Histogenesis of the unique morphology of proboscidean ivory

The chequered pattern (often called Schreger pattern), which can be seen by unaided eye on transverse profiles of several proboscidean tusks and which can be emphasized by the spreading pattern of the cracks or by mineral discoloration, is an autapomorph feature of the clade Elephantoidea. The pattern differs among proboscidean taxa; therefore, it allows the coarse differentiation of elephants, mammoths, and some other basal groups. Such identification methods could facilitate efforts concerned with protection of the remaining elephant populations through ivory trade restrictions, since the tooth dentine from extinct Mammuthusprimigenius and from extant Loxodontaafricana and Elephasmaximus are the most common raw materials of the ivory carvings. The aim of this study was to show the internal structure of proboscidean ivory and to revise the existing theories on the aforementioned pattern of the elephantoids with reflections on the events which lead to the development of this microstructure. Thin sections and natural crack surfaces with various orientations of M.primigenius, Elephasantiquus, Prodeinotherium, and Deinotherium tusk fragments were used to produce a three‐dimensional model which explains the features on all profiles. The “phase shift” model is introduced, which assumes a sinusoid undulation of the dentinal tubules in radial profiles in the case of elephantoids. The model was confirmed by photomicrographs, scanning electron microscopic images, interpretation of natural crack surfaces, and radial displacement analysis of the dentinal tubules. The latter proved that the adjacent waves are not in the same phase. Several new nondestructive distinguishing methods are described here on the basis of the correlation between some microscopic and macroscopic features related to the Schreger pattern. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.     

Biodegradation of ivory (natural apatite): possible involvement of fungal activity in biodeterioration of the Lewis Chessmen

Fungal biodeterioration of ivory was investigated with in vitro inoculation of samples obtained from boar and walrus tusks with the fungi Aspergillus niger and Serpula himantioides, species of known geoactive abilities. A combination of light and scanning electron microscopy together with associated analytical techniques was used to characterize fungal interactions with the ivory, including changes in ivory composition, dissolution and tunnelling, and the formation of new biominerals. The research was aimed at providing further understanding of the potential roles of fungi in the colonization and deterioration of ivory in terrestrial environments, but also contributes to our knowledge regarding the possible origins of the surface damage observed on early medieval sculptures made largely from walrus tusks, referred to as ‘the Lewis hoard of gaming pieces’, that were presumably produced for playing chess. The experiments have shown that the possibility of damage to ivory being caused by fungi is realistic. Scanning electron microscopy revealed penetration of fungal hyphae within cracks in the walrus tusk that showed also widespread tunnelling by fungal hyphae as well as ‘fungal footprints’ where the surface was etched as a consequence of mycelial colonization. Similar phenomena were observed with boar tusk ivory, while production of metabolites could lead to complete dissolution of the sample. Colonization of ivory and/or exposure to fungal activity lead to extensive secondary biomineral formation, and this was identified as calcium oxalate, mainly as the monohydrate, whewellite.     

The frequency distribution of Oculotrema hippopotami (Monogenea: Polystomatidae) on Hippopotamus amphibius

Oculotrema hippopotami Stunkard is a monogenean that is found around the nictitating membrane and under the eyelids of the hippopotamus. When specimens of O. hippopotami were collected from both eyes of 42 hippopotamuses in Uganda, 90.5% of the hippopotamuses were found to be infested. The maximum number of parasites on one hippopotamus was 41, and the mean number of parasites per hippopotamus was 8.26. The frequency distribution did not follow a Poisson distribution and is therefore considered to be non-random. Both mature and small immature worms were found in the same eye, therefore the infection does not immediately confer immunity on the host.     

Isolation of DNA from small amounts of elephant ivory

This protocol describes a method for the extraction of DNA from elephant ivory. These techniques are being used to assign geographic origin to poached ivory by comparing the ivory genotype to a geographic-based gene frequency map, developed separately. The method has three components: ivory pulverization, decalcification and DNA extraction. Pulverization occurs in a freezer mill while the sample is deep frozen in liquid nitrogen, preventing degradation of DNA during the process. Decalcification involves repeated agitation of the sample in 0.5 M ethylenediaminetetraacetic acid over a 4-d period. Extraction follows a modified Qiagen protocol for the extraction of DNA from animal tissue. This method can be used on all forms of ivory. However, DNA recovery is highest when the outermost layer of the tusk, the cementum, is used. When applied to extract DNA from 11 samples, in duplicate, the entire protocol can be completed in 6 d, although much of this time consists of pause points that do not require effort. The protocol provides 0.8 +/- 0.11 ng microl(-1) (mean +/- s.e., n = 48) of DNA per sample.     

Bone and ivory points in the Lower and Middle Paleolithic of Europe.

The existence of shaped bone and ivory points, to be used as awls or with wooden hafts, has been suggested for the Lower Paleolithic sites of Torralba and Ambrona and for several Middle Paleolithic sites, such as Vaufrey, Combe Grenal, Pech de l'Azé I and Camiac. The use of hafted bone and ivory points would imply a spear armature technology similar to that well documented in the Upper Paleolithic, often considered an innovation introduced to Europe by anatomically modern humans.The controversial ivory points from the two Spanish sites, whose fracture morphology is considered natural by G. Haynes (1991), have been reanalyzed, checking for putative traces of human manufacture and utilization as described by Howell & Freeman (1983), i.e., polish, flaking of stem, ground edges, striations from manufacture and contact with a haft or binding. We have been able to study 19 new proboscidean tusk tips from the ongoing Ambrona excavations by a Spanish team. For these and nine other Middle Paleolithic bone and antler points we use optical and SEM microscope analysis, taphonomic analysis, comparative observations of Upper Paleolithic bone points, experimental observations of manufacturing traces, modern tusk samples, and data on several bone and antler pseudo-points from carnivore accumulations.We show that none of the objects we have studied can be interpreted as an intentionally shaped point. The absence of hafted bone points in the Middle Paleolithic of Europe is contrasted with evidence of the use of hafted stone points since OIS 5 or earlier in Eurasia and Africa. We suggest that the absence of organic spear armatures in the Middle Paleolithic is not due to a deficiency in the technology of Neandertals but may be tied to the organizational strategies of the hunters and to patterns of game choice and capture.     

Tusk abnormalities in wild boar (<Emphasis Type="Italic">Sus scrofa</Emphasis> L.)

This paper describes pathological alterations in the permanent canines (tusks) of four male wild boars. The mandibular tusks of all individuals, and also some of the maxillary tusks, exhibited an extended enamel hypoplasia in their apical portion, denoting an impairment of secretory ameloblast function. Moreover, the pulp cavities of the mandibular tusks were exposed through cleft-like openings in the wear (whetting) surfaces of the teeth. Presence of a plug of reparative dentine within the pulp cavity was observed in a split mandibular tusk of one individual. In a second boar, the presence of a plug of reparative dentine within the pulp cavity of the mandibular tusks was indicated radiographically. These findings suggested a reparation process attempting to demarcate a vital, apical pulp portion from a necrotic, incisal portion. The enamel hypoplasias observed in the teeth are regarded to be sequelae of the pulp inflammation caused by bacterial invasion in the mandibular tusks. Most likely, bacterial invasion of the dental pulp occurred through the cleft-like openings in the tusks whetting surfaces, the openings resulting from insufficient formation of secondary dentine. It is, however, also conceivable that pulp inflammation and partial necrosis occurred as a consequence of bacterial invasion of patent dentinal tubules, and that the openings in the whetting surface developed secondarily as a consequence of the pulp changes. One mandibular tusk showed marked signs of resorption apically, suggesting a spread of the inflammation from the pulp into the periodontium.     

甘肃东乡几种早中新世哺乳动物化石

本文记述了在甘肃东乡椒子沟发现的几种早中新世哺乳动物化石:Gomphotherium sp、Dzungariotheriura orgosense、Rhinocerotidae gen. indet.和Paraentelodon macrognathus sp. nov.,着重讨论了全北区猪齿兽类的系统关系。根据化石的性质判断,东乡椒子沟化石点的地质时代应与欧洲Burdigalian早期,亦即MN_3相当或稍早。笔者将原定为上新世临夏组的第一、二岩性段划出,命名为椒子沟组,其时代为早中新世。     

甘肃临夏盆地的渐新世巨犀化石

描述了 2种巨犀化石 :霍尔果斯准噶尔巨犀 (Dzungariotheriumorgosense)和牙沟副巨犀(新种 ) (Paraceratheriumyagouensesp .nov.)。新种的主要特征是 :个体小 ;上颊齿齿冠高 ,有薄层白垩质覆盖 ;DP2～M1反前刺大 ,原尖后收缩沟明显 ,次尖有深的前收缩沟 ,中谷和后凹中常有附属小柱等。巨犀的演化历史可能比过去想象的更复杂。Indricotherium、Dzungariotherium和Paraceratherium为代表不同进化水平和支系的 3个属 ,不应合并为Paraceratherium一属。牙沟含巨犀化石层位的地质时代为晚渐新世。     

Illegal tusk harvest and the decline of tusk size in the African elephant

Harvesting of wild populations can cause the evolution of morphological, behavioral, and life history traits that may compromise natural or sexual selection. Despite the vulnerability of large mammals to rapid population decline from harvesting, the evolutionary effects of harvesting on mega‐fauna have received limited attention. In elephants, illegal ivory harvesting disproportionately affects older age classes and males because they carry large tusks, but its' effects on tusk size for age or tusk size for stature are less understood. We tested whether severe historical elephant harvests eliminated large tuskers among survivors and whether elephants born thereafter had smaller tusks. Adjusting for the influence of shoulder height – a metric strongly correlated with body size and age and often used as a proxy for age – we compared tusk size for elephants sampled in 1966–1968, prior to severe ivory harvesting in the late 1970s and early 1980s, with tusk size of survivors and elephants born during population recovery in the mid‐1990s. In a regional population, tusk length declined by ˜21% in male and by ˜27% in female elephants born during population recovery, while tusk length declined by 22% in males and 37% in females among survivors. Tusk circumference at lip declined by 5% in males but not in females born during population recovery, whereas tusk circumference reduced by 8% in male and by 11% in female survivors. In a single subpopulation, mean tusk length at mean basal tusk circumference declined by 12.4% in males and 21% in females. Tusk size varied between elephant social groups. Tusk homogeneity within social groups and the often high genetic similarity within social groups suggest that tusk size may be heritable. Our findings support a hypothesis of selection of large tuskers by poachers as a driver of the decline in tusk size for age proxy and contemporary tusk evolution in African elephants.     

An assessment of the maximum sustainable yield of ivory from African elephant populations.

A general, logistic population model is used to explore the dynamics of harvested elephant populations. The model includes two features peculiar to elephant populations and the harvesting of ivory. First, because of the shape of the growth curve of tusks with age, the conversion factor that relates the number of elephants killed to the ivory yield in weight is not constant, but a function of the population size. Second, tusks from animals that die from natural causes can be retrieved and included in the total yield of ivory. The implications of the relationship between tusk size and age of an animal on the maximum sustainable yield in terms of ivory tonnage and in terms of the number of tusks are explored. The nonequilibrium implications of the tusk growth curve on the population dynamics under different harvesting strategies are also investigated. Results indicate that the maximum sustainable yield is achieved at very low harvest rates with population levels close to the pristine equilibrium. When tusks from animals that die of natural causes are included in the harvest, the maximum yield may, depending on the mortality and recruitment parameters, occur when there is no direct harvest.     

宁夏同心中新世铲齿象化石

本文记述了宁夏同心地区中中新世哺乳动物群中铲齿象化石——同心铲齿象 (Platybelodon tongxinensis) (原定为同心嵌齿象 (Gomphotherium tongxinensis). 通过与国内外已现的有关铲齿象对比,确认其与国内已发现的葛氏种关系最近,可能属同一枝系.同心种与葛氏种相比,是性质相对原始分布层位较低的我国第二个铲齿象种.文章初步讨论了其 M_3 的某些变异性状.并结合现有的其它标本初步阐述了铲齿象类下门齿的两种结构类型,原始型的同心层状结构和衍生型的齿质柱状结构.建议根据这两种结构仍将铲齿象类划分为 Platybelodontinae 和 Amebelodontinae.     

Preliminary observations on increasing root length during the eruptive phase of tooth development in modern humans and great apes

Ground sections of incisors, canines, and molars were selected that showed clear incremental markings in root dentine. The sample comprised 98 Homo sapiens, 53 Pan troglodytes, and a more limited combined sample of 51 Gorilla and Pongo sections. Daily rates of root dentine formation, together with the orientation of incremental markings in roots close to the cement-dentine junction (CDJ), were used to calculate root extension rates for the first 10mm of root formed beyond the buccal enamel cervix. Modern human anterior tooth roots showed a more regular pattern of increase in root length than those in great apes. In Pan, root growth rose quickly to higher rates but then flattened off. The fastest extension rates in modern humans were in incisor roots (10-12 microm per day), followed by canines (8-9 microm per day). Extension rates in Pan rose to slightly greater values in canines ( approximately 12-14 microm per day) than in incisors ( approximately 10-11 microm per day). Molar tooth roots in both modern humans and great apes grew in a nonlinear manner. Peak rates in molars reduced from M1 to M3 (8, 7, and 6 microm per day, respectively). Like humans, root growth in Pan peaked earlier in M1s at rates of between 8 and 9 microm per day, and later in M3s at rates of 7 to 8 microm per day. The more limited data set for Gorilla and Pongo molars suggests that extension rates were generally higher than in Pan by approximately 1.0-1.5 microm per day. There were greater differences in peak extension rates, with Gorilla and Pongo extension rates being between 2.5 and 4.5 microm per day higher than those in Pan. These findings highlight for the first time that root growth rates differ between tooth types in both pattern and rate and between taxa. They provide the basis with which to explore further the potential comparative relationships between root growth, jaw growth, and the eruption process.     

Qu’est-ce que l’Ivoire ?

What is ivory? Though the term “ivory” has been generally applied to animal dental materials of commercial value, many specialists reserve the term “true ivory” for the enlarged incisors of elephants and extinct proboscideans. Compared even to the check teeth of the same species, these specialized incisors have chemical and structural properties that are unique, and which have substantial implications for the identification, analysis and interpretation of archaeological artifacts made of true ivory. Below, we present a definition of “true ivory” and an overview of its chemical and structural characteristics and the diagnostic features that can be used in its identification.     

EVALUATION OF AN EFFECTIVE METHOD TO ESTIMATE AGE OF CAPE FUR SEALS USING GROUND TOOTH SECTIONS

Teeth of known-age Cape fur seals Arctocephalus pusillus pusillus were used to validate age estimated from ground sections. In the canines, dentine growth layer groups (GLGs) reflected age accurately but no reliable readings could be obtained from GLGs in the cementum. Upper canines were the most suitable for age estimation. By contrast, in the postcanines where the cementum is thicker, only GLGs in the cementum could be used for age determination, but not with the same accuracy as for dentine in the canines. Therefore, it is recommended that GLGs in the dentine be used to determine age in the Cape fur seal. However, pulp cavities in canines closed at about 13 yr and consequently GLGs in the cementum of the postcanines should be used where the pulp cavities of canines are closed. Accurate estimation of age is not possible from the dentine of older animals.     

Late Pleistocene proboscidean ivory artifacts from the Hiscock site,NY

Here is described the corpus of proboscidean ivory artifacts – the fruit of 30 years excavating – within the Palaeo-American component at the Hiscock site, western New York State. Several types and varieties are newly recognized and unique for the North American archaeological record. They allow us to forge linkages between the Old and New Worlds.     

A simple,low-cost method to age mammals? An alternative to cementum annuli analysis

One of the most common and ubiquitous methods to age mammals is by counting the cementum annuli in molars, premolars, incisors, or canines. Despite the ubiquity and perceived simplicity of the method, cementum annuli analysis can be time-consuming, expensive, inaccurate, and imprecise, and require specialized equipment. Using beavers (Castor canadensis) as a test species, we developed a straightforward method to age mammals that requires little specialized equipment. The method consists of: (1) digitizing longitudinally sectioned teeth and measuring the proportion of tooth surface area comprised of cementum (“proportion cementum”), (2) evaluating the relationship between proportion cementum and specimen age (determined from either known-age samples or cementum annuli analysis), and (3) using the modeled relationship to estimate the age of other individuals based solely on proportion cementum. The relationship between proportion cementum and age was strongly correlated (R² = .97–.98 depending on observer), similar between observers, and similar between known-age specimens and those aged via cementum annuli analysis. Using this proportion cementum method, two independent observers accurately predicted the age of 80%–84% of specimens within 0.5 year and 96%–98% within 1 year. We suggest this aging method will likely work with most mammal species given the relatively consistent deposition of cementum throughout mammals' lives and has promise to be a simple and quick alternative to cementum annuli analysis regardless of whether one develops proportion cementum models using known-age specimens or those aged via alternative methods.     

Use of Poly (Amidoamine) Dendrimer for Dentinal Tubule Occlusion: A Preliminary Study

The occlusion of dentinal tubules is an effective method to alleviate the symptoms caused by dentin hypersensitivity, a significant health problem in dentistry and daily life. The in situ mineralization within dentinal tubules is a promising treatment for dentin hypersensitivity as it induces the formation of mineral on the sensitive regions and occludes the dentinal tubules. This study was carried out to evaluate the in vitro effect of a whole generation poly(amidoamine) (PAMAM) dendrimer (G3.0) on dentinal tubule occlusion by inducing mineralization within dentinal tubules. Dentin discs were treated with PAMAM dendrimers using two methods, followed by the in vitro characterization using Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). These results showed that G3.0 PAMAM dendrimers coated on dentin surface and infiltrated in dentinal tubules could induce hydroxyapatite formation and resulted in effective dentinal tubule occlusion. Moreover, crosslinked PAMAM dendrimers could induce the remineralization of demineralized dentin and thus had the potential in dentinal tubule occlusion. In this in vitro study, dentinal tubules occlusion could be achieved by using PAMAM dendrimers. This could lead to the development of a new therapeutic technique for the treatment of dentin hypersensitivity.     

WALRUS LIFE-HISTORY MOVEMENTS RECONSTRUCTED FROM LEAD ISOTOPES IN ANNUAL LAYERS OF TEETH

Putative life history movements of male Atlantic walrus ( Odobenus rosmarus nsmarus ) harvested at Sanirajak in northern Foxe Basin, Canada, were reconstructed by comparing Pb isotopes in tooth cementum growth layer groups (GLGs) to those in whole-cementum samples from other walrus of Foxe Basin and nearby areas. The analyses yielded three life history patterns including one, "prodigal sons," not previously recognized in large mammals. Isotope ratios in GLGs of "local" Sanirajak walrus were relatively constant over time and similar to the whole-cementum data for most walrus caught in northern Foxe Basin. An "immigrant" walrus acquired the local signal only in young adulthood. In two "prodigal sons," GLG Pb isotope ratios changed significantly from the local signature after weaning but returned to it in late maturity, shortly before being harvested. Possible recruitment and dispersal areas for the two types of outliers included regions in northern and eastern Hudson Bay, some 300–600 km distant. The return of mature males to their natal group after associating with other groups for several years, as seen in some of the walrus, may be more common among mammals than previously thought. However, without a reconsttuctive technique such as employed here, it could only be detected through long-term studies of known individuals and all the relevant social groups.     

The Laptev Sea walrus Odobenus rosmarus laptevi: an enigma revisited

The walrus ( Odobenus rosmarus ) is in some current systematic schemes divided into three subspecies: O. r. rosmarus in the North Atlantic, O.   r. divergens in the North Pacific and O.   r. laptevi in the Laptev Sea. These three subspecies have been described as differing in body size, but the taxonomic status of O.   r. laptevi is disputed. The current study applies molecular and morphometric methods to assess the taxonomic status of O.   r. laptevi and to analyse the systematic and phylogeographic relationships between the three purported walrus subspecies. Tusk length and tusk circumference were measured from the few skulls available of O.   r. laptevi , and the obtained values were within the ranges reported for Pacific walruses. Thus, morphologically, subspecies status for O.   r. laptevi is not supported according to the Amadon–Mayr '75% rule'. Phylogenetic analyses and haplotype networks based on mitochondrial nucleotide sequence data of NADH dehydrogenase 1, 16S rRNA, cytochrome oxidase I and the d -loop of the control region of the historic O.   r. laptevi bone material and contemporary O.   r. rosmarus and O.   r. divergens showed that the Laptev Sea walrus groups with individuals from the North Pacific. Thus, the mitochondrial sequence data do not support the recognition of three walrus subspecies as reciprocally monophyletic evolutionary units with independent evolutionary histories. Only O.   r. rosmarus and O.   r. divergens meet this criterion with the present sampling. Accordingly, we recommend that Odobenus r. laptevi be abandoned and the Laptev walrus instead be recognized as the westernmost population of the Pacific walrus, Odobenus r. divergens. However, further research is recommended to assess whether the Laptev walrus could be considered as a significant unit in terms of conservation and management, since it is unique in several ecological parameters.     

Exploitation des ivoires marins dans les sociétés de l’Arctique de l’Est nord-américain (∼ 2500 BC–1900 AD)

To present an overview of the evolution of the tool-kit and the technical practices from the first occupations of the Arctic until historic periods, the Foxe Basin region, including the Hudson Strait in his southern part, as well as the western coast of Greenland, have been taken as a case study. While around the Foxe Basin the exploitation of walrus tusks widely prevailed during Pre-Dorset and Dorset times (Paleoeskimo), it becomes more and more marginal for the Thule period (Neoeskimo), being gradually replaced by that of whalebone. In contrast, the exploitation of walrus and narwhal tusks is frequent for the Thule times on the northwestern coast of Greenland. The large quantity and diversity of ivory artefacts permit to get an overview of all the activities practiced by the Arctic societies: hunting, transportation, domestic and symbolic activities.