. 2004;Niven et al. 2004). Therefore, the presence of enamel hypoplasia is more commonly treated as an indicator of overall health during tooth development. ...
Article
Approximately 50,000–11,000 years ago many species around the world became extinct or were extirpated at a continental scale. The causes of the late Pleistocene extinctions have been extensively debated and continue to be poorly understood. Several extinction models have been proposed, including two nutritionally based extinction models: the coevolutionary disequilibrium and mosaic-nutrient models. These models draw upon the individualistic response of plant species to climate change to present a plausible scenario in which nutritional stress is considered one of the primary causes for the late Pleistocene extinctions. In this study, we tested predictions of the coevolutionary disequilibrium and mosaic-nutrient extinction models through the study of dental wear and enamel hypoplasia of Equus and Bison from various North American localities. The analysis of the dental wear (microwear and mesowear) of the samples yielded results that are consistent with predictions established for the coevolutionary disequilibrium model, but not for the mosaic-nutrient model. These ungulate species show statistically different dental wear patterns (suggesting dietary resource partitioning) during preglacial and full-glacial time intervals, but not during the postglacial in accordance with predictions of the coevolutionary disequilibrium model. In addition to changes in diet, these ungulates, specifically the equid species, show increased levels of enamel hypoplasia during the postglacial, indicating higher levels of systemic stress, a result that is consistent with the models tested and with other climate-based extinction models. The extent to which the increase in systemic stress was detrimental to equid populations remains to be further investigated, but suggests that environmental changes during the late Pleistocene significantly impacted North American equids.
... An investigation of ~ 2000 mandibular teeth belonging to S. hendeyi showed that deciduous teeth were unaffected by linear enamel hypoplasia, whereas all permanent teeth had defects (Franz-Odendaal et al 2003). This finding indicates that throughout development of the adult dentition [which in extant giraffes commences pre-birth and ends at around 5–6 years (Hall-Martin 1976)] , unfavourable and stressful conditions were experienced. ...
... Hence weaning in S. hendeyi occurred at a similar ontogenetic period to extant giraffes. Defects towards the base of the m1 (Franz-Odendaal et al 2003) might be associated with weaning as in humans (Goodman and Rose 1990) and pigs from archaeological sites (Dobney and Ervynck 2000), but linear defects present in the rest of the permanent dentition cannot be attributed to this particular systemic stress. ...
Article
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A high prevalence of enamel hypoplasia in several herbivores from the early Pliocene Langebaanweg locality, South Africa, indicates general systemic stress during the growing years of life. The presence of several linear enamel hypoplasias per tooth crown in many teeth further suggest that these stress events may be episodic. The delta18O values along tooth crowns of mandibular second molars of Sivatherium hendeyi (Artiodactyla, Giraffidae) were used to investigate the cause of the stress events in this tooth type. Results show that weaning in this fossil giraffid occurred at a similar ontogenetic age to that in extant giraffes, and that the observed enamel hypoplasia towards the base of this tooth type manifested post-weaning. Further, high-resolution oxygen isotope analyses across S. hendeyi third molars suggest that the entire development of defective tooth crowns occurred under conditions of increased aridity in which the cool, rainy part of the seasonal cycle was missing. The high prevalence of this defect in many herbivores suggests that climatic conditions were not favourable. This study reiterates the value of stable isotope analyses in determining both the behaviour of fossil animals and the environmental conditions that prevailed during tooth development.
... Concerning m3, it is the last tooth to develop and erupt. Hypoplasia on the last molars has been correlated with seasonality in sheep (Upex and Dobney, 2012) and fossil giraffe (Franz-Odendaal et al., 2004). The most affected loci are variable depending on the species (Figure 9). ...
... Very few loci are affected for B. brachypus and H. beonense but they imply similar causes: stresses around birth (D4, m1/M1) and environmental stresses (m3, M2). It would be interesting to investigate the prevalence of hypoplasia in other taxa from Béon 1 to confirm the role of environment as a stressor and to compare sensitivity across more distant species, like what has been done for the Pliocene herbivores of Langebaanweg (South Africa; Franz-Odendaal et al., 2004). ...
... DEHs are among the most conspicuous, manifesting as a visible localized thinning or absence of enamel (Goodman and Rose, 1990;Guatelli-Steinberg, 2001). DEHs are caused by impaired enamel secretion, a symptom of severe nutritional (Ablett and McCance, 1969;Dobney and Ervynck, 2000), pathological (Suckling et al., 1983;Hillson, 1986;Rose, 1990, 1991) or environmental stress (Mead, 1999;Franz-Odendaal, 2004;Franz-Odendaal et al., 2004;Niven et al., 2004;Byerly, 2007;Wu et al., 2012). The morphology of DEH can vary with the degree of metabolic stress (Witzel et al., 2006), but DEH are easily identified in ungulates with exposed enamel surfaces, such as moose. ...
... The morphology of DEH can vary with the degree of metabolic stress (Witzel et al., 2006), but DEH are easily identified in ungulates with exposed enamel surfaces, such as moose. In wild ungulates, hypoplasias have been attributed to weaning and seasonal stressors in extant and extinct giraffids (Giraffa, Sivatherium) (Franz-Odendaal, 2004;Franz-Odendaal et al., 2004); bison (Bison bison) (Wilson, 1988;Niven et al., 2004;Byerly, 2007;Barrón-Ortiz et al., 2019); horses (Equus spp.) (Barrón-Ortiz et al., 2019); white deer (Odocoileus virginianus) (Davis, 2013); and caribou (Rangifer tarandus groenlandicus) (Wu et al., 2012). ...
Article
Full-text available
Food shortages can leave diagnostic, and in the case of the dentition, irreversible changes in mineralized tissue that persist into historical and fossil records. Consequently, developmental defects of tooth enamel might be used to track ungulate population irruptions or declines in resource availability, but dental tissue’s capacity for preserving historical population density changes has yet to be investigated in wild populations. We test the ability of macroscopic enamel defects, mandible, and metapodial lengths to track changes in the well-known insular moose population of Isle Royale National Park. Our study demonstrates that (1) a moose density threshold exists on the island above for which there is a significant decrease in mandible and metatarsus length and a concomitant increase in enamel hypoplasias; (2) food limitation has a more pronounced effect on male than female skeletal and dental growth; and (3) combined data from tooth enamel hypoplasias and bone lengths reflect the relative density of this ungulate population and should be broadly applicable to other ungulate osteological samples. Developmental defects in dental enamel were among the highest recorded in a wild population, and even during low-density intervals the population density of Isle Royale moose has been high enough to negatively impact skeletal and dental growth, indicating the comparatively poor health of this isolated century-old ecosystem.
... An environmental stress-induced enamel hypoplasia appears reasonable in the case of P. germanicus because the seasonality might have caused recurrent droughts that contributed to nutritional stress in the extinct rhinoceros. Similar incidences of enamel hypoplasia in deciduous and permanent teeth have been reported in a number of studies including extinct rhinoceroses (Mead, 1999;Roohi et al., 2015), giraffids (Franz-Odendaal, Chinsamy & Lee- Thorp, 2004), pigs (Dobney, 2000), sheeps and goats (Kierdorf et al., 2012), bisons (Niven, Egeland & Todd, 2004), notoungluates (Braunn, Ribeiro & Ferigolo, 2014), and primates (Skinner, 1996;Lukacs, 2001). ...
... Although it is not possible to deduce a large-scale climate change (drying and opening) on basis of a single dentary with enamel hypoplasia, this highlights the potential of analyzing a larger sample of teeth in order to evaluate the frequency of hypoplasia. For instance, poor environmental conditions associated with browser-habitat destruction may have resulted in the prevalence of enamel hypoplasia (Franz-Odendaal et al., 2004;Roohi et al., 2015). ...
... Onset, duration and intensity of stress episodes affecting enamel matrix secretion have frequently been inferred from the proportion of the tooth crown exhibiting enamel hypoplasia on macroscopic inspection. This approach has also previously been applied in Sivatherium hendeyi [1]. More recently it has, however, been demonstrated in extant mammals that a reliable assessment of the duration of stress episodes causing enamel hypoplasia can only be performed by using microscopic techniques [2]. ...
... This contrasts with the observation that 75% of the labial crown surface exhibited enamel hypoplasia. The reconstructed duration of 5 to 6 months for the stress period causing enamel hypoplasia is compatible with the hypothesis that the hypoplastic defects reflect the impact of seasonal nutritional stress in S. hendeyi [1]. As micro-and mesowear analyses suggest that the species was a browser [3] it may be assumed that it was more intensely affected by seasonal food shortage than grazers from the same environment. ...
Conference Paper
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High prevalence of enamel hypoplasia has previously been reported in Sivatherium hendeyi from the Early Pliocene of Langebaanweg and attributed to seasonally occurring nutritional stress. This study histologically analyzed two permanent Sivatherium incisors, one showing severe enamel defects, the other exhibiting normal enamel. On external inspection, about 75% of the labial crown surface of the former tooth showed pitting of the enamel, indicative of enamel hypoplasia. Analysis of a labio-lingual ground section of this tooth revealed the presence of a zone of altered enamel structure that was sandwiched between a cuspally located, earlier-formed (inner) and a cervically located, later-formed (outer) zone of normal enamel structure. This finding indicates that the period of secretory ameloblast disturbance was both preceded and followed by a period of normal secretory activity. In areas where the entire enamel layer exhibited structural alterations and a reduced thickness, the ameloblast had apparently been affected during the complete secretory stage of amelogenesis. Based on the recording of daily incremental enamel markings (laminations) in the pathological incisor, and of a reduction in enamel extension rate in cervical direction, we conclude that about 40% of crown formation time of the Sivatherium incisor exhibiting enamel hypoplasia had been affected by a stress event. This is compatible with the hypothesis that the enamel defect was caused by seasonal nutritional stress. Our results further indicate that it is not possible to reliably reconstruct the duration of stress periods affecting enamel formation based only on external inspection of tooth crowns.
... [2,7,14,15,16,24]). One type of hypoplastic defect, mostly termed linear enamel hypoplasia (LEH), has been widely used as an indicator of periods of generalized physiological stress during tooth development in hominid and non-hominid primates [7e10, 22,24,29,33,34], domestic pigs and wild boar [3,4] and other extinct or extant ungulate species [5,6,26,30]. These studies demonstrated that the analysis of LEH is a useful means for retrospective assessment of the timing and intensity of systemic stress events during the period in which an individual's dentition is formed, and can thereby contribute to the understanding of past ecological and health conditions. ...
Article
Full-text available
Prevalence and intensity of enamel hypoplasia have been used as markers of generalized physiological stress during dental development in a wide range of mammalian taxa. We studied cattle (Bos taurus) cheek teeth exhibiting morphological characteristics that are of relevance to the diagnosis of enamel hypoplasia in this and other bovid species. These characteristics were multiple, more or less horizontally arranged (waveform) lines or grooves in the cementum of the tooth crown and the adjacent root area, leading to an imbricated appearance of the cementum. On macroscopic examination of tooth surfaces, these lines resembled linear enamel hypoplasia (LEH). Microscopic analysis of tooth sections, however, revealed that the lines occurred in the cementum only, and that the underlying enamel did not exhibit morphological irregularities. In cheek teeth of older cattle, a thick cementum layer is regularly found in the cervical crown portion and the adjacent root area. Apposition of this cementum is related to the uplifting of the teeth from their alveoli, a process that compensates for the shortening of the tooth crowns due to occlusal wear. In the studied specimens, a pronounced periodic nature of tooth uplifting and the related deposition of cementum is the likely cause for the observed imbricated appearance of the cementum. While this phenomenon may be misinterpreted as representing a case of LEH, presence of enamel hypoplasia in bovid teeth may be overlooked when the defects become filled with coronal cementum and are therefore not apparent on external inspection. This was the case in one of the cattle teeth analyzed by us, in which the hypoplastic enamel defects were, however, clearly discernible in ground sections. Microscopic analysis of tooth sections is recommended for recording of LEH in bovid teeth in cases where macroscopic examination of tooth surfaces alone does not produce unequivocal results.
... We compiled the new carbon and oxygen isotope data from tooth enamel produced in this study from Elandsfontein and Langebaanweg with the published data from Langebaanweg (Franz-Odendaal et al., 2002), Elandsfontein (Luyt et al., 2000) and Hoedjiespunt (Hare and Sealy, 2013 ) to examine environmental and climatic changes in southwestern South Africa over the past ~ 5 myr. We used mesowear, microwear and taxonomic analogy to classify the dietary behavior of taxa for samples from Langebaanweg and Elandsfontein (Sponheimer et al., 2001; Franz-Odendaal et al., 2004; Stynder, 2009 Stynder, , 2011). Dietary behaviors of Hoedjiespunt bovids are discussed in Hare and Sealy (2013). ...
... For instance, the identification of defects remains an issue, as no threshold has been proposed to differentiate between "normal" and pathological enamel, and as their manifestation on teeth is species-, tooth-, and individual-dependent (Neiburger, 1990;McGrath et al., 2021). The most commonly used approach is naked eye, sometimes coupled with hand-lens (5x or 10x), and it consists in spotting the defects, categorizing them (e.g., pit, linear), and caliper measurements (Ensor & Irish, 1995;Dobney & Ervynck, 1998;Franz-Odendaal et al., 2004;Niven et al., 2004;Fourvel et al., 2015;Bacon et al., 2018Bacon et al., , 2020. Some studies have also used microscopy (optic, SEM, or confocal) to investigate enamel hypoplasia, either through histology (Rose, 1977;Witzel et al., 2008;Sabel et al., 2010;Marchewka et al., 2014), or at the surface of the enamel (directly or on casts; Chollet & Teaford, 2010;Hassett, 2014;Henriquez & Oxenham, 2017;McGrath et al., 2018). ...
... Also, disturbances in growth rate can be inferred from differences in breadth between perikymata. When stress events have a major inhibiting factor on crown growth and effect enamel thickness locally, these defects known as enamel hypoplasias appear; these defects typically span multiple perikymata and are a frequently used as stress indicators in anthropology and paleoecology (Hillson 1996;Guatelli-Steinberg 2001;Franz-Odendaal et al. 2004;Kierdorf et al. 2012). ...
Chapter
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In order to study the impact of ecology on life history evolution, paleobiologists have begun to take a cue from dendrochronology, and have increasingly been making use of microstructural growth records available within mineralized tissues: dental enamel, dentin, and bone. These tissues contain regular growth increments whose periodicities range from 24-hour (circadian), to 2-week, to seasonal and annual cycles, and which have allowed us to generate absolute chronologies of growth in teeth and bone. The study of these increments is known as odontochronology with respect to teeth, and skeletochronology with respect to bone. These two related fields allow us to directly quantify how species’ growth patterns are correlated with a number of ecological factors over geological time. Moreover, because growth increments record individual stress events that occurred within individual animals’ lifetimes, they allow us to observe important ecological pressures that occurred on shorter timescales as well.
... Dental enamel hypoplasia results from disruption of the deposition of enamel during tooth formation (Hillson, 2005), and has been documented among very ancient animals (e.g. Franz-Odendaal, Chinsamy & Lee-Thorp, 2004) and also among prehistoric North American bison (Bison bison/B. antiquus) (Byerly, 2007). ...
Article
It has been argued by some neozoologists (those who study living animals) that the palaeozoological record is biased and incomplete (relative to an existing biological community) and therefore should not be consulted for purposes of conservation biology. An article published in a biology journal in 2011 lists numerous reasons why natural history collections (NHCs) of skins and skulls of animals collected over the past century or two are exceptionally valuable to conservation biologists because those collections provide significant time depth to numerous variables that document global biological change. Many of those same variables can be, and have been, identified in the palaeozoological record. Those variables are of major value to conservation biology, whether their values are taken from 100-year-old NHCs or from palaeozoological remains. Empirical examples in which the identified variables are measured in palaeozoological contexts indicate that the palaeozoological record should indeed be consulted by conservation biologists and can no longer be considered unsatisfactory for modern resource management.
... The world renowned Mio-Pliocene (7-5.1 Ma) locality, Langebaanweg on the south-western Cape coast of South Africa (SA), preserves abundant remains of vertebrates, including the phocid seal Homiphoca capensis (Hendey 1982). Many studies have investigated the rich vertebrates collected from Langebaanweg; however, investigations into palaeopathologies evident among the fossils have been limited to studies of the teeth of sivatheres (Franz-Odendaal et al. 2004) and skeletal pathologies in the phocid seals (Govender et al. 2011). ...
Article
This study investigates three presumed fractured phocid seal bones: An isolated metapodial and an ulna belonging to different individuals of the extinct phocid, Homiphoca capensis, from Langebaanweg and a mandible of a juvenile elephant seal (Mirounga leonina), which was included to assess the validity of the assumption that changes to bones caused by fractures are consistent across extant and extinct members of the same groups. The bones were studied using a multi-method approach, including gross morphology, microcomputed tomography (micro-CT) and histology. Micro-CT showed that the metapodial was not fractured and information drawn from other analyses suggested that the pathology was an osteosarcoma. Histology of normal and fractured regions of the mandible and ulna permitted an estimate about the fracture healing stage, and showed the bone tissue at the fracture sites to be histologically similar. A birth line found on the lateral surface of the elephant seal mandible emphasised its young age and marked the first example of a birth line in a bone of a semi-aquatic mammal. A large scope of information was obtained using this multi-method approach, which could permit insight into the life events and lifestyles of modern and extinct individuals, such as H. capensis.
... Ahmad et al. (2018) studied enamel hypoplasia (EH) in six jaw fragments and noted that EH is more prevalent in the members of the family Giraffidae than in other animals. He observed that it was due to environmental or nutritional stress during the development and growth period, specifying that environmental alteration in different regions would cause comparatively more stress to giraffids (Hall-Martin 1976;Franz-Odendaal 2004;Franz-Odendaal et al. 2004). In current study, PUPC 15/423 (M1) [ Fig. 4a] represents an enamel hypoplasic line (24.05 ...
Article
Giraffokeryx punjabiensis is reported from Dhok Bun Amir Khatoon (DBAK), district Chakwal, Punjab, Pakistan. The newly recovered material includes two maxillary fragments, three mandibular rami, and seven isolated teeth. The well-preserved specimens enhance our knowledge about G. punjabiensis and can be used as a reference material in the future. The existence of G. punjabiensis along with Dorcatherium and suids suggests the presence of wet meadows, floodplain, and open woodland at the time of the early Middle Miocene deposition in Dhok Bun Amir Khatoon, Lower Siwalik Subgroup. A few studied specimens clearly showed signs of enamel hypoplasia as a nutritional and ecological stress indicator for the late Middle Miocene giraffids of Dhok Bun Amir Khatoon.
... Enamel hypoplasia has been observed in teeth of many mammalian species, including the maxillary and mandibular canines of hippopotamids (Dietrich 1928;Matthes 1939;Kuss 1957;Franz-Odendaal et al. 2003). The occurrence of this developmental defect was linked to systemic stress caused by environmental or animal-related factors, including nutritional deficiencies, intoxication, disease, birth and weaning (Goodman and Rose 1990;Mead 1999;Dobney and Ervynck 2000;Franz-Odendaal et al. 2004;Witzel et al. 2008;Hillson 2014). Linear enamel hypoplasia in Miocene rhinoceroses of the genus Teleoceras has been related to stress episodes in calves due to separation from their mothers prior to the birth of the next offspring (Mead 1999). ...
... Enamel hypoplasia in mammals is commonly attributed to metabolic stress (Dobney and Ervynck 2000;Franz-Odendaal et al. 2004;Magnell and Carter 2007;Mead 1999). Among nonhuman primates, seasonal undernutrition or stress (e.g., dry season) has been invoked to explain the metabolic challenge (Guatelli-Steinberg and Benderlioglu 2006; Macho et al. 1996). ...
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A geographically and temporally widespread pattern of repetitive episodes of developmental stress, recorded as furrows of linear enamel hypoplasia (LEH) in most recent and fossil apes, requires explanation. I compared observations of LEH recurrence among museum specimens of Pan troglodytes and Pan paniscus with historical weather records of seasonally recurrent combinations of lower temperature, higher rain and wind (“cold discomfort”). I imaged samples of 34 canine teeth (N = 20 animals, 54 independent LEH) from P. troglodytes from Fongoli, Senegal, and Taï Forest, Côte d’Ivoire and P. paniscus from the Democratic Republic of Congo with a scanning electron microscope and counted perikymata between and within LEH events. I converted counts to time using published Retzius periodicities (the number of days taken to form enamel layers, visible in thin sections) and compared their recurrence and duration to seasonal peaks of incidence and the intensity of cold discomfort. Using the longest Retzius periodicity (9 days), chimpanzees and bonobos show LEH lasting about 7–9 weeks, respectively, recurring annually. Most bonobos also show just-under semiannual recurrence of LEH. “Colder, wetter, windier” weeks recur annually at the P. troglodytes locations and semiannually at P. paniscus sites. When the combination of “below median temperatures, above median rain and winds” peaks in intensity and incidence over a 7-week period, daily “minimum hourly” temperatures average 20–21°C (7–9°C below lower critical body temperature for chimpanzees) with wind 3 times and rainfall 30 times higher than usual. These findings suggest that seasonal cold discomfort may be an important factor in episodic enamel hypoplasia in many nonhuman primates.
... This relationship occurs because the infected ungulates do not effectively absorb proteins and nutrients, as has been noted by Braunn and Ferigolo (1998) for recent mammals in a case of anaemia due to parasitosis in a Hydrurga leptonyx (Blainville 1820). Physiological disturbances occurring during birth, weaning and the separation of calves from their mothers are supposed to have caused EH in fossil giraffes (Franz-Odendaal et al. 2004). As birth and weaning are critical periods, they may lead to physiological stresses on the young animals (Rodney 1983). ...
Article
Enamel hypoplasia is characterized by reduction in the enamel thickness, resulting from a disruption of ameloblast activity due to systemic physiological stress. The euhypsodont teeth of Toxodon, a notoungulate from the Pleistocene of South America, often exhibit signs of enamel hypoplasia, in the form of continuous grooves or a series of pits where the enamel is thinner than in normal areas. These defects alternate with areas of normal enamel, and sometimes more than one form of enamel hypoplasia is present on the same tooth. This study analysed teeth of Toxodon from the Pleistocene Touro Passo Formation and the coastal plain of State of Rio Grande do Sul, Southern Brazil. Six types of enamel hypoplasia were observed. Upper teeth present mainly superficial grooves on the buccal surface, and the defects are less severe than those observed in the lower teeth. In the lower incisors, deep grooves with mesiodistal rows of pits were observed, showing clearly cyclical changes, which to a lesser degree, exist in all teeth. These changes are likely related to the continuous growth of euhypsodont teeth. Seven specimens were analysed under scanning electron microscopy and optical microscopy, which showed the occurrence of microstructural changes associated with the macroscopic enamel defects. Enamel underlying in the vicinity of hypoplastic defects was aprismatic and associated with prominent pathologic striae. These pathological findings might indicate that toxodonts were exposed to some stressing conditions or that their teeth were more easily abraded due to a change in diet items, related to shifting climatic conditions.
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In this study we present the first palaeodietary investigation of three-toed horses from southern Africa and a systematic revision. The dietary regime of 'Eurygnathohippus' cf. baardi from Langebaanweg (South Africa) was evaluated using the mesowear method. This hipparion was originally identified as Hipparion cf. baardi. However, recent evidence discussed here suggests that it belongs to the Eurygnathohippus clade. Cluster analysis comparing this equid to other fossil hipparionines from central Europe and North America indicates that 'E.' cf. baardi was a dedicated grazer at Langebaanweg. Subtle differences in the feeding preference between populations of 'E.' cf. baardi from the two river channel deposits [Pelletal Phosphate Member (PPM), Beds 3aS and 3aN] and from the Quartzose Sand Member (QSM) were also found. 'Eurygnathohippus' cf. baardi from the two PPM deposits have similar grazing dietary signals, which are most similar to those of extant Connochaetes taurinus (wildebeest) and Alcelaphus buselaphus (hartebeest). 'Eurygnathohippus' cf. baardi from the QSM, a floodplain and salt marsh deposit underlying the river channel, clusters separately and is more similar to the grazing bovid, Damaliscus lunatus (topi). This study shows that 'Eurygnathohippus' cf. baardi was an eclectic feeder with a strong grazing signal. The presence of high-crowned dentitions in the 'Sivalhippus' Complex, to which 'Eurygnathohippus' cf. baardi belongs, can be considered an exaptation of the group. Our results also provide some evidence for either differential habitat or habitat change during the late Miocene/early Pliocene.
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The dietary preference of Sivatherium hendeyi (Harris, 1976), an extinct giraffid from the early Pliocene of South Africa, was investigated by applying three dietary reconstruction tools - hypsodonty, mesowear and microwear. The hypsodonty index for S. hendeyi is 1.51 ± 0.06, which is within the brachyodont category as in most ruminant browsers. The mesowear signature of S. hendeyi is most similar to the mixed feeders (the seasonal mixed feeders). Microwear investigations also support a mixed diet for S. hendeyi. Taken together, results indicate that the dietary preference of this extinct giraffid is most similar to that of seasonal mixed feeders and show no similarities with grazers. The slight differences in the type of mixed feeding are discussed and highlight the constraints of each method for the interpretation of diets of fossil herbivores. The importance of the results in terms of the evolution of dietary strategies amongst African Sivatheriinae are also discussed. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris.
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Enamel hypoplasia, a developmental tooth defect, provides a permanent record of systemic stress during early life. The incidence and distribution of linear enamel hypoplasia has been used by anthropologists and palaeontologists to assess the health status of past populations but has not been applied by wildlife biologists studying extant animals. This study investigates enamel hypoplasia in 23 Giraffa camelopardalis skulls from wild and captive animals of various ages and sex to determine whether any systemic stress events are unique to life in captivity. Results indicate that wild giraffes are relatively stress-free as they do not have linear defects. Based on the distribution of linear defects in other giraffes, three key stress periods during the first 6 years of giraffe life were identified. The first stress event occurs during weaning, the second at about 3 years of age and the third, which is the least common, at 4–5 years of age. All three stress events were observed in both male and female giraffes. This study highlights the usefulness of assessing enamel hypoplasia in both wild and captive animals as well as the need for further research on tooth developmental timings in many wild ungulates. Some left–right asymmetry was observed in the development of linear and non-linear defects, which has implications for the aetiology of these defects.
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The Hippopotaminae rapidly expanded in African habitats by the end of the Miocene. It was previously suggested that this sudden spread, termed the hippopotamine event (HE), was linked to the contemporaneous expansion of grasses with a C4 photosynthetic pathway. C4 plants have been recognised as a major component of late Miocene hippopotamine diets. Conversely, hippopotamids from the earliest Pliocene of Langebaanweg, South Africa, displayed an exclusive C3 diet. Testing the link between the C4 expansion and the HE required documenting the phylogenetic position and the exact diet of these Langebaanweg hippopotamids. Their first anatomical description demonstrates that they were early hippopotamines with a morphology strongly recalling that of the species marking the HE. The analysis of their dental microwear signal indicates that they had a diet dominated by grasses. This illustrates that enamel δ13C values documenting C3 signals alone are inconclusive regarding feeding modes (browsing vs. grazing). It also offers further support to the predominant feeding of early hippopotamines on herbaceous communities, whether dominated by C4 or C3 grasses. Despite a debate on C4 expansion significance, current literature indicates that this signal most likely testifies for late Miocene major changes in Afrotropical vegetation, possibly a dissociation of grassy biome evolution from that of forested biomes notably related to drier conditions and increased grazing pressure. We suggest that these floristic changes triggered the HE in the Afrotropical realm and impacted the subsequent evolution of the family, including at higher latitudes.
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Hypoplastic pits on human deciduous canine teeth are attributed to nutritionally induced thinning of the crypt wall prior to eruption, exposing ameloblasts to unspecified physical trauma through the fenestration. Traditionally known as localized hypoplasia of the primary canine (LHPC), this little-understood condition is reported in fields ranging from public health to bioarchaeology. We propose the defect be termed a ‘crypt fenestration hypoplastic enamel defect’ (CFED) to reflect that an analogous lesion is created postnatally on maxillary molars of pigs. Pigs are accepted as a suitable proxy for many studies in human biology. We compare fenestration defects and CFEDs between 50 Sick Pen pigs, who died naturally, and 20 Controls. Observations were made of the presence, number and size of fenestrations in molar crypts. CFEDs were counted on erupted deciduous last molars and permanent first molars. Signs of being underweight and cranio-dental infection at death were recorded. Sick pen pigs show significantly more fenestrations at death and CFEDs acquired before death. These conditions co-occur with infection and poor growth. The deep fibers of temporalis muscle lie adjacent to the crypt wall of maxillary molars. We propose that contraction of this muscle during suckling and chewing creates large compressive forces against fenestrated bony surfaces sufficient to have physiological consequences for physically unprotected ameloblasts. While we conclude that a pig model is appropriate to study fenestration-induced enamel defects, this naturalistic experiment leaves unresolved whether osteopenia in pigs, and by extension in human infants, is due to disease and/or malnutrition. link: http://onlinelibrary.wiley.com/doi/10.1002/ajpa.22497/abstract
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The paleoecological fluctuations left their impression marks on the tooth enamel of mammals during their tooth development. These marks can be used as stress indicators because they reflect the type of duress faced by the extinct mammalian species during their lives. The enamel hypoplasia (EH) is a common stress marker to trace out the paleoenvironment of the region and the likelihood of species extinction. The material used for current EH analysis belongs to the genus Deinotherium, family Deinotheriidae, collected from Middle Miocene (15.2–11.2 Ma) Siwaliks of Pakistan. In this analysis 35 samples consisting of 52 teeth of two species, Deinotherium pentapotamiae and D. indicum, are included. The results indicate that 13/52 (25%) of the analyzed teeth have occurrences of EH giving a prediction that these Siwalik deinotheriids were facing the physiological and/or ecological stresses during the Middle Miocene epoch of Pakistan. The higher frequency of EH in molars (30.30%) compared to premolars (21.05%) express that the individuals experienced a comparatively high stress at the adult stages of their lives. This higher magnitude of EH in molars supports the idea of ecological stressors, i.e., dietary, mating, disease, and predator-prey associations, amplify the likelihood of extinction by dint of EH occurrences.
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The developmental or usage patterns experienced in the dentition by certain mammals during their growth or later in life often are preserved in their fossilized remains and have extensively been used in reconstructing life-history or the habitat in which the animals lived. One such, though lesser emphasized, feature is the enamel hypoplasia (EH), which is a failure for the enamel to form properly leaving distinct linear or curved marking(s) on the teeth. EH is caused by environmental or physiological stresses in an animal's life at that particular time when the growth was taking place. Hence, the EH analysis in a faunal accumulation has been used for providing a unique perspective into environmental conditions present during the growing years of an extinct animal's life. The present study on EH of Siwalik Rhinocerotids has proved to be an important tool for not only understanding their past life-history but also in reconstructing local palaeoenvironment and regional palaeoclimate of the region.
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New fossils of Conohyus sindiensis have been collected from Middle Miocene localities of Lawa, Kallar Kahar and Dhok Bun Ameer Khatoon in district Chakwal. Conohyus sindiensis is very common suid in the Chinji type area of Pakistan. Its biostratigraphic range varies between Kamlial type areas to the base of Nagri Formation. The probable time range of C. sindiensis is from 15 to 11 million years. The sample comprises isolated molars. The morphometric description of these specimens will add new information regarding molar morphology as well as the biogeographic distribution of Conohyus sindiensis.
Book
This edited volume is based on the best papers accepted for presentation during the 1st Springer Conference of the Arabian Journal of Geosciences (CAJG-1), Tunisia 2018. The book is of interest to all researchers in the fields of Environmental Sciences, Geoecology, Agroforestry, Geography, Geoarcheology and Geotourism. The Mediterranean Basin, Middle East and surrounding regions are ecologically unique due to large differences in climatic, geographical, and geological features, which grant countries of these regions with significant socio-economic potentials in terms of fertile agricultural lands, rich natural resources, and the existence of strategic resources such as crude oil and natural gas. However, the valuation of ecosystem functions, goods and services of natural and cultural heritages and bioressources of these regions is still little known. This volume offers an overview of the latest information and ideas on the physical environment of these regions, assessment and monitoring of natural bioressources including flora and fauna, and the use of cutting-edge methods for the development of sustainable agricultural systems. It gives also new socio-economic insights on geotourism and archaeology. Main topics include: 1. Environmental Assessment and Monitoring of Agrisilvicultural Systems 2. Environmental Impacts and Restoration Ecology of Natural and Agricultural Habitats 3. Investigations and Applications in Environmental Biotechnology 4. Spatiotemporal Patterns of Marine Biodiversity and Terrestrial Paleobiodiversity 5. Socio-economics of Geotourism and Archaeology
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The technological advancements in agriculture have resulted in higher yields but lower ecological efficiency and nutritional value. Little innovations in later sectors such as integrating ecological functions in the production systems have crippled our agro-ecosystems to meet the ever-growing demands. The digitization of the agro-ecosystems has become the most essential entry point for any large scale sustainable developmental entities whether it is, crop diversification, sustainable intensification, input use efficiency, agronomic practices, to restoring ecosystem services and risk management. Recent advances in geoinformatics technology and big-data analytics enabled the diffusion of ecological functions in farm production to achieve the desired return (production follows functions). The overarching goal of the ongoing effort was to build an integrated farming system by leveraging technological diffusion with sound ecological functions to design an ‘inclusive agro-ecosystem’ for sustainable development. Meta-analytics of farming systems dynamics in spatial domains help quantifying changes, trajectories and drivers under changing climate, demography and degradation process to target site specific developmental interventions and scaling the proven technologies, such as intensification of food legumes in rice fallows, adoption of conservation agriculture, quantification of yield gaps, land/water productivity and transboundary cooperation.
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The sivatherine clade includes some of the largest giraffids and emerged during the late Miocene. Sivatherium hendeyi, the earliest known species of the Sivatherium genus, was first described from the lower Pliocene of Langebaanweg (5.15 ± 0.1 Ma, Cape Province, South Africa). Here we describe the first possible occurrence of Sivatherium from western Europe from the lower Pliocene (MN14) of Puerto de la Cadena (4.9 Ma, Murcia, Spain). The new material consists of dental and postcranial remains. The Puerto de la Cadena Sivatherium, together with the presence of Macaca sp. and Debruijnimys sp., indicates a connection between African and European faunas during the early Pliocene and a possible relationship between Sivatherium and the stem Iberian sivatherines Decennatherium and Birgerbohlinia.
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We studied the relationship between the macroscopic appearance of hypoplastic defects in the dental enamel of wild boar and domestic pigs, and microstructural enamel changes, at both the light and the scanning electron microscopic levels. Deviations from normal enamel microstructure were used to reconstruct the functional and related morphological changes of the secretory ameloblasts caused by the action of stress factors during amelogenesis. The deduced reaction pattern of the secretory ameloblasts can be grouped in a sequence of increasingly severe impairments of cell function. The reactions ranged from a slight enhancement of the periodicity of enamel matrix secretion, over a temporary reduction in the amount of secreted enamel matrix, with reduction of the distal portion of the Tomes' process, to either a temporary or a definite cessation of matrix formation. The results demonstrate that analysis of structural changes in dental enamel allows a detailed reconstruction of the reaction of secretory ameloblasts to stress events, enabling an assessment of duration and intensity of these events. Analysing the deviations from normal enamel microstructure provides a deeper insight into the cellular changes underlying the formation of hypoplastic enamel defects than can be achieved by mere inspection of tooth surface characteristics alone.
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New δ13C values are presented for tooth enamel of 65 herbivorous fossil mammal specimens from low- and middle-elevation localities in Argentina ranging in age from Deseadan (ca. 27 Ma) to Lujanian (potentially as young as ca. 10,000 yrs BP). Prior to the Huayquerian (late Miocene; 9-6.5 Ma), all faunal levels have mean δ13C values of about -11 ± 1‰, indicating ancient terrestrial ecosystems with predominantly C3 plants. During the late Miocene through Pleistocene (i.e., after ca. 8 Ma), there is a statistically significant carbon isotopic shift so that: (1) taken together, later faunal levels have a combined mean δ13C value of -7.6‰ and (2) the data set includes significantly larger ranges of δ13C values (i.e., individual specimens are as positive as ca. +1‰). These post-8 Ma data indicate isotopically mixed terrestrial plant communities containing a significant component of C4 grasses. Both the magnitude and timing of this ca. 3.5‰ mean carbon isotopic shift is consistent with data reported previously from numerous late Miocene localities in the northern hemisphere and selected equatorial regions. Analysis of the δ13C values for high-crowned, presumed grazing mammals from post-8 Ma localities between 21 to 35° S lat. (in Argentina and Bolivia) indicate an isotopic gradient in which mean δ13C values (and hence percentage of C3 plants) are proportional to latitude. The δ13C values presented here indicate that the original spread of grasslands during the middle Tertiary, and the so-called "precocious hypsodonty" of corresponding South American herbivores, occurred in a regime of predominantly C3 grasses. The modern ecological landscape in which grasses (and corresponding grassland biomes) are predominantly C4 in mid-latitudes, is a relatively recent global event that is first recorded in South America during the late Miocene and became relatively widespread thereafter.
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Chad is a key region for understanding early hominid geographic expansion in relation to late Miocene and Pliocene environmental changes, owing to its location 2500 km west from the Rift Valley and to the occurrence of sites ranging in age from about 6 to 3 Ma, some of which yield fossil hominids. To reconstruct changes in herbivore paleodiet and therefore changes in the paleoenvironment, we measured the carbon and oxygen isotope composition of 80 tooth-enamel samples from three time horizons for nine families of Perissodactyla, Proboscidea, and Artiodactyla. The absence of significant alteration of in vivo isotopic signatures can be determined for carbon, thus allowing paleodietary and paleoenvironmental interpretations to be made. While the results generally confirm previous dietary hypotheses, mostly based on relative crown height, there are some notable surprises. The main discrepancies are found among low-crowned proboscideans (e.g., Anancus) and high-crowned rhinocerotids (Ceratotherium). Both species were more opportunistic feeders than it is usually believed. This result confirms that ancient feeding ecology cannot always be inferred from dental morphology or extant relatives. There is an increase in the average carbon isotope composition of tooth enamel from the oldest unit to the youngest, suggesting that the environment became richer in C4 plants with time. In turn, more C4 plants indicate an opening of the plant cover during this period. This increase in carbon isotope composition is also recorded within genera such as Nyanzachoerus, Ceratotherium, and Hexaprotodon, indicating a change from a C3-dominated to a C4-dominated diet over time. It appears that, unlike other middle Pliocene hominid sites in eastern and southern Africa, this part of Chad was characterized by very open conditions and that savanna-like grasslands were already dominant when hominids were present in the area.
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Between 8 and 6 million years ago, there was a global increase in the biomass of plants using C 4 photosynthesis as indicated by changes in the carbon isotope ratios of fossil tooth enamel in Asia, Africa, North America and South America. This abrupt and widespread increase in C 4 biomass may be related to a decrease in atmospheric CO 2 concentrations below a threshold that favoured C 3-photosynthesizing plants. The change occurred earlier at lower latitudes, as the threshold for C 3 photosynthesis is higher at warmer temperatures.
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Evolutiona ry trends among mammals over the past 66 Myr have been profou ndly influenced by changing climat es, in tum the result of tectonic events. The global trop ical forest type of ecosystem of the early Tertiary was disrupted by Late Eocene climatic changes, with the extinction of most archaic mammalian lineages and the appearance of most modem famil ies. Later Tertiary trends reflect increasing aridity, with the appearance of open-habitat mammals such as grazing ungulate s, although true grasslands probably did not appear until the Late Miocene in the New World and the Pliocene in the Old World. Patterns of mammalian diversity track paleote mperature curves for the northern latitudes, with maxima in the early Mid dle Eocene and early Middle Miocene. Major dispersals occurred at times of sea level lows, resulting in loss of endemism in originally isolated continents such as South America and Afr ica, and changes in faunal composition across Holarctica. Dispersal in con junction with climatic changes accounted for maj or extinction events in the Late Eocene to Early Oligoce ne, at the end of the Miocene , and in the mid Pliocene. Outstanding problems include the origin and dispersal routes of many extant orders that appeared at the start of the Eocene and the
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Most analyses of dental enamel hypoplasia compare frequencies of disturbed tooth types, which do not account for variability in the area of affected enamel. An alternate methodology, hypoplastic area, is presented here that accounts for this variability by combining acute and continuous enamel hypoplasia into an interval-level variable. The method compares samples based on individuals, by multiple tooth type variables, or by a single value rather than by tooth types. Use of the hypoplastic area method is illustrated by analyzing human skeletal dentitions in three archaeological samples: Meroitic Nubians from Semna South, Sudan; Anasazi from Navajo Reservoir, New Mexico; and Mogollon from Grasshopper Pueblo, Arizona. Both univariate and multivariate statistical tests are employed to assess variation in defects between individuals and samples. By incorporating measurements of continuous defects, the hypoplastic area method provides information beyond that of frequency data in comparing levels of stress. Flexibility of the method is also discussed.
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The relationship between environmental change and hominin evolution remains obscure. For the most part, this stems from the difficulty of reconstructing ancient hominin habitats. Bovids are among the most frequently utilized paleoenvironmental indicators, but little is known about the habitat preferences of extinct taxa. It is generally assumed that fossil bovids both ate the same things and occupied the same habitats as their closest extant relatives. We test the first part of this assumption by reconstructing the diets of seven bovids from Makapansgat Limeworks, South Africa. Since diet and habitat are linked, these reconstructions have implications for our understanding of fossil bovid habitat tolerances. Ecomorphological and stable carbon isotope analyses are employed, allowing us to take advantage of the strengths and overcome the weaknesses of both. In most cases, fossil bovids did have similar diets to their extant relatives, and probably occupied similar habitats. Gazella vanhoepeni and Aepyceros sp., however, were almost exclusive browsers, and not mixed feeders like their living counterparts.
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Progressive changes are observed in both the composition of mammal faunas and vegetation during the Miocene epoch [24-5 mega-annum (Ma)]. These changes are usually interpreted as a response to climatic changes. In the traditional view, forests or woodlands gradually gave way to more open habitats, with grazing (grass-eating) ungulate (hoofed) mammal species replacing the browsing (leafy-vegetation-eating) species as grasslands expanded. However, data from fossil assemblages in the Great Plains region of North America show that this faunal change was not a one-for-one replacement of browsers by grazers, as usually thought. Typical late early Miocene (17 Ma) fossil communities included extraordinarily high numbers of browsing ungulate species, comprising a fauna that cannot be directly analogized with any present-day community. Both maximum species richness of all ungulates and the proportion of browsers declined steadily in ungulate communities through the middle Miocene, to levels comparable to those of the present by the late Miocene. The resulting dramatic, cumulative loss of browsing species constitutes one of the strongest faunal signals of the late Tertiary (but was not a single "event"). We suggest that the early Miocene browser-rich communities may reflect higher levels of primary productivity in Miocene vegetation, compared with equivalent present-day vegetation types. The observed decline in species richness may represent a gradual decline in primary productivity, which would be consistent with one current hypothesis of a mid-Miocene decrease in atmospheric CO2 concentrations from higher mid-Cenozoic values.
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A high prevalence of enamel hypoplasia in several herbivores from the early Pliocene Langebaanweg locality, South Africa, indicates general systemic stress during the growing years of life. The presence of several linear enamel hypoplasias per tooth crown in many teeth further suggest that these stress events may be episodic. The delta18O values along tooth crowns of mandibular second molars of Sivatherium hendeyi (Artiodactyla, Giraffidae) were used to investigate the cause of the stress events in this tooth type. Results show that weaning in this fossil giraffid occurred at a similar ontogenetic age to that in extant giraffes, and that the observed enamel hypoplasia towards the base of this tooth type manifested post-weaning. Further, high-resolution oxygen isotope analyses across S. hendeyi third molars suggest that the entire development of defective tooth crowns occurred under conditions of increased aridity in which the cool, rainy part of the seasonal cycle was missing. The high prevalence of this defect in many herbivores suggests that climatic conditions were not favourable. This study reiterates the value of stable isotope analyses in determining both the behaviour of fossil animals and the environmental conditions that prevailed during tooth development.
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Deals mainly with fossils from late Tertiary strata along the W coastal margin of the subcontinent ranging in age from early Miocene to late Pliocene. Terrestrial vertebrates are rare and most of the finds are in marine strata. Changes during the late Tertiary are summarised and there are notes on environmental changes and sea level fluctuations. -K.Clayton
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Centimetre-scale laminae in tusk and molar dentine of late Pleistocene mastodonts and mammoths have been interpreted as annual growth bands produced, in part, by seasonal variation in growth rate. To test this interpretation, we measured the oxygen isotope composition (δ18O) of the CO3 fraction of dentinal hydroxyapatite from samples covering consecutive inferred years of growth in tusks. We demonstrate that there are substantial variations in the oxygen isotope composition of proboscidean dentinal apatite, and that isotopic identifications of winter (ie low δ18O values) coincide with those based on growth rate (ie slow-growth zones). Finally, the potential of oxygen isotope analyses of terrestrial mammals for assessing the seasonality of paleoclimates is considered. -from Authors
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The carbon. and oxygen isotope composition of carbonate in enamel hydroxylapatite can provide information on photosynthetic pathways of plants at the base of food webs, and on hydrological conditions. Retrieval of palaeoenvironmental information from isotopic composition of vertebrate fossils is complicated by potential diagenetic overprinting. In this study alteration has been assessed by examining the extent to which expected biological carbon and oxygen isotope patterns are disrupted in fossils of species whose diets cart be independently predicted by other criteria. The biological patterns used are 1) the differences in carbon, isotope composition between grazers and browsers, and 2) the differences in oxygen isotope composition between hippopotamus and terrestrial herbivores. Results obtained on, enamel samples from Tighenif (Algeria, approximate to 700,000 yr), Melka-Kunture (Ethiopia, 0.7-1.5 myr), and Anabo Koma (Djibouti, approximate to 1.6 myr) suggest that in vivo carbon and oxygen isotope compositions are preserved in most cases. Moreover, in all three regions, modern, patterns of C-3 versus C-4 grass dominance were present within the Pleistocene.
An assessment of the possible roles of the minor constituents (e. g. CO//3**2** minus , HPO//4**2** minus , F** minus , Cl** minus , Na** plus , K** plus , Mg**2** plus ) and some trace elements (e. g. Sr**2** plus , Ba**2** plus , Pb**2** plus , Mn**2** plus , Cd**2** plus , Li** plus , P//2O//7**4** minus , etc. ) which are closely but nebulously associated with biological apatites is presented. Most of the data on synthetic apatites presented here are from published reports of other investigators and published and unpublished results of the author's past and current work.
Article
Quarry samples of lower cheek teeth of the Miocene rhinoceros Teleoceras are analyzed for the presence of enamel hypoplasia using macroscopic, thin-section, and scanning electron microscopic techniques. The presence of enamel pits, furrows, and grooves is noted predominantly on, but not limited to, the buccal side of dp4s. The enamel defect is not as common on permanent teeth, but does occur with decreasing frequency on p4s, mls, m2s, and m3s.Analysis of the formative sequence of deciduous cheek teeth in Teleoceras and the extant rhinoceros Diceros bicornis suggests that the Teleoceras dp4 was developing in the alveolus at the time of birth. Varying degrees of wear on the dp4s exhibiting enamel hypoplasia imply that the defect-producing stress did not result in immediate death. Isolation of the enamel hypoplasia to distinct bands on the Teleoceras dp4s suggests causes linked to non-lethal severe physiological stress due to metabolic disruption or nutritional deficiency occurring at or very near birth. The Teleoceras p4 was probably developing in the alveolus between three and five years of age. The observed p4-hypoplasias appear to reflect physiological stresses not related to weaning, but to some other stressful period such as cow-calf separation prior to the birth of the next offspring.
Article
A pattern of seasonal mobility between the coast and the hinterland by Khoekhoe pastoralism in the south-western Cape of South Africa was documented at the time of European contact. Because the region is characterized by a mosaic of geological substrates of various ages and vegetation types with different proportions of C-3 and C-4 plants, this mobility model for prehistoric herders can be tested by analysis of carbon, oxygen and strontium isotope ratios in domestic bovid tooth enamel. Isotopic analysis was performed on archaeological sheep, cattle, eland and steenbok teeth from the Late Stone Age site of Kasteelberg on the Vredenburg Peninsula. Sequential sampling of enamel provided a chronological record of the isotopic composition of diet during tooth formation. Results from carbon and oxygen isotope analysis of archaeological and modern steenbok teeth show seasonal variation in the delta C-13 of local pastures in the vicinity of the site (up to 2.9% in a single individual), which could be due to seasonal change in proportions of C-3 and C-4 plants and/or seasonal variation in the delta C-13 of C-3 plants. A pattern of seasonal change of 0.9-3.5% in the delta C-13 of tooth enamel is also observed in the sheep teeth. This amplitude of variation could be due to local seasonal changes, thus it is not possible, from the delta C-13 and Sr-87/Sr-86 values measured in a cow tooth suggest that this animal spent part of its life int he interior, even though it died at Kasteelberg. Results on this cow also suggest longer residence within habitats rather than seasonal mobility. A clear pattern of seasonal mobility attested in historical times might have developed only later in prehistory, when cattle pastoralism developed in the region.
Article
An understanding of enamel diagenesis is necessary to ensure sound isotopic palaeodietary and palaeoenvironmental reconstructions. Although carbon isotope signals of browsing and grazing herbivores remain distinct in enamel even after millions of years, subtle alteration of isotopic signatures does occur. To better understand this change we analysed modern and fossil enamel from a number of South African sites using Fourier Transform Infra-Red spectroscopy. Our results indicate that while there is little evidence of increased crystallinity in fossil enamel, there is a small but significant change in the proportion of carbonate ions occupying hydroxyl and phosphate sites. This seems to occur early in the process of fossilization, after which there is no noticeable change. It is also important to note that the degree of alteration varies significantly within and between sites. We suggest that this change results from one or some combination of three mechanisms: exogenous carbonate incorporation, endogenous carbonate loss, and endogenous carbonate reorganization. Determining which mechanism(s) contribute to this alteration is important because all three are likely to affect biogenic carbon isotope ratios differently. FTIR spectroscopy promises to increase our knowledge of diagenesis, and in so doing, should improve our palaeodietary and palaeoenvironmental reconstructions.
Article
Thirteen tooth eruption stages and their corresponding chronological ages are descri bed from a series of giraffe jaws. These can be used for age determination in giraffes with immature dentition. Significant correlations of the lingual crown height (r=0-957; P < 0001) and lingual occlusal surface width (r=0-959; P < 0001) with the number of dark staining incremental lines in the cementum of thin decalcified sections of the maxillary first molar were found. The regression equations derived from these relationships provide a further method for determining the age of a giraffe. A composite plate showing maxillary first molar wear patterns provides a means of roughly assigning an age to a particular specimen. Thin sections of undecalcified teeth, mandible measurements, various other indices of tooth wear and eye lens mass were investigated and found unsuitable for age determination in this
Article
Dental enamel hypoplasias are deficiencies in enamel thickness resulting from physiological perturbations (stress) during the secretory phase of amelogenesis. The results of a wide variety of experimental, clinical, and epidemiological studies strongly suggest that these defects and their associated histological abnormalities (such as accentuated stria of Retzius and Wilson bands) are relatively sensitive and nonspecific indicators of stress. Because of the inability of enamel to remodel, and the regular and ring-like nature of their development, these defects can provide an indelible, chronological record of stress during tooth crown formation. For these reasons, along with the ease with which they are studied, enamel hypoplasias have been increasingly employed as indicators of nutritional and disease status in paleopathology, and their study has begun to extend into other subdisciplines of physical anthropology.
Article
Previous isotopic studies of herbivorous mammals suggested that the dispersal of the grazing mammals, Mammuthus and Bison resulted in the endemic grazers incorporating more browse into their diets. In order to test this hypothesis, we analyzed 84 bulk enamel samples from six co-occurring genera from the Pleistocene of Florida to determine their carbon isotopic composition. We also analyzed 145 samples taken from along the growth axis of the tooth (serial sampling) from 12 specimens of three co-occurring genera in order to investigate seasonal resource partitioning. Our results suggest that:1.There were no inter-generic or intra-generic differences in feeding strategy for Equus, Bison, and Mammuthus throughout the Pleistocene of Florida.2.Significant isotopic differences observed in the feeding strategy of Hemiauchenia and Platygonus are due to floral shifts or to interactions with other grazers in Florida.3.The three late Pleistocene sympatric grazers displayed similar seasonal carbon isotopic variations, suggesting either the lack of forage specificity or abundant resources making forage partitioning unneccessary.4.Because these organisms did coexist, niche partitioning must have occurred by some aspect not discernible through analyzing stable carbon and oxygen isotopes.Stable isotopic analysis of herbivore tooth enamel allows for the quantitative understanding of specific paleoecological interactions among ancient animals. Further analysis of seasonal-scale changes of ancient ecosystems will bring us closer to the scale of understanding seen in present-day ecosystems.
Article
By recording abnormal incremental lines, known as linear enamel hypoplasia (LEH), visible on the tooth crowns of numerous archaeological pigs' teeth, it has been possible to construct a chronology of physiological stress for five different archaeological assemblages. The results confirm that LEH is a common occurrence in all the populations investigated. Given the geographical and temporal differences between the sites studied, LEH in pigs is thus likely to be a frequently observable phenomenon. Analysis of the frequency distribution of the height of each LEH lesion on the lingual surface of each cusp of each molar shows that the occurrences of LEH follow clear patterns. Taking into account the published data on tooth crown growth in the modern domestic pig, it is proposed that birth and weaning are the direct causal agents of the two discrete peaks noted on the first permanent molar (M1), whilst a period of under-nutrition encountered during the first winter of the animals' life is thought to be the main causal factor for the occurrence of the single distinct LEH peak noted on the second permanent molar (M2). A broad peak on the third permanent molar (M3) is similarly interpreted. These links between patterns of LEH and the normal developmental physiology of the animal open a number of possibilities for interpretation.
Article
The etiology of growth disturbance in early childhood is complex. Since skeletal indicators of growth disturbance are non-specific, attempts to understand this syndrome in ancient populations must rely on a biocultural approach. This paper presents a biocultural approach to data from Lower Nubia. Accentuated striae of Retzius, an indicator of disruption in enamel formation, are used to determine the age-related distribution of growth disturbance in two ancient Lower Nubian populations. This data is then discussed in the context of a modern Sudanese analogy. The sample consists of 105 first permanent molars (M1) from the Meroitic (100 b.c. to a.d. 300) and X-Group (a.d. 300 to 600) periods. Etched ground sections were made, and the location of accentuated striae along the dentioenamel junction (DEJ) was determined for the mesiobuccal and distolingual cusps. Location scores were converted to percentages of DEJ length, and compiled into frequency distributions. Published ages for M1 crown completion were then used to develop an age scale. Age-segments, each comprising 20% of M1 crown development, were compared to determine age-related patterns of accentuated stria occurrence. Interpopulation comparisons were made with the Kolmogorov-Smirnov two-sample test. There is no significant difference in the age of accentuated stria formation between populations (for either cusp). Frequencies remain low during the first half-year of life, and then rise dramatically in the second year of life. Accentuated stria formation remains high during the major portion of the third year of life. A tentative reconstruction based upon previous ancient Nubian data and modern Sudanese data suggests that the second-year rise may reflect a weaning “crisis” occurring in the context of a pattern of multiparous reproduction, extended lactation, and infectious disease. Further research is needed before this hypothesis can be tested.
Article
The δ18O of Canadian beaver (Castor canadensis) teeth should reflect variations in the isotopic composition of the water in which the beavers live, as their incisors grow rapidly and continuously. We observe seasonal variations in phosphate δ18O using samples of enamel taken along the length of single teeth. In the spring the δ18O of the enamel being deposited gradually declines, reflecting a retarded input of δ18O depleted winter water. After mid-year, enamel δ18O is higher than average (as represented by the δ18O of bone phosphate from the same animal) and passes through a maximum in late summer or early fall. Overall, the amplitude of seasonal excursions in enamel δ18O (4‰) is much smaller than the expected summer-winter range in the δ18O of meteoric water (> 10‰). This is because hydrologic mixing processes, gradual admixing of environmental water with beaver body water, long-term plant growth, and oxygen inputs of relatively constant value (particularly atmospheric oxygen) tend to even out summer-winter differences in the δ18O of oxygen inputs to the beaver. The δ18O of bone from adult beavers was uniform at 11.9 ± 0.5‰ over the study area. Analyses of a Sangamon age giant beaver (Castoroides ohioensis) incisor from Hopwood Farm, Illinois, show a slightly larger 5.5‰ seasonal cycle of δ18O with an average enamel δ18O of 18‰. This suggests that average temperatures were warmer during the Sangamon than today and that seasonal temperature differences and/or relative humidity variations were larger.
Article
Significant differences in the δ18Op value between teeth, and even within a single tooth were observed in a detailed study of the oxygen isotope composition of tooth enamel phosphate (δ18Op) of hypsodont teeth from bison and sheep jaws. The permanent molars and premolars of a fossil adult bison from eastern Wyoming (∼500 yr B.P.) and a modern sheep from California were analyzed. The bison is assumed to have been free-ranging with a variety of possible water sources, whereas the sheep was raised on a ranch. Inter-tooth variability in δ18Op for the bison compared to the sheep (5.6‰ and 3.5‰, respectively) may be a result of behavioral differences. Analyses of multiple samples from the m3 of both the bison and sheep vary to a similar degree (3.5‰) in a similar cyclic pattern down the length of the tooth, a pattern which is interpreted to be seasonal. When present, inter- and intra-tooth variations in δ18Op are controlled by the water and food ingested by the mammals during the period of enamel formation. In these localities, well waters, surface waters, and mother's milk have different isotopic compositions at different times of the year.The data underscore the role of biology and behavior in determining δ18Op values, and the need to understand how they vary for a population of interest. If these variations are taken into account, the δ18Op values of single samples from small, late-forming teeth (e.g. premolars) can be used as a proxy for the δ18O value of local meteoric water for long-term climate studies. Multiple samples from a single third molar may provide information on the duration and timing of enamel growth, seasonality, as well as long-term climate change.
Article
Oxygen isotopic, elemental, and X-ray data are presented for a suite of 24 fossil horse teeth from Nebraska ranging in age from 18.2 to 8.5 Ma, to test the use of δ18O of enamel phosphate (δ18OP04) as a quantitative record of continental climate. Modern equid teeth were analyzed to estimate a relationship between δ8OP04 and environment water. Multiple samples of seven different fossil species from Burge Quarry, a ∼ 12 Ma attritional fossil deposit, indicate the diagenetic overprints exist but can be detected by decreased P concentration and increased crystallinity relative to modern enamel. Isotopic variation for the pristine samples from Burge Quarry is ±1.5% (1σ, n=9), which may represent the resolution of the procedure within a stratigraphic horizon. There are no apparent correlations with body size, hypsodonty, or phylogeny. A range of 7%0 in δ18OP04 occurs over the 10 m.y. interval. A trend towards depleted δ18OP04 of about 4% corresponds to a depletion of up to 6%0 in δ18O of precipitation between 18.2 and 8.5 Ma, but the range of variation of Burge is large relative to the climate signal. Our results demonstrate that δ18OP04 should be useful in quantitatively reconstructing Cenozoic continental paleoclimate on 106-year timescales. Isotopic variation due to taphonomic bias and the terrestrial rock record will likely obscure higher-order climate signals.
Article
Current knowledge of aspects of the geology, soils and palaeontology relevant to the study of the palaeoecology of the fynbos region, the southern margin of the African continent, is surveyed in nine essays and three introductory reviews. Precambrian sediments, granites and rocks of the early Phanerozoic Cape Supergroup, underlie the greater part of the region and the distribution of the main rock units is shown on an accompanying map. The main physiographic features were established by folding during the Cape orogeny (278-215 Myr) and by subsequent erosion and faulting, in part associated with the outlining of the continental margin at the end of the Jurassic (140 Myr). The Cenozoic deposits (0-65 Myr) are discussed in a synopsis of the evolution of the modern landscape. Soils as indicators of palaeoenvironments are reviewed and a description and maps of soils of the Cape coastal platform are included. The palaeontological record as known from the study of the late Tertiary vertebrates, Quaternary large and small mammals. Cretaceous and Cenozoic plant microfossils and macrofossils, is described and the palaeoenvironmental implications are reviewed. The history of human occupation of the region is put into perspective. It is clear that the fynbos region, an ancient landscape of high terrain diversity, showing varied substrate lithologies and a mosaic of eutrophic and dystrophic soils, has not been a constant environment over geological time. It is in this setting under conditions of dynamic environmental change that the composition of the modern biota has been determined and the specialized character of fynbos ecosystems has developed.
Article
Two hundred black and white adult human skeletons and 200 living black and white children from the greater Cleveland area were examined for evidence of enamel hypoplasia. Enamel hypoplasia, present in varying expressings (pits, lines and grooves), was found to be more prevalent in both skeletal samples, than in the living groups. In the majority of cases, sex differences between white and black males and females through time and space are highly significant for all tooth catagories. Regardless of the mechanisms behind it, prevalence of enamel hypoplasia for both white and black group has significantly declined through time. No evidence suggesting specific etiologies responsible for enamel hypoplasia can be found. In the majority of previously published reports, the etiology is still idiopathic. The reduction in the prevalence of enamel hypoplasia in the groups examined through time may be related to improved nutritional conditions and the elimination or decline of childhood diseases that have been implicated in this condition.
Article
Recent studies of teeth from prehistoric children have reported a localized, roughly circular patch of deficient enamel on the labial aspect of the primary canine, which reaches its highest prevalence in the Upper Paleolithic of Europe. This study reports social and biological correlates of 33 affected kindergarten-aged children from Vancouver, Canada (2.4% of 1,350 examined). Affected children can be characterized as coming from low-income families often of East Asian or Chinese origin in which there is a degree of milk avoidance and reduced breastfeeding. The defect appears to be due to minor physical trauma to the face approximately 6 months after birth occasioned by normal motor development, involving handling and mouthing objects, which damages the developing tooth crown through deficient cortical bone over the canine crypt. Reduced cortical bone in the face of the infant is attributed to nutritional factors, involving calcium deficiency, of the mother and/or developing infant.
Article
Scanning electron microscopy of surface enamel lesions in fluorosed permanent premolars and molars of free-ranging Roe deer revealed two types of pits. Post-eruptive lesions that resulted from mechanical stress on hypomineralized enamel during mastication were characterized by steep walls and a typical honeycomb structure on their bottom, a result of fracture of enamel rods; holes left by fractured rods were surrounded by interrod enamel. Pits of developmental origin (hypoplasias), either as shallow depressions of enamel surfaces or narrow holes running deep into the enamel, were characterized by convex, rounded walls covered by numerous Tomes' process pits. Pits of hypoplastic and post-eruptive origin were often found in the same tooth. Intact enamel surfaces of fluorosed teeth resembled that of controls.
Article
An abnormality of enamel formation, detected only recently in living children, was found in a majority of prehistoric children, some from more than 20,000 years ago. The lesion, roughly a circular area of enamel hypoplasia approximately one millimeter in diameter, occurs on the labial surface of the primary canine tooth. A clinical examination of 2,367 school children in the Vancouver, Canada, area showed the defect occurring in fewer than one percent.
Article
A roughly circular hypoplastic defect restricted to the labial enamel surface of the deciduous canine is described. This pathology is quite common in available samples of Upper Paleolithic and Neolithic children and a cadaver sample of recent Calcuttans, affecting 44% to 70% of individuals. It is rare in a Neanderthal sample and in children from a clinical practice in Vancouver. The lesion occurs twice as commonly in the lower jaw. The defect appears to commence at or after birth owing to localized pressure on thin or nonexistent alveolar bone overlying the bulging crypt of the deciduous canine. Population differences in the incidence of the pathology probably reflect innate and acquired variation in hard and soft tissue thicknesses in this region.
Article
abstract – The frequency of developmental disturbances in the permanent dentition due to traumatic injuries to primary teeth was examined in a Danish population sample consisting of 487 schoolchildren 9–17 years old. Of these children, 147 (30%) had a history of traumatic injuries to the primary dentition. Frequencies of 57.8% and 45.3% of developmental disturbances were found in the trauma and in the non-trauma group, respectively. The folloing types of developmental disturbances were more frequent in the trauma group than in the non-trauma group: (1) internal white enamel hypoplasia with a diameter of 0.5 mm or more, (2) internal and external white and yellow-brown enamel hypoplasia, (3) white and yellow-brown enamel hypoplasia and horizontal enamel hypoplasia. Internal white enamel hypoplasia with a diameter of less than 0.5 mm, and generalized internal and external white enamel hypoplasias were found with the same frequency in the two groups. About 10% of enamel hypoplasias in anterior teeth are due to trauma.
Article
This paper attempts to review present knowledge on the ingestion and metabolism of fluoride in relation to the occurrence of endemic dental fluorosis, a condition caused by an excessive intake of fluoride during tooth formation. The clinical appearance of dental fluorosis is characterized by lustreless opaque white patches in the enamel which may become striated, mottled and/or pitted. The opaque areas may become stained yellow to dark brown. The affected teeth may show a pronounced accentuation of the perikymata and, in more severe cases, multiple pits and larger areas of hypoplasia of the enamel appear so that the normal morphology of the tooth is lost. Due to the universal presence of fluoride in water, soil and the atmosphere it is not surprising that humans are exposed to various levels of fluoride intake , not only through food and water, but in industrial and pharmaceutical products and other sources. Water-borne fluoride, however, has been said to represent the largest single component of this element's daily intake, except where unusual dietary patterns exist. The daily amount of fluoride intake through water varies with climate (maximum daily temperature) and age. It has been postulated that significant changes in patterns of food and beverage ingestion, because of changes in available products and the ways in which they are marketed as well as many foods and beverages being processed in fluoridated communities, may have caused a change in the prevalence and severity of dental fluorosis over the past 30 years. Since fluoride remains pre-eminent among the measures available for increasing the resistance of teeth to caries attack, continued and renewed research on the ingestion and metabolism still has high priority.
Article
An earlier study showed that some of the variation in appearance of defects of enamel in sheep incisor teeth induced by trauma during tooth development was related to the phase of activity of the ameloblasts at the time of injury. In the present study, sixteen selected defects were examined by microhardness and microradiography. It was found that in some of the fully formed teeth, the defects had retained the pattern of mineralization present at the time of trauma, i.e., mineralization had ceased. In other teeth, further mineralization of the defects occurred after trauma, resulting in well-mineralized enamel, although sometimes of incomplete thickness. It was concluded that the trauma, depending on its severity, leads to either permanent or temporary dysfunction of the ameloblasts, which also influences the appearance of the resulting lesions.
Article
This article discusses the abnormalities of orofacial structures that can occur in association with various congenital disorders and syndromes. The importance of the association between orofacial anomalies and other congenital malformations can be appreciated when one considers that the dysmorphic development of various tissue and organ systems is often associated with craniofacial malformation. Certain specific alterations of craniofacial form, structure, or function are found to be associated with certain syndromes and systemic disturbances to an extent that they may be classified as cardinal features of those conditions. Because of this, it is important for the clinician to be cognizant of dysmorphologic changes of orofacial structures in order to alert him or her to consider certain specific disease entities and to rule out the involvement of other tissues and organ systems that may be syndromically related. Dysmorphic changes of craniofacial structures should be discussed using the same descriptive terminology and nomenclature and the same systems of classification that have been standardized in the field. In this article, we will provide a brief review and discussion of the general principles of dysmorphology; the identification and recognition of craniofacial dysmorphology; dental abnormalities associated with common congenital disorders; and orofacial considerations (other than teeth) in the diagnosis of syndromes.
Article
Using macroscopic, microradiographic and scanning electron-microscopic methods, the effects of increased fluoride exposure on enamel and dentine formation were studied in fluorosed mandibular premolars and molars of roe deer from the heavily industrialized Ruhr area, Germany. Macroscopically, fluorosed teeth were characterized by opaque and stained enamel and in more severe cases also by enamel surface lesions, reduction or loss of enamel ridges on their occlusal surfaces and increased wear. Microradiographically, fluorosed enamel exhibited different degrees of subsurface hypomineralization, in part apparently indicating a fluoride effect during enamel maturation. In some specimens, a pronounced but varying enhancement of the pattern of Retzius lines was observed throughout the enamel, denoting strongly intermittent fluoride exposure during enamel matrix secretion. This variation in exposure was also reflected histologically in dentine, by bands of interglobular dentine and marked accentuation of incremental lines. Microradiography of sections through enamel surface hypoplastic lesions showed the enamel forming the bottom and partly also the walls of the lesions to be highly mineralized. Scanning electron microscopy showed that the outer enamel along the more pronounced hypoplastic lesions consisted of stacked, thin layers of 'aprismatic' enamel, indicating that the ameloblasts in these areas had lost the distal (rod-forming) regions of their Tomes' processes. These observations demonstrate that the origin of enamel hypoplasias in deer clearly differs from that in rodents, where fluoride induces the formation of subameloblastic cysts. The differences in the degree of fluorotic alteration between the teeth of a single tooth row could be related to the developmental sequence of the dentition in roe deer. The roe deer is thus considered to be a very sensitive and useful bioindicator of environmental pollution by fluorides.
Article
Enamel hypoplasia (EH) is a deficiency in enamel thickness due to physiological insults that compromise ameloblast function during the secretory phase of amelogenesis. The prevalence of EH in the deciduous teeth of nonhuman primates is largely unknown. One exception is the recent discovery of EH in the deciduous teeth of extant great apes which exhibit significant differences in prevalence between genera (Lukacs, 1999 a, 2000 a, Am. J. phys. Anthrop.110, 351-363). EH in deciduous teeth of other primates, living and fossil, remain undocumented. This communication describes a "plane form" type of EH known as localized hypoplasia of primary canines (LHPC) (Skinner, 1986 a, Am. J. phys. Anthrop.69, 59-69) in early Miocene catarrhines from Kenya. Specimens were examined macroscopically, with a 10x hand lens and with a variable power (10-30x) binocular microscope. Fédération Dentaire International (FDI)/Defects of Dental Enamel (DDE) standards were employed in recognition and recording of enamel defects (Fédération Dentaire International, 1982, Int. Dent. J.32, 159-167; Clarkson, 1989, Adv. Dental Res.3, 104-109). Size, shape and location of defects were measured and recorded on an outline drawing of the tooth crown. The Kenya National Museum study sample includes six genera of early Miocene catarrhines (n=66 specimens, with n=80 teeth). Seven deciduous teeth were afflicted with EH, yielding an overall prevalence of 8.75%. Two taxa, Kalepithecus (n=1 deciduous canine) and Proconsul (n=3 deciduous canines), were affected with LHPC. Expression of LHPC in fossil catarrhines is consistent with the expression of EH observed in skeletal samples of extant great apes. This report establishes an approximately 17-23 Ma antiquity for EH among early catarrhines and suggests that the neonatal stage of ontogenetic development was sufficiently stressful physiologically to produce disruption in amelogenesis. These physiological stresses impacted neonates of fossil taxa with a wide range of adult body sizes, from large-bodied Proconsul major ( approximately 75 kg) to one of the smaller-bodied catarrhines, Kalepithecus ( approximately 5 kg).
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Sponheimer M, Reed K and Lee-Thorp J A 2001 Isotopic palaeoecology of Makapansgat Limeworks Perissodactyla; S. Afr. J. Sci. 97 327–329
The Paleodiet of Giraffidae; in Antelopes, deer and relatives. Fossil record, behavioural ecology, systematics and conservation
  • N Solounias
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  • L E S Werdelin
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Solounias N, McGraw W S, Hayek L and Werdelin L 2000 The Paleodiet of Giraffidae; in Antelopes, deer and relatives. Fossil record, behavioural ecology, systematics and conservation (eds) E S Vrba and G B Schaller (New York: Yale University) chapter 6, pp 83–95
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Suga S 1982 Progressive Mineralisation Pattern of Developing Enamel During the Maturation Stage; J. Dental Res. 61 (Special Issue) 1532–1542
Climatic Change in Southern Africa during the Neogene and Quaternary ; in Paleoclimate and evolution with emphasis on human origins
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Southern African late tertiary vertebrates; in Southern African prehistory and palaeoenvironments
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Hendey Q B 1984 Southern African late tertiary vertebrates; in Southern African prehistory and palaeoenvironments (ed.) R G Klein (Rotterdam: A A Balkema) pp 81–106
High prevalence of enamel Hypoplasia in an Early Pliocene giraffid (Sivatherium hendeyi) assemblage; J. Vertebr. Paleontol . (in press) Franz-Odendaal T A, Lee-Thorp J A and Chinsamy A 2002 New evidence for the lack of C 4 grassland expansions during the Early Pliocene at Langebaanweg, South Africa
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Franz-Odendaal T A, Chinsamy A and Lee-Thorp J A 2004 High prevalence of enamel Hypoplasia in an Early Pliocene giraffid (Sivatherium hendeyi) assemblage; J. Vertebr. Paleontol. (in press) Franz-Odendaal T A, Lee-Thorp J A and Chinsamy A 2002 New evidence for the lack of C 4 grassland expansions during the Early Pliocene at Langebaanweg, South Africa; Paleobiology 28 378–388
Isotopic ecology of the Makapansgat Limeworks Vertebrate Fauna
  • M Sponheimer
  • J A Lee-Thorp
  • K Reed
  • De Ruiter
Sponheimer M, Lee-Thorp J A, Reed K and De Ruiter D J 2003 Isotopic ecology of the Makapansgat Limeworks Vertebrate Fauna; J. Vertebr. Paleontol. (in press)
Enamel Hypoplasia in Bison: Paleoecological implications for modelling hunter-gatherer procurement and processing on the northwestern plains
  • L Niven
Niven L B 2002 Enamel Hypoplasia in Bison: Paleoecological implications for modelling hunter-gatherer procurement and processing on the northwestern plains; Archaeozoologica 11 101–112