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Ciancio MR, Vieytes EC, Castro MC, Carlini AA. Dental enamel structure in long-nosed armadillos (Xenarthra: Dasypus) and its evolutionary implications. Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Most xenarthrans have a reduced and simplified dentition that lacks enamel. However, the presence of prismatic enamel has been recorded in the Eocene armadillos Utaetus buccatus (Euphractinae) and Astegotherium dichotomus (Astegotheriini). Among extant xenarthrans, the occurrence of enamel has been recognized only in the long-nosed armadillo, Dasypus novemcinctus (Dasypodinae), but its microstructure has never been described. In this contribution, we analyse the enamel microstructure in deciduous and permanent teeth of four Dasypus species. In deciduous molariform teeth of some species, we identify an apical cap of vestigial enamel (without crystalline structure), interpreted as an amorphous ameloblastic secretion. In permanent teeth, a thin layer of true enamel is found in the apical portion of unworn molariforms. The enamel is prismatic in D. novemcinctus, but in Dasypus hybridus, Dasypus sabanicola and Dasypus punctatus it is prismless. Taking into account the Eocene species of armadillos, the ancestral condition of enamel in cingulates could have been more complex (as in other placentals) and undergone progressive reduction, as shown in the Dasypus lineage. In light of previous genetic and developmental studies, we review and briefly discuss the processes that can account for the reduction/loss of enamel in extant and extinct armadillos. The retention of enamel and the fact that this genus is the only living xenarthran with two functional generations of teeth support the early divergence of the Dasypus lineage among living cingulates. This is in agreement with morphological and molecular analyses.
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Affiliation(s)
- Martín R Ciancio
- Laboratorio de Morfología Evolutiva y Desarrollo (MORPHOS) y División Paleontología Vertebrados, Museo de La Plata, CONICET, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
- Cátedra Anatomía Comparada, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
| | - Emma C Vieytes
- Cátedra Anatomía Comparada, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
- División Zoología Vertebrados, Museo de La Plata, CONICET, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
| | - Mariela C Castro
- Departamento de Ciências Biológicas, IBiotec, Universidade Federal de Catalão, Avenida Dr. Lamartine Pinto de Avelar, 1120, 75704-020, Catalão, Brazil
| | - Alfredo A Carlini
- Laboratorio de Morfología Evolutiva y Desarrollo (MORPHOS) y División Paleontología Vertebrados, Museo de La Plata, CONICET, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
- Cátedra Anatomía Comparada, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
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Nasoori A. Formation, structure, and function of extra-skeletal bones in mammals. Biol Rev Camb Philos Soc 2020; 95:986-1019. [PMID: 32338826 DOI: 10.1111/brv.12597] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 03/07/2020] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
Abstract
This review describes the formation, structure, and function of bony compartments in antlers, horns, ossicones, osteoderm and the os penis/os clitoris (collectively referred to herein as AHOOO structures) in extant mammals. AHOOOs are extra-skeletal bones that originate from subcutaneous (dermal) tissues in a wide variety of mammals, and this review elaborates on the co-development of the bone and skin in these structures. During foetal stages, primordial cells for the bony compartments arise in subcutaneous tissues. The epithelial-mesenchymal transition is assumed to play a key role in the differentiation of bone, cartilage, skin and other tissues in AHOOO structures. AHOOO ossification takes place after skeletal bone formation, and may depend on sexual maturity. Skin keratinization occurs in tandem with ossification and may be under the control of androgens. Both endochondral and intramembranous ossification participate in bony compartment formation. There is variation in gradients of density in different AHOOO structures. These gradients, which vary according to function and species, primarily reduce mechanical stress. Anchorage of AHOOOs to their surrounding tissues fortifies these structures and is accomplished by bone-bone fusion and Sharpey fibres. The presence of the integument is essential for the protection and function of the bony compartments. Three major functions can be attributed to AHOOOs: mechanical, visual, and thermoregulatory. This review provides the first extensive comparative description of the skeletal and integumentary systems of AHOOOs in a variety of mammals.
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Affiliation(s)
- Alireza Nasoori
- School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan
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Scarano AC, Ciancio MR, Barbeito-Andrés J, Barbeito CG, Krmpotic CM. Micromorphology of osteoderms in Dasypodidae (Cingulata, Mammalia): Characterization and 3D-reconstructions. J Morphol 2019; 281:258-272. [PMID: 31880831 DOI: 10.1002/jmor.21096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 10/24/2019] [Accepted: 12/11/2019] [Indexed: 11/08/2022]
Abstract
Osteoderms are present in a variety of extinct and extant vertebrates, but among mammals, the presence of osteoderms is essentially restricted to armadillos (Cingulata, Dasypodidae). Osteoderms have been proposed to exhibit a variety of functionalities in Dasypodidae, mainly protection and thermoregulation, and they have been considered as one of the synapomorphies of this group. In this study, we use high-resolution microcomputed tomography to describe the osteoderm micromorphology of several extant species of Dasypodidae in a comparative context. This study allowed the identification, 3D-reconstruction and volume quantification of different internal structures of osteoderms as well as their interrelations. This detailed characterization of the internal osteoderm morphology was compared in a phylogenetic context to assess the evolutionary trends of the species involved. This enables the identification of distinctive patterns for the most widely recognized clades, the Dasypodinae and Euphractinae with a morphological homogeneity in the microstructure of their osteoderms, in comparison with Tolypeutinae where it has not been possible to establish a common morphological pattern. The most important features for linage differentiation is the degree of compaction of the osteoderms, the number of cavities and the development of hairs. It is likely that the differential development of the various structures occurred as adaptive response to climate changes.
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Affiliation(s)
- Alejo C Scarano
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina.,Laboratorio de Morfología Evolutiva y Desarrollo (MORPHOS), Museo de la Plata, Facultad de Ciencias Naturales y Museo, UNLP, La Plata, Argentina.,Universidad Nacional de Avellaneda (UNDAV), Avellaneda, Buenos Aires, Argentina
| | - Martin R Ciancio
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina.,Laboratorio de Morfología Evolutiva y Desarrollo (MORPHOS), Museo de la Plata, Facultad de Ciencias Naturales y Museo, UNLP, La Plata, Argentina
| | - Jimena Barbeito-Andrés
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina.,ENyS, Estudios en Neurociencias y Sistemas Complejos, CONICET, Hospital El Cruce Dr, "Néstor C. Kirchner", Universidad Arturo Jauretche, Buenos Aires, Argentina
| | - Claudio G Barbeito
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina.,Laboratorio de Histología y Embriología Descriptiva, Experimental y Comparada (LHYEDEC), Facultad de Ciencias Veterinarias, UNLP, La Plata, Provincia de Buenos Aires, Argentina
| | - Cecilia M Krmpotic
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina.,Laboratorio de Morfología Evolutiva y Desarrollo (MORPHOS), Museo de la Plata, Facultad de Ciencias Naturales y Museo, UNLP, La Plata, Argentina
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Broeckhoven C, Mouton PLLFN, Hui C. Proximate causes of variation in dermal armour: insights from armadillo lizards. OIKOS 2018. [DOI: 10.1111/oik.05401] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Chris Broeckhoven
- Laboratory of Functional Morphology, Dept of Biology; Univ. of Antwerp; Universiteitsplein 1 BE-2610 Wilrijk Belgium
- Dept of Mathematical Sciences; Stellenbosch Univ.; Stellenbosch South Africa
| | | | - Cang Hui
- Dept of Mathematical Sciences; Stellenbosch Univ.; Stellenbosch South Africa
- Theoretical and Physical Biosciences; African Inst. for Mathematical Sciences; Cape Town South Africa
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