A new species of Eutatus Gervais (Xenarthra, Dasypodidae) from the Late Pleistocene of the Northern Pampean Region, Argentina (original) (raw)
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Journal of Vertebrate Paleontology, 2019
A new specimen of Pucatherium parvum from the lower levels of the Upper Lumbrera Formation of Salta Province is reported. An almost complete dorsal carapace and several postcranial remains were preserved, providing important information about this particular taxon. The specimen is comparable in size to Dasypus novemcinctus, although the osteoderms are very small. The dorsal carapace seems to be completely integrated by movable osteoderms, providing a high degree of mobility in the anteroposterior axis. There is no evidence of pseudoshield, scapular shield, or pelvic shield. The dating of 39.9 ± 0.4 Ma (U-Pb zircon), taken from a tuff close to the top of the Upper Lumbrera Formation, allows us to refer this record of P. parvum to the middle Eocene (Bartonian). This, together with its broad geographic distribution, allows correlating the Upper Lumbrera Formation with the Quebrada de los Colorados Formation in Salta Province and with the Casa Grande Formation in Jujuy Province. On the other hand, the estimated depositional age of 37.3-35.4 Ma for the Geste Formation in Salta Province extends the biocron of P. parvum to the late Eocene.
Annals of the Carnegie Museum
The external surfaces of the bones of the skull of the yellow amiadillo Euphractiis sexinctiis are described in detail based on six museum specimens (five from the Carnegie Museum of Natural History, the last from the Field Museum). Soft-tissue structures (e.g., nerves, arteries, veins, and muscles) are reconstructed onto the skulls based on a serially sectioned, 105-mm crown rump length yellow armadillo fetus (also from the Field Museum). One osteological specimen, a juvenile, retains sutures in the basicranium fused in the adults, which confirm the presence of a compound auditory bulla (with entotympanic and ectotympanic elements), a long anterior process of the malleus fonning the lateral border of the Glaserian fissure, and a well-developed postglenoid process of the squamosal fonning the anterolateral surface of the tubular external acoustic meatus (the postgleiioid process has been reported as absent in extant xenarthrans). To place the cranial osteology of the yellow annadillo in a phylogenetic context, the morphology of 58 soft-tissue conduits (e.g., grooves, canals, and foramina) are compared among E. sexcinctus, the dasypodid Dasypus kappleri, the bradypodid Bradypits variegatiis, the mynnecophagids Tamandua telradactyla and T. mexicana, the dog Cams familahs, the Eocene palaeanodont Metacheiromys sp. and M. simpsoni. the Oligocene leptictid Leptictis dakotensis, and the Late Cretaceous stem placental Zalamhdalestes lechei. Of the conduits considered, 11 distinguish Euphractus sexcinctus; 16 distinguish Dasypodidae; 12 distinguish Pilosa; 5 distinguish Bradypus variegatiis; 4 distinguish Tamandua; 13 distinguish Xenarthra; and 4 distinguish Xenarthra + Metacheiromys. Noteworthy results within the E. sexcinctus sample are plasticity in number, size, and position both between and within individuals in some nervous and vascular foramina (e.g., the foramina on the palate for the major, accessory, and palatine nerves and vessels, the foramina in the squamosal, parietal, and frontal for the rami temporales of the stapedial artery).
Evolution of the axial skeleton in armadillos (Mammalia, Dasypodidae)
… Biology-Zeitschrift fur …, 2010
Intraspecific and interspecific variation in cervical, thoracic, and lumbar region of the vertebral column of Dasypodidae were examined in a phylogenetic framework. The number of vertebrae for each region were recorded for 86 specimens and metric data for each vertebra (centrum length, high, and width) were recorded for 72 specimens, including eight of the nine living genera. The number of vertebrae and degree of fusion between them were used to define four characters which were plotted on two alternative phylogenies of Dasypodidae. The ratio between centrum height and width is similar across all taxa analyzed except for Chlamyphorus, which exhibits a deviation in the last two lumbars. Tolypeutes matacus is unique among the taxa examined in having a second co-osified bone called postcervical bone, which is a fusion of the seventh cervical and first thoracic vertebrae. The thoraco-lumbar numbers of dasypodids are reduced when compared with other xenarthrans and are more diverse than those of some other mammalian clades of similar geological age and higher ecomorphological diversity. Changes in size are somewhat coupled with changes in the number of body segments. Independent of the phylogenetic framework taken, changes in size are accompanied with small changes in numbers of thoracolumbar vertebrae within each genus. There are functional and phylogenetic correlates for changes in number of thoraco-lumbar vertebrae in dasypodids.
The last horned armadillos: phylogeny and decline of Peltephilidae (Xenarthra, Cingulata
Papers in Palaeontology, 2023
Peltephilidae (Xenarthra, Cingulata) is an ancient lineage of medium–large-sized ‘armadillos’ from South America, characterized by chisel-shaped molariforms, a U-shaped dental arcade, and cephalic osteoderms modified into hornlike structures. Although the biochron of the group extends from the early Eocene to the Late Miocene, the most abundant and complete records come from the Early Miocene of Patagonia. Remains from the Late Miocene are very scarce, and the last records of the group are from the Chasicoan Stage (Tortonian). The only taxon known from this interval is Epipeltephilus kanti from the Arroyo Chasicó Formation (9.23 +- 0.09 Ma; Buenos Aires Province, Argentina), a species previously represented only by a few isolated osteoderms. Here we report new remains assigned to E. kanti from the Late Miocene of Loma de Las Tapias Formation (c. 9.0–7.8 Ma; San Juan Province, Argentina), including a hemimandible and several fixed and mobile osteoderms. These new specimens constitute the youngest record of Peltephilidae. The inclusion of E. kanti within Epipeltephilus and the monophyly of the genera Peltephilus and Epipeltephilus are corroborated for the first time through a cladistic analysis. The decline and eventual disappearance of this ‘armadillo’ group in the Late Miocene is chronologically coincident with the replacement of subtropical/tropical environments by more open and arid ones and with the proliferation of other large armadillos such as Vetelia, Macrochorobates, and Macroeuphractus.
Comparative histology and ontogenetic change in the carapace of armadillos (Mammalia: Dasypodidae)
Zoomorphology, 2015
Among extant mammals, the presence of osteoderms is limited to armadillos (Xenarthra, Dasypodidae), being one of its distinctive features. The osteoderms are articulated to form a carapace that covers their body dorsally. In this paper we study the integumentary structures of the armadillos Chaetophractus vellerosus, Chaetophractus villosus, Euphractus sexcinctus, and Zaedyus pichiy (Euphractinae), Dasypus hybridus, and Dasypus novemcinctus (Dasypodinae) within a comparative framework, aiming to identify patterns common to the family and to the subfamilies Dasypodinae and Euphractinae, as well as peculiarities of each species. Differences between the two subfamilies were observed in the dorsal integument, related to the production of blood cells and the mobility of the carapace. The Euphractinae present more numerous and larger cavities filled with adipose tissue in the osteoderms, as well as more marginal follicles than the Dasypodinae. These provide thermal insulation that could be related to their distribution in cooler climates. The sebaceous glands associated with surface follicles are also more developed in the Euphractinae and could be related to preventing the desiccation of the cornified scales in arid climates. Keywords Armadillo Á Osteoderm Á Cornified scales Á Histology Á Dasypodinae Á Euphractinae Communicated by A. Schmidt-Rhaesa.
Acta Paleontologica Polonica, 2021
Vetelia is a Miocene genus of armadillos from Argentina and Chile, traditionally included within the subfamily Euphrac tinae (Chlamyphoridae, Cingulata, Xenarthra). It includes the species Vetelia puncta (early-middle Miocene), Vetelia perforata (middle-late Miocene), and Vetelia gandhii (late Miocene), mostly known by isolated osteoderms. In this con tribution, we provide the first description of the skull for this genus, based on new materials (PVSJ289 and PVSJ154) here assigned to V. gandhii. A detailed characterization allows us to amend the diagnosis of the three known species, and to include, for the first time, the genus Vetelia into a morphological phylogenetic analysis. Phylogenetic results reveal a closer affinity to the Tolypeutinae, including the extant genera Priodontes (giant armadillos), Cabassous (nakedtailed armadillos), and Tolypeutes (three banded armadillos), and the fossil genera Pedrolypeutes and Kuntinaru, than to the Euphractinae. More specifically, Vetelia is included within the Priodontini, as sister group of the clade composed by Cabassous + Priodontes. Taking into account the scarce record of fossil Tolypeutinae, this new proposal fills an impor tant temporal gap in the evolutionary history of this linage. Finally, we also provide new information on the diagnostic morphological characters of the Priodontini and Tolypeutini.
Journal of South American Earth Sciences, 2020
The extinct euphractine Prozaedyus was recognized remarking the evident morphological resemblance of the dorsal carapace with the extant piche or pygmy armadillo Zaedyus pichiy. From a phylogenetic viewpoint, Prozaedyus has been interpreted as an early diverging Euphractinae restricted, at the moment, to the late Oligocene and early mid Miocene levels (Deseadan to Laventan SALMAs) of southern South America (Argentina, Chile, and Bolivia). We report here a specimen (MSJ-317) coming from the late Miocene (Loma de Las Tapias Formation;~9 Ma, Chasicoan Stage/Age) of western Argentina (San Juan Province), which represents a new species of Prozaedyus. The specimen includes an almost complete skull with complete dental series, some articulated fragments of the dorsal carapace and several isolated fixed and mobile osteoderms. Absence of teeth in the premaxillae, ornamentation pattern of fixed osteoderms, and presence of small foramina in the posterior and lateral margins of both mobile and fixed osteoderms, are characters that allow its inclusion within the genus Prozaedyus. Differences with the other known species of this genus include smaller size (~35-40%), cranial characters (e.g. position of the infraorbital foramen, palatine suture, morphology of the occipital condyles), and ornamentation pattern of mobile osteoderms. The phylogenetic analysis carried out support its relation as a sister group of the other Prozaedyus species, revealing an ancient divergence for the new taxon, occurred before that of the late Oligocene-early mid Miocene forms, and a distant phylogenetic position from Zaedyus pichiy. This new finding represents the youngest record of the genus, extending its biochron several millions of years, and provides novel information on the poorly know post-Santacrucian forms. Additionally, the cranial anatomy of the new species suggests a carnivore/omnivore habit, similar to extant euphractine armadillos but contrary to the insectivore habit proposed for the other Prozaedyus species.