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Virginia opossum Didelphis virginiana

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... Em Didelphis, além da atrição, ocorre perda de estruturas dentais em função da abrasão, que ocorre quando o animal "fricciona" os caninos superiores contra os inferiores na intenção de produzir som durante o comportamento de corte, encontros agressivos entre os adultos e quando a mãe quer chamar os filhotes (GARDNER, 1982), contribuindo para a formação de dentina terciária no terço oclusal dos caninos. ...
... A presença de dentina terciária no terço oclusal dos caninos ocorreu, provavelmente, devido a fraturas seguidas de desgaste. A presença de desgaste do esmalte e, algumas vezes, também de dentina na face mesial dos caninos superiores e na face distal dos caninos inferiores, deve ser resultado da abrasão durante vocalizações comportamentais, como relatou GARDNER (1982). ...
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This work deals with the study of dental wear down (atrittion and/or abrasion) in 168 specimens of Didelphis albiventris and D. marsupialis from Southern Brazil. Wear down was very important, with high frequency of tertiary dentine and exposition of the pulp cavity/radicular canal, due to the association of fractures and wear down. Fractures predispose wear down which, on the other side, favors fractures. The degree of attrition increased with age. The order of growing frequency of tertiary dentin in poscanines was: first, second and third molars, third and second premolars, and finally fourth molar. Differently from others omnivorous in Didelphis tooth wear down seems rather related to fractures due to food (followed by attrition) than to teeth contact. Contrary to literature, tribosphenic molars seems not to be “ideals” for such omnivorous diet, as is evident from the high frequency of wear down, fractures and teeth cavities exposition.
... In opossums, skeletal injuries (eg, rib and scapular fractures) caused by MVCs tend to occur cranially (Gardner, 1982;Mead and Patterson, 2009). An explanation as to how an impact from a tyre would break one or two ribs without seriously damaging other hard and soft tissues was not apparent (Mead and Patterson, 2009). ...
Article
Motor vehicle collisions (MVCs) are a severe threat to wildlife biodiversity worldwide and most vertebrate species are at risk. However, there is a considerable knowledge gap on the traumatic features and potential patterns of MVCs in wildlife. We investigated traumatic injuries (TIs) caused by MVCs (MVCs-TIs) in 430 neotropical wild mammals representing 44 species from Brazil. Injuries were classified topographically into four categories: abdomen/pelvis (AP), chest (TX), head/neck (HN) and extremities (EX). We also determined the prevalence of pathological changes in MVC fatalities. AP (n = 381; 89%) was the most affected body segment, followed by TX (n = 372; 87%), HN (n = 363; 84%) and EX (n = 288; 67%). The most prevalent gross pathological findings were single or multiple bone fractures (n = 397; 92%), visceral organ rupture (n = 371; 86%), haemothorax (n = 220; 51%) and pulmonary haemorrhage (n = 212; 49%). Microscopically, pulmonary oedema (n = 324; 82%) and haemorrhage (n = 272; 69%) were the most prevalent lesions. No distinct TI patterns were evident across the various taxonomic groups, although trends were found in some taxa, such as armadillos. These results may help clinicians performing emergency care on MVC wildlife patients and may be of value in pathological and forensic investigations where a MVC has been deemed a likely contributory factor to death.
... There was high activity overlap between armadillos, P. lotor and D. virginiana, indicating coexistence with sympatric mesocarnivores (Almeida Jácomo 2004, Zhao 2020. Armadillos are most likely capturing distinct prey species, because they are primarily insectivores , whereas raccoons and opossums are both omnivorous with diets including plant material as well as carrion and diverse animal prey (Harman & Stains 1979, Gardner 1982. The primary commensal rodents (S. hispidus & O. palustris) also had moderate to high activity overlap with armadillos, but these species are primarily herbivorous and carnivorous respectively (Cameron & Eshelman 1996& Sharp Jr. 1967. ...
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The nine-banded armadillo (Dasypus novemcinctus) has become a species of local abundance in many southeastern habitats and is viewed as a nuisance and invasive by many land managers. My objective was to examine both negative and positive effects of armadillos on the Georgia coastal islands by 1) quantifying armadillo predation of sea turtle nests and comparing it to other predators; and 2) quantifying behavior and activity of armadillo burrow associates. I found that while armadillos do indeed predate sea turtle nests, they are not a major contributor to total egg loss across the coast. I recorded 33 armadillo burrow associates, including 26 species not previously reported in the literature and multiple species of conservation concern. This research provides a data-driven basis for management of armadillos and provides a template for objectively evaluating the ecosystem effects of other "invasive" species.
... P < 0.0001. Different letters indicate species that statistically differed from one another in post hoc pairwise comparisons includes a broader range of other items (Gardner 1982;Kasparian et al. 2002). While the remaining species are all classified as carnivores, there is considerable variation among them in how much they rely on meat in their diet, with species such as coyotes, grey foxes, and raccoons being far more opportunistic and omnivorous (Bekoff 1977;Saunders 1988;Davis and Schmidly 1994;Kasparian et al. 2002;Bekoff and Gese 2003). ...
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Metal pollution commonly occurs in many terrestrial environments and may pose a threat for the animals inhabiting such areas. Here, we present concentrations of six metals (cadmium [Cd], copper [Cu], nickel [Ni], lead [Pb], selenium [Se], and zinc [Zn]) in the liver tissues of seven species of mammals obtained from a study that examined the impact of mesopredator removal on northern bobwhite (Colinus virginianus) populations. A total of 1326 samples were collected from 2003 to 2006 at four sites in southwest Georgia and north Florida from nine-banded armadillos (Dasypus novemcinctus), bobcats (Lynx rufus), feral cats (Felis catus), coyotes (Canis latrans), grey foxes (Urocyon cinereoargenteus), opossums (Didelphis virginiana), and raccoons (Procyon lotor). Data from armadillos, bobcats, opossums, and raccoons were published previously to examine age, sex, spatial (between sites), and temporal (between years) variation. In this paper, we present similar comparisons for the remaining three species as well as comparisons of metal concentrations among all seven species. Concentrations of Cu and Pb exhibited strong negative relationships with body weight in coyotes, while Ni was positively correlated with weight in feral cats. Concentrations of these metals, as well as the other two tested (Cd and Zn), were not significantly correlated with one another in any of the three species. The only sex difference in liver metal concentrations was observed in female feral cats, which had higher levels of Pb than did males. Coyotes exhibited significant differences in Cu concentrations between sites and between years (2005 versus 2006). We also found significant differences between sites in Pb concentrations for both feral cats and grey foxes. There were significant differences in metal concentrations among all seven species for all metals except Cd. With the exception of Cd and Se (tested only in bobcats and opossums), a three-way ANOVA with species, year, and site as the three factors revealed significant differences among species for every metal but only a single main effect of year for Cu, and no main effects of site. In sum, our results provide an extensive survey of metal concentrations in a diverse assemblage of mammals and suggest that metal accumulation may be heavily influenced by species identity, which in turn may reflect ecological lifestyle.
... If they represent an established population in the Guadalupe Mountains, then the possibility exists that opossums may eventually be discovered in the mountainous portion of the park. However, because opossums generally occupy wooded habitats with permanent water such as streams, rivers, marshes, and swamps (McManus 1974;Jones et al. 1983;Gardner 1999), Rattlesnake Springs is the most likely place for individuals to be discovered in the park. Thus far, opossums have not been reported at Rattlesnake Springs or along the 154 BULLETIN OF THE UNIVERSITY OF NEBRASKA STATE MUSEUM Pecos River, except for those early reports of escaped individuals near Carlsbad in the 1920s (Bailey 1928;Bermudez et al. 1995). ...
Article
Carlsbad Cavern was established as a national park on 14 May 1930, after being designated as a national monument for nearly seven years. The park is located in southeastern New Mexico, and today it encompasses 189.3 km2 (73.1 mi2). Eighty-eight percent of the park lies in the rugged Guadalupe Mountains, while 12% is located on relatively flat land along the base of the mountains. The park contains a variety of habitats ranging from desert scrub at the lowest elevations to coniferous woodlands on the highest summits.
... Most work on small mammal diets is based on stomach or faecal contents (Reichman 1975;Hunsaker 1977;Charles-Dominique et al. 198 1 ;Meserve 198 1 ;Gardner 1982;Cordero and Nicolas 1987). Such methods may determine the diet in the wild for a given region. ...
Article
Adaptation of wild mammals to captivity is a decisive and limiting step in laboratory research. Here we describe a method to determine a diet that meets the nutritional and water requirements of small wild mammals in captivity. Several kinds of food are offered to the animals and a preference index (P) is calculated. A diet prepared with foods obtaining P ≥ 1.00 for 50% or more of the individuals is given to the animals. This diet contains the same proportions of proteins, lipids, and glucides determined by the food preferences experiment. Two groups are fed on this diet, one with free water and the other without, and their weights are monitored for approximately 12 days. The results allow the detection of water and nutritional deficiencies. We used these procedures with the grey four-eyed opossum, Philander opossum (Polyprotodontia, Didelphidae), and obtained a balanced diet of eggs, meat, banana, and orange that has proved suitable for keeping these animals in good condition.
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The epipubic bones of the marsupials have been little studied and the meaning of their linear dimensions is poorly known. We therefore evaluated epipubic bone size of Virginia Opossum (Didelphis virginiana) from Mexico, and estimated their proportions relative to skull size of individuals. Results showed that males have larger skull and acetabulum size than females, epipubic bones of females are almost half the size of a female’s skull while that of the male is a little less than a third of the male cranial size. Therefore, epipubic bones are an important landmark of sexual dimorphism in D. virginiana, and our data may be useful to learn more about epipubic bones of other marsupials.
Article
Eutherians give birth to relatively large infants. Females have larger pelves than males, though males typically have larger nonpelvic bones. Pelvic dimorphism is an adaptation for parturition. Metatherian females, who give birth to markedly small infants, should not show pelvic adaptations for parturition and should have smaller pelves than males. Adult females and males of the Virginia opossum, Didelphis virginiana, are compared. Males are significantly larger than females in absolute size for 14 of 16 pelvic and 8 nonpelvic measures. Sexes did not differ significantly for lower iliac length and posterior space of midplane. However, relative lengths for females are significantly larger than for males for these 2 measures and for the pubis. These pelvic dimorphisms in opossums cannot be adaptations for parturition. These dimorphisms result from asynchrony among skeletal elements in growth cessation and sexual differences in adulthood growth.
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How do traits change through time and with speciation? We present a simple and generally applicable method for comparing various models of the macroevolution of traits within a maximum likelihood framework. We illustrate four such models: 1) variance among species accumulates in direct proportion to time separating them (gradual model); 2) variation accumulates with the number of speciation events separating them (speciational model); 3) differences between species are unrelated to phylogenetic relatedness (pitchfork model); and 4) a free model where the trait evolves at its own idiosyncratic rate among lineages. Using species-specific body size, we compare the four models across two data sets: twenty-one clades of vertebrate species, and two clades of bird families. For the twenty-one vertebrate trees, the pitchfork model is most successful, though not significantly, and the most successful by far for the youngest clades. The speciational model seems to be preferred for older clades. For both clades of bird families, the speciational model offers the best fit to family-level body size evolution. However, the pitchfork model does much worse for one clade than for the other, suggesting a difference in the relationship between diversification and body-size evolution in the two groups. These examples highlight some possibilities afforded by this simple approach.
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