Dental microwear of a basal ankylosaurine dinosaur, Jinyunpelta and its implication on evolution of chewing mechanism in ankylosaurs.

Jinyunpelta sinensis is a basal ankylosaurine dinosaur excavated from the mid Cretaceous Liangtoutang Formation of Jinyun County, Zhejiang Province, China. In the present study, its dental microwear was observed using a confocal laser microscope. Jinyunpelta had steep wear facets that covered most of buccal surfaces of posterior dentary teeth. Observation of dental microwear on the wear facet revealed that scratch orientation varied according to its location within the wear facet: vertically (i.e. apicobasally) oriented scratches were dominant in the upper half of the wear facet, and horizontally (i.e. mesiolaterally) oriented ones were in the bottom of the facet. These findings indicated that Jinyunpelta adopted precise tooth occlusion and biphasal jaw movement (orthal closure and palinal lower jaw movement). The biphasal jaw movement was widely observed among nodosaurids, among ankylosaurids, it was previously only known from the Late Cretaceous North American taxa, and not known among Asian ankylosaurids. The finding of biphasal jaw movement in Jinyunpelta showed sophisticate feeding adaptations emerged among ankylosaurids much earlier (during Albian or Cenomanian) than previously thought (during Campanian). The Evolution of the biphasal jaw mechanism that contemporaneously occurred among two lineages of ankylosaurs, ankylosaurids and nodosaurids, showed high evolutionary plasticity of ankylosaur jaw mechanics.

Avaliação das alterações odontológicas em sincrânios de Cerdocyon thous oriundos de atropelamentos na rodovia ES-060, Espírito Santo / Evaluation of dental changes in sincranium of Cerdocyon thous from running over in the ES-060 road, Espirito Santo

Os cachorros-do-mato (Cerdocyon thous Linnaeus, 1766) são animais amplamente encontrados em países da América do Sul. Apesar de não ser uma espécie ameaçada de extinção, é possível que muitas populações sofram impactos decorrentes de atropelamentos de indivíduos nas rodovias do país, pois, trata-se de uma das espécies de carnívoros com elevada ocorrência de mortes deste tipo. Foram avaliados 32 sincrânios de C. thous, oriundos de vida livre, armazenados na coleção osteológica do Laboratório de Anatomia Veterinária da Universidade Vila Velha (Vila Velha/ES), a fim de diagnosticar doenças que acometeram estes indivíduos enquanto vivos. As lesões macroscópicas identificadas foram: apinhamento dentário, ausência dentária, cálculo dentário, dentina terciária, desgaste, escurecimento dentário, exposição de polpa, fenestração óssea, fratura dentária, fratura de esmalte, giroversão, pigmentação e reabsorção da crista alveolar. Os achados mais comumente observados foram: ausência dentária, desgaste dentário e fratura dentária. Ausências dentárias anteriores à morte, alterações ósseas, cálculos dentários, apinhamento e giroversão aparentemente não causaram quaisquer prejuízos aos animais enquanto vivos.

The crab-eating foxes (Cerdocyon thous Linnaeus, 1766) are animals widely found in South American countries. Although it is not an endangered species, it is possible that many of them suffer impacts from being hit by car on the highways of the country, and this is the reason why it is one of the carnivores' species with high frequency of deaths. 32 free living sincranium stored in the osteological collection in the Laboratory of Veterinary Anatomy of Vila Velha University (Vila Velha/ES) were studied in order to diagnose diseases suffered by these individuals while alive. The main lesions identified were: crowding, no dental, dental calculus, tertiary dentin, detrition, darkening tooth, exposure of pulp, bone fenestration, fractured tooth, enamel fracture, giroversion, pigmentation and resorption of the alveolar crest. The most common findings were: no dental, dental detrition and fractured tooth. No dental before death, bone changes, dental calculus, crowding and giroversion apparently did not cause any harm to the animals while alive.