Internal Morphology of Osteoderms of Extinct Armadillos and Its Relationship with Environmental Conditions

The most complete and continuous fossil record of armadillos is composed mostly by isolated osteoderms, frequently found in paleontological and archaeological sites that bear continental South American mammals. Their external morphology has been used to define several species. In the last decade, many authors have focused on the internal structure of vertebrate osteoderms using histological and paleohistological studies. These studies allowed identification of useful features in systematic and phylogenetic contexts. In armadillos, osteoderms are constituted by compact bone tissue (primary and secondary osteons, and concentric layers or lamellae) that delimits cavities, which could contain different soft tissues (adipose tissue, hair follicles, bone marrow, and sweat and sebaceous glands). Traditional paleohistological techniques have allowed the recognition of homologous cavities to those found in osteoderms of current species and from comparison deduce which kind of tissue could had occupied them.We have recently utilized 3D reconstructions in osteoderms of extant species of armadillos to analyze the micromorphology, disposition, and the relationship of different cavities and understand them in depth. Here, we present the results of the application of paleohistology and microtomography in osteoderms of representatives of diferent taxa of extinct Dasypodidae (Astegotheriini, Stegotheriini, "Utaetini", Euphractini, Eutatini), which allowed us to compare homologous structures based on their three-dimensional reconstruction. The results, added to the previous external morphology studies, have allowed us to define morphological patterns (consistent within each linage). The variation of the volume and extension of cavities associated with different tissues could be strongly associated with changes in the climate and environmental conditions of the species distribution areas.Facultad de Ciencias Naturales y Muse

A new species of Peltephilidae (Mammalia: Xenarthra: Cingulata) from the late Miocene (Chasicoan SALMA) of Argentina

González-Ruiz, Laureano R., Scillato-Yané, Gustavo J., Krmpotic, Cecilia M., Carlini, Alfredo A. (2012): A new species of Peltephilidae (Mammalia: Xenarthra: Cingulata) from the late Miocene (Chasicoan SALMA) of Argentina. Zootaxa 3359: 55-64, DOI: 10.5281/zenodo.21031

A New Eocene Dasypodid with Caniniforms (Mammalia, Xenarthra, Cingulata) from Northwest Argentina

The aim of this work is to present a new genus and species of Dasypodidae from the Lumbrera Formation (“lower Lumbrera”), early-middle Eocene of Salta Province, northwest Argentina. The new taxon, documented by one specimen, consists of an incomplete skull and jaw with teeth housed in their alveoli, postcranial remains, and isolated osteoderms. Lumbreratherium oblitum, gen. et sp. nov., is characterized by heterodont dentition, with a caniniform as the first tooth, diastema between caniniform and first molariform, teeth with closed roots, and a peculiar morphology of the osteoderms. A phylogenetic analysis indicates that Lumbreratherium oblitum, gen. et sp. nov., and Pucatherium parvum belong to a monophyletic clade in a basal position within the Cingulata. The singularity of the morphological characteristics of these Paleogene armadillos of northwest Argentina reinforces the hypothesis of an intertropical origin of mammal clades different from those of the Paleogene in more austral regions of Argentina.Fil: Herrera, Claudia Marcela Reina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Powell, Jaime Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Esteban, Graciela Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: del Papa, Cecilia Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentin