Master of Science in Biological Sciences, Youngstown State University, 2018, Department of Biological Sciences and Chemistry

Armadillos (Family: Dasypodidae) are the most diverse group of the basal superorder Xenarthra, which is evident by their various lifestyles and range of scratch-digging ability. Descriptions of myology and quantifications of osteology reflect adaptations of the post-cranium and are essential for understanding the functional morphology of animal limbs. While there have been several studies on the limb bone proportions in numerous armadillos, limb myology has been reported for a limited number of species. Many of these descriptions need updating, and quantitive muscle data are available for only a single species. The objective of this study is to assess the forelimb myology of the pichi (Z. pichiy), screaming hairy (Cha. vellerosus), big hairy (Cha. villosus), and pink fairy (Chl. truncatus) armadillos with comparisons to previous documentations, and evaluate numerous osteological features of the forelimb among multiple species. Several myological features were variable among cingulates, such as the origin of m. trapezius pars cervicalis, variable presence of a distinct m. rhomboideus profundus, and number of heads present for m. triceps brachii and m. flexor digitorum profundus. Multiple osteological traits associated with greater fossoriality were also indicated, including robust limb bones, a prominent olecranon process, and short distal limb elements, which corresponded with the predictions of scratch-digging ability by Discriminant Function Analysis. Strong negative allometry of the humeral mid-shaft width/depth also reinforced the necessity for increased bone robustness as body size increases. These morphological features indicate various scratch-digging specializations among cingulates and their potential reorganization into separate families with future phylogenetic assessments of ancestral versus dervived traits associated with their lifestyles.

Committee: Michael Butcher PhD (Committee Chair); Thomas Diggins PhD (Committee Member); Mark Womble PhD (Committee Member) Subjects: Anatomy and Physiology; Animals; Biology; Zoology

Doctor of Philosophy, The Ohio State University, 1969, Graduate School

Committee: Not Provided (Other) Subjects: Biology

Master of Science, University of Akron, 2011, Biology

Physiological development is a function of an organism's genotype, its environment, and the interaction between these two factors. Assessing the relative influence of these factors on an animal's physiology has occupied researchers for decades. Clonal offspring, such as those in the nine-banded armadillo (Dasypus novemcinctus) provide a unique opportunity to essentially eliminate genotypic variation and focus on environmental causes of physiological variation. Typically, variation in offspring physiology is significantly less within litters than between litters, a phenomenon known as the “sibling effect”. Ten D. novemcinctus neonates were removed from their mother following birth and hand-reared in identical environments. As juveniles, the armadillos, comprised of four litters, were exposed to acute hypoxia/hypercapnia, mimicking severe burrow conditions, and O2 consumption and CO2 production were measured via flow through respirometry. The physiological challenge of burrow conditions provides a view of sibling variation under stress. Although, the gas stressor in this study was acute, the burrow conditions in the wild are chronic for neonates. Resting O2 consumption and CO2 excretion were also measured to determine mass-specific basal metabolic rate (BMR). D. novemcinctus is known for having a lower mass-specific BMR and lower body temperature in comparison to other mammals. Although adult armadillos have been reported as a unique mammal in regards to energetics, the armadillo juveniles follow the same trends as other mammalian neonates and juveniles. Armadillo juveniles, similar to other mammalian juveniles, follow a trend toward decreased mass-specific BMR over time. When exposed to acute hypoxia/hypercapnia, an increase in mass-specific O2 consumption and mass-specific CO2 production was seen in all armadillo juveniles, consistent with previous research of neonatal mammals exposed to hypoxia and hypercapnia. By controlling the neonatal environment (i.e. feeding (open full item for complete abstract)

Committee: Brian Bagatto Dr. (Advisor); Francisco Moore Dr. (Committee Member); Rolando Ramirez Dr. (Committee Member) Subjects: Biology

Master of Science, University of Akron, 2011, Biology

In mammals, the degree to which the maternal environment shapes developmental trajectories of fetuses is largely unknown. This study examined such characteristics in utero in the nine-banded armadillo (Dasypus novemcinctus). In addition, little is known about the energetics of reproduction in D. novemcinctus. This study is the first to examine the impacts of gestation and lactation on the energy budget of armadillos. Armadillos have a unique reproductive physiology in that they are the only known mammals to exhibit obligate polyembryony, with each pregnancy producing a set of genetically identical quadruplets. Because genetic variation is negligible, the maternal environment produces the majority of variation measured during development. It has been established that physiological variation exists within and between litters of D. novemcinctus as early as day four post-parturition. The first aim of this study was to determine if and when developmental differences arise in utero in the armadillo. Skull size and heart rate were not significantly different between fetuses of the same litter. There were, however, significant differences in some skull measurements between whole litters. There was also a significant negative correlation between maternal mass and fetal skull size. Maternal and fetal heart rates were significantly correlated. In addition to a unique reproductive physiology, D. novemcinctus has an unusually low body temperature (~34.5°C) and basal metabolic rate (BMR) (~50% lower per g) when compared to other mammals. There is a trend in other mammals for the non-mass-specific BMR to increase significantly during pregnancy and lactation. The second aim of this study was to investigate the metabolic costs of pregnancy and lactation in armadillos by calculating BMR in pregnant, lactating, and non-pregnant individuals using flow-through respirometry. Comparison of BMR within pregnant and post-pregnant animals indicated that reproduction resulted in a 39.7% inc (open full item for complete abstract)

Committee: Brian Bagatto Dr. (Advisor); Francisco Moore Dr. (Committee Member); Rolando Ramirez Dr. (Committee Member) Subjects: Biology; Developmental Biology; Physiology