Plate-like permanent dental laminae of upper jaw dentition in adult gobiid fish, Sicyopterus japonicus

Sicyopterus japonicus (Teleostei, Gobiidae) possesses a unique upper jaw dentition different from that known for any other teleosts. In the adults, many (up to 30) replacement teeth, from initiation to attachment, are arranged orderly in a semicircular-like strand within a capsule of connective tissue on the labial side of each premaxillary bone. We have applied histological, ultrastructural, and three-dimensional imaging from serial sections to obtain insights into the distribution and morphological features of the dental lamina in the upper jaw dentition of adult S. japonicus. The adult fish has numerous permanent dental laminae, each of which is an infolding of the oral epithelium at the labial side of the functional tooth and forms a thin plate-like structure with a wavy contour. All replacement teeth of a semicircular-like strand are connected to the plate-like dental lamina by the outer dental epithelium and form a tooth family; neighboring tooth families are completely separated from each other. The new tooth germ directly buds off from the ventro-labial margin of the dental lamina, whereas no distinct free end of the dental lamina is present, even adjacent to this region. Cell proliferation concentrated at the ventro-labial margin of the dental lamina suggests that this region is the site for repeated tooth initiation. During tooth development, the replacement tooth migrates along a semicircular-like strand and eventually erupts through the dental lamina into the oral epithelium at the labial side of the functional tooth. This unique thin plate-like permanent dental lamina and the semicircular-like strand of replacement teeth in the upper jaw dentition of adult S. japonicus probably evolved as a dental adaptation related to the rapid replacement of teeth dictated by the specialized feeding habit of this algae-scraping fish.     

Comparison of teeth and dermal denticles (odontodes) in the teleost Denticeps clupeoides (Clupeomorpha)

The present work is a contribution to an extensive comparative structural and developmental study we have undertaken to understand the evolution of the dermal skeleton in osteichthyans. We have investigated the structure of developing and functional tooth-like dermal denticles located on the head of Denticeps clupeoides, a clupeomorph, and compared their features to those of oral teeth. Morphological (scanning electron microscopy) and structural (light microscopy and transmission electron microscopy) observations clearly demonstrate that these small, sharp, conical and slightly backward-oriented denticles are true odontodes, i.e., homologous to oral teeth. They are composed of a dentine cone surrounding a pulp cavity, the top being covered by a hypermineralized cap. These odontodes are attached to a circular pedicel of attachment bone by a ligament that mineralizes, and the attachment bone matrix merges with that of the bony support. The pedicel of attachment bone surrounds a vascular cavity that is connected to the pulp cavity which is devoid of blood vessels and of nerve endings. Once the odontode is functional, the deposition of collagen matrix (called circumpulpar dentine) continues against the dentine, ligament, and attachment bone surfaces, thereby provoking a narrowing of the pulp cavity. Odontodes are shed by resorption occurring at the base, but their pedicels of attachment bone persist at the bone surface and become embedded in the bone matrix, within which they are clearly visible. The oral teeth are similar in shape, size, and structure to the odontodes, and they show only small differences probably related to the different function of these elements: They are more firmly anchored to the attachment bone, and the amount of dentine is relatively smaller than in odontodes. Despite their different functions, this close structural agreement between teeth and odontodes in Denticeps suggests that 1) competent cells from the same (ecto)mesenchymal population might be involved and 2) the genetic control of the developmental processes could be identical. It is suggested that the odontode expression in extra-oral positions is a relatively late novelty in this lineage. J. Morphol. 237:237–255, 1998. © 1998 Wiley-Liss, Inc.     

Histology of tooth attachment tissues and plicidentine in Varanus (Reptilia: Squamata), and a discussion of the evolution of amniote tooth attachment

Few recent studies have examined the histological basis for tooth attachment in squamates. In the past few years, a surge of interest in this topic has led to the intriguing suggestion that the major tissues derived from the tooth germ (enamel, dentine, cementum and alveolar bone), are conservative and are present in all amniotes. In this study, we describe the histology and development of the tooth attachment complex in Varanus rudicollis, the rough‐neck monitor. We provide the first published evidence for the role of cementum and alveolar bone in tooth attachment in varanoid lizards. In Varanus, cementum is deposited on the external surface of the tooth root as well as at the base of the tooth, where it plays a role in the attachment of the tooth to the jawbone. Alveolar bone is also involved in tooth ankylosis. Our results support the hypothesis that the major tooth germ tissues are found in all amniotes. We provide insights into the structure and development of plicidentine, defined as infolding of the dentine around the tooth base. This feature is unique to varanoids among extant tetrapods and is the third tissue implicated in tooth attachment in Varanus. Plicidentine develops asymmetrically along the labial‐lingual axis of a tooth. Varanus is characterized by the presence of both primary and higher‐order lamellae, which anastomose to form a honeycomb‐like surface that then interacts with the more basal attachment tissues. J. Morphol. 2011. © 2011 Wiley‐Liss, Inc.     

Observations on the polyphyodont dentition of Hemiphractus proboscideus (Anura: Hylidae)

In Hemiphractus fang–like teeth are ankylosed to the premaxilla, maxilla and prevomer, and bony odontoids are found on the dentary, angular and palatine bones. The odontoids are small, but a larger pair at the front of the lower jaw project upwards and backwards into the mouth and fit into a diastema between the anterior premaxillary teeth when the mouth is closed.
The teeth are unipartite and monocuspid, and each consists of a strongly recurved and elongated cone of orthodentine, capped at the tip by a thin layer of enamel. The inner circumpulpal layer of the dentine is tubular, but no tubules are present in the outer pallial layer. During tooth development, dentine is formed before the enamel matrix is produced, and the tooth germs lie horizontally beneath the ventral surface of each dentigerous bone. On eruption, the tooth germs migrate horizontally and become ankylosed to the outer edge of the jaw bone by a layer of cellular cementum.
During tooth replacement, the vast majority of the dentine of each tooth, and the cementum at the tooth base, are resorbed by osteoclasts. It is not clear whether the tips of the teeth are shed or not.     

Structure and formation of ankylosis in Xenopus laevis

The structure of ankylotic teeth in Xenopus laevis was studied by light, transmission, and scanning electron microscopy as well as by microradiography in decalcified and undecalcified specimens. The mature teeth of Xenopus laevis are calcified from the crown to the base, fused to the jaw bone, and have no uncalcified area, such as a fibrous ring separating the tooth into the crown and pedicle. Microradiography shows that the mature tooth and jaw bone appear as an X-ray opaque area, except for the basal region of the dentine. This region is composed of an X-ray translucent area and an X-ray opaque thin layer on the lingual side of the translucent area. The mature tooth is composed of two differently calcified areas: (1) a highly calcified area, which makes up almost all of the tooth and contains a thin layer of the basal dentine on the lingual side, and (2) a lowly calcified basal dentine, which is fused to the jaw bone. Therefore, the lowly calcified area does not completely separate the dentine and jaw bone. Repeating banding patterns among the collagen fibrils differ among the dentine-forming area and the matrices of dentine and jaw bone. During the formation of ankylosis of the tooth germ, collagen bundles in the dentine-forming area accumulate directly on the surface of the jaw bone. Consequently, the mature teeth of Xenopus laevis fuse to the jaw bone directly without the mediation of the other structures.     

Tooth development and replacement in the Atlantic Cutlassfish,Trichiurus lepturus,with comparisons to other Scombroidei

Atlantic Cutlassfish, Trichiurus lepturus, have large, barbed, premaxillary and dentary fangs, and sharp dagger-shaped teeth in their oral jaws. Functional teeth firmly ankylose to the dentigerous bones. We used dry skeletons, histology, SEM, and micro-CT scanning to study 92 specimens of T. lepturus from the western North Atlantic to describe its dentition and tooth replacement. We identified three modes of intraosseous tooth replacement in T. lepturus depending on the location of the tooth in the jaw. Mode 1 relates to replacement of premaxillary fangs, in which new tooth germs enter the lingual surface of the premaxilla, develop horizontally, and rotate into position. We suggest that growth of large fangs in the premaxilla is accommodated by this horizontal development. Mode 2 occurs for dentary fangs: new tooth germs enter the labial surface of the dentary, develop vertically, and erupt into position. Mode 3 describes replacement of lateral teeth, in which new tooth germs enter a trench along the crest of the dentigerous bone, develop vertically, and erupt into position. Such distinct modes of tooth replacement in a teleostean species are unknown. We compared modes of replacement in T. lepturus to 20 species of scombroids to explore the phylogenetic distribution of these three replacement modes. Alternate tooth replacement (in which new teeth erupt between two functional teeth), ankylosis, and intraosseous tooth development are plesiomorphic to Bluefish + other Scombroidei. Our study highlights the complexity and variability of intraosseous tooth replacement. Within tooth replacement systems, key variables include sites of formation of tooth germs, points of entry of tooth germs into dentigerous bones, coupling of tooth germ migration and bone erosion, whether teeth develop horizontally or immediately beneath the tooth to be replaced, and how tooth eruption and ankylosis occur. Developmentally different tooth replacement processes can yield remarkably similar dentitions.     

Structure, attachment, replacement and growth of teeth in bluefish, Pomatomus saltatrix (), a teleost with deeply socketed teeth

Tooth replacement poses many questions about development, pattern formation, tooth attachment mechanisms, functional morphology and the evolution of vertebrate dentitions. Although most vertebrate species have polyphyodont dentitions, detailed knowledge of tooth structure and replacement is poor for most groups, particularly actinopterygians. We examined the oral dentition of the bluefish, Pomatomus saltatrix, a pelagic and coastal marine predator, using a sample of 50 individuals. The oral teeth are located on the dentary and premaxillary bones, and we scored each tooth locus in the dentary and premaxillary bones using a four-part functional classification: absent (A), incoming (I), functional (F=fully ankylosed) or eroding (E). The homodont oral teeth of Pomatomus are sharp, deeply socketed and firmly ankylosed to the bone of attachment. Replacement is intraosseus and occurs in alternate tooth loci with long waves of replacement passing from rear to front. The much higher percentage of functional as opposed to eroding teeth suggests that replacement rates are low but that individual teeth are quickly lost once erosion begins. Tooth number increases ontogenetically, ranging from 15–31 dentary teeth and 15–39 premaxillary teeth in the sample studied. Teeth increase in size with every replacement cycle. Remodeling of the attachment bone occurs continuously to accommodate growth. New tooth germs originate from a discontinuous dental lamina and migrate from the lingual (dentary) or labial (premaxillary) epithelium through pores in the bone of attachment into the resorption spaces beneath the existing teeth. Pomatomus shares unique aspects of tooth replacement with barracudas and other scombroids and this supports the interpretation that Pomatomus is more closely related to scombroids than to carangoids.     

Structure and Development of Teeth in Three Armoured Catfish, Corydoras aeneus, C. arcuatus and Hoplosternum littorale (Siluriformes, Callichthyidae)

We have studied the premaxillary teeth in three armoured catfish, Corydoras aeneus, C. arcuatus and Hoplosternum littorale , by means of light and electron microscopy, in order to compare their development, fine structure and mode of attachment with that of odontodes and other teleost teeth. A premaxillary dentition consisting of small (50–100 μm long) slender pointed teeth showing no true replacement is only present in larval and juvenile stages and is subsequently lost, possibly in relation to a change in feeding mode from predatory to bottom feeder. Like odontodes, teeth are composed of dentine surrounding a pulp cavity and are covered by a hypermineralized cap. Particular features, also found in odontodes, are the absence of dentinal tubules and of nerves and capillaries in the pulp cavity, both possibly related to the small size of the teeth. The irregular pattern of implantation and the variability in attachment mode (primary and/or secondary attachment bone, fusion, mere apposition or ligamentous connection) distinguish the teeth from most other teleost teeth and from odontodes and are interpreted as reflecting considerable differences in dynamics of remodeling of the supporting element (premaxillary bone vs scute). This comparison of teeth and odontodes strongly supports current views according to which teeth and odontodes are two very closely related phenotypic expressions of a single, modifiable, morphogenetic system probably rooted in the earliest stages of vertebrate evolution.     

Structure of comblike teeth of the ayu sweetfish,Plecoglossus altivelis (Teleostei: Isospondyli): I. Denticles and tooth attachment

The structure and tooth attachment of the comblike teeth and denticles of the ayu sweetfish, Plecoglossus altivelis, were examined by light and scanning electron microscopy. The denticle is composed of a spoonlike crown with a spine pointed anteriorly, a triangular plate in the cervical region, and a root that curves laterally and tapers off to a point. The root apex is fused with a long thin pedicle that turns abruptly anteriad toward the jaw bone. Planes of the spine, the spoonlike crown, the triangle plate and the root of the denticle are varied, and the denticle is twisted in the region of the triangle plane. The superficial layer of the dentine is homogeneously calcified and is considered to be enameloid, because some of the inner dentinal epithelial cells in the tooth germ are columnar and possess cellular processes at their apical ends. The dentine is fibrous and fine dentinal tubules are visible in dentine treated with sodium hydroxide and observed by scanning electron microscopy. The upper half of the root is surrounded by a dense layer of collagen fibers running parallel to the tooth axis, and the lower half is encompassed by interlaced collagen fibers. The lower part of the root is open on its lingual side. The pedicle is a long rod which is homogeneously calcified and enmeshed by interlaced collagen fibers, and it curves mediad as it nears the jaw bone. The pedicles are interposed between a layer of gelatinous connective tissue and the jaw bone and terminate on the periosteum. Comparative aspects of ayu tooth morphology are discussed. © 1993 Wiley-Liss, Inc.     

Structure and Development of the Odontodes in an Armoured Catfish,Corydoras aeneus (Siluriformes,Callichthyidae)

Abstract In some living osteichthyans (e.g. the armoured catfishes) the postcranial dermal skeleton exhibits tooth-like structures (odontodes) similar to those present in the dermal skeleton of the ancient craniates. We have undertaken this work to compare odontode with tooth development, structure, attachment to a bony support and replacement. We studied the odontodes fixed on the scutes (i.e. postcranial dermal plates) in a growth series of Corydoras aeneus using light, scanning and transmission electron microscopy. Odontodes are constituted of a pulp cavity surrounded by a cone of dentine itself capped with hypermineralized substance. The pulp cavity is devoid of nerves and blood vessels and there are no odontoblastic processes in the dentine. The dentine cone is firmly attached to a circular bony protuberance of the scute surface, the pedicel or attachment bone, by means of a ligament. An odontode anlage develops as a small invagination of a dermal papilla projecting into the epidermis, the basal cell layer of which constitutes a dental epithelium. First, dentine is deposited, next the hypermineralized substance, then the ligament and attachment bone. Odontodes develop in two positions with regard to the scute surface: a primary position when new odontodes form at the posterior border of the enlarging scute; a secondary position when new odontodes replace old odontodes that have been shed during thickening of the scute. In this case, the ligament and part of the base of the dentine cone are resorbed but not the pedicel of attachment bone, which is covered by deposition of scute matrix after the odontode has been shed. Within the scute matrix, the embedded pedicels of successive generations of odontodes are preserved, forming piles in the scutes of adult specimens.     

Dental histology of Coelophysis bauri and the evolution of tooth attachment tissues in early dinosaurs

Studies of dinosaur teeth have focused primarily on external crown morphology and thus, use shed or in situ tooth crowns, and are limited to the enamel and dentine dental tissues. As a result, the full suites of periodontal tissues that attach teeth to the jaws remain poorly documented, particularly in early dinosaurs. These tissues are an integral part of the tooth and thus essential to a more complete understanding of dental anatomy, development, and evolution in dinosaurs. To identify the tooth attachment tissues in early dinosaurs, histological thin sections were prepared from the maxilla and dentary of a partial skull of the early theropod Coelophysis bauri from the Upper Triassic (Rhaetian‐ 209–201 Ma) Whitaker Quarry, New Mexico, USA. As one of the phylogenetically and geologically oldest dinosaurs, it is an ideal candidate for examining dental tissues near the base of the dinosaurian clade. The teeth of C. bauri exhibited a fibrous tooth attachment in which the teeth possessed five tissues: enamel, dentine, cementum, periodontal ligament (PDL), and alveolar bone. Our findings, coupled with those of more recent studies of ornithischian teeth, indicate that a tripartite periodontium, similar to that of crocodilians and mammals, is the plesiomorphic condition for dinosaurs. The occurrence of a tripartite periodontium in dinosaurs adds to the growing consensus that the presence of these tissues is the plesiomorphic condition for the major amniote clades. Furthermore, this study establishes the relative timing of tissue development and growth directions of periodontal tissues and provides the first comparative framework for future studies of dinosaur periodontal development, tooth replacement, and histology. J. Morphol. 277:916–924, 2016. © 2016 Wiley Periodicals, Inc.     

Structure, attachment, replacement and growth of teeth in bluefish, Pomatomus saltatrix (Linnaeus, 1776), a teleost with deeply socketed teeth

Tooth replacement poses many questions about development, pattern formation, tooth attachment mechanisms, functional morphology and the evolution of vertebrate dentitions. Although most vertebrate species have polyphyodont dentitions, detailed knowledge of tooth structure and replacement is poor for most groups, particularly actinopterygians. We examined the oral dentition of the bluefish, Pomatomus saltatrix, a pelagic and coastal marine predator, using a sample of 50 individuals. The oral teeth are located on the dentary and premaxillary bones, and we scored each tooth locus in the dentary and premaxillary bones using a four-part functional classification: absent (A), incoming (I), functional (F=fully ankylosed) or eroding (E). The homodont oral teeth of Pomatomus are sharp, deeply socketed and firmly ankylosed to the bone of attachment. Replacement is intraosseus and occurs in alternate tooth loci with long waves of replacement passing from rear to front. The much higher percentage of functional as opposed to eroding teeth suggests that replacement rates are low but that individual teeth are quickly lost once erosion begins. Tooth number increases ontogenetically, ranging from 15–31 dentary teeth and 15–39 premaxillary teeth in the sample studied. Teeth increase in size with every replacement cycle. Remodeling of the attachment bone occurs continuously to accommodate growth. New tooth germs originate from a discontinuous dental lamina and migrate from the lingual (dentary) or labial (premaxillary) epithelium through pores in the bone of attachment into the resorption spaces beneath the existing teeth. Pomatomus shares unique aspects of tooth replacement with barracudas and other scombroids and this supports the interpretation that Pomatomus is more closely related to scombroids than to carangoids.     

Teeth of extant Polypteridae and Amiidae have plicidentine organization

The study of teeth of the lower jaws of Amia calva and Polypterus senegalus, with non -destructive X-ray tomography, has revealed that there are dentine folds in the tooth pulp cavity in both species. These folds are simple and present only in the base of the pulp cavity where they strengthen the fixation of teeth on the jaw. So the teeth of these two basal actinopterygian taxa have a simplexodont type of plicidentine like the extinct †Cheirolepis and various extant teleostean predators, whereas the extant Lepisosteids, the sister group of Amiidae, have polyplocodont plicidentine. The phylogenetic/adaptive significance of this simplexodont plicidentine is discussed.     

Surface changes in the naturally ankylosed teeth of the frog Rana pipiens during growth and maturation: an SEM study

An SEM study of the surface morphology of the major stages of mature and developing teeth of the leopard frog was made using anorganic preparations of the teeth and jaws. After initial development, the crown area changed little during subsequent tooth eruption, ankylosis and maturation. The thin enamel covering extended further down the shaft than expected. After ankylosis, the surfaces of the tooth continued to mature. The unmineralized gap between the crown and the pedestal, which is prominent in most amphibians, gradually filled in as the ankylosed tooth aged. The upper portion of the pedestal initially formed a dentine surface which was globular in appearance due to partial calcification of the surface collagen fibres but became smooth with uniformly calcified fibres as the ankylosed tooth matured. The lower portion of the pedestal was more variable and there was a gradual transition of dentine into a more cellular, bone-like tissue which contained lacunae and larger fibre bundles. This bone-like tissue was very distinct in surface morphology from the bone of the adjacent jaw, and as the tooth matured it changed from a coarse, woven appearance to one more like lamellar bone. Resorption bays were present in both the dentine and bony areas of teeth which were being shed. During development, the pedestal, which attaches the tooth to the jaw, formed as a separate calcification site and did not form a complete ring until fusion of its buccal surface with that of the overlying crown. A bony buccal lip formed early as part of the pedestal.     

Development of larval and transformed teeth in Ambystoma mexicanum (Urodela, Amphibia): an ultrastructural study

Odontogenesis of early larval non-pedicellate teeth, late larval teeth with a more or less distinct dividing zone and fully transformed pedicellate teeth in Ambystoma mexicanum (Urodela) was studied to obtain insights into the development of differently structured teeth in lower vertebrates. Using transmission electron microscopy we investigated five developmental stages: (1) papilla; (2) bell stage (secretion of the matrix begins); (3) primordium (mineralization and activity of ameloblasts starts); (4) replacement tooth (young, old); and (5) established, functional tooth. Development of the differently structured teeth is largely identical in the first three stages. Mineralization takes place in apico-basal direction up to the (prospective) pedicel (early and some late larvae) or up to the zone that divides the late larval and transformed tooth in pedicel and dentine shaft (pedicellate condition). Mineralization starts directly at the collagen and by means of matrix vesicles. First odontoblasts develop small processes that extend to the basal lamina of the inner epithelial layer of the enamel organ. The processes are small and lack organelles in early larval teeth, but become larger, arborescent, and contain some organelles in late larval and transformed teeth. The processes are surrounded by unmineralized matrix (predentine). Odontoblasts at the basis of the teeth, at the pedicel, and in the zone of division do not develop significant cytoplasmic processes that extend into the matrix. Cells of the inner enamel epithelium differentiate to ameloblasts that secrete the enamel. In the early larval tooth they show an extensive basal labyrinth that becomes regressive when the enamel layer is completed. In late larval and transformed teeth, however, a large cavity arises between the basal ruffled border of ameloblasts and their basal lamina. This cavity appears to mediate amelogenesis. A small apical zone in early, but not in late larval teeth directly below the thin enamel layer consists of enameloid and is free of dentine channels.     

The structure and stratigraphy of<Emphasis Type="Italic">Speonesydrion</Emphasis> from New South Wales,Australia, and the dentition of primitive dipnoans

New material ofSpeonesydrion iani, an Early Devonian dipnoan from New South Wales, has provided additional Information on the dentition and jaws. Two new partial palates have been found, and X-rays of the parasphenoid shows that the structure is well preserved. The palatal teeth are well worn even in partly grown material, and they do not originate at a growth point, but at a thickening of the palate. More mandibles have been collected, and thin sections have been prepared to allow a discussion of their histology. On the mandible the teeth are clear, and they are much more defined than they are on the palate. The dental heel is variably developed, and grows in phases by thickening of the dentine at the contact with the bone. Dentine forms on the bone at the base of the heel, partly by Solution of the bone and the addition of dentine from the pulp canals, but also by direct growth from the pulp canals dorsal to the bone. In the latter case the dentine and bone are in contact, and the two tissues intermingle. The teeth are also formed on a thickened bone and consist of dentine capped with enamel making a crest. Dentine and bone are related as in the heel. We conclude that the teeth inSpeonesydrion are not homologous with the teeth in other dipnoans, and are formed by a different process involving the aggregation of denticles.     

New ischnacanthid acanthodians from the Early Devonian of Australia, with comments on acanthodian interrelationships

Rockycampacanthus milesi n.gen., n.sp. is described from a single jaw from the Rocky Camp member of Lower Devonian Buchan Group, E Victoria. Rockycampacanthus differs from other ischnacanthiforms in having large multicuspidate teeth with dual rows of secondary cusps forming a posteromesial flange, a mesial tooth row beginning opposite the fourth cusp of the main tooth row, and in the gnathal bone being deepest in the anterior half. Taemasacanthus erroli n. gen., n. sp. is described from several jaw bones from the Lower Devonian Murrumbidgee Group, New South Wales. Taemasacanthus has a well developed posterolabial flange with secondary cusps developed, vertical rows of denticles on the cusps of the main tooth row and a well developed mesial tooth row separated from the main row by a prominent ridge. The labial face of the jaw has a circular ridge which may have supported labial cartilages. The complex mandibular joint in climatiforms, acanthodiiforms and some primitive sharks differs from the simple jaw articulation of ischnacanthids. It is suggested that ischnacanthids are the plesiomorphic sister group to climatiforms plus acanthodiiforms. The interrelationships of ischnacanthids, climatiforms and acanthodiforms are discussed.     

Morphology and mechanics of the teeth and jaws of white-spotted bamboo sharks (Chiloscyllium plagiosum)

The teeth of white-spotted bamboo sharks (Chiloscyllium plagiosum) are used to clutch soft-bodied prey and crush hard prey; however, the dual function is not evident from tooth morphology alone. Teeth exhibit characteristics that are in agreement with a clutching-type tooth morphology that is well suited for grasping and holding soft-bodied prey, but not for crushing hard prey. The dual role of this single tooth morphology is facilitated by features of the dental ligament and jaw joint. Tooth attachment is flexible and elastic, allowing movement in both sagittal and frontal planes. During prey capture spike-like tooth cusps pierce the flesh of soft prey, thereby preventing escape. When processing prey harder than the teeth can pierce the teeth passively depress, rotating inward towards the oral cavity such that the broader labial faces of the teeth are nearly parallel to the surface of the jaws and form a crushing surface. Movement into the depressed position increases the tooth surface area contacting prey and decreases the total stress applied to the tooth, thereby decreasing the risk of structural failure. This action is aided by a jaw joint that is ventrally offset from the occlusal planes of the jaws. The offset joint position allows many teeth to contact prey simultaneously and orients force vectors at contact points between the jaws and prey in a manner that shears or rolls prey between the jaws during a bite, thus, aiding in processing while reducing forward slip of hard prey from the mouth. Together the teeth, dental ligament, and jaws form an integrated system that may be beneficial to the feeding ecology of C. plagiosum, allowing for a diet that includes prey of varying hardness and elusiveness.