Cheek tooth erosion in male babirusa (genus Babyrousa)

The wear on the occlusal surfaces of male babirusa cheek teeth was evaluated in 53 skulls of Babyrousa babyrussa from Buru and the Sula Islands and 87 skulls of B. celebensis from Sulawesi, Indonesia. Based on the comparative lengths of their continually growing maxillary canine teeth, the skulls were divided into five ‘age categories’ (A–E). Numerical and symbolic codes representing tooth wear were applied to each pillar (cusp region) of the mandibular and maxillary permanent third and fourth premolar teeth, and the first, second and third permanent molar teeth. There was no significant difference between the tooth wear patters of skulls in groups A and B, or in groups C and D, and so these were amalgamated. There was close correspondence in wear patterns between each side of the mouth in both species and in each age group. The wear patterns of the mandibular and maxillary teeth, although not identical, were very similar, as were the wear patterns of both species. In group A + B for both species tooth wear was relatively slight, with the M1 teeth experiencing most relative wear. There was almost no wear of the M3 teeth. In group C + D substantial wear of upper and lower M1 was evident. In group E more widespread wear of the cheek teeth was seen, with increased severity of M1 tooth wear, yet there was comparatively much less M2 and M3 tooth wear. The pattern of cheek tooth wear of the Babyrousa spp. was different from that shown by Sus scrofa. Differences in diet selection and processing were highlighted as potential contributing factors. The pattern of cheek tooth wear in male babirusa was not adequate for use to monitor their age.     

Morphogenesis of the pharyngeal teeth in the japanese dace,Tribolodon hakonensis(Pisces: Cyprinidae)

The appearance pattern of pharyngeal tooth germs was investigated in the larval Japanese dace, Tribolodon hakonensis, which has a bilaterally asymmetrical dentition. Teeth develop in a series of replacement waves beginning with the initial central tooth (Ce) and continuing with teeth of anterior (An) and posterior (Po) positions relative to the initial one. Identified by wave number (n) and tooth position (r), according to the formula _n-1[r], tooth germs appeared in the order of tooth ₀[Ce0], ₁[Po1], ₁[Anl], ₂[Ce0], ₂[An2], ₃[Po1], ₃[An1], ₄[Ce0], 4[An2], ₅[Po1], ₅[An1], ₅[An3], ₆[Ce0], ₆[An2] during the larval period. Dentition on the right side, however, lacks the first tooth at position An2 (tooth ₂[An2]) and teeth at position An3. Tooth germs on the first, second, and third replacement waves appeared simultaneously on the arches of both sides. During following waves, tooth germs on the left side appeared later than those on the right. Delay of tooth germ appearance On the left side is interpreted as an inhibitory influence of existing tooth germs in accordance with Osborn's (Proc. R. Soc. Lond. Ser. B 179:261--289, '71) theory. The delay of tooth germ appearance on the left arch is most pronounced on the seventh replacement wave. Teeth of the right major row in adults of this species are replaced more frequently than those of the left major row, apparently in correlation with the absence of the first larval tooth at position An2 and teeth at position An3. It is hypothesized that cyprinids evolved the minor rows and specialized teeth of their adult dentition as apomorphic characteristics by the process of neoteny.     

Development and microstructure of tooth histotypes in the blue shark,Prionace glauca (Carcharhiniformes: Carcharhinidae) and the great white shark,Carcharodon carcharias (Lamniformes: Lamnidae)

Elasmobranchs exhibit two distinct arrangements of mineralized tissues in the teeth that are known as orthodont and osteodont histotypes. Traditionally, it has been said that orthodont teeth maintain a pulp cavity throughout tooth development whereas osteodont teeth are filled with osteodentine and lack a pulp cavity when fully developed. We used light microscopy, scanning electron microscopy, and high‐resolution micro‐computed tomography to compare the structure and development of elasmobranch teeth representing the two histotypes. As an example of the orthodont histotype, we studied teeth of the blue shark, Prionace glauca (Carcharhiniformes: Carcharhinidae). For the osteodont histotype, we studied teeth of the great white shark, Carcharodon carcharias (Lamniformes: Lamnidae). We document similarities and differences in tooth development and the microstructure of tissues in these two species and review the history of definitions and interpretations of elasmobranch tooth histotypes. We discuss a possible correlation between tooth histotype and tooth replacement and review the history of histotype differentiation in sharks. We find that contrary to a long held misconception, there is no orthodentine in the osteodont teeth of C. carcharias. J. Morphol. 276:797–817, 2015. © 2015 Wiley Periodicals, Inc.     

Ultrastructure and the importance of wear in the dentition of the halfbeak (Pisces: Hemiramphidae) pharyngeal mill

To assess how tooth microstructure and composition might facilitate the pharyngeal mill mechanism of halfbeaks, apatite structure and iron content were determined by scanning electron microscopy and energy dispersive X‐ray analysis for Hyporhamphus regularis ardelio, Arrhamphus sclerolepis krefftii, and Hemiramphus robustus. Iron was present in developing teeth and was concentrated along the shearing edge of spatulate incisiform teeth, which dominate the occlusive wear zone in all three species. A model based on tooth structure and wear rate is proposed to explain how halfbeaks maintain a fully functional occlusion zone throughout growth and consequent tooth addition and replacement. Replacement teeth erupt and wear rapidly so that a constant occlusion plane is always present. Iron within the tooth tissue reduces the wear rate of the cutting edge while simultaneously maintaining its sharpness and efficiency. J. Morphol. 2009. © 2008 Wiley‐Liss, Inc.     

Dentition of the apron ray Discopyge tschudii (Elasmobranchii: Narcinidae)

The present study provides quantitative and qualitative analyses of the dentition of Discopyge tschudii. Overall, 193 individuals (99 males and 94 females) of D. tschudii were collected on scientific trawl surveys conducted by the National Institute for Fisheries Research and Development (INIDEP) and commercial vessels in Argentina. Discopyge tschudii has rhombic‐shaped teeth, arranged in a semipavement‐like dentition; each tooth has an erect cusp slightly inclined posteriorly and holaulachorized root. Mature males have greater tooth lengths than females and immature specimens. Discopyge tschudii exhibits dignathic homodonty and gradient monognathic heterodonty where teeth of the commissural row are shorter than those of the symphyseal and internal rows.     

Diversity of macrociliary size,tooth patterns,and distribution in Beroe (Ctenophora)

Summary Macrocilia are compound ciliary feeding organelles found inside the mouth of beroid ctenophores. Each macrocilium contains multiple 9+2 axonemes surrounded by a common membrane and bears a distinct capping structure at the distal end. The cap consists of extensions of axonemal microtubules that are embedded in an electron-dense matrix to form pointed projections or teeth. The teeth change from a straight to a hooked configuration during the beat cycle of macrocilia, and these changes in tip shape are thought to aid ingestion and/or breakup of prey. Using light and electron microscopy we found a remarkable diversity in macrociliary size, tooth pattern, and distribution among traditional morphospecies of Beroe. These differences distinguish two major groups of Beroida. Group 1 includes most of the described nominal species [B. cucumis, B. abyssicola, B. ovata, B. gracilis, and B. sp. (Gloria)]. Their macrocilia are relatively small (typically 25–30 m long, 5 m diameter) and are restricted to a band around the inside of the lips. Two main types of macrociliary tooth patterns are found: 3–12 equally-sized teeth [B. cucumis (Mon), B. ovata, B. sp. (Gloria)] or 3 teeth with the middle tooth being larger (B. cucumis (CC), B. gracilis) or smaller (B. abyssicola). Group 2 species (B. forskali, B. mitrata) have greatly flattened bodies and wide mouths. Their macrocilia cover an extensive area of the stomodaeal cavity, and are longer and stouter (80–100 m long, 12–15 m in diameter). The shaft of the macrocilium is not hexagonal in transverse section, as in Group 1 species, but is wedge-shaped, being broader on the recovery-stroke (oral) side. The macrociliary tips are blunt and finely serrated, bearing one or more rows of 10–12 short teeth running at right angles to the beat plane. This diversity in macrociliary patterns is apparently related to differences in diet, feeding methods, and/or mechanism of prey digestion among various species. However, direct evidence for the functional significance of macrociliary diversity has not yet been obtained. The macrociliary patterns may be useful for clarifying problems of species identification and relationships within the Beroida. In particular, macrociliary differences found between and within traditionally distinguished morphospecies of Beroe raise the possibility of the existence of complexes of sibling species in this group.     

Dental Ontogeny in Macroscelides proboscideus (Afrotheria) and Erinaceus europaeus (Lipotyphla)

We investigated the state of dental eruption in specimens of Macroscelides proboscideus and Erinaceus europaeus of known age. When M. proboscideus reaches adult size and sexual maturity, few or none of its replaced permanent cheek teeth have erupted. The approximate sequence of upper tooth eruption is P1, [I3, C, M1], [I1–2], M2, P4, [P2, P3]. Chronologically, E. europaeus erupts its molars and most premolars prior to M. proboscideus; but its first two upper incisors erupt after those of M. proboscideus, and its canines erupt around the same time. The approximate sequence of upper tooth eruption in E. europaeus is [M1, M2, P2, I3], C, M3, P4, P3, I2, I1. Unlike M. proboscideus, E. europaeus does not reach adult size until all permanent teeth except for the anterior incisors have erupted. While not unique among mammals, the attainment of adult body size prior to complete eruption of the permanent cheek teeth is particularly common among macroscelidids and other afrotherians.     

Tooth crown morphology in caecilians (Amphibia: Gymnophiona)

The morphology of tooth crowns is variable inter-specifically among caecilians. Cusp number and shape, crown dimensions, and crown curvature characterize various species and have both functional and phylogenetic implications. Ichthyophis, Uraeotyphlus, Hypogeophis, and Geotrypetes have bicuspid teeth; Dermophis, Gymnopis, Caecilia, and Typhlonectes monocuspid. Crown morphology as revealed by scanning electron microscopy is associated with prey grasping and, in one case, possible specialization of prey type.     

Supernumerary teeth in a subadult rhino mandible (<Emphasis Type="Italic">Stephanorhinus hundsheimensis</Emphasis>) from the middle Pleistocene of Mosbach in Wiesbaden (Germany)

A well preserved subadult rhino mandible from Mosbach 2 can be attributed toStephanorhinus hundsheimensis based on a metrical and morphological analysis. A comparison to tooth eruption of livingDiceros bicornis suggests an individual age for the animal of about 7 years at death. The described mandible shows a significant tooth anomaly: two teeth occupy the p3 position on each side of the mandible. Comparisons with three younger juvenileStephanorhinus hundsheimensis from Mosbach 2 show the sequence of tooth eruption for the species and allow us to determine that the anomalous teeth are not persistent milk teeth but are supernumerary teeth, which are morphologically intermediate between normal p2 and p3. The animal’s occlusion was compromised to some degree by the anomaly, and the functional disadvantage may have been critical during a harsh period.      

ASPECTS OF CONE AND OVULE ONTOGENY IN CRYPTOMERIA (TAXODIACEAE)

The axillary complex of female cones of Cryptomeria is initiated as a tangentially extended triangular structure with a rounded apex. It is bilaterally symmetrical. Structures interpreted as prophylls are differentiated first, but they become insignificant in later development. They are succeeded by two successive pairs of lobes, each lobe being the common primordium for an adaxial ovule and a tooth. The ovule initially much exceeds the tooth. The apex of the complex has a diversity of fates and may differentiate as an ovule-tooth pair. A one-to-one relation between teeth and ovules may be lost by abortion of ovules. The initial relation between teeth and ovules is obscured in later development due to extension of tissues at the base of the complex associated with considerable enlargement of the teeth. Histogenesis of the various parts is described, together with the vascular system. There is a vascular supply to the tooth but not the ovule. The results support a direct comparison with the extinct transition conifers Pseudovoltzia and Aethophyllum but do not fully support Florin's generalized model for the arrangement of parts in the axillary complex of conifers.     

New species of the genus <Emphasis Type="Italic">Bathycongrus—B. parviporus</Emphasis> (Congridae,Anguilliformes)—from waters of Central Vietnam (Nha Trang and Van Phong Bays)

Bathycongrus parviporus sp. nova is described from specimens collected in the South China Sea, in the coastal waters of central Vietnam. By its characters (short snout, elongate-oval vomerine tooth patch with numerous small teeth of approximately the same size, slender relatively short tail, and residual leptocephalic pigmentation as a series of small melanophores just below lateral line in adults), the species belongs to the group of species of this genus represented by B. bleekeri, B. trimaculatus, and B. unimaculatus in the western part of the Pacific Ocean and B. dubius in the western Atlantic Ocean but differs in small infraorbital pores which are enlarged in all known species of the genus Bathycongrus. By the number of preanal pores, the new species is similar to B. bleekeri from Philippine waters but differs from it in a higher number of vertebrae (120–122), in more numerous rows of teeth on the premaxilloethmoid, in more number of branchiostegal rays (9–10), a shorter head, and in some other proportions of head and body. Topography of canals and pores of the cephalic seismosensory system of B. parviporus sp. nova is described. Morphometric and osteological characters for placing this species in the genus Bathycongrus are noted.     

The appearance pattern of tooth germs in the round crucian carp,Carassius auratus grandoculis

Cyprinid fishes generally replace their teeth alternately and cephalad. The larvae ofCarassius auratus grandoculis also replace their teeth alternately and cephalad, in a pattern of 4-2-3-1-. However, adults ofCarassius species replace their teeth from anterior to posterior, in a pattern of 1-2-3-4-1-. So I analyzed the appearance pattern of tooth germs in larvae and juveniles inCarassius auratus grandoculis. At stage 5 of the post-larval period, developmental difference is made between both sides. In the pharyngeal dentition on one side developing poorly, the anterior tooth on the fifth replacement wave, tooth₄[An2] appeared later than the central teeth on following replacement wave, tooth₅[Pol]. Moreover, the anterior tooth on the seventh replacement wave, tooth₆[An2], appeared later than the central teeth on the following replacement wave, tooth₇[Pol], on both sides. The reverse of tooth germ appearance between anterior teeth and central teeth makes a change of replacement pattern from 4-2-3-1-4- to 1-2-3-4-1-. The change of replacement pattern is caused by the confusion of tooth germs of anterior teeth on both sides.Mylopharyngodon piceus andCyprinus carpio make a change of replacement patterns in the early juvenile period, too. This change of replacement pattern may be a specialized character among the subfamily Cyprininae.     

Permanent tooth mineralization in bonobos (Pan paniscus) and chimpanzees (P. troglodytes)

The timing of tooth mineralization in bonobos (Pan paniscus) is virtually uncharacterized. Analysis of these developmental features in bonobos and the possible differences with its sister species, the chimpanzee (P. troglodytes), is important to properly quantify the normal ranges of dental growth variation in closely related primate species. Understanding this variation among bonobo, chimpanzee and modern human dental development is necessary to better contextualize the life histories of extinct hominins. This study tests whether bonobos and chimpanzees are distinguished from each other by covariance among the relative timing and sequences of tooth crown initiation, mineralization, root extension, and completion. Using multivariate statistical analyses, we compared the relative timing of permanent tooth crypt formation, crown mineralization, and root extension between 34 P. paniscus and 80 P. troglodytes mandibles radiographed in lateral and occlusal views. Covariance among our 12 assigned dental scores failed to statistically distinguish between bonobos and chimpanzees. Rather than clustering by species, individuals clustered by age group (infant, younger or older juvenile, and adult). Dental scores covaried similarly between the incisors, as well as between both premolars. Conversely, covariance among dental scores distinguished the canine and each of the three molars not only from each other, but also from the rest of the anterior teeth. Our study showed no significant differences in the relative timing of permanent tooth crown and root formation between bonobos and chimpanzees. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.     

Tooth development and histology patterns in lamniform sharks (Elasmobranchii,Lamniformes) revisited

The dentition of lamniforme sharks exhibits several characters that have been used extensively to resolve the phylogenetic relationships of extant taxa, yet some uncertainties remain. Also, the development of different teeth of a tooth file within the jaws of most extant lamniforms has not been documented to date. High‐resolution micro‐computed tomography is used here to re‐evaluate the importance of two dental characters within the order Lamniformes, which were considered not to be phylogenetically informative, the histotype and the number of teeth per tooth file. Additionally, the development and mineralization patterns of the teeth of the two osteodont lamniforms Lamna nasus and Alopias superciliosus were compared. We discuss the importance of these dental characters for phylogenetic interpretations to assess the quality of these characters in resolving lamniform relationships. The dental characters suggest that (1) Lamniformes are the only modern‐level sharks exhibiting the osteodont histotype, (2) the osteodont histotype in lamniform sharks is a derived state in modern‐level sharks (Elasmobranchii), (3) the osteodont type, conversely is convergently achieved when the clade Chondrichthyes is considered and thus might comprise a functional rather than a phylogenetic signal, and (4) there is an increase in the number of teeth per file throughout lamniform phylogeny. Structural development of the teeth of L. nasus and A. superciliosus is congruent with a previous investigation of the lamniform shark Carcharodon carcharias. J. Morphol. 277:1584–1598, 2016. © 2016 Wiley Periodicals, Inc.     

General morphology and ultrastructure of the radula of Testudinalia testudinalis (O. F. Müller, 1776) (Patellogastropoda,Gastropoda)

The radular morphology of the patellid species Testudinalia testudinalis (O. F. Müller, 1776) from the White Sea was studied using light, electron, and confocal microscopy. The radula is of the docoglossan type with four teeth per row and consisting of six zones. We characterize teeth formation in T. testidinalis as follows: one tooth is formed by numerous and extremely narrow odontoblasts through apocrine secretion; this initially formed tooth consists of numerous vesicles; the synthetic apparatus of the odontoblasts is localized in the apical and central parts of the cells throughout the cytoplasm and is penetrated by microtubules which are involved in the transport of the synthesized products to the apical part of the odontoblast; the newly formed teeth consist of unpolymerized chitin. Mitotic activity is located in the lateral parts of the formation zone. The first four rows contain an irregular arrangement of teeth, but the radular teeth are regularly arranged after the fifth row. The irregularly arranged teeth early on could be a consequence of the asynchronous formation of teeth and the distance between the odontoblasts and the membranoblasts. The morphological data obtained significantly expands our knowledge of the morphological diversity of the radula formation in Gastropoda.     

Functional and phylogenetic significance of integrated growth and form in occluding monkey canine teeth (Alouatta caraya and Macaca mulatta)

Crown-root lengths in paired apposing, functionally interacting monkey canine teeth (Alouatta caraya and Macaca mulatta) are highly correlated throughout their concurrent development. Regression is rectilinear and growth pattern accretional. The differential growth rate is not significantly different in the sexes within each species during concurrent tooth pair development. These integrated morphological characteristics are adaptations to functional needs imposed by jaw anatomy and masticatory dynamics. Divergence from rectilinearity occurs in the mature male Macaca mulatta with the continued growth of the maxillary canine fang after cessation of growth of the apposing mandibular canine tooth. This altered tooth pair crown-root length relationship is associated with the subordination of mastication in these predominantly piercing and slashing teeth. Species differences in regression are significant and afford insight into possible preadaptive factors determining divergent paths in the evolution of canine tooth sexual dimorphism.     

Applied zooarchaeology and Oregon Coast sea otters (Enhydra lutris)

The sea otter (Enhydra lutris) was nearly driven to extinction on the Pacific Coast in the 19th century due to intensive commercial hunting and the maritime fur trade. Despite successful reintroduction efforts elsewhere in North America, the Oregon sea otter population remains locally extirpated and listed as endangered. Prior study addressed precontact sea otter teeth from Oregon and found they were not significantly different in absolute size from modern California sea otter (Enhydra lutris nereis) teeth, and smaller than modern Alaska sea otter (Enhydra lutris lutris) teeth. These geographic groupings were later confirmed by an ancient DNA study. The conclusion that distinct geographic populations exist based on tooth size was founded on small samples. Larger samples of teeth, as well as new data on humeri and femora, indicate dimensions vary significantly along a latitudinal cline from California to Alaska. Morphometric analyses of ancient animal remains can be used to examine spatial relationships of phenotypic features and inform conservation biology decisions.     

Tooth loss rate from two captive sandtiger sharks (Carcharias taurus)

For 6 months, two sandtiger sharks (Carcharias taurus) were held captive together in a small enclosure at the Lisbon Zoo. During that period, the gravel was monitored daily for teeth shed by the animals. At the end of their stay, the number of teeth divided by the number of days yielded a tooth loss rate of 1.06 teeth per day per shark. The plotting of mean monthly values for tooth loss rate against mean monthly temperatures showed that these two variables increased with time, suggesting that the animals' metabolism was influenced by the increase in water temperature. Zoo Biol 18:313–317, 1999. © 1999 Wiley‐Liss, Inc.     

Ultrastructural study of the jaw structures in two species of Ampharetidae (Annelida: Polychaeta)

Two species of jaw bearing Ampharetidae (Adercodon pleijeli (Mackie 1994) and Ampharete sp. B) were investigated in order to describe the microanatomy of the mouth parts and especially jaws of these enigmatic polychaetes. The animals of both studied species have 14–18 mouth tentacles that are about 30 µm in diameter each. In both species, the ventral pharyngeal organ is well developed and situated on the ventral side of the buccal cavity. It is composed of a ventral muscle bulb and investing muscles. The bulb consists of posterior and anterior parts separated by a deep median transversal groove. In both species, the triangular teeth or denticles are arranged in a single transversal row on the surface of the posterior part of the ventral bulb just in front of its posterior edge. There are 36 denticles in Adercodon pleijeli and 50 in Ampharete sp. B. The height of the denticles (6–12 µm) is similar in both species. Each tooth is composed of two main layers. The outer one (dental) is the electron‐dense sclerotized layer that covers the tooth. The inner one consists of long microvilli with a collagen matrix between them. The thickness of the dental layer ranges from 0.95 to 0.6 µm. The jaws of the studied worms may play a certain role in scraping off microfouling. The fine structure of the jaws in Ampharetidae is very similar to that of the mandibles of Dorvilleidae, the mandibles and the maxillae of Lumbrineridae, Eunicidae and Onuphidae, and the jaws of other Aciculata. This type of jaw is characterized by unlimited growth and the absence of replacement. The occurrence of jaws in a few smaller Ampharetidae is considered as an apomorphic state.     

Observations on tooth development and implantation in the upper pharyngeal jaws in Astatotilapia elegans (Teleostei,Cichlidae)

Prominent stages in the development of teeth, associated with the upper pharyngeal jaws in early postembryonic stages of the mouth brooding cichlid A statotilapia elegans were studied on semithin sections in relation to changes in the underlying endoskeletal parts and to the formation of the dentigerous bone. Because the pattern of tooth implantation on infrapharyngobranchial III-IV is constant, at least in early postembryonic stages, it is possible to trace the life history of a given tooth by tracing its homologue throughout the ontogenetic series. A probable causal relationship exists between tooth development and erosion of the underlying cartilage. Fully developed, though unerupted teeth, differentiate annular bone of attachment, which, depending on its position, is formed either outside the cartilage or within the previously induced erosion cavities. Attachment bone of adjacent teeth fuses to build up the dentigerous bone, which, as a result, may be situated within the area previously occupied by cartilage. As soon as the tooth has built up its bone of attachment, it may erupt. The collagenous matrix between tooth and attachment bone persists and gives rise to the movable connection between both. Differentiation of teeth on infrapharyngobranchial III-IV, together with enlargement of the dentigerous bone, proceeds from the lateral and the rostral border, where new germs constantly form. The appearance of new germs on infrapharyngobranchial II is more unpredictable.