Dental erosion in South Atlantic dolphins (Cetacea: Delphinidae): A macro and microscopic approach

Loch, Carolina; Grando, Liliane Janete; Schwass, Donald R.; Fordyce, R. Ewan; Simões‐Lopes, Paulo C.

doi:10.1111/j.1748-7692.2012.00562.x

Cited by 13 publications

(12 citation statements)

References 27 publications

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“…Loch et al . () reported that extreme dental erosion, which is induced by acidification in the oral cavity in odontocetes, caused loss of tooth structure. However, it is unlikely that dental erosion caused the tooth loss observed.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, some young specimens had already lost one or more teeth, indicating that this phenomenon is unlikely the result of senile regression of the gums. Loch et al (2013) reported that extreme dental erosion, which is induced by acidification in the oral cavity in odontocetes, caused loss of tooth structure. However, it is unlikely that dental erosion caused the tooth loss observed.…”

Section: Discussionmentioning

confidence: 99%

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Decrease in tooth count in melon‐headed whales

2016

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A total of 62 skulls from two herds of melon‐headed whales stranded on Japanese coasts were examined. Although the species originally had around 22 teeth in each tooth row, older specimens (30–35 years old) possessed only an average of 9.2 teeth on each side of the upper jaw. Significant shortening of the root caused the tooth loss observed in this species. In addition, we observed the following trends with respect to the pattern of tooth loss: (1) teeth are lost from the posterior to the anterior part of the tooth row, (2) the loss of teeth in the upper jaw precedes that in the lower jaw, and (3) tooth count decreases with age. The above‐mentioned tendencies were found in both herds. Bony tissues at the alveoli seem to push out the teeth: the bottom of the tooth socket rises both during the root‐shortening process and after the tooth falls out. There were no signs of accidental tooth loss such as resorption of alveolar bones due to gingival disease or injuries on alveolar bones by physical impacts. Therefore, the postnatal tooth count decrease is considered an ontogenetic event of this species. The ontogenetic decrease in tooth count coincides with the tendency of evolutionary tooth number reduction in odontocetes at two particular points, the secondary reduction from polyodontia and the more progressed decrease in teeth in the upper jaw than in the lower jaw. Therefore, the evolutionary tooth count reduction seems to be repeated in the lifetime of the melon‐headed whale.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Decrease in tooth count in melon‐headed whales

2016

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“…Evidence of dental erosion is also present in CCNHM 104 (Figures 51 and 60). Many teeth (left I2, PC3-4, PC6-9; right PC4-7; left pc2, pc6, right pc6-7) exhibit slight narrowing of the crown cervix (sensu [97]). This is most pronounced anteriorly, such as left I2 and left PC3-4, where the posterolingual portion of the crown cervix exhibits a transverse trough; in labial and lingual view the distal margin of the tooth is concave just basal to the crown, and the enamel appears slightly undercut in left PC3-4.…”

Section: Mandiblementioning

confidence: 99%

New Skeletons of the Ancient Dolphin Xenorophus sloanii and Xenorophus simplicidens sp. nov. (Mammalia, Cetacea) from the Oligocene of South Carolina and the Ontogeny, Functional Anatomy, Asymmetry, Pathology, and Evolution of the Earliest Odontoceti

Boessenecker,

Geisler

2023

Diversity

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The early diverging, dolphin-sized, cetacean clade Xenorophidae are a short-lived radiation of toothed whales (Odontoceti) that independently evolved two features long thought to be odontocete synapomorphies: the craniofacial and cochlear morphology underlying echolocation and retrograde cranial telescoping (i.e., posterior migration of the viscerocranium). This family was based on Xenorophus sloanii, which, for the past century, has been known only by a partial skull lacking a braincase and tympanoperiotics, collected around 1900 from the Ashley Formation (28–29 Ma, Rupelian) near Ladson, South Carolina. A large collection of new skulls and skeletons (ChM PV 5022, 7677; CCNHM 104, 168, 1077, 5995) from the Ashley Formation considerably expands the hypodigm for this species, now the best known of any stem odontocete and permitting evaluation of intraspecific variation and ontogenetic changes. This collection reveals that the holotype (USNM 11049) is a juvenile. Xenorophus sloanii is a relatively large odontocete (70–74 cm CBL; BZW = 29–31 cm; estimated body length 2.6–3 m) with a moderately long rostrum (RPI = 2.5), marked heterodonty, limited polydonty (13–14 teeth), prominent sagittal crest and intertemporal constriction, and drastically larger brain size than basilosaurid archaeocetes (EQ = 2.9). Dental morphology, thickened cementum, a dorsoventrally robust rostrum, and thick rugose enamel suggest raptorial feeding; oral pathology indicates traumatic tooth loss associated with mechanically risky predation attempts. Ontogenetic changes include increased palatal vomer exposure; fusion of the nasofrontal, occipito-parietal, and median frontal sutures; anterior lengthening of the nasals; elaboration of the nuchal crests; and blunting and thickening of the antorbital process. The consistent deviation of the rostrum 2–5° to the left and asymmetry of the palate, dentition, neurocranium, mandibles, and vertebrae in multiple specimens of Xenorophus sloanii suggest novel adaptations for directional hearing driven by the asymmetrically oriented pan bones of the mandibles. A second collection consisting of a skeleton and several skulls from the overlying Chandler Bridge Formation (24–23 Ma, Chattian) represents a new species, Xenorophus simplicidens n. sp., differing from Xenorophus sloanii in possessing shorter nasals, anteroposteriorly shorter supraorbital processes of the frontal, and teeth with fewer accessory cusps and less rugose enamel. Phylogenetic analysis supports monophyly of Xenorophus, with specimens of Xenorophus simplicidens nested within paraphyletic X. sloanii; in concert with stratigraphic data, these results support the interpretation of these species as part of an anagenetic lineage. New clade names are provided for the sister taxon to Xenorophidae (Ambyloccipita), and the odontocete clade excluding Xenorophidae, Ashleycetus, Mirocetus, and Simocetidae (Stegoceti). Analyses of tooth size, body size, temporal fossa length, orbit morphology, and the rostral proportion index, prompted by well-preserved remains of Xenorophus, provide insight into the early evolution of Odontoceti.

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“…If acid was the cause, a gastric origin can be discounted-if not because of the seeming implausibility, then for the reason that lingual tooth surfaces would be affected (Loch et al, 2013). More likely the cause is diet-related.…”

Section: Differential Diagnosismentioning

confidence: 99%

Root grooves on two adjacent anterior teeth ofAustralopithecus africanus

Towle

Irish

Elliott

et al. 2017

Preprint

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Tooth root grooves and other ante-mortem dental tissue loss not associated with caries found on or near the cementoenamel junction (CEJ) are commonly termed noncarious cervical lesions. Three main processes are implicated in forming these lesions: abrasion, dental erosion, and abfraction. As yet, these lesions have not been described in non-Homo hominins. In this study South African fossil hominin collections were examined for evidence of any type of non-carious cervical lesion. Only one individual shows ante-mortem root grooves consistent with non-carious cervical lesions. Two teeth, a mandibular right permanent lateral incisor (STW 270) and canine (STW 213), belonging to the same Australopithecus africanus individual, show clear ante-mortem grooves on the labial root surface. These lesions start below the CEJ, extend over a third of the way toward the apex, and taper to a point towards the lingual side. Microscopic examination revealed no clear directional striations. The shape of these grooves is extremely similar to clinical examples of dental erosion, with the lack of striations supporting this diagnosis. These are the oldest hominin examples of noncarious cervical lesions and first described in a genus other than Homo; further, the lesions suggest that this individual regularly consumed or processed acidic food items.

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Dental erosion in South Atlantic dolphins (Cetacea: Delphinidae): A macro and microscopic approach

Cited by 13 publications

References 27 publications

Decrease in tooth count in melon‐headed whales

Decrease in tooth count in melon‐headed whales

New Skeletons of the Ancient Dolphin Xenorophus sloanii and Xenorophus simplicidens sp. nov. (Mammalia, Cetacea) from the Oligocene of South Carolina and the Ontogeny, Functional Anatomy, Asymmetry, Pathology, and Evolution of the Earliest Odontoceti

Root grooves on two adjacent anterior teeth ofAustralopithecus africanus

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